Others: Stanley Glacier



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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: Stanley Glacier
Phylum: Stanley Glacier
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: Stanley Glacier
Feeding strategies: Stanley Glacier
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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Sidneyia inexpectans

3D animation of Sidneyia inexpectans.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Kingdom: Stanley Glacier
Phylum: Stanley Glacier
Higher Taxonomic assignment: Unranked clade (stem group arthropods)
Species name: Sidneyia inexpectans
Remarks:

Sidneyia is usually considered to be closely related to the chelicerates, but its exact position relative to this group remains unclear (Budd and Telford, 2009). Sidneyia has been variously placed as the sister group to the chelicerates (Hou and Bergström, 1997), close to the crown on the chelicerate stem lineage (Bruton, 1981; Edgecombe and Ramsköld, 1999; Hendricks and Lieberman, 2008), or basal in the chelicerate stem lineage (Briggs and Fortey, 1989; Wills et al., 1998; Cotton and Braddy, 2004).

Described by: Walcott
Description date: 1911
Etymology:

Sidneyia – after Walcott’s son Sidney, who discovered the first specimen in August of 1910.

inexpectans – from the Latin inexpectans, “unexpected,” since Walcott did not expect to find such a fossil in strata older than the Ordovician.

Type Specimens: Lectotype –USNM57487 (S. inexpectans) in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none.

Other deposits: A single specimen from the Chengjiang Fauna in China was used to describe a second species, Sidneyia sinica (Zhang et al. 2002), however this was later shown to be incorrectly attributed to Sidneyia (Briggs et al. 2008).

Age & Localities:

Age:
Middle Cambrian, Bathyuriscus-Elrathina Zone (approximately 505 million years ago).
Principal localities:

Burgess Shale and vicinity: The Walcott, Raymond and Collins Quarries on Fossil Ridge, Mount Field and Mount Stephen – Tulip Beds (S7) and other smaller localities – Odaray Mountain and Stanley Glacier.

Other deposits: Sidneyia has been described from the Wheeler Formation (Briggs and Robison, 1984) and the Spence Shale (Briggs et al. 2008) in Utah, and the Kinzers Formation in Pennsylvania (Resser and Howell, 1938).

History of Research:

Brief history of research:

Sidneyia was the first fossil to be described by Walcott (1911) from the Burgess Shale. Further details were added by Walcott the following year (Walcott, 1912), and Strømer (1944) and Simonetta (1963) made minor revisions to Walcott’s reconstruction. A large appendage found in isolation was originally suggested to be the large frontal appendage of Sidneyia (Walcott, 1911), but this was later found to belong to the anomalocaridid Laggania (Whittington and Briggs, 1985). A major study by Bruton (1981) redescribed the species based on the hundreds of available specimens.

Description:

Morphology:

Sidneyia has a short, wide head shield that is convexly domed and roughly square. The two front lateral corners are notched to allow an antenna and a stalked eye to protrude. Other than the pair of antennae, which are long and thin with at least 20 segments, there are no cephalic appendages. The hemispherical and highly reflective eyes are above and posterior to the antennae.

The thorax of Sidneyia has nine wide, thin body segments that widen from the first to the fourth segment and then get progressively narrower posteriorly. The first four thoracic segments bear appendages with a large, spiny basal segment (the coxa) and 8 thinner segments, ending in a sharp claw. The next five thoracic appendages have a similar appendage but also have flap-like filaments in association with the limbs.

The abdomen consists of three circular rings that are much narrower than the thorax, with a terminal, triangular telson. The last segment of the abdomen has a pair of wide flaps that articulate with the telson to form a tail fan. A trace of the straight gut can be seen in some specimens extending from the anterior mouth to the anus on the telson, and pieces of broken trilobites are sometimes preserved in the gut.

Abundance:

Sidneyia is a relatively common arthropod in the Walcott Quarry, comprising 0.3% of the specimens counted (Caron and Jackson, 2008). Hundreds of specimens have been collected from the Walcott Quarry (Bruton, 1981) and in other nearby localities.

Maximum Size:
160 mm

Ecology:

Life habits: Stanley Glacier
Feeding strategies: Stanley Glacier
Ecological Interpretations:

Sidneyia walked and swam above the sea floor. Its anterior four thoracic appendages were used for walking, and the spiny basal coxa would crush food items and move them towards the mouth. The posterior five thoracic appendages were used for swimming, with the flap-like filaments undulating through the water column to create propulsion. These filaments were also likely used for breathing, like gills.

The predatory nature of Sidneyia is indicated by its spiny coxa used to masticate food, and the presence of crushed fossil debris in its gut. Sidneyia would have walked or swam above the sea floor, using its eyes and antennae to seek out prey, which it would capture and crush with its anterior appendages.

References:

BRIGGS, D. E. G. AND R. A. FORTEY. 1989. The early radiation and relationships of the major arthropod groups. Science, 246: 241-243.

BRIGGS, D. E. G. AND R. A. ROBISON. 1984. Exceptionally preserved non-trilobite arthropods and Anomalocaris from the Middle Cambrian of Utah. The University of Kansas Paleontological Contributions, 111: 1-24.

BRIGGS, D. E. G., B. S. LIEBERMAN, J. R. HENDRICKS, S. L. HALGEDAHL AND R. D. JARRARD. 2008. Middle Cambrian arthropods from Utah. Journal of Paleontology, 82(2): 238-254.

BRUTON, D. L. 1981. The arthropod Sidneyia inexpectans, Middle Cambrian, Burgess Shale, British Columbia. Philosophical Transactions of the Royal Society of London B, 295: 619-653.

BUDD, G. E. AND M. J. TELFORD. 2009. The origin and evolution of arthropods. Nature, 457(7231): 812-817.

CARON, J.-B. AND D. A. JACKSON. 2008. Paleoecology of the Greater Phyllopod Bed community, Burgess Shale. Palaeogeography, Palaeoclimatology, Palaeoecology, 258: 222-256.

