Feeding Strategies: Predator



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Yohoia tenuis

3D animation of Yohoia tenuis.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Kingdom: Predator
Phylum: Predator
Higher Taxonomic assignment: Megacheirans, Clade Cheiromorpha
Species name: Yohoia tenuis
Remarks:

Henriksen (1928) created the family Yohoiidae, and later Simonetta and Delle Cave (1975) erected the order Yohoiida—however, they have so far remained monogeneric (no other included genus other than Yohoia), and are therefore not taxonomically meaningful. Yohoia was originally considered to be a branchiopod crustacean (Walcott, 1912; Simonetta, 1970), but it is now understood as an iconic representative of the class Megacheira. Megacheirans are basal true arthropods with a frontal appendage pointing upward and made of multiple claws (the cheira, or “great appendage”). The relationship of megacheirans with respect to extant lineages is still debated, but cumulative evidence has recently favoured a closer affinity with chelicerates (Aria, 2022).

Described by: Walcott
Description date: 1912
Etymology:

Yohoia – from the Yoho River, Lake, Pass, Glacier, Peak (2,760 m) and Park, British Columbia, Canada. “Yoho” is a Cree word expressing astonishment.

tenuis – from the Latin tenuis, “thin,” referring to its slender body.

Type Specimens: Lectoype –USNM57699 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none.

Other deposits: none.

Age & Localities:

Age:
Middle Cambrian, Wuliuan stage, Burgess Shale Formation (approximately 505 million years ago).
Principal localities:

The Walcott, Raymond and Collins Quarries on Fossil Ridge.

History of Research:

Brief history of research:

Yohoia was first described by Walcott (1912), who designated the type species Y. tenuis based on six specimens, and a second species, Y. plena, based on one specimen. Additional specimens of Y. tenuis were described by Simonetta (1970), and a major redescription of Yohoia tenuis was then undertaken by Whittington (1974), based on over 400 specimens of this species. Whittington (1974) invalidated Y. plena, upgrading it to its own genus, Plenocaris plena, leaving Y. tenuis as the only species of Yohoia. Another thorough revision was published much later by Haug et al. (2012), who specifically compared the raptorial appendages of Yohoia with chelicerae. Yohoia appears to represent an evolutionary intermediate between early megacheiran taxa called jianfengiids and the relatives of Leanchoilia (Aria et al., 2020).

Description:

Morphology:

The body of Yohoia consists of a head region encapsulated in a cephalic shield and 13 trunk segments, ending in a paddle-shaped telson. The dorsal head shield is roughly square and extends over the dorsal and lateral regions of the head. There is a pair of great appendages, or cheirae, at the front of the head. Each appendage consists of two long segments that bend like an elbow at their articulation, with four long spines at the tip. Three pairs of biramous appendages with walking and increasingly long swimming branches project from beneath the head shield behind the great appendages. The body behind the head consists of ten segments that extend over the back and down the side of the animal, ending in backward-facing triangular points. These trunk segments bear appendages similar to those in the head. The last three body segments have no appendages, and the telson is a paddle-shaped plate with distal spines.

Abundance:

Over 700 specimens of Yohoia are known from the Walcott Quarry, comprising 1.3% of the specimens counted (Caron and Jackson, 2008) but only few specimens are known from the Raymond and Collins Quarries.

Maximum Size:
23 mm

Ecology:

Life habits: Predator
Feeding strategies: Predator
Ecological Interpretations:

Like other megacheirans, and a number of modern crustaceans, Yohoia was probably living close to the sea floor and using its raptorial appendages to prey on small animals. Prey items were most likely non-biomineralized, owing to the lack of strong masticatory devices. Breathing could have taken place through the thin, paddle-shaped branches of the appendages, but it is also possible that Yohoia shared dedicated gills with other megacheirans (Liu et al., 2021; Aria et al., 2023).

References:

  • ARIA, C. (2022) The origin and early evolution of arthropods. Biological Reviews 97, 1786–1809.
  • ARIA, C., VANNIER, J., PARK, T.S. & GAINES, R.R. (2023) Interpreting fossilized nervous tissues. BioEssays, 2200167.
  • ARIA, C., ZHAO, F., ZENG, H., GUO, J. & ZHU, M. (2020) Fossils from South China redefine the ancestral euarthropod body plan. BMC Evolutionary Biology 20, 4.
  • HAUG, J.T., WALOSZEK, D., MAAS, A., LIU, Y. & HAUG, C. (2012) Functional morphology, ontogeny and evolution of mantis shrimp-like predators in the Cambrian. Palaeontology 55, 369–399.
  • HENRIKSEN, K.L. (1928) Critical notes upon some Cambrian arthropods described by Charles D. Walcott. Videnskabelige Meddelelser fra Dansk Naturhistorisk Forening: Khobenhavn 86, 1–20.
  • LIU, Y., EDGECOMBE, G.D., SCHMIDT, M., BOND, A.D., MELZER, R.R., ZHAI, D., MAI, H., ZHANG, M. & HOU, X. (2021) Exites in Cambrian arthropods and homology of arthropod limb branches. Nature Communications 12, 4619.
  • SIMONETTA, A.M. (1970) Studies on non trilobite arthropods of the Burgess Shale (Middle Cambrian). Palaeontographia Italica 66 (New series 36), 35–45.
  • SIMONETTA, A.M. & DELLE CAVE, L. (1975) The Cambrian non trilobite arthropods from the Burgess Shale of British Columbia. A study of their comparative morphology taxinomy and evolutionary significance. Palaeontographia Italica 69, 1–37.
  • WALCOTT, C. (1912) Cambrian Geology and Paleontology II. Middle Cambrian Branchiopoda, Malacostraca, Trilobita and Merostomata. Smithsonian Miscellaneous Collections 57(6), 145–228.
  • WHITTINGTON, H.B. (1974) Yohoia Walcott and Plenocaris n. gen., arthropods from the Burgess Shale, Middle Cambrian, British Columbia. Geological Survey of Canada Bulletin, Department of Energy, Mines and Resources Canada 231, 1–21.
Other Links:

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Stanleycaris hirpex

Stanleycaris hirpex (ROM 59944) – Holotype, part and counterpart. Individual claw. Specimen length = 29 mm. Specimen dry – polarized light. Stanley Glacier.

© ROYAL ONTARIO MUSEUM. PHOTOS: JEAN-BERNARD CARON

Taxonomy:

Kingdom: Predator
Phylum: Predator
Higher Taxonomic assignment: Order Radiodonta, Family Hurdiidae
Species name: Stanleycaris hirpex
Remarks:

With its single pair of jointed frontal appendages, lateral swimming flaps, and a circular mouth structure, Stanleycaris possesses all the hallmarks of Radiodonta, part of the stem group to the true arthropods which also includes the iconic Anomalocaris (Collins 1996). The frontal appendages with comb or rake-like inner spines are characteristic of the family Hurdiidae. However, other features like the small carapace, short head, and long, streamlined body probably represent ancestral radiodontan traits. Accordingly, Stanleycaris has been recovered as the sister species to all other hurdiid radiodontans in the most recent phylogenetic analysis (Moysiuk and Caron 2022).

Described by: Caron et al.
Description date: 2010
Etymology:

Genus – From Stanley Glacier, 40 kilometres southeast of the Burgess Shale in Kootenay National Park, where the fossils come from and the Latin caris, meaning “shrimp.” The name Stanley was given after Frederick Arthur Stanley (1841-1908), Canada’s sixth Governor General.

species – from the Latin, hirpex, meaning “large rake,” in reference to the rake-like aspect of the appendage.

Type Specimens: Holotype –ROM59944 in the Royal Ontario Museum, Toronto, Canada.
Other species:

Burgess Shale and vicinity: none.

Other deposits: Stanleycaris sp. from the mid-Cambrian Wheeler Formation of Utah (Pates et al. 2017).

Age & Localities:

Age:
Middle Cambrian, Wuliuan stage, Burgess Shale Formation (approximately 505 million years ago).
Principal localities:

Stanley Glacier in Kootenay National Park and the Collins Quarry on Fossil Ridge, Yoho National Park. Smaller collections from the Walcott and Raymond Quarries on Fossil Ridge, Tokumm Creek, Mount Odaray, Mount Stephen, and Mount Field.

History of Research:

Brief history of research:

Isolated appendages and oral structures of this species were collected by the Royal Ontario Museum in 1996 from talus slopes at Stanley Glacier, but it was not until 2008, during a larger expedition, that additional specimens were discovered in their proper stratigraphic context. A description of this new genus and species soon followed (Caron et al. 2010). A single isolated appendage from the Wheeler Formation of Utah was described in 2017, representing the only possible occurrence reported outside of the Burgess Shale (Pates et al. 2017). Subsequently, it was noted that the original description of Stanleycaris did not satisfy the requirements of the International Code of Zoological Nomenclature due to its publication in an online-only repository prior to 2012 (Zhuravlev and Gámez Vintaned 2018). The name was ultimately validated by Pates, Daley, and Ortega-Hernández (2018). Moysiuk and Caron later redescribed the original type material, along with new specimens from Stanley Glacier and Tokumm Creek, in detail (2021). Most recently, a large collection of exceptional whole-body remains, mainly from ROM collections on Fossil Ridge in the 1980s and 90s, was recognized as belonging to the species, allowing the first full reconstruction (Moysiuk and Caron 2022). While there had been some debate as to whether radiodontans possessed externally developed body segmentation, the complete Stanleycaris material confirmed this, suggesting that traces of segmentation in other species are merely obscured due to preservation and weathering.

Description:

Morphology:

Stanleycaris has a short head and a relatively long body, the latter composed of 17 well-formed segments plus four filamentous tail blades. A small, oval, domed carapace covers the front of the head. The head bears a pair a pair of stalked compound lateral eyes and a large median eye situated behind the carapace. A pair of frontal appendages project from the head. Each has a series of curving, rake like inner spines, trident-shaped medial spines, and hooked outer spines. The mouth opening, on the underside of the head, is square and surrounded by an array of tooth-bearing plates. Each body segment has a row of gill blades along the underside and a pair of swimming flaps at the sides. The digestive tract includes a long foregut and a segmentally organized midgut. Elements of the nervous system of Stanleycaris are also preserved, including a two-segmented brain, visual processing centers in the eyes, and a pair of ventral nerve cords.

Abundance:

Collectively known from about 300 specimens, the species is most common at the Collins Quarry on Fossil Ridge and Stanley Glacier. It is rare at other localities.

Maximum Size:
About 200 mm.

Ecology:

Life habits: Predator
Feeding strategies: Predator
Ecological Interpretations:

The multitool-like frontal appendages of Stanleycaris could have enabled a variety of feeding functions. They are long and flexible, allowing grappling of prey with the hooked spines at their tips. The rake-like inner spines have been hypothesized to be adapted for sediment sifting, while trident-shaped medial spines would have opposed those on the opposite appendage, together acting like a jaw to tear and crush soft prey. Additional food processing would have been accomplished by the tooth-bearing plates around the mouth (Moysiuk and Caron 2019, 2021). The large compound eyes, particularly in juveniles, show that Stanleycaris was a visual hunter, but the relatively modest number of lenses (estimated at ~1000) suggest it may have been most active in low light conditions (Moysiuk and Caron 2022, 2023). As in other radiodontans, swimming was facilitated by undulation of the lateral flaps while respiration would have been accomplished primarily through the rows of gill blades on the body (Usami 2006; Daley et al. 2013). Stanleycaris has the most completely known growth series of any radiodontan, demonstrating that segments were added to the body during early development. Specimens of Stanleycaris showing shriveling of the body and flaps, disarticulation of the appendages and mouthparts, and loss of the top portion of the head have been interpreted as moult remains, providing direct evidence that Stanleycaris moulted periodically as it grew (Moysiuk and Caron 2022, 2023).

