Media: Drawing



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Balhuticaris voltae

Balhuticaris voltae, holotype ROMIP 66238

Taxonomy:

Kingdom: Drawing
Phylum: Drawing
Higher Taxonomic Assignment: Hymenocarines, Family: Odaraiidae
Species name: Balhuticaris voltae
Remarks:

Hymenocarines were early arthropods with bivalved carapaces and mandibles, forming the bulk of the first mandibulates (represented today by myriapods, crustaceans and insects) (Aria and Caron 2017; Vannier et al. 2018). In many hymenocarines, including Balhuticaris, determining the exact number and types of appendages in their head remains difficult, which hinders a detailed understanding of the evolutionary relationships inside this group. Balhuticaris most probably belongs to the family Odaraiidae, a group of hymenocarines with highly multisegmented bodies, reduced or absent antennae and highly multisegmented legs.

Described by: Izquierdo-López & Caron
Description date: 2022
Etymology:

Balhuticaris–from the mythological creature Balhut, a giant aquatic animal in some Persian cosmologies, and the latin caris, meaning “crab” or “shrimp”, and voltae- from the Catalan word volta, an arch-like structure.

Type Specimens: Holotype ROMIP66238
Other species:

Burgess Shale and vicinity: None
Other deposits: None

Age & Localities:

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

Marble Canyon, Tokumm Creek

History of Research:

Brief history of research:

Balhuticaris has been found from both the Marble Canyon and the Tokumm Creek localities of the Burgess Shale during several expeditions between 2012 to 2022. The different specimens of Balhuticaris were originally not recognized as belonging to the same organism. Instead, these were identified as different undescribed euarthropods or potential radiodonts (Nanglu et al. 2020). Balhuticaris was formally described in 2022 (Izquierdo-López and Caron 2022).

Description:

Morphology:

Balhuticaris is a large bivalved arthropod that can reach up to 25 cm in length. The carapace only covers the first quarter of the total body length. It has a dome-like shape. In frontal view, the carapace looks like an arch: each valve extends towards the ventral side of the animal, surpassing the length of the legs. The dorsal side of the carapace extends towards the posterior side of the animal, giving the valves a “bean-like” shape in lateral view. The head bears a pair of well-developed, pedunculate, bilobate eyes. The head also bears one pair of short antennulae and a sclerotized structure that may represent a head sclerite. The body is highly multisegmented, with approximately 110 segments posterior to the head. Approximately the first ten segments are longer, and bear legs that become smaller towards the head. All segments bear a pair of legs, each subdivided into two branches (biramous): a walking leg (endopod) and a paddle-like flap (exopod). The endopod is thin and subdivided into around 14 segments. The exopod is ovoid, almost as long as the endopod. The last segment is longer than the rest, and has a flattened triangular shape. This segment bears two paddle-like legs (caudal rami). Each of these is subdivided into three segments, bears three spines on their outer edge and elongated filaments (setae) on their posterior edge.

Abundance:

Balhuticaris is rare, only known from a dozen specimens from the Marble Canyon and Tokumm Creek sites.

Maximum Size:
About 25 cm

Ecology:

Life habits: Drawing
Feeding strategies: Drawing
Ecological Interpretations:

Balhuticaris is the largest bivalved arthropod to date, surpassing in length Tuzoia (Vannier et al. 2007) and Nereocaris exilis (Legg et al. 2012), and rivalling other arthropods from the Burgess Shale, such as radiodonts, including the largest complete Anomalocaris (Briggs 1975) and Cambroraster (Moysiuk and Caron 2019), but smaller than the estimated 50 cm long Titanokorys (Caron and Moysiuk 2021). The general anatomy of Balhuticaris, including its elongated body and large segmented caudal rami, indicates that it was probably a good swimmer. It was hypothesized that it could be swimming upside-down (Izquierdo-López and Caron 2022), similar to its relatives Fibulacaris and Odaraia (Briggs 1981; Izquierdo-López and Caron 2019). Balhuticaris’ feeding could have ranged from suspension-feeder to predator (Izquierdo-López and Caron 2022), similar to some of the largest fairy shrimps today (Fryer 1966).