CARON, J.-B., R. GAINES, G. MANGANO, M. STRENG, AND A. DALEY. 2010. A new Burgess Shale-type assemblage from the “thin” Stephen Formation of the Southern Canadian Rockies. Geology, 38: 811-814.

COTTON, T. J. AND S. J. BRADDY. 2004. The phylogeny of arachnomorph arthropods and the origin of the Chelicerata. Transactions of the Royal Society of Edinburgh: Earth Sciences, 94: 169-193.

EDGECOMBE, G. D. AND L. RAMSKÖLD. 1999. Relationships of Cambrian Arachnata and the systematic position of Trilobita. Jounral of Paleontology, 73: 263-287.

HENDRICKS , J. R. AND B. S. LIEBERMAN. 2008. Phylogenetic insights into the Cambrian radiation of arachnomorph arthropods. Journal of Paleontology, 82: 585-594.

HOU, X. AND J. BERGSTRÖM. 1997. Arthropods of the Lower Cambrian Chengjiang fauna, southwest China. Fossils and Strata, 45: 1-116.

RASSER, C. E. AND B. F. HOWELL. 1938. Lower Cambrian Olenellus zone of the Appalachians. Bulletin of the Geological Society of America, 49: 195-248.

SIMONETTA, A. M. 1963. Osservazioni sugli artropodi non trilobiti della Burgess Shale (Cambriano medio). II. Contributo: I Generai Sidneyia ed Amiella Walcott 1911. Monitore Zoologico Italiano, 70: 97-108.

STØMER, L. 1944. On the relationships and phylogeny of fossil and recent Arachnomorpha. Norsk Videnskaps-Akademi Skrifter I. Matematisk-Naturvidenskaplig Klasse, 5: 1-158.

WALCOTT, C. D. 1911. Middle Cambrian Merostomata. Cambrian geology and paleontology II. Smithsonian Miscellaneous Collections, 57: 17-40.

WALCOTT, C. D. 1912. Cambrian Geology and Paleontology II. Middle Cambrian Branchiopoda, Malacostraca, Trilobita and Merostomata. Smithsonian Miscellaneous Collections, 57(6): 145-228.

WHITTINGTON, H. B. AND D. E. G. BRIGGS. 1985. The largest Cambrian animal, Anomalocaris, Burgess Shale, British-Columbia. Philosophical Transactions of the Royal Society of London Series B-Biological Sciences, 309: 569-609.

WILLS, M. A., D. E. G. BRIGGS, R. A. FORTEY, M. WILKINSON AND P. H. A. SNEATH. 1998. An arthropod phylogeny based on fossil and recent taxa, pp. 33-105. In G. D. Edgecombe (ed.), Arthropod fossils and phylogeny. Columbia University Press, New York.

ZHU, X., H. JIAN AND S. DEGAN. 2002. New occurrence of the Burgess Shale arthropod Sidneyia in the Early Cambrian Chengjiang Lagerstätte (South China), and revision of the arthropod Urokodia. Alcheringa: An Australasian Journal of Palaeontology, 26: 1-18.

Other Links:

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



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Isoxys acutangulus

3D animation of Isoxys carinatus.

Animation by Phlesch Bubble © Royal Ontario Museum

Taxonomy:

Kingdom: Stanley Glacier
Phylum: Stanley Glacier
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: Stanley Glacier
Feeding strategies: Stanley Glacier
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:

None



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Hurdia victoria

3D animation of Hurdia victoria.

Animation by Phlesch Bubble © Royal Ontario Museum

Taxonomy:

Kingdom: Stanley Glacier
Phylum: Stanley Glacier
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: Stanley Glacier
Feeding strategies: Stanley Glacier
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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Haplophrentis carinatus

3D animation of Haplophrentis carinatus.

Animation by Phlesch Bubble © Royal Ontario Museum

Taxonomy:

Kingdom: Stanley Glacier
Phylum: Stanley Glacier
Higher Taxonomic assignment: Hyolitha (Order: Hyolithida, stem group molluscs)
Species name: Haplophrentis carinatus
Remarks:

Haplophrentis belongs to a group of enigmatic cone-shaped to tubular fossils called hyoliths that are known only from the Palaeozoic. Their taxonomic position is uncertain, but the Hyolitha have been regarded as a separate phylum, an extinct Class within Mollusca (Malinky and Yochelson, 2007), or as stem-group molluscs.

Described by: Matthew
Description date: 1899
Etymology:

Haplophrentis – from the Greek haploos, “single,” and phrentikos, “wall,” in reference to the single wall within the shell.

carinatus – from the Latin carinatus, “keel-shaped,” referring to the morphological similarity to the bottom of a boat.

Type Specimens: Lectotype –ROM8463a in the Royal Ontario Museum, Toronto, Canada.
Other species:

Burgess Shale and vicinity: none

Other deposits: H. reesei Babcock & Robinson, 1988 (type species), from the lower Middle Cambrian Spence Shale and elsewhere in Utah; H.? cf. carinatus from the Middle Cambrian Kaili deposit in China (Chen et al., 2003).

Age & Localities:

Age:
Middle Cambrian, Albertella Zone to Bathyuriscus-Elrathina Zone (approximately 505 million years ago).
Principal localities:

The Walcott, Raymond and Collins Quarries on Fossil Ridge, the Trilobite Beds on Mount Stephen and Stanley Glacier in Kootenay National Park.

History of Research:

Brief history of research:

Matthew described Hyolithes carinatus from the Trilobite Beds in 1899 based on five incomplete specimens. Babcock and Robison (1988) reviewed the original fossils, along with additional specimens collected by the Royal Ontario Museum from various Burgess Shale localities. They concluded that the species carinatus didn’t belong in Hyolithes, and established a new genus, Haplophrentis, to accommodate it.

Description:

Morphology:

Like all hyoliths, Haplophrentis had a weakly-mineralized skeleton that grew by accretion, consisting of a conical living shell (conch), capped with a clam-like “lid” (operculum), with two slender, curved and rigid structures known as “helens” protruding from the shell’s opening. The function of these helens is still debated, but one possibility was to allow settlement and stabilization on the sea floor. Haplophrentis had a wiggly gut whose preserved contents are similar to the surrounding mud.