References:

  • CARON, J.-B., GAINES, R. R., MÁNGANO, M. G., STRENG, M. and DALEY, A. C. 2010. A new Burgess Shale-type assemblage from the “thin” Stephen Formation of the southern Canadian Rockies. Geology, 38: 811–814.
  • COLLINS, D. 1996. The “evolution” of Anomalocaris and its classification in the arthropod class Dinocarida (nov.) and order Radiodonta (nov.). Journal of Paleontology, 70: 280–293.
  • DALEY, A. C., BUDD, G. E. and CARON, J.-B. 2013. Morphology and systematics of the anomalocaridid arthropod Hurdia from the Middle Cambrian of British Columbia and Utah. Journal of Systematic Palaeontology, 11: 743–787.
  • MOYSIUK, J. and CARON, J.-B. 2019. A new hurdiid radiodont from the Burgess Shale evinces the exploitation of Cambrian infaunal food sources. Proceedings of the Royal Society B, 286: 20191079.
  • MOYSIUK, J. and CARON, J.-B. 2021. Exceptional multifunctionality in the feeding apparatus of a mid-Cambrian radiodont. Paleobiology, 47: 704–724.
  • MOYSIUK, J. and CARON, J.-B. 2022. A three-eyed radiodont with fossilized neuroanatomy informs the origin of the arthropod head and segmentation. Current Biology, 32: 1–15.
  • MOYSIUK, J. and CARON, J.-B. 2023. A quantitative assessment of ontogeny and moulting in a Cambrian radiodont and the evolution of arthropod development. Paleobiology, 22 pg, IN REVIEW.
  • PATES, S., DALEY, A. C. and ORTEGA-HERNÁNDEZ, J. 2017. Aysheaia prolata from the Utah Wheeler Formation (Drumian, Cambrian) is a frontal appendage of the radiodontan Stanleycaris. Acta Palaeontologica Polonica, 62: 619–625.
  • PATES, S., DALEY, A. C. and ORTEGA-HERNÁNDEZ, J. 2018. Response to Comment on “Aysheaia prolata from the Utah Wheeler Formation (Drumian, Cambrian) is a frontal appendage of the radiodontan Stanleycaris” with the formal description of Stanleycaris. Acta Palaeontologica Polonica, 63: 105–110.
  • USAMI, Y. 2006. Theoretical study on the body form and swimming pattern of Anomalocaris based on hydrodynamic simulation. Journal of Theoretical Biology, 238: 11–17.
  • ZHURAVLEV, A. and GÁMEZ VINTANED, J. 2018. Comment on “Aysheaia prolata from the Utah Wheeler Formation (Drumian, Cambrian) is a frontal appendage of the radiodontan Stanleycaris” by Stephen Pates, Allison C. Daley, and Javier Ortega-Hernanández. Acta Palaeontologica Polonica, 63: 103–104.
Other Links:

http://geology.geoscienceworld.org/cgi/content/full/38/9/811?ijkey=ZQFY537sTggAw&keytype=ref&siteid=gsgeology



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Isoxys acutangulus

3D animation of Isoxys carinatus.

Animation by Phlesch Bubble © Royal Ontario Museum

Taxonomy:

Kingdom: Predator
Phylum: Predator
Higher Taxonomic assignment: Family Isoxyidae
Species name: Isoxys acutangulus
Remarks:

Isoxys is included with Surusicaris in the family isoxyidae, based on the type of carapace, eyes, and frontal pair of raptorial appendages (Aria & Caron, 2015). Current evidence draws out a consensus among authors placing isoxyids as sister taxa to true arthropods (Edgecombe, 2020; Aria, 2022), although it is not clear whether Surusicaris and Isoxys are part of a single separate lineage (that is, form a monophyletic group). However, key characters such as the segmentation of the trunk and trunk appendages are still being investigated.

Described by: Walcott
Description date: 1908
Etymology:

Isoxys – from the Greek isos, “equal,” and xystos, “smooth surface”; thus referring to the pair of smooth valves.

acutangulus – from the Latin acutus, “sharp, pointed,” and angulus, “angle”; thus referring to the acute angle of the cardinal spines.

Type Specimens: USNM56521 (I. acutangulus) and Holotype –USNM189170 (I. longissimus) in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: I. longissimus from Walcott, Raymond and Collins Quarries on Fossil Ridge.

Other deposits: I. chilhoweanus from the Chilhowee Group, Tennessee, USA; I. auritus, I. paradoxus and I. curvirostratus from the Maotianshan Shale of China; I. bispinatus from the Shuijingtuo Formation, Hubei, China; I. wudingensis from the Guanshan fauna of China; I. communis and I. glaessneri from the Emu Bay Shale of Australia; I. volucris from the Buen Formation, Sirius Passet in Greenland; I. carbonelli from the Sierro Morena of Spain, and I. zhurensis from the Profallotaspis jakutensis Zone of Western Siberia. Undescribed species from Canada; Mount Cap Formation in the Mackenzie Mountains, Northwest Territories and the Eager Formation near Cranbrook. Other undescribed species in the Kaili Formation, Guizhou Province, China and the Kinzers Formation, Pennsylvania, USA. See references in Briggs et al. (2008), García-Bellido et al. (2009b; 2009a), Stein et al. (2010), Vannier and Chen (2000).

Age & Localities:

Age:
Middle Cambrian, Wuliuan Stage, upper part of the Burgess Shale Formation (around 505 million years old).
Principal localities:

The Walcott, Raymond and Collins Quarries on Fossil Ridge. Additional localities are known on Mount Field, Mount Stephen – the Tulip Beds (S7), the Trilobite Beds, near Stanley Glacier and across Marble Canyon localities, Kootenay National Park, British Columbia.

History of Research:

Brief history of research:

Walcott gave the name Isoxys to specimens from the lower Cambrian Chilhowee Group of Tennessee, USA, in 1890. He then later designated the first species from the Trilobite Beds on Mount Stephen, Anomalocaris? acutangulus (Walcott, 1908), erroneously placing it within the genus Anomalocaris. Simonetta and Delle Cave (1975) renamed it Isoxys acutangulus and discovered a second Burgess Shale species, I. longissimus. The original designations were based on carapaces only, making research on the ecology and affinity of Isoxys difficult. Since then, eyes, appendages and tailpiece have been described (García-Bellido et al., 2009b; Vannier et al., 2009; Fu, Zhang & Shu, 2011; Legg & Vannier, 2013; Fu et al., 2014). Trunk appendages seem atypical, with broad attachment of outer and inner branches—as in Surusicaris—and close contact of paired inner branches, which has been further illustrated in the related form Erratus sperare (Fu et al., 2022). Sexual dimorphism has also been proposed in Isoxys volucris based on the relative width of the doublure (Nielsen, Rasmussen & Harper, 2017).

Description:

Morphology:

The most prominent feature of Isoxys is the non-biomineralized carapace, which ranged in length from 1 cm to almost 4 cm, and covered most of the body. It was folded to give two equal hemispherical valves, and had pronounced spines at the front and back. A pair of bulbous, spherical eyes protrudes forward and laterally from under the carapace. They are attached to the head by very short stalks. A pair of frontal appendages that are segmented and non-branching (uniramous) is adjacent to the eyes. In I. acutangulus, the flexible appendages are curved with a serrated outline and five segments in total, including a basal part, three segments with stout outgrowths, and a pointed terminal segment. The trunk of the body has 13 pairs of evenly spaced appendages that are segmented and branch into two (biramous), with slender limbs and large, paddle-like flaps fringed with long setae. Outer and inner branches are broadly attached at their base, and pairs of inner branches also seem bound together. The tailpiece would be a tailfan, as in dinocaridids (Legg & Vannier, 2013). A cylindrical gut passes from the head to the ventral terminus of the telson, and is lined dorsally by large concatenate, triangular gut glands. I. longissimus is distinguished from I. acutangulus by the presence of extremely long spines and an elongate body shape.

Abundance:

Isoxys is known from hundreds of specimens collected on Fossil Ridge. In the Walcott Quarry, Isoxys acutangulus is relatively common and represents about 0.35% of the community whereas Isoxys longissimus is extremely rare (Caron and Jackson, 2008).

Maximum Size:
About 40 mm.

Ecology:

Life habits: Predator
Feeding strategies: Predator
Ecological Interpretations:

The streamlined body, thin carapace, the presence of paddle-shaped flaps in the appendages and a flap-bearing tailfan all suggest that Isoxys was a free-swimming animal. A predatory lifestyle is indicated by the large eyes, frontal appendage, and large gut glands. Isoxys would have swum just above the sea floor, seeking out prey in the water column and at the sediment-water interface. Isoxys is commonly found among benthic/nektobenthic assemblages (Caron & Jackson, 2008) and possess general morphological characteristics of other nektobenthic Cambrian arthropods.

References:

  • ARIA, C. (2022) The origin and early evolution of arthropods. Biological Reviews 97, 1786–1809.
  • ARIA, C. & CARON, J.-B. (2015) Cephalic and limb anatomy of a new isoxyid from the Burgess Shale and the role of ‘stem bivalved arthropods’ in the disparity of the frontalmost appendage. PLoS ONE 10, e0124979.
  • BRIGGS, D.E.G., LIEBERMAN, B.S., HENDRICKS, J.R., HALGEDAHL, S.L. & JARRARD, R.D. (2008) Middle Cambrian arthropods from Utah. J Paleontol 82, 238–254.
  • CARON, J.B. & JACKSON, D.A. (2008) Paleoecology of the Greater Phyllopod Bed community, Burgess Shale. Palaeogeography, Palaeoclimatology, Palaeoecology 258, 222–256.
  • EDGECOMBE, G.D. (2020) Arthropod origins: Integrating paleontological and molecular evidence. Annual Review of Ecology, Evolution, and Systematics 51, 1–25.
  • FU, D., LEGG, D.A., DALEY, A.C., BUDD, G.E., WU, Y. & ZHANG, X. (2022) The evolution of biramous appendages revealed by a carapace-bearing Cambrian arthropod. Philosophical Transactions of the Royal Society B: Biological Sciences 377, 20210034.
  • FU, D., ZHANG, X., BUDD, G.E., LIU, W. & PAN, X. (2014) Ontogeny and dimorphism of Isoxys auritus (Arthropoda) from the Early Cambrian Chengjiang biota, South China. Gondwana Research 25, 975–982.
  • FU, D.J., ZHANG, X.L. & SHU, D.G. (2011) Soft anatomy of the Early Cambrian arthropod Isoxys curvirostratus from the Chengjiang biota of South China with a discussion on the origination of great appendages. Acta Palaeontologica Polonica 56, 843–852.
  • GARCÍA-BELLIDO, D.C., PATERSON, J.R., EDGECOMBE, G.D., JAGO, J.B., GEHLING, J.G. & LEE, M.S.Y. (2009a) The bivalved arthropods Isoxys and Tuzoia with soft-part preservation from the Lower Cambrian Emu Bay Shale Lagerstätte (Kangaroo Island, Australia). Palaeontology 52, 1221–1241.
  • GARCÍA-BELLIDO, D.C., VANNIER, J. & COLLINS, D. (2009b) Soft-part preservation in two species of the arthropod Isoxys from the middle Cambrian Burgess Shale of British Columbia, Canada. Acta Palaeontologica Polonica 54, 699–712.
  • LEGG, D.A. & VANNIER, J. (2013) The affinities of the cosmopolitan arthropod Isoxys and its implications for the origin of arthropods. Lethaia 46, 540–550.
  • NIELSEN, M.L., RASMUSSEN, J.A. & HARPER, D.A.T. (2017) Sexual dimorphism within the stem-group arthropod Isoxys volucris from the Sirius Passet Lagerstätte, North Greenland. Bulletin of the Geological Society of Denmark 65, 47–58.
  • STEIN, M., PEEL, J.S., SIVETER, D.J. & WILLIAMS, M. (2010) Isoxys (Arthropoda) with preserved soft anatomy from the Sirius Passet Lagerstätte, lower Cambrian of North Greenland. Lethaia 43, 258–265.
  • VANNIER, J. & CHEN, J.Y. (2000) The Early Cambrian colonization of pelagic niches exemplified by Isoxys (Arthropoda). Lethaia 33, 295–311.
  • VANNIER, J., GARCÍA-BELLIDO, D.C., HU, S.X. & CHEN, A.L. (2009) Arthropod visual predators in the early pelagic ecosystem: evidence from the Burgess Shale and Chengjiang biotas. Proceedings of the Royal Society of London Series B 276, 2567–2574.
Other Links:

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Hurdia victoria

3D animation of Hurdia victoria.