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. 1975. Anomalocaris, the largest known Cambrian arthropod. Palaeontology, 22: 631–664.
  • 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.
  • CARON, J.-B. and MOYSIUK, J. 2021. A giant nektobenthic radiodont from the Burgess Shale and the significance of hurdiid carapace diversity. Royal Society Open Science, 8: 210664.
  • FRYER, G. 1966. Branchinecta gigas Lynch, a non‐filter‐feeding raptatory anostracan, with notes on the feeding habits of certain other anostracans. Proceedings of the Linnean Society of London, 177: 19–34.
  • IZQUIERDO-LÓPEZ, A. and CARON, J. B. 2019. A possible case of inverted lifestyle in a new bivalved arthropod from the Burgess Shale. Royal Society Open Science, 6: 191350:
  • IZQUIERDO-LÓPEZ, A. and CARON, J. B. 2021. A Burgess Shale mandibulate arthropod with a pygidium: a case of convergent evolution. Papers in Palaeontology, 7: 1877–1894.
  • IZQUIERDO-LÓPEZ, A. and CARON, J. B. 2022. Extreme multisegmentation in a giant bivalved arthropod from the Cambrian Burgess Shale. IScience, 25, 104675.
  • LEGG, D. A., SUTTON, M. D., EDGECOMBE, G. D. and CARON, J. B. 2012. Cambrian bivalved arthropod reveals origin of arthrodization. Proceedings of the Royal Society B: Biological Sciences, 279: 4699–4704.
  • 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: Biological Sciences, 286:201910.
  • NANGLU, K., CARON, J. and GAINES, R. 2020. The Burgess Shale paleocommunity with new insights from Marble Canyon, British Columbia. Paleobiology, 46(1): 58–81.
  • 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.
Other Links:


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Zacanthoides romingeri

Zacanthoides romingeri (figure 3) illustrated by Rominger (1887) as Embolimus spinosa.

Taxonomy:

Kingdom: Drawing
Phylum: Drawing
Higher Taxonomic assignment: Class Trilobita, Order Corynexochida
Species name: Zacanthoides romingeri
Remarks:

Trilobites are, by a large margin, the most diverse of extinct arthropod classes, encompassing more than 2000 species, although the biomineralization of their cuticle is likely largely responsible for their much better-known diversity. A recent probabilistic analysis of trilobite relationships suggests that many of the diagnostic traits used for the taxonomy of the main groups remain highly variable across lineages (Paterson, Edgecombe & Lee, 2019), which explains long-standing difficulties in resolving the trilobite evolutionary tree. The kinship of trilobites relative to other arthropod groups has been a historical dilemma also (Cotton & Braddy, 2004; Aria, Caron & Gaines, 2015; Paterson, 2020). Antennules and some other characters, on the one hand, would ally them with mandibulate arthropods (the Gnathomorpha or Antennulata hypothesis), while others would place them within the chelicerate lineage (the Arachnomorpha hypothesis). Recent phylogenetic results have brought increased support to Arachnomorpha, but there is still no consensus on the question (Aria, 2022).

Described by: Rominger
Description date: 1887
Etymology:

Zacanthoides – probably from the Greek z(a), “very,” and akanthion, “thistle” or “porcupine” or “hedgehog,” and oides, “resembling;” thus, very thistle- or porcupine-like.

romingeri – after Carl Rominger, a Michigan paleontologist who in 1887 published the first descriptions of trilobites from Mount Stephen.

Type Specimens: Type status under review – UMMP 4871 (2 specimens), University of Michigan Museum of Paleontology, Ann Arbor, Michigan, USA.
Other species:

Burgess Shale and vicinity: Zacanthoides sexdentatus, Z. submuticus, Z. longipygus, Z. planifrons, Z. divergens, all from older and younger Middle Cambrian rocks on Mount Stephen, Mount Odaray, and Park Mountain (Rasetti, 1951).

Other deposits: other species elsewhere in North America.

Age & Localities:

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

The Trilobite Beds on Mount Stephen.

History of Research:

Brief history of research:

In 1887 Carl Rominger published an engraving of a nearly complete and markedly spiny trilobite and named it Embolimus spinosa. In 1908 Charles Walcott introduced the combination Zacanthoides spinosus for the Mount Stephen species and for a similar trilobite from Nevada. The next change came in 1942, when Charles Resser at the United States National Museum asserted that the Mount Stephen species was sufficiently distinct that it required a new name. Resser chose to honour the man who first formally described many of the common Mount Stephen trilobites, and Zacanthoides romingeri remains the combination in use today.