H. carinatus usually grew to around 25 mm in length, although some specimens reached as much as 40 mm; the species is distinguished from H. reesei, its cousin from Utah, by the faint grooves on its upper surface, the more pronounced net-like pattern on its “lid” (operculum), and its wider, more broadly-angled living shell (conch).

Haplophrentis can be distinguished from the similar hyolith genus Hyolithes because it bears a longitudinal wall running down the inner surface of the top of its living-shell.

Abundance:

Haplophrentis is relatively common on Fossil Ridge and in the Walcott Quarry in particular, accounting for 0.35% of the community there (Caron and Jackson, 2008).

Maximum Size:
40 mm

Ecology:

Life habits: Stanley Glacier
Feeding strategies: Stanley Glacier
Ecological Interpretations:

Haplophrentis probably moved very little; its helens appear unsuited for use in locomotion (See Butterfield and Nicholas, 1996; Martí Mus and Bergström, 2005; Runnegar et al., 1975). Whilst Haplophrentis feeding mode remains somewhat conjectural, it probably consumed small organic particles from the seafloor. Numerous specimens have been found in aggregates or in the gut of the priapulid worm Ottoia prolifica suggesting Haplophrentis was actively preyed upon and ingested (Conway Morris, 1977; Babcock and Robison, 1988).

References:

BABCOCK, L. E. AND R. A. ROBISON. 1988. Taxonomy and paleobiology of some Middle Cambrian Scenella (Cnidaria) and hyolithids (Mollusca) from western North America. University of Kansas Paleontological Contributions, Paper, 121: 1-22.

BUTTERFIELD, N. J. AND C. NICHOLAS. 1996. Burgess Shale-type preservation of both non-mineralizing and “shelly” Cambrian organisms from the Mackenzie Mountains, Northwestern Canada. Journal of Paleontology, 70: 893-899.

CARON, J.-B. AND D. A. JACKSON. 2008. Paleoecology of the Greater Phyllopod Bed community, Burgess Shale. Palaeogeography, Palaeoclimatology, Palaeoecology, 258: 222-256.

CHEN, X. Y. ZHAO AND P. WANG. 2003. Preliminary research on hyolithids from the Kaili Biota, Guizhou. Acta Micropalaeontologica Sinica, 20: 296-302.

CONWAY MORRIS, S. 1977. Fossil priapulid worms. Special Papers in Palaeontology, 20: 1-95.

MALINKY, J. M. AND E. L. YOCHELSON. 2007. On the systematic position of the Hyolitha (Kingdom Animalia). Memoir of the Association of Australasian Palaeontologists, 34: 521-536.

MARTÍ MUS, M. AND J. BERGSTRÖM. 2005. The morphology of hyolithids and its functional implications. Palaeontology, 48:1139-1167.

MATTHEW, G. F. 1899. Studies on Cambrian faunas, No. 3. Upper Cambrian fauna of Mount Stephen, British Columbia. The trilobites and worms. Transactions of the Royal Society of Canada, Series 2, 4: 39-66.

RUNNEGAR, B., J. POJETA, N. J. MORRIS, J. D. TAYLOR, M. E. TAYLOR AND G. MCCLUNG. 1975. Biology of the Hyolitha. Lethaia, 8: 181-191.

Other Links:

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

http://www.kumip.ku.edu/cambrianlife/Utah-Mollusks-Hyolithids.html



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Diagoniella hindei

3D animation of Diagoniella cyathiformis and other sponges (Choia ridleyi, Eiffelia globosa, Hazelia conferta, Pirania muricata, Vauxia bellula, and Wapkia elongata) and Chancelloria eros a sponge-like form covered of star-shaped spines.

Animation by Phlesch Bubble © Royal Ontario Museum

Taxonomy:

Kingdom: Stanley Glacier
Phylum: Stanley Glacier
Higher Taxonomic assignment: Hexactinellida (Order: Reticulosa)
Species name: Diagoniella hindei
Remarks:

Diagoniella is placed in the Family Protospongiidae (primitive hexactinellids) and may be confused with Protospongia (Rigby, 1986). Hexactinellid sponges (glass sponges) have a skeleton composed of four to six-pointed siliceous spicules. They are considered to be an early branch within the Porifera phylum due to their distinctive composition.

Described by: Walcott
Description date: 1920
Etymology:

Diagoniella – from the Greek dia, “throughout, during or across”, and gon, “corner, joint or angle” refering to the diagonal spicules of this sponge.

hindei – for Dr. G. J. Hinde, a British palaeontologist who worked on fossil sponges.

Type Specimens: Lectotype –USNM66503 (D. hindei), in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA. (D. cyathiformis type and repository information unknown.)
Other species:

Burgess Shale and vicinity: D. cyathiformis (Dawson, 1889) from the Trilobite Beds and Tulip Beds on Mount Stephen, Walcott Quarry on Fossil Ridge and Stanley Glacier (Caron et al., 2010).

Other deposits: D. coronata Dawson, 1890 from the Ordovician of Québec at Little Métis.

Age & Localities:

Age:
Middle Cambrian, Bathyuriscus-Elrathina Zone to late Middle Cambrian Bolaspidella Assemblage Zone (approximately 505 million years ago). Back to top
Principal localities:

Burgess Shale and vicinity: This sponge has been found at the Walcott Quarry on Fossil Ridge, the Trilobite Beds and Tulip Beds (S7) localities on Mount Stephen and from Stanley Glacier in Kootenay National Park.

Other deposits: D. cyathiformis (Dawson, 1889) from the Ordovician of Québec at Little Métis to the Middle Cambrian Wheeler and Marjum Formations in Utah (for D. cyathiformis) D. hindei Walcott, 1920 from the Cambrian of Utah and Nevada as well (Rigby, 1978, 1983).