Animation by Phlesch Bubble © Royal Ontario Museum

Taxonomy:

Kingdom: Predator
Phylum: Predator
Higher Taxonomic assignment: Radiodonta, Family Hurdiidae
Species name: Hurdia victoria
Remarks:

With its single pair of jointed frontal appendages, lateral swimming flaps, and circular mouth structure, Hurdia possesses all the hallmarks of Radiodonta, part of the stem group to the true arthropods which also includes the iconic Anomalocaris (Collins, 1996). It is the namesake of the radiodontan family Hurdiidae, characterized by frontal appendages with comb or rake-like inner spines (Lerosey-Aubril & Pates, 2018). Hurdia is part of a diverse subgroup of hurdiids with large, elaborate carapaces (Caron & Moysiuk, 2021).

Described by: Walcott
Description date: 1912
Etymology:

Hurdia – from Mount Hurd (2,993 m), a mountain northeast of the now defunct Leanchoil railway station on the Canadian Pacific Railway in Yoho National Park. The peak was named by Tom Wilson for Major M. F. Hurd, a CPR survey engineer who explored the Rocky Mountain passes starting in the 1870s.

victoria – unspecified; perhaps from Mount Victoria (3,464 m) on the border of Yoho and Banff National Parks, named by Norman Collie in 1897 to honour Queen Victoria.

Type Specimens: Lectotypes –USNM57718 (H. victoria) andUSNM57721 (H. triangulata) in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: Hurdia triangulata.

Other deposits: Potentially other species are represented in the Langston and Wheeler Formations of Utah (Lerosey-Aubril et al., 2020; Pates et al., 2018), and possibly the Pioche Formation of Nevada (Pates, Daley, Edgecombe, et al., 2019), the Jince Formation in the Czech Republic (Chlupáč & Kordule, 2002). and the Shuijingtuo Formation in Hubei Province, China (Cui & Huo, 1990).

Age & Localities:

Age:
Middle Cambrian, Wuliuan Stage, Burgess Shale Formation (around 505 million years old).
Principal localities:

The Walcott, Raymond, and Collins Quarries on Fossil Ridge. Also known from other localities on Mount Field, Mount Stephen – Tulip Beds (S7) – and near Stanley Glacier and the Monarch.

History of Research:

Brief history of research:

Although isolated parts of the body of Hurdia were first identified in the early 1900s, no affinity could be determined until the description of whole-body specimens by Daley et al. in 2009. Hurdia victoria was the name originally given to an isolated triangular carapace that Walcott (1912) suggested belonged to an unknown arthropod. Proboscicaris, another isolated carapace, was originally described as a crustacean (Rolfe, 1962). Hurdia’s frontal appendages were first described by Walcott (1911b) as the feeding limbs of Sidneyia, but were later removed from this genus and referred to as “Appendage F” with unknown affinity (Briggs, 1979). Like other radiodontans, the mouthparts were first described as the jellyfish Peytoia nathorsti (Walcott, 1911a). Whittington and Briggs (1985) discovered the first whole body specimens of Peytoia, associating the mouthparts with the former “Appendage F”. When describing Peytoia and Anomalocaris, Whittington and Briggs (1985) also figured a mouth apparatus with extra rows of teeth.

After two decades of collecting at the Burgess Shale, Desmond Collins from the Royal Ontario Museum (ROM) discovered that this extra-spiny mouth part actually belonged to a third type of radiodontan, which also had an “Appendage F” pair and a frontal carapace complex consisting of one Hurdia carapace and two Proboscicaris carapaces (Daley et al., 2009). This is the Hurdia animal. ROM specimens of “Appendage F” showed that it has four distinct morphologies, two of which belong to Hurdia (known from two species, H. victoria and H. triangulata), one to Peytoia nathorsti, and one to an as yet unnamed species (Daley et al., 2013; Daley & Budd, 2010).

Description:

Morphology:

Hurdia has a bilaterally symmetrical body that is broadly divisible into two sections of equal lengths. The anterior region is a complex of non-biomineralized carapaces consisting of one dorsal triangular H-element (previously called Hurdia) and two lateral paddle-shaped P-elements (from Proboscicaris). These carapaces wrap around the anterior margin of the head with the H-element spine protruding forward. The surfaces of the H- and P-elements are covered in a distinctive polygonal pattern similar to that seen on Tuzoia carapaces. A pair of oval eyes on short stalks protrudes upwards through notches in the overlapping posterior corners of the H- and P-elements. Hurdia triangulata differs from Hurdia victoria by having a wider and shorter H-element (Daley et al., 2013). Mouthparts are on the ventral surface of the head, and consist of a circlet of 32 tapering and overlapping plates, 4 large and 28 small, with spines lining the square central opening. Within the central opening are up to five inner rows of toothed plates. A pair of appendages flanks the mouth part, each with nine thin segments with short outer spines and eight elongated ventral spines (Daley et al., 2013; Pates, Daley, & Butterfield, 2019). The posterior half of the body consists of a series of seven to nine segments that extend laterally into triangular flaps. Recently, Van Roy and colleagues (2015) suggested that a second row of flaps might also be present in Hurdia. Each body segment is associated with a band of elongated blades interpreted to be gill structures. The body terminates abruptly in two rounded lobes (Daley et al., 2013). Complete specimens are up to 20 cm in length, although disarticulated fragments suggest a maximum body size up to 30 cm long (Caron & Moysiuk, 2021).

Abundance:

Over 700 specimens of Hurdia have been identified, most of which are disarticulated. Hurdia is found in all Burgess Shale quarries on Fossil Ridge, and is particularly abundant in Raymond Quarry, where it makes up almost 1% of the community (240 specimens). A total of 7 complete body specimens exist.

Maximum Size:
300 mm

Ecology:

Life habits: Predator
Feeding strategies: Predator
Ecological Interpretations:

Hurdia was likely an active swimmer. Like other radiodontans, the animal propelled itself through the water column by undulating its flaps (Usami, 2006) and respiration would have been accomplished through the multiple rows of gills (Daley et al., 2013). The large dorsal carapace, upward facing eyes, and stubby body suggest it spent most of its time near the sea floor and may have fed primarily on burrowing organisms (Moysiuk & Caron, 2019). The function of the frontal carapace remains unknown, although it has been speculated to have played a role in feeding (Caron & Moysiuk, 2021; Daley et al., 2013). Prey items were funneled towards the mouth by a sweeping motion of the of the frontal appendages, with their rake-like inner spines forming a rigid net or cage (de Vivo et al., 2021; Moysiuk & Caron, 2019). Compared to Cambroraster and Titanokorys, the widely spaced spines on Hurdia’s appendages suggest it fed on relatively larger prey items (Caron & Moysiuk, 2021).

References:

  • BRIGGS, D. E. G. (1979). Anomalocaris: The largest known Cambrian arthropod. Palaeontology, 22(3), 631–664.
  • CARON, J.-B., & MOYSIUK, J. (2021). A giant nektobenthic radiodont from the Burgess Shale and the significance of hurdiid carapace diversity. Royal Society Open Science, 8(9), 210664. https://doi.org/10.1098/RSOS.210664
  • CHLUPÁČ, I., & KORDULE, V. (2002). Arthropods of Burgess Shale type from the Middle Cambrian of Bohemia (Czech Republic). Bulletin of the Czech Geological Survey, 77, 167–182.
  • COLLINS, D. (1996). The “evolution” of Anomalocaris and its classification in the arthropod class Dinocarida (nov.) and order Radiodonta (nov.). Journal of Paleontology, 70(2), 280–293. https://doi.org/10.1017/S0022336000023362
  • CUI, Z.-L., & HUO, S.-C. (1990). New discoveries of Lower Cambrian crustacean fossils from western Hubei. Acta Palaeontologica Sinica, 29, 321–330.
  • DALEY, A. C., & BUDD, G. E. (2010). New anomalocaridid appendages from the Burgess Shale, Canada. Palaeontology, 53(4), 721–738. https://doi.org/10.1111/j.1475-4983.2010.00955.x
  • DALEY, A. C., BUDD, G. E., & CARON, J.-B. (2013). Morphology and systematics of the anomalocaridid arthropod Hurdia from the Middle Cambrian of British Columbia and Utah. Journal of Systematic Palaeontology, 11(7), 743–787. https://doi.org/10.1080/14772019.2012.732723
  • DALEY, A. C., BUDD, G. E., CARON, J.-B., EDGECOMBE, G. D., & COLLINS, D. (2009). The Burgess Shale anomalocaridid Hurdia and its significance for early euarthropod evolution. Science, 323(5921), 1597–1600. https://doi.org/10.1126/science.1169514
  • DE VIVO, G., LAUTENSCHLAGER, S., & VINTHER, J. (2021). Three-dimensional modelling, disparity and ecology of the first Cambrian apex predators. Proceedings of the Royal Society B, 288(1955). https://doi.org/10.1098/RSPB.2021.1176
  • LEROSEY-AUBRIL, R., KIMMIG, J., PATES, S., SKABELUND, J., WEUG, A., & ORTEGA-HERNÁNDEZ, J. (2020). New exceptionally preserved panarthropods from the Drumian Wheeler Konservat-Lagerstätte of the House Range of Utah. Papers in Palaeontology, 6(4), 501–531. https://doi.org/10.1002/spp2.1307
  • LEROSEY-AUBRIL, R., & PATES, S. (2018). New suspension-feeding radiodont suggests evolution of microplanktivory in Cambrian macronekton. Nature Communications, 9(1), 3774. https://doi.org/10.1038/s41467-018-06229-7
  • MOYSIUK, J., & CARON, J.-B. (2019). A new hurdiid radiodont from the Burgess Shale evinces the exploitation of Cambrian infaunal food sources. Proceedings of the Royal Society B, 286(1908), 20191079. https://doi.org/10.1098/rspb.2019.1079
  • PATES, S., DALEY, A. C., & BUTTERFIELD, N. J. (2019). First report of paired ventral endites in a hurdiid radiodont. Zoological Letters, 5(1), 18. https://doi.org/10.1186/s40851-019-0132-4
  • PATES, S., DALEY, A. C., EDGECOMBE, G. D., CONG, P., & LIEBERMAN, B. S. (2019). Systematics, preservation and biogeography of radiodonts from the southern Great Basin, USA, during the upper Dyeran (Cambrian Series 2, Stage 4). Papers in Palaeontology, 7(1), 235–262. https://doi.org/10.1002/spp2.1277
  • PATES, S., DALEY, A. C., & LIEBERMAN, B. S. (2018). Hurdiid radiodontans from the middle Cambrian (Series 3) of Utah. Journal of Paleontology, 92(1), 99–113. https://doi.org/10.1017/jpa.2017.11
  • ROLFE, W. D. (1962). Two new arthropod carapaces from the Burgess Shale (Middle Cambrian) of Canada. Breviora Museum of Comparative Zoology, 60, 1–9.
  • USAMI, Y. (2006). Theoretical study on the body form and swimming pattern of Anomalocaris based on hydrodynamic simulation. Journal of Theoretical Biology, 238, 11–17.
  • VAN ROY, P., DALEY, A. C., & BRIGGS, D. E. G. (2015). Anomalocaridid trunk limb homology revealed by a giant filter-feeder with paired flaps. Nature, 522(7554), 77. https://doi.org/10.1038/nature14256
  • WALCOTT, C. D. (1911a). Middle Cambrian holothurian and medusae. Smithsonian Miscellaneous Collections, 57, 41–68.
  • WALCOTT, C. D. (1911b). Middle Cambrian Merostomata. Cambrian Geology and Paleontology II. Smithsonian Miscellaneous Collections, 57, 17–40.
  • WALCOTT, C. D. (1912). Middle Cambrian Branchiopoda, Malacostraca, Trilobita and Merostomata. Smithsonian Miscellaneous Collections, 57, 145–228.
  • WHITTINGTON, H. B., & BRIGGS, D. E. G. (1985). The largest Cambrian animal, Anomalocaris, Burgess Shale, British Columbia. Philosophical Transactions of the Royal Society B: Biological Sciences, 309(1141), 569–609. https://doi.org/10.1098/rstb.1985.0096
Other Links:

http://www.sciencemag.org/content/323/5921/1597.abstract



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Liangshanella burgessensis

3D animation of Liangshanella burgessensis.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Kingdom: Predator
Phylum: Predator
Higher Taxonomic assignment: Hymenocarines?, Order Bradoriida (Raymond 1935).
Species name: Liangshanella burgessensis
Remarks:

Liangshanella is a bradoriid belonging to the family Svealutidae (Siveter & Williams 1997). The bradoriids were traditionally compared to other bivalved arthropods within or close to crustaceans, such as Recent ostracods (e.g. Sylvester-Bradley, 1961) and Cambrian phosphatocopids (e.g. Maas et al. (2003)). More recently, authors have argued bradoriids to represent more basal members of the arthropod stem group (e.g. Hou et al. (1996); Shu et al. (1999); Hou et al. (2010)). A recent reexamination of appendage morphology in the bradoriid Kunmingella supports a placement of these arthropods outside of crown groups (Zhai et al. 2019), but their exact phylogenetic placement remains unclear.