Description:

Morphology:

Hard parts: adult dorsal exoskeletons can reach up to 6 cm in length, tapering back from a large crescentic cephalon through a thorax of nine segments, to a relatively small rounded-triangular pygidium with long marginal spines.

The wide free cheeks bear strong genal spines; short, thorn-like intragenal spines mark the posterior corners of the fixed cheeks. The glabella is long and narrow, slightly expanded forwards. There are four pairs of lateral glabellar furrows; the anterior two pairs are weaker and angled to the front, the stronger posterior two are angled back. Very long narrow eyes that bow strongly outward are located far back on the cephalon. The occipital ring extends rearward into a strong, broad-based spine. Long, blade-shaped terminal spines on the wide pleurae curve progressively more backwards. A slender needle-like spine arises from the axial ring of the eighth thoracic segment. There are four pygidial axial rings; five pairs of marginal spines, each successively shorter, are directed rearwards and extend beyond the tip of the pygidium.

Unmineralized anatomy: not known.

Abundance:

Zacanthoides romingeri is moderately abundant at the Mount Stephen Trilobite Beds but absent from Fossil Ridge. Complete trilobites with the free cheeks in place are very scarce, and this species is mostly found as disarticulated sclerites. Its distinctive characteristics, however, usually allow even isolated pieces to be readily identified.

Maximum Size:
60 mm

Ecology:

Life habits: Drawing
Feeding strategies: Drawing
Ecological Interpretations:

Zacanthoides romingeri adults very likely walked along the sea bed. The overall spinosity of this species may have served as a deterrent to predators, or possibly helped to break up the visual outline of the animal, making it harder to see on the sea floor (Rudkin, 1996).

References:

  • ARIA, C. (2022) The origin and early evolution of arthropods. Biological Reviews 97, 1786–1809.
  • ARIA, C., CARON, J.-B. & GAINES, R. (2015) A large new leanchoiliid from the Burgess Shale and the influence of inapplicable states on stem arthropod phylogeny. Palaeontology 58, 629–660.
  • COTTON, T.J. & BRADDY, S.J. (2004) The phylogeny of arachnomorph arthropods and the origin of the Chelicerata. Transactions of the Royal Society of Edinburgh-Earth Sciences 94, 169–193.
  • PATERSON, J.R. (2020) The trouble with trilobites: classification, phylogeny and the cryptogenesis problem. Geological Magazine 157, 35–46.
  • PATERSON, J.R., EDGECOMBE, G.D. & LEE, M.S.Y. (2019) Trilobite evolutionary rates constrain the duration of the Cambrian explosion. Proceedings of the National Academy of Sciences of the United States of America 116, 4394–4399.
  • RASETTI, F. 1951. Middle Cambrian stratigraphy and faunas of the Canadian Rocky Mountains. Smithsonian Miscellaneous Collections, 116 (5): 1-277.
  • RESSER, C. E. 1942. Fifth contribution to nomenclature of Cambrian trilobites. Smithsonian Miscellaneous Collections, 101 (15): 1-58.
  • ROMINGER, C. 1887. Description of primordial fossils from Mount Stephens, N. W. Territory of Canada. Proceedings of the Academy of Natural Sciences of Philadelphia, 1887: 12-19.
  • RUDKIN, D. M. 1996. The Trilobite Beds of Mount Stephen, Yoho National Park, p. 59-68. In R. Ludvigsen (ed.), Life in Stone – A Natural History of British Columbia’s Fossils. UBC Press, Vancouver.
  • RUDKIN, D. M. 2009. The Mount Stephen Trilobite Beds, p. 90-102. In J.-B. Caron and D. Rudkin (eds.), A Burgess Shale Primer – History, Geology, and Research Highlights. The Burgess Shale Consortium, Toronto.
  • SCHOLTZ, G. AND G. D. EDGECOMBE. 2006. The evolution of arthropod heads: reconciling morphological, developmental and palaeontological evidence. Development Genes and Evolution, 216: 395-415.
  • WALCOTT, C. D. 1888. Cambrian fossils from Mount Stephens, Northwest Territory of Canada. American Journal of Science, Series 3, 36: 163-166.
  • WALCOTT, C. D. 1908. Mount Stephen rocks and fossils. Canadian Alpine Journal, 1:232-248.
Other Links:

http://www.trilobites.info/ordcorynexochida.htm



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Kootenia burgessensis

Kootenia burgessensis (ROM 60761). Disarticulated specimen. Specimen dry – direct light (left) and coated with ammonium chloride sublimate to show details (right). Specimen length = 44 mm. Walcott Quarry.