History of Research:

Brief history of research:

Diagoniella was described by Rauff in 1894 as a subgenus of Protospongia. Walcott described a new species, D. hindei, in his 1920 monograph of the sponges from the Burgess Shale and made Diagoniella a valid genus, considering it distinct from Protospongia. Ribgy (1986) restudied the sponges of the Burgess Shale including D. hindei and Rigby and Collins (2004) concluded that another species, known in other Cambrian deposits, D. cyathiformis, is also present in the Burgess Shale.

Description:

Morphology:

D. hindei is a small and simple conical sac-like sponge. The skeleton is composed of diagonally orientated coarse spicules along the length of the sponge. These spicules are known as stauracts, and differ from the normal six rayed spicules of the hexactinellid sponges in that they have two rays reduced which gives them a distinctive cross-shape. The spicules knit together to form a net, although, unlike some hexactinellid sponges this net is not fused, which make the sponges very delicate. D. cyathiformis is a larger (up to 120 mm) and more elongate, conical species. The long spicules form a tuft-like root structure at the base of the sponge.

Abundance:

Diagoniella is relatively common but represents only 0.24% of the Walcott Quarry community (Caron and Jackson, 2008).

Maximum Size:
18 mm

Ecology:

Life habits: Stanley Glacier
Feeding strategies: Stanley Glacier
Ecological Interpretations:

Diagoniella would have lived attached to the sea floor. Particles of organic matter were extracted from the water as they passed through canals in the sponge’s wall.

References:

CARON, J.-B. AND D. A. JACKSON. 2008. Paleoecology of the Greater Phyllopod Bed community, Burgess Shale. Palaeogeography, Palaeoclimatology, Palaeoecology, 258: 222-256.

CARON, J.-B., R. GAINES, G. MANGANO, M. STRENG AND A. DALEY. 2010. A new Burgess Shale-type assemblage from the “thin” Stephen Formation of the Southern Canadian Rockies. Geology, 38: 811-814.

RIGBY, J. K. 1978. Porifera of the Middle Cambrian Wheeler Shale, from the Wheeler Amphitheater, House Range, in Western Utah. Journal of Paleontology, 52: 1325-1345.

RIGBY, J. K. 1983. Sponges of the Middle Cambrian Marjum Limestone from the House Range and Drum Mountains of Western Millard County, Utah. Journal of Paleontology, 57: 240-270.

RIGBY, J. K. 1986. Sponges of the Burgess Shale (Middle Cambrian), British Columbia. Palaeontographica Canadiana, 2: 105 p.

RIGBY, J. K. AND D. COLLINS. 2004. Sponges of the Middle Cambrian Burgess Shale and Stephen Formations, British Columbia. Royal Ontario Museum Contributions in Science (1): 155 p.

WALCOTT, C. D. 1920. Middle Cambrian Spongiae. Cambrian Geology and Paleontology IV. Smithsonian Miscellaneous Collections, 67(6): 261-365.

Other Links:

None



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Mollisonia symmetrica

Mollisonia symmetrica (USNM 57659) – Holotype. Exoskeleton preserved in dorsal view. Specimen length = 48 mm. Specimen dry – direct light (with different angles of low angle light). Trilobite Beds on Mount Stephen.

© SMITHSONIAN INSTITUTION – NATIONAL MUSEUM OF NATURAL HISTORY. PHOTOS: JEAN-BERNARD CARON

Taxonomy:

Kingdom: Stanley Glacier
Phylum: Stanley Glacier
Higher Taxonomic assignment: Unranked clade (stem group arthropods)
Species name: Mollisonia symmetrica
Remarks:

The affinity of Mollisonia has not been considered in detail because the appendages are unknown and the specimens are poorly preserved.

Described by: Walcott
Description date: 1912
Etymology:

Mollisonia – from Mount Mollison (2,952 m), southwest of Field in British Columbia, named by Joseph H. Scattergood in 1898 after the Mollison sisters, who managed some of the Canadian Pacific Railway hotels in the Rocky Mountains.

symmetrica – from the Greek syn, “plus,” and metron, “measure,” referring to the symmetrical nature of the body.

Type Specimens: Holotype –USNM57659 (M. symmetrica) in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: A possible new species from Stanley Glacier (Caron et al., 2010).

Other deposits: M. sinica from the Middle Cambrian Kaili Formation of southwest China (Zhang et al., 2002).

Age & Localities:

Age:
Middle Cambrian, Bathyuriscus-Elrathina Zone (approximately 505 million years ago).
Principal localities:

The Walcott Quarry on Fossil Ridge. A few specimens potentially representing different species are known from the Trilobite Beds on Mount Stephen and Stanley Glacier.

History of Research:

Brief history of research:

Two definite species of Mollisonia were originally described by Walcott (1912), M. symmetricaand M. gracilis, based on one specimen each. A second specimen of M. gracilis discovered in 1925 and preserved with soft-tissues was removed from the genus and renamed Houghtonites gracilis by Raymond (1931). A third possible species, Mollisonia? rara, was described from several fragmentary specimens. Simonetta and Delle Cave (1975) restudied these specimens and synonymized Mollisonia? rara with M. symmetrica. Specimens of M. symmetrica have also been found in the Wheeler Formation and Spence Shale of Utah (Robison, 1991; Briggs et al. 2008).

Description:

Morphology:

The body of M. symmetica is elongated and symmetrical, with a convex dorsal surface. The rounded head shield has two anterior projections and several pairs of central oval structures. The body consists of seven thoracic segments that are all of equal width. The tail shield is rounded and of similar shape to the head shield, but with three posterior projections.

Abundance:

One specimen of M. symmetrica is known from the Mount Stephen Trilobite beds. A few dozen specimens are known from the Walcott Quarry where itrepresents less than 0.04% of the community (Caron and Jackson, 2008).

Maximum Size:
79 mm

Ecology:

Life habits: Stanley Glacier
Feeding strategies: Stanley Glacier
Ecological Interpretations:

Mollisonia symmetrica is too poorly known to allow detailed studies of its ecology but comparisons with a related form called Hougthonites gracilis suggest a nektobenthic lifestyle.