Described by: Siveter and Williams
Description date: 1997
Etymology:

Liangshanella – from Liangshan, a region in South Shaanxi, China.

burgessensis – from the Burgess Shale. The name is derived from Mount Burgess (2,599 m), a mountain peak in Yoho National Park. Mount Burgess was named in 1886 by Otto Klotz, the Dominion topographical surveyor, after Alexander Burgess, a former Deputy Minister of the Department of the Interior.

Type Specimens: Holotype –USNM272083 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none.

Other deposits: L. circumbolina from the Flinders Ranges in South Australia; L. liangshanensis, L. rotundata, L. orbicularis, L. yunnanensis and L. baensis from southern China; L. lubrica from the Tongying Formation in Hubei, China; L. sayutinae from the Trans-Baikal area in the Russian Far-East and Greenland; L. birkenmajeri from Antarctica. See references in Siveter and Williams (1997).

Age & Localities:

Age:
Middle Cambrian, Wuliuan stage, Burgess Shale Formation (approximately 505 million years ago).
Principal localities:

The Walcott and Raymond Quarries on Fossil Ridge.

History of Research:

Brief history of research:

Liangshanella liangshanensis is the type species of this genus and was first described by Huo (1956) from Lower Cambrian rocks of south China. urther species have since been described in China (Zhang, 1974; Li, 1975; Qian and Zhang, 1983; Zhang, 2007), Russia and Greenland (Melnikova, 1988), Australia (Topper et al., in press) and Antarctica (Wrona, 2009). Liangshanella burgessensis from the Burgess Shale was described by Siveter and Williams (1997), and the genus has been included in studies on the biogeography, evolution and affinity of the bradoriids (e.g. Shu and Chen, 1994; Williams et al., 2007). The most recent insight on the morphoanatomy of these arthropods comes from computed tomographic imagery of Kunmingella species from the Chengjiang biota (Zhai et al. 2019), which confirms both the presence of biramous enditic appendages and the lack of clear crown-group synapomorphies.

Description:

Morphology:

Like all bradoriids, Liangshanella burgessensis has a small bivalved carapace with a straight dorsal hinge held together by a band of cuticle. The carapaces range in length from 0.66 mm – 4.25 mm and were soft and unmineralized. The bivalved carapace of L. burgessensis is sub-circular, with the anterior end being slightly narrower than the posterior end. There is a marginal ridge along the lateral surface of the valves. A centrally situated, sub-circular muscle scar composed of numerous small pits can be seen inside the valve. Based on appendicular evidence from other bradoriid taxa, L. burgessensis would have possessed short, spinose antennules, very reduced eyes—if at all present—, and biramous post-frontal appendages characterized by the presence of well-developed “fingers” on the inner side, called endites.

Abundance:

Liangshanella burgessensis is known from thousands of specimens and is the most common taxon in the Walcott Quarry (11.8% of the community, Caron and Jackson, 2008).

Maximum Size:
10 mm

Ecology:

Life habits: Predator
Feeding strategies: Predator
Ecological Interpretations:

Williams et al. (2007) considered bradoriids to be most likely epibenthic dwellers feeding on organic detritus or small non-biomineralized prey items; an ecology comparable to that of ostracods. These authors also pointed out that the large disparity of carapace shapes probably reflected a variety of different sub-niches and lifestyles. Their size and abundance would have made them in turn a common food source for larger animals, as indicated by coprolite composition (Vannier & Chen 2005).

References:

  • CARON, J. B. and JACKSON, D. A. 2008. Paleoecology of the Greater Phyllopod Bed community, Burgess Shale. Palaeogeography, Palaeoclimatology, Palaeoecology, 258, 222–256.
  • HOU, X., WILLIAMS, M., SIVETER, D. J., SIVETER, D. J., ALDRIDGE, R. J. and SANSOM, R. S. 2010. Soft-part anatomy of the Early Cambrian bivalved arthropods Kunyangella and Kunmingella : significance for the phylogenetic relationships of Bradoriida. Proceedings of the Royal Society B: Biological Sciences, 277, 1835–1841.
  • HOU, X., SIVETER, D. J., WILLIAMS, M., WALOSSEK, D., BERGSTRÖM, J., SMITH, M. P. and THOMAS, A. T. 1996. Appendages of the arthropod Kunmingella from the Early Cambrian of China; its bearing on the systematic position of the Bradoriida and the fossil record of the Ostracoda. Palaeontology Newsletter, 32.
  • HUO, S. 1956. Brief notes on lower Cambrian Archaeostraca from Shensi and Yunnan. Acta Palaeontologica Sinica, 4, 1131–1145.
  • LI, Y. 1975. On the Cambrian ostracods with new material from Sichuan, Yunnan and Shaanxi, China. Professional Papers on Stratigraphy & Palaeontology, 2, 37–72.
  • MAAS, A., WALOSZEK, D. and MÜLLER, K. J. 2003. Morphology, ontogeny and phylogeny of the Phosphatocopina (Crustacea) from the Upper Cambrian ‘Orsten’ of Sweden. Fossil and Strata. Vol. 49. Taylor & Francis, Oslo.
  • MELNIKOVA, L. M. 1988. Nekotoryye bradoriidy (Crustacea) iz botomskogo yarusa vostochnogo Zabaykal’ya. Paleontologicheskiy Zhurnal, 1, 114–117.
  • MILLER, S. A. 1889. North American geology and palaeontology for the use of amateurs, students and scientists. Western Methodist Book Concern, Cincinnati.
  • QIAN, Y. and ZHANG, S. 1983. Small shelly fossils from the Xihaoping Member of the Tongying Formation in Fangxian County of Hubei Province and their stratigraphical significance. Acta Palaeontologica Sinica, 22, 82–94.
  • SHU, D. and CHEN, L. 1994. Cambrian palaeobiogeography of Bradoriida. Journal of Southeast Asian Earth Sciences, 9, 289–299.
  • SHU, D. G., VANNIER, J., LUO, H. L., CHEN, L., ZHANG, X. L. and HU, S. X. 1999. Anatomy and lifestyle of Kunmingella (Arthropoda, Bradoriida) from the Chengjiang fossil Lagerstätte (lower Cambrian; Southwest China). Lethaia, 32, 279–298.
  • SIVETER, D. J. and WILLIAMS, M. 1997. Cambrian bradoriid and phosphatocopid arthropods of North America. Special Papers in Palaeontology, 57, 67.
  • TOPPER, T. P., SKOVSTED, C. E., BROCK, G. A. and PATERSON, J. R. 2007. New bradoriids from the lower Cambrian Mernmerna Formation, South Australia: systematics, biostratigraphy and biogeography. Memoirs of the Association of Australasian Palaeontologists, 33, 67–100.
  • VANNIER, J. and CHEN, J. 2005. Early Cambrian food chain: New evidence from fossil aggregates in the Maotianshan Shale biota, SW China. PALAIOS, 20, 3–26.
  • WILLIAMS, M., SIVETER, D. J., POPOV, L. E. and VANNIER, J. M. C. 2007. Biogeography and affinities of the bradoriid arthropods: Cosmopolitan microbenthos of the Cambrian seas. Palaeogeography, Palaeoclimatology, Palaeoecology, 248, 202–232.
  • WRONA, R. 2009. Early Cambrian bradoriide and phosphatocopide arthropods from King George Island, West Antarctica: Biogeographic implications. Polish Polar Research, 30, 347–377.
  • ZHAI, D., WILLIAMS, M., SIVETER, D. J., HARVEY, T. H. P., SANSOM, R. S., GABBOTT, S. E., SIVETER, D. J., MA, X., ZHOU, R., LIU, Y. and HOU, X. 2019. Variation in appendages in early Cambrian bradoriids reveals a wide range of body plans in stem-euarthropods. Communications Biology, 2, 329.
  • ZHANG, W. 1974. Bradoriida. In Handbook of Stratigraphy and Palaeontology of Southwest China, Science Press, Beijing, 107–111 pp.
  • ZHANG, X.-G. 2007. Phosphatized Bradoriids (Arthropoda) from the Cambrian of China. Palaeontographica Abteilung A, 281, 93–173.
Other Links:

None



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Opabinia regalis

3D animation of Opabinia regalis.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Kingdom: Predator
Phylum: Predator
Higher Taxonomic assignment: ‘Dinocarida’, Family Opabiniidae
Species name: Opabinia regalis
Remarks:

Opabinia’s bizarre morphology has made its affinity challenging to resolve. Although it was initially considered a crustacean by Walcott (1912), later researchers beginning with Whittington (1975) suggested a more distant relationship with arthropods. Collins (1996) proposed the name Dinocarida for a group including radiodontans (Anomalocaris and its relatives) and Opabinia, though this has not been generally supported. The flexible frontal “nozzle” and possible lobopodous appendages suggest a connection with lobopodians, implying that Opabinia might have diverged before the evolutionary split between radiodontans and true arthropods. On the other hand, Opabinia has a backward facing mouth and five eyes, which could suggest a position closer to the some of the earliest true arthropods which share these features. Both placements have been found in recent analyses (Lerosey-Aubril and Pates 2018; Aria et al. 2020; Zeng et al. 2020; Pates et al. 2021; Moysiuk and Caron 2022). Several less well-preserved fossils have been proposed to share close affinities with Opabinia, including Utaurora comosa (Pates et al. 2021) and Myoscolex ateles (Briggs and Nedin 1997).

Described by: Walcott
Description date: 1912
Etymology:

Genus – Opabinia – from Opabin Pass (2,606 m) between Mount Hungabee and Mount Biddle in Yoho National Park. From the Stoney First Nation Nakoda word for “rocky,” a descriptive name for the pass given by Samuel Allen in 1894.

species – regalis – from the Latin regalis, “royal, or regal.”

Type Specimens: Lectotype –USNM57683 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none.

Other deposits: none.

Age & Localities:

Age:
Middle Cambrian, Wuliuan stage, Burgess Shale Formation (approximately 505 million years ago).
Principal localities:

The Walcott and Raymond Quarries on Fossil Ridge.

History of Research:

Brief history of research:

Opabinia regalis was first described by Walcott (1912) as an anostracan crustacean. Owing to its unique morphology with a bizarre frontal “nozzle,” Opabinia became a flagship fossil for the Burgess Shale, leading to much speculation on its affinity and lifestyle. One famous early reconstruction even shows the animal swimming upside down like a living anostracan (Hutchinson 1930). It wasn’t until the detailed redescription by Whittington (1975) that Opabinia was revealed to be one of the most enigmatic of all fossils. It was so unusual, in fact, that when Whittington showed an early version of his reconstruction in a meeting of palaeontologists in 1972, the whole room burst out laughing! Owing to its unique morphology with a bizarre frontal “nozzle,” Opabinia became a flagship fossil for the Burgess Shale, leading to much speculation on its affinity and lifestyle. Later work by Bergström (1986) identified similarities between Opabinia and the recently discovered whole-body specimens of Anomalocaris (Whittington and Briggs 1985), and updated the morphology of the gills and frontal proboscis. Budd (1996) was the first to place Opabinia in the stem lineage of the true arthropods, and also suggested the animal had lobopodous limbs in addition to lateral swimming flaps, although this idea was contested by Zhang and Briggs (2007). The issue of whether Opabinia had lobopodous limbs remains controversial. Budd and Daley (2012) figured additional material and provided further arguments in support of this hypothesis. However, other authors have noted similar features in other Burgess Shale arthropods and in decay experiments which appear to represent decayed remains of internal tissues or body cavities extending into the appendages rather than distinct appendages in themselves (Aria and Caron 2015; Butler et al. 2015; Mayers et al. 2018; Moysiuk and Caron 2022). While the morphology of Opabinia remains unique, several recent discoveries have shown that some of its unusual traits are shared by other Cambrian arthropods. Anomalocaris canadensis from the Burgess Shale possessed a similar tail fan (Collins 1996). Several radiodontans, including Stanleycaris and Peytoia appear to share the presence of a large median eye with Opabinia (Moysiuk and Caron 2022). Another animal, Kylinxia zhangi from the Chengjiang deposit, has an even more similar cluster of five large eyes, while also possessing traits of true arthropods like biramous limbs and a headshield (Zeng et al. 2020).

Description:

Morphology:

Opabinia has five eyes, a frontal “nozzle,” or proboscis, a body with segmentally repeated lateral lobes and gills, and a prominent tail fan. The whole body length ranges between 4.3 and 7.0 cm (excluding proboscis). The head has a rounded anterior margin, with a cluster of four bulbous eyes on short stalks and a large fifth eye positioned centrally on the dorsal surface of the head. The annulated frontal proboscis is four times longer than the head. It is highly flexible, and has a fused pair of appendages at the distal end, consisting of two opposing claws with five or six spines each. The mouth was ventral and faced to the rear. The trunk was divided into 15 segments, each bearing a pair of lateral lobes in association with gill structures consisting of bands of lanceolate blades. There is some controversy as to the exact location of the gills (dorsal, ventral or posterior) relative to the lobes. The tail fan consists of three pairs of upward-directed flaps. The trunk ends in a pair of tiny, rigid spines. The gut begins with a U-shaped bend near the rearward opening ventral mouth end extends to the body termination. Paired, segmentally arranged digestive glands flank the gut. There are also controversial triangular features in the central region of the body, connected to a dark stain surrounding the gut, which have alternatively been interpreted as lobopod-like walking limbs (Budd 1996; Budd and Daley 2012), or extensions of the gut or haemolymph cavities into the flaps (Whittington 1975; Zhang and Briggs 2007; Aria and Caron 2015; Moysiuk and Caron 2022).

Abundance:

Opabinia is rare, with only 42 specimens known from all collections. In the Walcott Quarry, Opabinia represents only 0.006% of the community (Caron and Jackson, 2008).

Maximum Size:
101 mm

Ecology:

Life habits: Predator
Feeding strategies: Predator
Ecological Interpretations:

Opabinia was a swimmer. As for Anomalocaris (Usami 2006; Sheppard et al. 2018), undulatory waves along its lateral flaps could have propelled it forward, while it used its tail fan to steer. Opabinia probably used the claws at the tip of its flexible nozzle to grasp food items and carry them towards its ventral mouth. The spinous morphology of the claws, the large eyes, and the paired digestive glands suggest that Opabinia was an active predator (Whittington 1975; Vannier et al. 2014).

References:

  • ARIA, C. and CARON, J.-B. 2015. Cephalic and limb anatomy of a new isoxyid from the Burgess Shale and the role of ‘stem bivalved arthropods’ in the disparity of the frontalmost appendage. PLoS ONE, 10: e0124979.
  • ARIA, C., ZHAO, F., ZENG, H., GUO, J. and ZHU, M. 2020. Fossils from South China redefine the ancestral euarthropod body plan. BMC Evolutionary Biology, 20: 1–17.
  • BERGSTRÖM, J. 1986. Opabinia Anomalocaris, unique Cambrian ‘arthropods’. Lethaia, 19: 241–246.
  • BRIGGS, D. E. G. and NEDIN, C. 1997. The taphonomy and affinities of the problematic fossil Myoscolex from the Lower Cambrian Emu Bay Shale of South Australia. Journal of Paleontology, 71: 22–32.
  • BUDD, G. E. 1996. The morphology of Opabinia regalis and the reconstruction of the arthropod stem-group. Lethaia, 29: 1–14.
  • BUDD, G. E. and DALEY, A. C. 2012. The lobes and lobopods of Opabinia regalis from the middle Cambrian Burgess Shale. Lethaia, 45: 83–95.
  • BUTLER, A. D., CUNNINGHAM, J. A., BUDD, G. E. and DONOGHUE, P. C. J. 2015. Experimental taphonomy of Artemia reveals the role of endogenous microbes in mediating decay and fossilization. Proceedings of the Royal Society B: Biological Sciences, 282: 20150476.
  • CARON, J.-B. and JACKSON, D. A. 2008. Paleoecology of the Greater Phyllopod Bed community, Burgess Shale. Palaeogeography, Palaeoclimatology, Palaeoecology, 258: 222–256.
  • COLLINS, D. 1996. The ‘evolution’ of Anomalocaris and its classification in the arthropod class Dinocarida (nov.) and order Radiodonta (nov.). Journal of Paleontology, 70: 280–293.
  • HUTCHINSON, G. E. 1930. Restudy of some Burgess Shale fossils. Proceedings of the United States National Museum, 78: 1–11.
  • LEROSEY-AUBRIL, R. and PATES, S. 2018. New suspension-feeding radiodont suggests evolution of microplanktivory in Cambrian macronekton. Nature Communications, 9: 3774.
  • MAYERS, B., ARIA, C. and CARON, J.-B. 2018. Three new naraoiid species from the Burgess Shale, with a morphometric and phylogenetic reinvestigation of Naraoiidae. Palaeontology, 62: 1–32.
  • MOYSIUK, J. and CARON, J.-B. 2022. A three-eyed radiodont with fossilized neuroanatomy informs the origin of the arthropod head and segmentation. Current Biology, 32: 3302–3316.
  • PATES, S., WOLFE, J. M., LEROSEY-AUBRIL, R., DALEY, A. C. and ORTEGA-HERNÁNDEZ, J. 2021. New opabiniid diversifies the weirdest wonders of the euarthropod stem group. Proceedings of the Royal Society B, 289: 20212093.
  • SHEPPARD, K. A., RIVAL, D. E. and CARON, J. B. 2018. On the Hydrodynamics of Anomalocaris Tail Fins. Integrative and comparative biology,.
  • USAMI, Y. 2006. Theoretical study on the body form and swimming pattern of Anomalocaris based on hydrodynamic simulation. Journal of Theoretical Biology, 238: 11–17.
  • VANNIER, J., LIU, J., LEROSEY-AUBRIL, R., VINTHER, J. and DALEY, A. C. 2014. Sophisticated digestive systems in early arthropods. Nature Communications, 5: 3641.
  • WALCOTT, C. D. 1912. Middle Cambrian Branchiopoda, Malacostraca, Trilobita and Merostomata. Smithsonian Miscellaneous Collections, 57: 145–228.
  • WHITTINGTON, H. B. 1975. The enigmatic animal Opabinia regalis, middle Cambrian, Burgess Shale, British Columbia. Philosophical Transactions of the Royal Society B: Biological Sciences, 271: 1–43.
  • WHITTINGTON, H. B. and BRIGGS, D. E. G. 1985. The largest Cambrian animal, Anomalocaris, Burgess Shale, British Columbia. Philosophical Transactions of the Royal Society B: Biological Sciences, 309: 569–609.
  • ZENG, H., ZHAO, F., NIU, K., ZHU, M. and HUANG, D. 2020. An early Cambrian euarthropod with radiodont-like raptorial appendages. Nature, 588: 101–105.
  • ZHANG, X. and BRIGGS, D. E. G. 2007. The nature and significance of the appendages of Opabinia from the Middle Cambrian Burgess Shale. Lethaia, 40: 161–17.
Other Links:

http://paleobiology.si.edu/burgess/opabinia.html



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Odaraia alata

3D animation of Odaraia alata.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Kingdom: Predator
Phylum: Predator
Higher Taxonomic assignment: Hymenocarines, Family Odaraiidae
Species name: Odaraia alata
Remarks:

Odaraia was originally considered a crustacean (Walcott 1912; Briggs 1981; Briggs and Fortey 1989; Hou and Bergstrom 1997; Wills et al. 1998), following previous interpretations on the affinities of other bivalved arthropods (hymenocarines), like Branchiocaris (Briggs 1976) or Canadaspis (Briggs 1978). In the early 2000s, the affinities of Odaraia were re-evaluated and placed in the stem lineage of arthropods (Budd 2002, 2008). Following the discovery of mandibles in several hymenocarines and the re-interpretation of this group as early mandibulate arthropods (which include myriapods, crustaceans and insects), Odaraia was moved to the stem of mandibulates (Aria and Caron 2017; Vannier et al. 2018), and was perhaps even more closely related to myriapods (Aria et al. 2021). Odaraia gives its name to the family Odaraiidae, a group of hymenocarines with highly multisegmented bodies, reduced or absent antennulae and highly multisegmented legs, which includes other Burgess Shale taxa such as Nereocaris or Fibulacaris.

Described by: Walcott
Description date: 1912
Etymology:

Odaraia – from Odaray Mountain (3,159 m) in Yoho Park, which was named by J. J. McArthur in 1887 from the Stoney First Nation Nakoda expression for “many waterfalls.”

alata – from the Latin ala, “wing,” referring to the wing-like fins of the tail.

Type Specimens: Lectotype –USNM57722 (O. alata) in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none.

Other deposits: none.

Age & Localities:

Age:
Cambrien moyen, étage Wuliuen, formation des schistes de Burgess (environ 505 millions d’années).
Principal localities:

The Walcott and Raymond Quarries on Fossil Ridge.

History of Research:

Brief history of research:

Odaraia was first described by Walcott (1912), and was re-examined briefly by Simonetta and Delle Cave (1975) A major restudy of Odaraia was published by Briggs (1981). New morphological features of the head were later incorporated, including a sclerite (Budd 2008) and nervous tissue (Ortega-Hernández 2015). A triad of organs or simple eyes at the front of the head have been associated with a sclerite known in other early arthropods (Ortega-Hernández 2015). The legs of Odaraia have been redescribed, highlighting a potential differentiation between the proximal and distal part (Aria and Caron 2017), a study which also illustrated the sternites (ventral segments) of the animal. Several closely related species to Odaraia, Jugatacaris agilis and different species of Pectocaris (Hou et al. 2004; Jin et al. 2021) have been discovered from the Lower Cambrian Chengjiang in China (Fu and Zhang 2011). The family Odaraidae was originally defined by Simonetta and Delle Cave, 1975. Since then, it has not been formally re-defined, but many other hymenocarines probably belong to this group.

Description:

Morphology:

Much of the body of Odaraia is contained within a prominent bivalved carapace in which the valves extend and meet on the ventral surface, similar to Nereocaris briggsi. The carapace forms a tube open at the front and back. The anteriormost, visible part of the head, protruding from the front of the carapace, consists of a rounded projection housing three organs or small eyes arranged triangularly, covered by a possible sclerite, and to which is attached pair of large, spherical eyes. Behind the head, the body consisted of approximately 47 narrow segments, each bearing a pair of appendages. Each limb is biramous, and has a segmented inner branch (endopod) and a paddle-like outer branch (exopod). The tail or telson has three blades or flukes, two of which extend laterally and the third of which extends vertically into a fin-like structure. The gut is typically straight with phosphatized paired midgut glands.

Abundance:

Odaraia typically makes up less than 0.5% of the community in Walcott Quarry, from which over 200 specimens have been collected (Caron and Jackson, 2008). About a dozen specimens are known from Raymond Quarry.

Maximum Size:
150 mm

Ecology:

Life habits: Predator
Feeding strategies: Predator
Ecological Interpretations:

The tubular carapace of Odaraia would have enclosed the ventral appendages, making it difficult for the animal to use its appendages for walking on the sea floor. It therefore seems to have swum through the water column by waving the outer branches of its biramous appendages, although this does not rule out interactions with other organisms on the sea floor. The large eyes and phosphatized gut glands (Butterfield 2002) suggest that Odaraia was a predator, seeking out floating or swimming organisms and sieving them out the water as the current passed through the tubular carapace. However, the lack of prehensile or sensory appendages also suggest Odaraia might have been a suspension feeder. To minimize the drag created by its dorsal hinge, it was proposed that Odaraia swam on its back, similar to horseshoe crabs, and the related hymenocarine Fibulacaris. The large telson would have been used to stabilize the animal while swimming to prevent it from rolling, and to help with steering and braking.