References:

BRIGGS, D. E. G., B. S. LIEBERMAN, J. R. HENDRICKS, S. L. HALGEDAHL AND R. D. JARRARD. 2008. Middle Cambrian arthropods from Utah. Journal of Paleontology, 82(2): 238-254.

CARON, J.-B. AND D. A. JACKSON. 2008. Paleoecology of the Greater Phyllopod Bed community, Burgess Shale. Palaeogeography, Palaeoclimatology, Palaeoecology, 258: 222-256.

CARON, J.-B., R. GAINES, G. MANGANO, M. STRENG AND A. DALEY. 2010. A new Burgess Shale-type assemblage from the “thin” Stephen Formation of the Southern Canadian Rockies. Geology, 38: 811-814.

RAYMOND, P. E. 1931. Notes on invertebrate fossils, with descriptions of new species. Bulletin of the Museum of Comparative Zoology, Harvard University, 55: 165-213.

ROBISON, R. A. 1991. Middle Cambrian biotic diversity: Examples from four Utah Lagerstätten, p. 77-98. In A. Simonetta and S. Conway Morris (eds.), The Early Evolution of Metazoa and the Significance of Problematic Taxa. Cambridge University Press, Cambridge.

SIMONETTA, A. M. AND L. DELLE CAVE. 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: 1-37.

WALCOTT, C. D. 1912. Cambrian Geology and Paleontology II. Middle Cambrian Branchiopoda, Malacostraca, Trilobita and Merostomata. Smithsonian Miscellaneous Collections, 57(6): 145-228.

ZHANG, X., Y. ZHAO, R. YANG AND D. SHU. 2002. The Burgess Shale arthropod Mollisonia(M. sinica new species): New occurrence from the Middle Cambrian Kaili fauna of southwest China. Journal of Paleontology, 76: 1106-1108.

Other Links:

None



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Anomalocaris canadensis

3D animation of Anomalocaris canadensis.

Animation by Phlesch Bubble © Royal Ontario Museum

Taxonomy:

Kingdom: Stanley Glacier
Phylum: Stanley Glacier
Higher Taxonomic assignment: Order Radiodonta, Family Anomalocarididae
Species name: Anomalocaris canadensis
Remarks:

Anomalocaris is the most iconic member of Radiodonta, the extinct group of arthropods characterized by a circular tooth-lined mouth and a single pair of jointed frontal appendages (Collins 1996). Within this group, Anomalocaris belongs to the eponymous family Anomalocarididae, which possess long, multisegmented grasping appendages with numerous trident-like spines (Vinther et al. 2014).

Described by: Whiteaves
Description date: 1892
Etymology:

Anomalocaris – from the Greek anomoios, “unlike,” and the Latin caris, “crab” or “shrimp,” thus, “unlike other shrimp.”

canadensis – from Canada, the country where the Burgess Shale is located.

Type Specimens: Lectotype – GSC3418 in the Geological Survey of Canada, Ottawa, Canada.
Other species:

Burgess Shale and vicinity: none.

Other deposits:

Other deposits: Several species have been described from widely distributed deposits, including Anomalocaris pennsylvanica from the Kinzers Formation, USA (Pates and Daley 2018), Anomalocaris magnabasis from the Pioche and Carrara Formations (Pates et al. 2019), A. cf. canadensis from the Emu Bay Shale, Australia (Daley et al. 2013), A. cf. canadensis. from the Eager Formation (Briggs 1979), British Columbia, Canada, and possibly A. sp. from the Balang Formation of China (Liu 2013). As a consequence of the complex history of research on Anomalocaris (see below), several species previously assigned to this genus likely belong to other genera (e.g., Daley et al., 2013; Wang et al., 2013; Wu et al., 2021), but not all have yet been reassigned.

Age & Localities:

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

The Collins, Raymond and Walcott Quarries on Fossil Ridge. The Trilobite Beds, Tulip Beds (S7) and the Collins Quarry on Mount Stephen. Additional localities on Mount Field, Mount Stephen, and near Stanley Glacier.

History of Research:

Brief history of research:

Anomalocaris famously has a complex history of description because parts of its body were described in isolation before it was realized they all belonged to the same animal. The frontal appendage of Anomalocaris was described by Whiteaves (1892) as the body of a shrimp. The mouth parts were described by Walcott (1911) as a jellyfish called Peytoia nathorsti. A full body radiodontan specimen was originally described as the sea cucumber Laggania cambria (Walcott 1911), and re-examined by Conway Morris (1978) who concluded it was a superimposition of the “jellyfish” Peytoia nathorsti on top of a sponge. Henriksen (1928) attached Anomalocaris to the carapace of Tuzoia, but Briggs (1979) suggested instead that it was the appendage of an unknown arthropod, an idea that turned out to be correct. In the early 1980s, Harry Whittington was preparing an unidentified Burgess Shale fossil from the Geological Survey of Canada by chipping away layers of rock to reveal underlying structures, when he solved the mystery of Anomalocaris‘s identity. Much to his surprise, Whittington uncovered two Anomalocaris “shrimp” attached to the head region of a large body, which also had the “jellyfish” Peytoia as the mouth apparatus. Similar preparations of other fossils from the Smithsonian Institution in Washington DC revealed the same general morphology, including the Laggania cambria specimen studied by Conway Morris (1978), which was reinterpreted as a second species of Anomalocaris. Thus, Whittington and Briggs (1985) were able to describe two species: Anomalocaris canadensis, which had a pair of Anomalocaris appendages, and Anomalocaris nathorsti, which had a different type of frontal appendage and includes the original specimen of Laggania cambria and Peytoia nathorsti. Bergström (1986) re-examined the morphology and affinity of Anomalocaris and suggested it had similarities to the arthropods. Collecting at the Burgess Shale by the Royal Ontario Museum in the early 1990s led to the discovery of several complete specimens, which Collins (1996) used to reconstruct Anomalocaris canadensis with greater accuracy. This also led to a name change of Anomalocaris nathorsti to Laggania cambria, although it was later argued that the name Peytoia nathorsti had priority (Daley and Bergström 2012). Daley and Bergström (2012) re-examined the material and were the first to recognize that the mouthpart of A. canadensis was triradially organized, distinct from prior interpretations of a tetraradial organization as in Peytoia. Daley and Edgecombe (2014) conducted the most recent comprehensive revision of A. canadensis based on all available material. Anomalocaris has been the subject of many studies discussing its morphology (e.g. Moysiuk and Caron 2019; Paterson et al. 2020; Zeng et al. 2022), affinity (e.g., Chen et al., 2004; Daley et al., 2009; Hou et al., 1995; Vinther et al., 2014), ecology (e.g., Nedin, 1999; Rudkin, 1979; Vannier et al., 2014) and functional morphology (e.g., de Vivo et al., 2021; Sheppard et al., 2018; Usami, 2006).