References:

  • ARIA, C. and CARON, J. B. 2017. Burgess Shale fossils illustrate the origin of the mandibulate body plan. Nature, 545: 89–92.
  • BRIGGS, D. E. G. 1976. The arthropod Branchiocaris n. gen., middle Cambrian, Burgess Shale, British Columbia. Geological Survey of Canada, Energy, Mines and Resources Canada, 264: 1–29.
  • BRIGGS, D. E. G. 1978. The morphology, mode of life, and affinities of Canadaspis perfecta (Crustacea: Phyllocarida), middle Cambrian, Burgess Shale, British Columbia. Phylosophical Transactions of The Royal Society of London, 281: 439–487.
  • BRIGGS, D. E. G. 1981. The arthropod Odaraia alata Walcott, middle Cambrian, Burgess Shale, British Columbia. Philosophical Transactions of the Royal Society of London. B, Biological Sciences, 291: 541–582.
  • BRIGGS, D. E. G. and FORTEY, R. A. 1989. The early radiation and relationships of the major arthropod groups. Science, 246: 241–243.
  • BUDD, G. E. 2002. A palaeontological solution to the arthropod head problem. Nature, 417: 271–275.
  • BUDD, G. E. 2008. Head structure in upper stem-group euarthropods. Palaeontology, 51: 561–573.
  • BUTTERFIELD, N. J. 2002. Leanchoilia guts and the interpretation of three-dimensional structures in Burgess Shale-type fossils. Paleobiology, 28: 155–171.
  • FU, D. and ZHANG, X. 2011. A new arthropod Jugatacaris agilis n. gen. n. sp. from the early Cambrian Chengjiang Biota, South China. Journal of Paleontology, 85: 567–586.
  • HOU, X.-G. and BERGSTROM, J. 1997. Arthropods of the Lower Cambrian Chengjiang fauna, southwest China. Fossils and Strata No, 45: 1–116.
  • HOU, X.-G., BERGSTRÖM, J. and XU, G.-H. 2004. The Lower Cambrian Crustacean Pectocaris from the Chengjiang Biota , Yunnan , China. Journal of Paleontology, 78: 700–708.
  • JIN, C., MAI, H., CHEN, H., LIU, Y. U., HOU, X.-G., WEN, R. and ZHAI, D. 2021. A new species of the Cambrian bivalved euarthropod Pectocaris with axially differentiated enditic armatures. Papers in Palaeontology, 7: 1781–1792.
  • ORTEGA-HERNÁNDEZ, J. 2015. Homology of head sclerites in Burgess Shale euarthropods. Current Biology, 25: 1625–1631.
  • SIMONETTA, A. M. and DELLE CAVE, L. 1975. The Cambrian non trilobite arthropods from the Burgess Shale of British Columbia. A study of their comparative morphology, taxonomy and evolutionary significance. Palaeontographia italica, 69 (n.s. 3: 1–37.
  • VANNIER, J., ARIA, C., TAYLOR, R. S. and CARON, J. B. 2018. Waptia fieldensis Walcott, a mandibulate arthropod from the middle Cambrian Burgess Shale. Royal Society Open Science, 5:172206:
  • WALCOTT, C. D. 1912. Cambrian geology and paleontology II: Middle Cambrian Branchiopoda, Malacostraca, Trilobita and Merostomata. Smithsonian Miscellaneous Collections, 57: 145–228.
  • WILLS, M. A., BRIGGS, D. E. G., FORTEY, R. A., WILKINSON, M. and SNEATH, P. H. A. 1998. An arthropod phylogeny based on fossil and recent taxa. In EDGECOMBE, G. D. (ed.) Arthropod Fossils and Phylogeny, Columbia University Press, New York, 33.105 pp.
Other Links:

None



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Leanchoilia superlata

3D animation of Leanchoilia superlata.

Animation by Phlesch Bubble © Royal Ontario Museum

Taxonomy:

Kingdom: Predator
Phylum: Predator
Higher Taxonomic assignment: Megacheirans, Family Leanchoiliidae
Species name: Leanchoilia superlata
Remarks:

Megacheirans are basal true arthropods with a frontal appendage pointing upward and made of multiple claws (the cheira, or “great appendage”). Leanchoilia and other leanchoiliidae characteristically also bear long filaments on their frontal appendages, called flagellae, and most likely used as sensory devices. Megacheirans are generally considered to be among the first true arthropods (that is, arthropods with both articulated bodies and appendages), and possibly the earliest representatives of the extended chelicerate lineage (Aria, 2022).

Described by: Walcott
Description date: 1912
Etymology:

Leanchoilia – from the Scottish name Leanchoil, the name given to a now defunct railway station on the Canadian Pacific Railway southwest of Field in Yoho National Park.

superlata – from the Latin superlata, “exaggerated.”

Type Specimens: Holotypes –USNM57709 (L. superlata),USNM155651 (L. persephone),USNM(155648) (L. protagonia) in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: L. persephone from Walcott Quarry and Raymond Quarry on Fossil Ridge, as well as other sites on Mount Stephen and Mount Field (Simonetta, 1970; García-Bellido & Collins, 2007); L. protagonia from the Walcott Quarry (Simonetta, 1970; Briggs et al., 2008).

Other deposits: L. illecebrosa and L. obesa from the Lower Cambrian Chengjiang biota (Liu, Hou & Bergstrom, 2007; He et al., 2017); L.? protagonia, and L.? hanceyi from the Middle Cambrian of Utah (Briggs et al., 2008).

Age & Localities:

Age:
Middle Cambrian, Wuliuan stage, Burgess Shale Formation (approximately 505 million years ago).
Principal localities:

Burgess Shale and vicinity: The Walcott and Raymond Quarries, Fossil Ridge. Additional localities are known on Mount Field and Mount Stephen – Tulip Beds (S7). Other deposits: L. superlata, from the Middle Cambrian of Utah (Briggs et al., 2008); L. illecebrosa and L. obesa from the Lower Cambrian Chengjiang biota (Liu et al., 2007; He et al., 2017).

History of Research:

Brief history of research:

Leanchoilia superlata was first described by Walcott in 1912, and later revised by Simonetta (1970), who added the second and third species L. persephone and L. protagonia. L. superlata was later restudied in detail by Bruton and Whittington (1983) and García-Bellido and Collins (2007), who included in their study an analysis of L. persephone. The three-dimensionally preserved digestive system of Leanchoilia was analyzed by Butterfield (2002). A more detailed description of L. protagonia was provided by Briggs et al. (2008) who also identified L. superlata from the Cambrian sediments of Utah. Haug et al. (2012) later provided a new revision of the fossil material for L. superlata. Due to a long history of research and its abundance in both the Burgess Shale and Chengjiang biota, Leanchoilia frequently continues to feature in studies of early arthropod evolution as a model for Leanchoiliidae, megacheirans, and more broadly basal true arthropods. Tomographic studies of juvenile specimens from China have revealed information about the development of appendages and important oral structures (Liu et al., 2014, 2016, 2020). Poorly-preserved specimens from China were used more recently to argue for the presence of detailed brains (Lan et al., 2021), but this was refuted (Aria et al., 2023). Additional tomographic investigation of an adult Leanchoilia illecebrosa specimen revealed the presence of additional lamellate gills at the base of the limbs (Liu et al., 2021).

Description:

Morphology:

Leanchoilia was a relatively large predator. The body lacks any biomineralization. Like other leanchoiliid megacheirans, it is characterized by flagellate frontal appendages (cheirae) made of three long claws, and a body divided into two regions (tagmata): the cephalon, covered by a single shield, and the segmented trunk. At the front of the head, leanchoiliids bore a pair of large short-stalked lateral eyes and a pair of smaller, mushroom-shaped median eyes. The megacheiran appendages were of similar simple morphology throughout the body, reflecting the typical arthropod biramous limb: sub-cylindrical basis with teeth for mastication (basipod), relatively strong walking legs (endopods), and paddle-like, semi-rigid flaps (exopods) fringed with lamellae. Pleurae (lateral extensions of the segments) were characteristically sub-horizontal and serrated. The trunk was composed of 11 segments, and expressed two strong parallel carinae on its dorsum. The tail is a single element called a telson, here spinose and the shape of spear’s tip (lanceolate).

Abundance:

L. superlata is rare in the Walcott Quarry (0.1% of the community, Caron and Jackson (2008)) but is abundant in the Raymond Quarry, with more than 1,200 specimens known from that site. L. persephone occurs in both localities but represents only a fraction of the number of L. superlata specimens. L. protagonia is extremely rare and is currently known from only two specimens in the Walcott Quarry.

Maximum Size:
About 12 cm.

Ecology:

Life habits: Predator
Feeding strategies: Predator
Ecological Interpretations:

Like other leanchoiliid megacheirans, Leanchoilia used its combined sensing and grasping frontal appendages to detect and catch prey items. Food caught was brought under the body where it might have been rudimentarily masticated between the bases of limbs (basipods), before being channeled back to the mouth. As a leanchoiliid, Leanchoilia also had large digestive glands atop its gut, suggesting it was either storing food for extended periods of time, or compensating rough mastication with additional enzymes. The megacheiran body appendages, made of relatively strong walking legs (endopods) as well as paddle-like, semi-rigid flaps (exopods), would have allowed for both comfortable locomotion on the sea floor and swimming. The exopods likely served for gas exchanges (like breathing) as well, but recent studies also showed that megacheirans and other Cambrian arthropods possessed dedicated gills (Liu et al., 2021).

References:

  • ARIA, C., VANNIER, J., PARK, T.S. & GAINES, R.R. (2023) Interpreting fossilized nervous tissues. BioEssays, 2200167.
  • BRIGGS, D.E.G., LIEBERMAN, B.S., HENDRICKS, J.R., HALGEDAHL, S.L. & JARRARD, R.D. (2008) Middle Cambrian arthropods from Utah. J Paleontol 82, 238–254.
  • BRUTON, D.L. & WHITTINGTON, H.B. (1983) Emeraldella and Leanchoilia, two arthropods from the Burgess Shale, Middle Cambrian, British Columbia. Philosophical Transactions of the Royal Society of London, Series B 300, 553–582.
  • BUTTERFIELD, N.J. (2002) Leanchoilia guts and the interpretation of three-dimensional structures in Burgess Shale-type fossils. Paleobiology 28, 155–171.
  • CARON, J.B. & JACKSON, D.A. (2008) Paleoecology of the Greater Phyllopod Bed community, Burgess Shale. Palaeogeography, Palaeoclimatology, Palaeoecology 258, 222–256.
  • GARCÍA-BELLIDO, D.C. & COLLINS, D. (2007) Reassessment of the genus Leanchoilia (Arthropoda, Arachnomorpha) from the middle Cambrian Burgess Shale, British Columbia, Canada. Palaeontology 50, 693–709.
  • HAUG, J.T., BRIGGS, D.E.G. & HAUG, C. (2012) Morphology and function in the Cambrian Burgess Shale megacheiran arthropod Leanchoilia superlata and the application of a descriptive matrix. BMC Evolutionary Biology 12, 162.
  • HE, Y.-Y., CONG, P.-Y., LIU, Y., EDGECOMBE, G.D. & HOU, X.-G. (2017) Telson morphology of Leanchoiliidae (Arthropoda: Megacheira) highlighted by a new Leanchoilia from the Cambrian Chengjiang biota. Alcheringa: An Australasian Journal of Palaeontology 41, 581–589.
  • LAN, T., ZHAO, Y., ZHAO, F., HE, Y., MARTINEZ, P. & STRAUSFELD, N.J. (2021) Leanchoiliidae reveals the ancestral organization of the stem euarthropod brain. Current Biology, S0960982221010381.
  • LIU, Y., EDGECOMBE, G.D., SCHMIDT, M., BOND, A.D., MELZER, R.R., ZHAI, D., MAI, H., ZHANG, M. & HOU, X. (2021) Exites in Cambrian arthropods and homology of arthropod limb branches. Nature Communications 12, 4619.
  • LIU, Y., HAUG, J.T., HAUG, C., BRIGGS, D.E.G. & HOU, X. (2014) A 520 million-year-old chelicerate larva. Nature Communications 5, 4440.
  • LIU, Y., HOU, X.G. & BERGSTROM, J. (2007) Chengjiang arthropod Leanchoilia illecebrosa (Hou, 1987) reconsidered. GFF 129, 263–272.
  • LIU, Y., MELZER, R.R., HAUG, J.T., HAUG, C., BRIGGS, D.E.G., HOERNIG, M.K., HE, Y. & HOU, X. (2016) Three-dimensionally preserved minute larva of a great-appendage arthropod from the early Cambrian Chengjiang biota. Proceedings of the National Academy of Sciences of the United States of America 113, 5542–5546.
  • LIU, Y., ORTEGA-HERNÁNDEZ, J., ZHAI, D. & HOU, X. (2020) A reduced labrum in a Cambrian great-appendage euarthropod. Current Biology 30, 3057-3061.e2.
  • SIMONETTA, A.M. (1970) Studies on non trilobite arthropods of the Burgess Shale (Middle Cambrian). Palaeontographia Italica 66 (New series 36), 35–45.
Other Links:

http://paleobiology.si.edu/burgess/leanchoilia.html



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Waptia fieldensis

Reconstruction of Waptia fieldensis.

© MARIANNE COLLINS

Taxonomy:

Kingdom: Predator
Phylum: Predator
Higher Taxonomic assignment: Hymenocarines, Family Protocarididae (Miller 1889).
Species name: Waptia fieldensis
Remarks:

Waptia belongs to its own family, Waptiidae, along with a few other similar forms, most notably Chuandianella from China (Hou & Bergström 1991). Outside of its palp-bearing mandibles, Waptia possesses limbs with 5-segmented distal branches typical of pancrustaceans (the group including crustaceans and hexapods) (Vannier et al. 2018), but the pancrustacean affinity of waptiids and other hymenocarines remains in question.

Described by: Walcott
Description date: 1912
Etymology:

Waptia – from Wapta Mountain (2,778 m), just north of Fossil Ridge, in British Columbia, Canada, named after the Stoney First Nation Nakoda word “Wapta” meaning “running water”.

fieldensis – from Field, the mountain peak (2,643 m) and small town near Fossil Ridge, British Columbia, Canada. The name was given by William Cornelius Van Horne (General Manager of the Canadian Pacific Railway), to honor Cyrus West Field, a promoter of the first telegraph cable across the Atlantic Ocean.

Type Specimens: Holotype USNM80483, in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none.

Other deposits: Waptia cf. fieldensis from the Spence Shale Member of the Langston Formation, Utah (Briggs et al. 2008).

Age & Localities:

Age:
Middle Cambrian, Wuliuan stage, Burgess Shale Formation (approximately 505 million years ago).
Principal localities:

The Walcott and Raymond Quarries on Fossil Ridge

History of Research:

Brief history of research:

Waptia was first described by Walcott (1912), who designated Waptia fieldensis as the type species of the genus. Various authors commented on its affinities (e.g., Briggs 1983; Briggs et al. 1994; Hou & Bergström 1997; Walossek & Müller 1998; Wills et al. 1998; Bergström & Hou 2005). Waptia cf. fieldensis has been described from the Spence Shale in Utah (Briggs et al. 2008), and Waptia has been compared to Pauloterminus spinodorsalis from the Sirius Passet biota in North Greenland (Taylor 2002). Waptia-like specimens from southwest China (Li 1975; Hou & Bergström 1991) were at one point assigned to Waptia (Chen 2004), but a re-examination of the specimens showed they were different enough to be assigned to their own genus, Chuandianella (Liu & Shu 2004, 2008; Hou et al. 2009; Zhai et al. 2022). Waptia specimens from the Burgess Shale were more recently comprehensively restudied and redescribed by Vannier et al. (2018), documenting clear mandibulate affinities and possible shared characters with pancrustaceans. Waptia and Chuandianella have also served to document early brood care via the preservation of eggs under the carapace, with different egg sizes between genera (Caron & Vannier 2016; Ou et al. 2020), and later developmental stages (Liu et al. 2022).

Description:

Morphology:

Like other hymenocarines, Waptia has a tubular body with segmental “rings” enclosed in a bivalved carapace. Mandibles are well developed and located very anteriorly, close to the insertion of the two large, pedunculate eyes and elongate antennules, without evidence of post-antennular appendage. Between the eyes, a sclerite covers additional sensory organs. It also bears paired semi-rigid flaps for its tailpiece, called caudal rami. However, the morphoanatomy of Waptia also substantially departs from that of other hymenocarines. The maxillules, behind the mandibules, are differentiated, bearing a rounded brush-like element distally. The following three pairs of appendages are similar and raptorial: they are uniramous, with four basal podomeres (limb segments) bearing strong spinose extensions called endites, and five terminal podomeres, including the claw. The seventh pair of appendage has a similar distal part with five podomeres, but the basal part is instead made of annulations bearing short lamellae. The following six pairs are entirely annulated, and bear much longer and wider lamellae. Body segments bearing these limbs are distinct, but segments housing the last two pairs are fused. The remaining posterior body is an abdomen (limbless).

Abundance:

Waptia is common in the Burgess Shale, with over 1,400 specimens collected from the Walcott Quarry (Conway Morris 1986; Caron & Jackson 2008) and 70 specimens collected from the Raymond Quarry.

Maximum Size:
About 8 cm.

Ecology:

Life habits: Predator
Feeding strategies: Predator
Ecological Interpretations:

The large lamellar thoracic appendages of Waptia clearly point to a swimming lifestyle. The frontal “basket” of raptorial limbs and mandibles with palps point in turn to a distinct role in predation, food manipulation and mastication. Similar to a number of modern crustaceans, like shrimps, Waptia was brooding eggs under its carapace rather than depositing them in sediment.

References:

  • ARIA, C. and CARON, J. B. 2017. Burgess Shale fossils illustrate the origin of the mandibulate body plan. Nature, 545, 89–92.
  • BERGSTRÖM, J. and HOU, X. 2005. Early Palaeozoic non-lamellipedian arthropods. In KOENEMANN, S. and R. A. JENNER, R. A. (eds.) Crustaceans and Arthropod Relationships, Festschrift for Fredrick R. Schram., Taylor and Francis, Boca Raton, London, New York, Singapore., 73–93 pp.
  • BRIGGS, D. E. G. 1983. Affinities and early evolution of the Crustacea: the evidence of the Cambrian fossils. In Crustacean Phylogeny. Crustacean Issues, Vol. 1. Taylor & Francis, Rotterdam, 1–22 pp.
  • BRIGGS, D. E. G., ERWIN, D. H. and COLLIER, F. J. 1994. The fossils of the Burgess Shale. Smithsonian Institution Press, Washington, D.C.
  • BRIGGS, D. E. G., LIEBERMAN, B. S., HENDRICKS, J. R., HALGEDAHL, S. L. and JARRARD, R. D. 2008. Middle Cambrian arthropods from Utah. J Paleontol, 82, 238–254.
  • CARON, J. B. and JACKSON, D. A. 2008. Paleoecology of the Greater Phyllopod Bed community, Burgess Shale. Palaeogeography, Palaeoclimatology, Palaeoecology, 258, 222–256.
  • CARON, J.-B. and VANNIER, J. 2016. Waptia and the diversification of brood care in early arthropods. Current Biology, 26, 69–74.
  • CHEN, J. Y. 2004. The Dawn of Animal World. Jiangsu Science and Technical Press, Nanjing.
  • CONWAY MORRIS, S. 1986. The community structure of the Middle Cambrian phyllopod bed (Burgess Shale). Palaeontology, 29, 423–467.
  • HOU, X. G. and BERGSTRÖM, J. 1991. The arthropods of the Lower Cambrian Chengjiang fauna, with relationships and evolutionary significance. In SIMONETTA, A. M. and CONWAY MORRIS, S. (eds.) The Early Evolution of Metazoa and the Significance of Problematic Taxa., Cambridge University Press, Camerino, 179–187 pp.
  • HOU, X. G. and BERGSTRÖM, J. 1997. Arthropods of the Lower Cambrian Chengjiang fauna, southwest China. Fossils and Strata, 45, 1–116.
  • HOU, X.-G., SIVETER, D. J., ALDRIDGE, R. J. and SIVETER, D. J. 2009. A new arthropod in chain-like associations from the Chengjiang Lagerstätte (Lower Cambrian), Yunnan, China. Palaeontology, 52, 951–961.
  • LI, Y. 1975. On the Cambrian ostracods with new material from Sichuan, Yunnan and Shaanxi, China. Professional Papers on Stratigraphy & Palaeontology, 2, 37–72.
  • LIU, C., FU, D. and ZHANG, X. 2022. Developmental dynamics is revealed in the early Cambrian arthropod Chuandianella ovata. IScience, 25, 103591.
  • LIU, H. and SHU, D. 2004. New information on Chuandianella from the Lower Cambrian Chengjiang Fauna, Yunnan, China. Journal of Northwest University, 34, 453-456 (in Chinese with English abstract).
  • LIU, H. and SHU, D. 2008. Chuandianella ovata from Lower Cambrian Chengjiang biota. Acta Palaeontologica Sinica. Acta Palaeontologica Sinica, 47, 352–361.
  • MILLER, S. A. 1889. North American geology and palaeontology for the use of amateurs, students and scientists. Western Methodist Book Concern, Cincinnati.
  • OU, Q., VANNIER, J., YANG, X., CHEN, A., MAI, H., SHU, D., HAN, J., FU, D., WANG, R. and MAYER, G. 2020. Evolutionary trade-off in reproduction of Cambrian arthropods. Science Advances, 6, eaaz3376.
  • TAYLOR, R. S. 2002. A new bivalved arthropod from the Early Cambrian Sirius Passet fauna, North Greenland. Palaeontology, 45, 97–123.
  • VANNIER, J., ARIA, C., TAYLOR, R. S. and CARON, J. B. 2018. Waptia fieldensis Walcott, a mandibulate arthropod from the middle Cambrian Burgess Shale. Royal Society Open Science, 5:172206.
  • WALCOTT, C. 1912. Cambrian Geology and Paleontology II. Middle Cambrian Branchiopoda, Malacostraca, Trilobita and Merostomata. Smithsonian Miscellaneous Collections, 57(6), 145–228.
  • WALOSSEK, D. and MÜLLER, K. J. 1998. Cambrian ’Orsten’-type arthropods and the phylogeny of Crustacea. In FORTEY, R. R. and THOMAS, R. (eds.) Arthropod Relationships, Chapman & Hall, London, 139–153 pp.
  • WILLS, M. A., BRIGGS, D. E. G., FORTEY, R. A., WILKINSON, M. and SNEATH, P. H. A. 1998. An arthropod phylogeny based on fossil and recent taxa. In EDGECOMBE, G. D. (ed.) Arthropod Fossils and Phylogeny, Columbia University Press, New York, 33–105 pp.
  • ZHAI, D., WILLIAMS, M., SIVETER, D., SIVETER, D., HARVEY, T., SANSOM, R., MAI, H., ZHOU, R. and HOU, X. 2022. Chuandianella ovata: An early Cambrian stem euarthropod with feather-like appendages. Palaeontologia Electronica.
Other Links:

http://paleobiology.si.edu/burgess/waptia.html



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Tuzoia burgessensis

Outlines of Tuzoia canadensis (left), Tuzoia burgessensis (middle) and Tuzoia retifera (right).

© MARIANNE COLLINS

Taxonomy:

Kingdom: Predator
Phylum: Predator
Higher Taxonomic assignment: Hymenocarines, Family Tuzoiidae
Species name: Tuzoia burgessensis
Remarks:

Tuzoia is known as one of the most diverse and widespread hymenocarines, but, besides isolated carapaces, other soft-tissues are scarce. Tuzoia may represent one of the earliest hymenocarine representatives.

Described by: Resser
Description date: 1929
Etymology:

Tuzoia – from Mount Tuzo, in the Valley of the Ten Peaks, named in 1907 after Henrietta Tuzo, who was the first to climb this mountain.

burgessensis – from Mount Burgess (2,599 m), a mountain peak in Yoho National Park. Mount Burgess. The name was given in 1886 by Otto Klotz, the Dominion topographical surveyor, after Alexander Burgess, a former Deputy Minister of the Department of the Interior.

Type Specimens: Holotypes –USNM80477b (T. burgessensis),USNM57720 (T. retifera),USNM80478b (T. canadensis) in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale: T. retifera and T. canadensis from the Tuzoia layer above the Raymond Quarry, the Raymond and Walcott Quarries on Fossil Ridge, and other sites on Mount Field and Stanley Glacier. (See Vannier et al., 2007 for references).