Description:

Morphology:

Anomalocaris is a dorsoventrally flattened animal with a relatively flexible exoskeleton. It has a segmented body, with sixteen lateral swimming flaps bearing gills, and a prominent tail fan, which consists of three pairs of prominent fins that extend upward from the body (Daley and Edgecombe 2014). Repeated paired gut glands are associated with the body segments in some specimens. The head region bears one pair of frontal jointed appendages, two large dorsal eyes on stalks, three small rounded plates, and a ventrally oriented circular mouth apparatus (Whittington and Briggs 1985; Daley and Edgecombe 2014; Moysiuk and Caron 2019). The mouthparts are composed of three large, tubercle-covered plates separated by a series of smaller plates, all with orally-directed teeth (Daley and Bergström 2012). The frontal appendages are elongated and have fourteen segments, each with a pair of trident-like spikes projecting from the ventral surface (Briggs 1979). The most complete Anomalocaris specimen is 25 cm in length, although isolated fragments suggest individuals could reach a larger size, perhaps up to 100 cm.

Abundance:

The Anomalocaris frontal appendage is extremely common at the Mount Stephen Trilobite Beds, and several hundred specimens of isolated frontal appendages and mouth parts have been collected from Mount Stephen and the Raymond Quarry on Fossil Ridge (O’Brien and Caron 2016; Nanglu et al. 2020). These parts are relatively rare at Walcott Quarry, where fewer than 50 specimens are known (Caron and Jackson 2008). About ten complete body specimens are known from the Raymond Quarry.

Maximum Size:
About 100 cm.

Ecology:

Life habits: Stanley Glacier
Feeding strategies: Stanley Glacier
Ecological Interpretations:

The streamlined body would have been ideal for swimming. Undulatory movements of the lateral flaps propelled the animal through the water column and might have also served in gill ventilation (Whittington and Briggs 1985; Usami 2006). The tail fan would have enabled rapid turning, allowing Anomalocaris to chase fast-moving prey (Sheppard et al. 2018). A predatory lifestyle is suggested by the large eyes, frontal appendages with spines, gut glands, and spiny mouth apparatus (Whittington and Briggs 1985; Vannier et al. 2014). The frontal appendages are highly flexible, suggesting an ability to precisely manipulate prey items (de Vivo et al. 2021). The circular ring of plates around the mouth, shared with other radiodontans, is unique in the animal kingdom. Although the precise functioning of these mouthparts remains unclear, it seems likely that the plates could be pivoted to bring the teeth into contact with prey or to create suction to draw prey into the mouth (Daley and Bergström 2012). It has been suggested that Anomalocaris may have preyed on trilobites because some Cambrian trilobites have round or W-shaped healed wounds, interpreted as bite marks (Rudkin 1979), and large fecal pellets composed of trilobite parts have been found in the Cambrian rock record (Nedin 1999). It was proposed that Anomalocaris could have fed by grasping one end of the trilobite in the mouth apparatus and rocking the other end back and forth with the frontal appendages until the exoskeleton cracked (Nedin 1999). However, the non-biomineralized mouth apparatus of Anomalocaris was arguably too weak to penetrate the calcified shell of trilobites and it never shows any sign of breakage or wear, rendering this hypothesis less plausible (Whittington and Briggs 1985; Daley and Bergström 2012). Other Cambrian predators, such as larger trilobites, have been proposed as alternative candidates responsible for coprolites and trilobite injuries (Bicknell et al. 2021, 2022). It remains conceivable that Anomalocaris could have fed on freshly moulted “soft-shell” trilobites as well as other soft bodied organisms (Rudkin 2009).

References:

  • BERGSTRÖM, J. 1986. Opabinia Anomalocaris, unique Cambrian ‘arthropods’. Lethaia, 19: 241–246.
  • BICKNELL, R. D. C., HOLMES, J. D., PATES, S., GARCÍA-BELLIDO, D. C. and PATERSON, J. R. 2022. Cambrian carnage: Trilobite predator-prey interactions in the Emu Bay Shale of South Australia. Palaeogeography, Palaeoclimatology, Palaeoecology, 591: 110877.
  • BICKNELL, R. D. C., HOLMES, J. D., EDGECOMBE, G. D., LOSSO, S. R., ORTEGA-HERNÁNDEZ, J., WROE, S. and PATERSON, J. R. 2021. Biomechanical analyses of Cambrian euarthropod limbs reveal their effectiveness in mastication and durophagy. Proceedings of the Royal Society B, 288: 20202075.
  • BRIGGS, D. E. G. 1979. Anomalocaris: The largest known Cambrian arthropod. Palaeontology, 22: 631–664.
  • CARON, J.-B. and JACKSON, D. A. 2008. Paleoecology of the Greater Phyllopod Bed community, Burgess Shale. Palaeogeography, Palaeoclimatology, Palaeoecology, 258: 222–256.
  • CHEN, J., WALOSZEK, D. and MAAS, A. 2004. A new ‘great-appendage’ arthropod from the Lower Cambrian of China and homology of chelicerate chelicerae and raptorial antero-ventral appendages. Lethaia, 37: 3–20.
  • 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.
  • CONWAY MORRIS, S. 1978. Laggania cambria Walcott: a composite fossil. Journal of Paleontology, 52: 126–131.
  • DALEY, A. C. and BERGSTRÖM, J. 2012. The oral cone of Anomalocaris is not a classic ‘peytoia’. Naturwissenschaften, 99: 501–504.
  • DALEY, A. C.  and EDGECOMBE, G. D. 2014. Morphology of Anomalocaris canadensis from the Burgess Shale. Journal of Paleontology, 88: 68–91.
  • DALEY, A. C., BUDD, G. E., CARON, J.-B., EDGECOMBE, G. D. and COLLINS, D. 2009. The Burgess Shale anomalocaridid Hurdia and its significance for early euarthropod evolution. Science, 323: 1597–1600.
  • DALEY, A. C., PATERSON, J. R., EDGECOMBE, G. D., GARCÍA-BELLIDO, D. C. and JAGO, J. B. 2013. New anatomical information on Anomalocaris from the Cambrian Emu Bay Shale of South Australia and a reassessment of its inferred predatory habits. Palaeontology, 56: 971–990.
  • HENRIKSEN, K. L. 1928. Critical notes upon some Cambrian arthropods described from Charles D. Walcott. Videnskabelige Meddelelser fra Dansk Naturhistorisk Forening: Khobenhavn, 86: 1–20.
  • HOU, X., BERGSTRÖM, J. and AHLBERG, P. 1995. Anomalocaris and other large animals in the Lower Cambrian Chengjiang fauna of southwest China. GFF, 117: 163–183.
  • LIU, Q. 2013. The first discovery of anomalocaridid appendages from the Balang Formation (Cambrian Series 2) in Hunan, China. Alcheringa, 37: 338–343.
  • 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.
  • NANGLU, K., CARON, J.-B. and GAINES, R. R. 2020. The Burgess Shale paleocommunity with new insights from Marble Canyon, British Columbia. Paleobiology, 46: 58–81.
  • NEDIN, C. 1999. Anomalocaris predation on nonmineralized and mineralized trilobites. Geology, 27: 987–990.
  • O’BRIEN, L. J. and CARON, J. B. 2016. Paleocommunity analysis of the Burgess Shale Tulip Beds, Mount Stephen, British Columbia: Comparison with the Walcott Quarry and implications for community variation in the Burgess Shale. Paleobiology, 42: 27–53.
  • PATERSON, J. R., EDGECOMBE, G. D. and GARCÍA-BELLIDO, D. C. 2020. Disparate compound eyes of Cambrian radiodonts reveal their developmental growth mode and diverse visual ecology. Science Advances, 6: eabc6721.
  • PATES, S. and DALEY, A. C. 2018. The Kinzers Formation (Pennsylvania, USA): The most diverse assemblage of Cambrian Stage 4 radiodonts. Geological Magazine, 156: 1233–1246.
  • PATES, S. and DALEY, A. C, EDGECOMBE, G. D., CONG, P. and 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: 235–262.
  • RUDKIN, D. M. 1979. Healed injuries in Ogygosis klotzi (Trilobita) from the Middle Cambrian of British Columbia. Royal Ontario Museum, Life Sciences Occasional Paper, 32: 1–8.
  • RUDKIN, D. M. 2009. The Mount Stephen Trilobite Beds. In CARON, J.-B. and RUDKIN, D. M. (eds.) A Burgess Shale Primer – History, Geology, and Research Highlights, The Burgess Shale Consortium, Toronto, 90–102 pp.
  • 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.
  • VINTHER, J., STEIN, M., LONGRICH, N. R. and HARPER, D. A. T. 2014. A suspension-feeding anomalocarid from the Early Cambrian. Nature, 507: 496.
  • DE VIVO, G., LAUTENSCHLAGER, S. and VINTHER, J. 2021. Three-dimensional modelling, disparity and ecology of the first Cambrian apex predators. Proceedings of the Royal Society B, 288: 20211176.
  • WALCOTT, C. D. 1911. Middle Cambrian holothurian and medusae. Smithsonian Miscellaneous Collections, 57: 41–68.
  • WANG, Y. Y., HUANG, D. Y. and HU, S. X. 2013. New anomalocardid frontal appendages from the Guanshan biota, eastern Yunnan. Chinese Science Bulletin, 58: 3937–3942.
  • WHITEAVES, J. F. 1892. Description of a new genus and species of phyllocarid Crustacea from the Middle Cambrian of Mount Stephen, B.C. Canadian Record of Science, 5: 205–208.
  • 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.
  • WU, Y., FU, D., MA, J., LIN, W., SUN, A. and ZHANG, X. 2021. Houcaris gen. nov. from the early Cambrian (Stage 3) Chengjiang Lagerstätte expanded the palaeogeographical distribution of tamisiocaridids (Panarthropoda: Radiodonta). PalZ, 95: 209–221.
  • ZENG, H., ZHAO, F. and ZHU, M. 2022. Innovatiocaris, a complete radiodont from the early Cambrian Chengjiang Lagerstätte and its implications for the phylogeny of Radiodonta. Journal of the Geological Society, jgs2021-164:.
Other Links:

www.trilobites.info/anohome.html

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



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Micromitra burgessensis

3D animation of Micromitra burgessensis and other brachiopods (Acrothyra gregaria, Diraphora bellicostata, Nisusia burgessensis, and Paterina zenobia).

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Kingdom: Stanley Glacier
Phylum: Stanley Glacier
Higher Taxonomic assignment: Paterinata (Order: Paterinida)
Species name: Micromitra burgessensis
Remarks:

Micromitra belongs within the Family Paterinidae.

Described by: Walcott
Description date: 1908
Etymology:

Micromitra – from the Greek mikros, “small,” and mitra, “turban.”

burgessensis – 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 –USNM69646 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none to date. The Burgess Shale brachiopods, in particular from the Trilobite Beds on Mount Stephen, need to be re-examined (see also Brief history of research).