Other deposits: T. australis from the Lower Cambrian Emu Bay Shale of Australia (Glaessner 1979; García-Bellido et al. 2009). T. bispinosa from the Lower Cambrian Balang Formation of China (Wen et al. 2019) and the Wuliuan Kaili Formation of China (Yuan and Zhao 1999; Wen et al. 2015). T. guntheri from the Middle Cambrian Marjum and Pioche Formations of Utah and Nevada (Robison and Richards 1981; Lieberman 2003). T. jianheensis from the Lower Cambrian Tsinghsutung Formation of China (Chen et al. 2017). T. lazizhaeiensis from the Lower Cambrian Balang Formation of China (Wen et al. 2019). T. polleni from the Lower Cambrian Eager Formation of British Columbia (Resser 1929), the Lower Cambrian Kinzers Formation of Pennsylvania (Resser 1929; Vannier et al. 2007), the Lower Cambrian Parker Quarry in Vermont (Pari et al. 2022) and the Wuliuan Pioche Formation of Utah and Nevada (Resser and Howell 1938). Other species of Tuzoia are known (e.g., T. manchuriensis), albeit poorly documented or with open nomenclature. (See Lieberman 2003; Vannier et al. 2007; Wen et al. 2019; Izquierdo-López and Caron 2022a for references).

Age & Localities:

Age:
Middle Cambrian, Wuliuan stage, Burgess Shale Formation (approximately 505 million years ago).
Principal localities:

The Walcott and Raymond Quarries, the Tuzoia layer above the Raymond Quarry and the Collins Quarry on Fossil Ridge. The Tulip Beds (S7) on Mount Stephen. Marble Canyon and Stanley Glacier in Kootenay National Park.

History of Research:

Brief history of research:

Tuzoia was first described by Charles Walcott (1912) based on a single carapace specimen from the Burgess Shale, which was later expanded in more detail by Resser (1929). Since then, Tuzoia has been described from multiple other Cambrian sites: Utah (Robison and Richards 1981) and Nevada (Lieberman 2003) in the USA, Australia (Glaessner 1979; Luo et al. 1999; Yuan and Zhao 1999; Wen et al. 2015, 2019; Wu and Liu 2022), the Czech Republic (Chlupáč and Kordule 2002), and multiple localities in China (Pan 1957; Shu 1990; Luo et al. 1999; Yuan and Zhao 1999; Wen et al. 2015, 2019; Wu and Liu 2022) ), making it one of the geographically most widespread arthropod species of that period (Hendricks et al. 2008). Given its distribution, more than 20 species of Tuzoia have been historically defined, but major redescriptions have reduced this number to lower than 10 (Vannier et al. 2007; Wen et al. 2019). Several species, though, remain poorly known or with open nomenclature. In 2021, a new genera to the family tuzoiidae, Duplapex, was described from the Qingjiang Biota of China (Ma et al. 2021). Soft parts such as eyes, potential antennae and gut structures were first reported by Vannier et al. (2007), and were followed by new information on the anatomy of the head (Wen et al. 2019) and legs (Caron et al. 2010; Wen et al. 2019; Du et al. 2020), albeit generally poorly preserved. A re-study of Tuzoia, including new material from the Marble Canyon and adjacent outcrops at the Burgess Shale (Caron et al. 2014) found fully-preserved legs and a tailpiece, as well as new details of the head, allowing for a first comprehensive reconstruction of its anatomy and evaluation of its affinities (Izquierdo-López and Caron 2022).

Description:

Morphology:

The most prominent feature of Tuzoia is its large, bivalved carapace. The two dome-shaped carapace valves have convexly rounded ventral margins and are joined along a straight dorsal margin that usually extends at the front and back into pointed spines, or cardinal processes. Most species of Tuzoia have two main spines on the mid-posterior and posteroventral margin of the carapace. Smaller spines are usually present along the posterior, ventral and dorsal side of the carapace; they vary in number, size, and orientation between species. A lateral ridge passes horizontally, perpendicular to the surface of the carapace valves, which is often spinose. The carapaces are covered in a polygonal pattern. The head bears a pair of large, spherical eyes on short stalks, and projects forwards from underneath the carapace and bears a pair of antennae and a pair of lobes between the eyes. The trunk is short, and is completely covered by the carapace. It bears a total of 12 thick biramous legs. Each leg is divided into a base (basipod), which is elongated and bears a few isolated spines and an inner branch (endopod), divided into seven segments, with the terminal one having a claw-like shape. The basipod of the first anterior legs may bear dentate projections (endites), and all segments of the endopod bear spines. The remaining, more posterior legs do not show these projections, and spines are limited to a couple of segments. The legs may also have a paddle-like outer branch (exopod), although its shape is not clear. The body terminates into two pairs of broad fan-like appendages (caudal rami). Besides the carapace, anatomical details are a composite between different species of Tuzoia from the Burgess Shale formation, mainly T. burgessensis and T. retifera. Possible anatomical differences across species are currently unknown.

Abundance:

As the name suggests, the Tuzoia beds between the Raymond and Collins Quarries on Fossil Ridge yield abundant Tuzoia burgessensis specimens, with over 160 specimens found so far. T. burgessensis is also found rarely in Raymond Quarry, where T. retifera is more common, with 87 known specimens. Tuzoia is also found rarely in other sites on Mount Field and Mount Stephen. Tuzoia is also found at Stanley Glacier and in the Marble Canyon and Tokumm Creek localities, albeit not highly abundant.

Maximum Size:
About 20 cm.

Ecology:

Life habits: Predator
Feeding strategies: Predator
Ecological Interpretations:

Tuzoia is suggested to be free-swimming animal. The midposterior and posteroventral spines probably acted as a keel to provide directional stability to the animal while swimming, and the lateral ridge may have allowed directional control to improve the streamlining of the animal while preventing sinking. The reticulate pattern of the carapace is interpreted as a way of strengthening the carapace without adding so much weight that the animal would be unable to swim. Spines and the lateral ridge may also have provided protection from predation. The legs end in claw-like structures, suggesting that Tuzoia may have also been able to walk on the benthos or anchor itself to structures such as carcasses. If that was the case, the carapace must have been able to open partially. The large, frontally-directed eyes, as well as the spines on the anterior legs, also reinforce the idea that it was a predator or scavenger. The spines present on the more posterior legs could have also been used to attach to surfaces or manipulate food.

References:

  • ARIA, C. and CARON, J. B. 2017. Burgess Shale fossils illustrate the origin of the mandibulate body plan. Nature, 545: 89–92.
  • CARON, J. B., GAINES, R. R., MÁNGANO, M. G., STRENG, M. and DALEY, A. C. 2010. A new Burgess Shale-type assemblage from the “thin” Stephen Formation of the southern Canadian Rockies. Geology, 38: 811–814.
  • CARON, J. B., GAINES, R. R., ARIA, C., MÁNGANO, M. G. and STRENG, M. 2014. A new phyllopod bed-like assemblage from the Burgess Shale of the Canadian Rockies. Nature communications, 5: 3210.
  • CHEN, W. Y., ZHAO, Y. L., YANG, X. L. and WEN, R. Q. 2017. Tuzoia Walcott, 1912 from the Cambrian ‘Tsinghsutung Formation’ of Guizhou, China. Palaeontologica Sinica, 56: 301–311.
  • CHLUPÁČ, I. and KORDULE, V. 2002. Arthropods of Burgess Shale type from the Middle Cambrian of Bohemia (Czech Republic). Vestnik Ceskeho Geologickeho Ustavu, 77: 167–182.
  • DU, K.-S., ORTEGA-HERNÁNDEZ, J., YANG, J., YANG, X., GUO, Q., WEI, L., HE, J., LI, K., DU, J., HOU, J. and ZHANG, X. 2020. A new early Cambrian Konservat-Lagerstätte expands the occurrence of Burgess Shale-type deposits on the Yangtze Platform. Earth-Science Reviews, 211:.
  • GARCÍA-BELLIDO, D. C., PATERSON, J. R., EDGECOMBE, G. D., JAGO, J. B., GEHLING, J. G. and LEE, M. S. Y. 2009. The bivalved arthropods Isoxys and Tuzoia with soft-part preservation from the lower Cambrian Emu Bay Shale lagerstätte (Kangaroo Island, Australia). Palaeontology, 52: 1221–1241.
  • GLAESSNER, M. G. 1979. Lower Cambrian Crustacea and annelid worms from Kangaroo Island, South Australia. Alcheringa, 3: 21–31.
  • HENDRICKS, J. R., LIEBERMAN, B. S. and STIGALL, A. L. 2008. Using GIS to study palaeobiogeographic and macroevolutionary patterns in soft-bodied Cambrian arthropods. Palaeogeography, Palaeoclimatology, Palaeoecology, 264: 163–175.
  • IZQUIERDO-LÓPEZ, A. and CARON, J.-B. 2022. The problematic Cambrian arthropod Tuzoia and the origin of mandibulates revisited. Royal Society Open Science, 9:.
  • LIEBERMAN, B. S. 2003. A new soft-bodied fauna: The Pioche formation of Nevada. Journal of Paleontology, 77: 674–690.
  • LUO, H.-L., HU, S.-X., CHEN, S., ZHANG, S. S. and TAO, Y. H. 1999. Early Cambrian Chengjiang Fauna from Kunming Region, China. .
  • MA, J., LIN, W., LIU, C., SUN, A., WU, Y., WU, Y. and FU, D. 2021. A new bivalved arthropod from Cambrian (Stage 3) Qingjiang biota expands the palaeogeographical distribution and increases the diversity of Tuzoiidae. Journal of the Geological Society, 179(1):
  • PAN, K. 1957. On the discovery of Homopoda from South China. Palaeontologica Sinica, 5: 523–526.
  • PARI, G., BRIGGS, D. E. G. and GAINES, R. R. 2022. The soft-bodied biota of the Cambrian Series 2 Parker Quarry Lagerstätte of northwestern Vermont, USA. Journal of Paleontology, 1–21.
  • RESSER, C. E. 1929. New Lower and Middle Cambrian Crustacea. Proceedings of the U.S. National Museum, 76: 1–18.
  • RESSER, C. E. and HOWELL, B. F. 1938. Lower Cambrian Olenellus Zone of the Appalachians. Geological Society of America Bulletin, 49: 195–248.
  • ROBISON, R. A. and RICHARDS, B. C. 1981. Larger bivalve arthropods from the Middle Cambrian of Utah. Paleontological Contributions of the University of Kansas, 106: 1–19.
  • SHU, D. G. 1990. Cambrian and Lower Ordovician Bradoriida from Zhejiang. Northwest University Press, Xian, Hunan and Shaanxi Provinces.
  • VANNIER, J., ARIA, C., TAYLOR, R. S. and CARON, J. B. 2018. Waptia fieldensis Walcott, a mandibulate arthropod from the middle Cambrian Burgess Shale. Royal Society Open Science, 5:172206:
  • VANNIER, J., CARON, J. B., YUAN, J., BRIGGS, D. E. G., COLLINS, D., ZHAO, Y. and ZHU, M. 2007. Tuzoia: morphology and lifestyle of a large bivalved arthropod of the Cambrian seas. Journal of Paleontology, 81(3): 445–471.
  • WALCOTT, C. D. 1912. Cambrian geology and paleontology II: Middle Cambrian Branchiopoda, Malacostraca, Trilobita and Merostomata. Smithsonian Miscellaneous Collections, 57: 145–228.
  • WEN, R., BABCOCK, L. E., PENG, J., LIU, S. and LIANG, B. 2019. The bivalved arthropod Tuzoia from the Balang Formation (Cambrian Stage 4) of Guizhou, China, and new observations on comparative species. Papers in Palaeontology, 5: 719–742.
  • WEN, R. Q., ZHAO, Y. L. and PENG, J. 2015. Morphology and ontogeny of Tuzoia bispinosa from the Kaili Biota (Cambrian Stage 5) of eastern Guizhou, China. Palaeoworld, 24: 61–70.
  • WU, Y. and LIU, J. 2022. New data on the bivalved arthropod Tuzoia from the Cambrian (Series 2 , Stage 4) Guanshan Biota in Kunming, Yunnan, Southwest China. Frontiers in Earch Sciences, 10:862679: 1–11.
  • YUAN, J. L. and ZHAO, Y. L. 1999. Tuzoia (bivalved arthropods) from the Lower-Middle Cambrian Kaili Formation of Taijiang, Guizhou. Palaeontologica Sinica, 38: (Suppl.), 88-93.
Other Links:

http://www.bioone.org/doi/abs/10.1666/pleo05070.1