Other deposits: Numerous species, all from the Cambrian, are known worldwide.

Age & Localities:

Age:
Middle Cambrian, Bathyuriscus-Elrathina Zone (approximately 505 million years ago).
Principal localities:

The Walcott and Raymond Quarries on Fossil Ridge. Additional localities are known on Mount Field, Mount Stephen, and near Stanley Glacier.

History of Research:

Brief history of research:

Originally identified as Micromitra (Iphidella) pannula by Walcott (1908) from the Trilobite Beds on Mount Stephen (see also Walcott, 1912), it was redescribed as a new species by Resser (1938). Resser’s description fails to distinguish Micromitra burgessensis from any other species of the genus, it was based upon only a single valve, and it was not illustrated. The validity of this species is questionable and needs reassessment.

Description:

Morphology:

This species is the most ornamented of the Burgess Shale brachiopods. The shell was originally mineralized. It has pronounced growth lines and fine raised lines which cut obliquely across the shell. The intersection between the different lines creates small diamonds on the surface of the shell. The valves are subcircular with the hinge nearly straight. Perhaps the most striking of the preserved features of this animal are long and slender bristles (setae) which extend far beyond the margins of the shell. These would have been attached to the edge of the mantle along both the dorsal and ventral valves.

Abundance:

Micromitra burgessensis is relatively common in the Walcott Quarry but overall represents a small fraction of the fauna (<0.3%) (Caron and Jackson, 2008). This species is also present in the Raymond Quarry on Fossil Ridge.

Maximum Size:
10 mm

Ecology:

Life habits: Stanley Glacier
Feeding strategies: Stanley Glacier
Ecological Interpretations:

Many specimens of Micromitra burgessensis are preserved attached to spicules of the sponge Pirania, suggesting that this species was epibenthic, supported above the sediment-water interface. In this way the brachiopod would have been relatively protected from flocculent mud travelling along the sediment-water interface, which could have been detrimental to its filter-feeding apparatus (located between the shells) called a lophophore – The bristles might have also helped reduce mud particles.

References:

CARON, J.-B. AND D. A. JACKSON. 2008. Paleoecology of the Greater Phyllopod Bed community, Burgess Shale. Palaeogeography, Palaeoclimatology, Palaeoecology, 258: 222-256.

RESSER, C. E. 1938. Fourth contribution to nomenclature of Cambrian Fossils. Smithsonian Miscellaneous Collections, 97: 1-43.

WALCOTT, C. 1908. Mount Stephen rocks and fossils. Canadian Alpine Journal, 1: 232-248.

WALCOTT, C. D. 1912. Cambrian Brachiopoda. United States Geological Survey, Monograph, 51: part I, 812 p; part II, 363 p.

Other Links:

None



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Herpetogaster collinsi

3D animation of Herpetogaster collinsi.

Animation by Phlesch Bubble © Royal Ontario Museum

Taxonomy:

Kingdom: Stanley Glacier
Phylum: Stanley Glacier
Higher Taxonomic assignment: Unranked clade Cambroernida (stem group ambulacrarians)
Species name: Herpetogaster collinsi
Remarks:

Herpetogaster, together with other pedunculate or discoidal fossils such as Eldonia, probably belongs in the stem group to a clade known as the Ambulacraria, represented by both echinoderms and hemichordates (Caron et al., 2010).

Described by: Caron and Conway Morris
Description date: 2010
Etymology:

Herpetogaster – from the Greek, herpo, “to creep,” and gaster, “stomach.” The name refers to the creeping aspect of the animal and the large stomach.

collinsi – after Desmond Collins, a former curator of palaeontology at the Royal Ontario Museum who led expeditions to the Burgess Shale between 1975-2000.

Type Specimens: Holotype –ROM58051 in the Royal Ontario Museum, Toronto, Canada.
Other species:

Burgess Shale and vicinity: none.

Other deposits: none.

Age & Localities:

Age:
Middle Cambrian, Bathyuriscus-Elrathina Zone (approximately 505 million years ago).
Principal localities:

The Walcott and Raymond Quarries on Fossil Ridge. The Collins Quarry on Mount Stephen and Stanley Glacier in Kootenay National Park.

History of Research:

Brief history of research:

Herpetogaster was described in 2010 as a possible member of the ambulacrarians (Caron and Conway Morris, 2010).

Description:

Morphology:

Herpetogaster consists of a main body with a pair of tentacles at the front and a flexible stolon. The body is divided into thirteen segments and coils clockwise when seen dorsally. The tentacles are long and flexible and branch several times. The stomach is the most conspicuous portion of the gut and is often preserved as a highly reflective film, as in Eldonia, a closely related form. The anus is terminal and the mouth is located between the tentacles. The stolon sometimes exceeds the length of the main body, and terminates with a flat disk. This structure was evidently used for anchoring the organism to the seabed, or to other organisms).

Abundance:

This animal is known from 101 specimens. Only 6 come from the Walcott Quarry, where it represents only 0.011% of the specimens counted in the community (Caron and Jackson, 2008); most specimens (68) come from the Raymond Quarry.

Maximum Size:
48 mm

Ecology:

Life habits: Stanley Glacier
Feeding strategies: Stanley Glacier
Ecological Interpretations:

Specimens of Herpetogaster were found associated with the sponge Vauxia, suggesting the animal lived on or near the seabed. It is not clear if Herpetogaster was permanently anchored, and whether or not it fed only on particulate matter in the water column, or could hunt small preys using its prehensile tentacles.

References:

CARON, J.-B. AND D. A. JACKSON. 2008. Paleoecology of the Greater Phyllopod Bed community, Burgess Shale. Palaeogeography, Palaeoclimatology, Palaeoecology, 258: 222-256.

CARON, J.-B., S. CONWAY MORRIS AND D. SHU. 2010. Tentaculate fossils from the Cambrian of Canada (British Columbia) and China (Yunnan) interpreted as primitive deuterostomes. PLoS ONE, 5(3): e9586.

Other Links:

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0009586