© Royal Ontario Museum. Photo: Jean-Bernard Caron

Taxonomy:

Kingdom: Drawing
Phylum: Drawing
Higher Taxonomic assignment: Class Trilobita, Order Corynexochida
Species name: Kootenia burgessensis
Remarks:

Trilobites are, by a large margin, the most diverse of extinct arthropod classes, encompassing more than 2000 species, although the biomineralization of their cuticle is likely largely responsible for their much better-known diversity. A recent probabilistic analysis of trilobite relationships suggests that many of the diagnostic traits used for the taxonomy of the main groups remain highly variable across lineages (Paterson, Edgecombe & Lee, 2019), which explains long-standing difficulties in resolving the trilobite evolutionary tree. The kinship of trilobites relative to other arthropod groups has been a historical dilemma also (Cotton & Braddy, 2004; Aria, Caron & Gaines, 2015; Paterson, 2020). Antennules and some other characters, on the one hand, would ally them with mandibulate arthropods (the Gnathomorpha or Antennulata hypothesis), while others would place them within the chelicerate lineage (the Arachnomorpha hypothesis). Recent phylogenetic results have brought increased support to Arachnomorpha, but there is still no consensus on the question (Aria, 2022).

Described by: Resser
Description date: 1942
Etymology:

Burgess Shale and vicinity: Kootenia dawsoni. However, see below regarding a possible synonymy with the genus Olenoides.

Other deposits: other species attributed to Kootenia are widespread in the Cambrian of North America, and have been recorded in Greenland, China, Australia, and elsewhere.

Type Specimens: Holotype (K. burgessensis) – USNM65511 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA (Resser, 1942); Type status under review – (K. dawsoni), University of Michigan Museum of Paleontology, Ann Arbor, Michigan, USA.
Other species:

Burgess Shale and vicinity: Kootenia dawsoni; Olenoides serratus. (Species of Kootenia are no longer considered different enough from those in Olenoides to warrant placement in a separate genus, but Kootenia is retained here for ease of reference to historical literature).

Other deposits: other species attributed to Kootenia are widespread in the Cambrian of North America, and have been recorded in Greenland, China, Australia, and elsewhere.

Age & Localities:

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

The Walcott Quarry on Fossil Ridge, and nearby localities on Mount Field; K. dawsoni is known from the Trilobite Beds and elsewhere on Mount Stephen.

History of Research:

Brief history of research:

Kootenia burgessensis was established by Charles Resser based on material Walcott included in K. dawsoni. Kootenia originally appeared as a subgenus of Bathyuriscus in Walcott’s 1889 paper revising many of Rominger’s Mount Stephen trilobite identifications. Walcott named B. (Kootenia) dawsoni after G. M. Dawson of the Geological Survey of Canada as a replacement for what Rominger had illustrated as Bathyurus (?) in 1887. In 1908, Walcott followed G. F. Matthew (1899) in calling this Dorypyge (Kootenia) dawsoni, but regarded Kootenia as a full genus in 1918. Harry Whittington included Kootenia burgessensis in his 1975 redescription of Burgess Shale appendage-bearing trilobites, illustrating a single specimen showing biramous thoracic limbs on one side. In 1994, Melzak and Westrop pointed out that the diagnostic character of Kootenia (depth of “interpleural” furrows on the pygidium) showed intraspecific variability, and argued that Kootenia—and perhaps other dorypygids trilobites—may have to be subsumed within Olenoides. We maintain Kootenia as a separate genus here pending formal taxonomic clarification.

Description:

Morphology:

Hard parts: adult dorsal exoskeletons may reach 5.5 cm in length and are broadly oval in outline. In most general features, Kootenia burgessensis resembles the co-occurring Olenoides serratus, with a semi-circular cephalon bearing genal spines, a thorax of seven segments, and a semi-circular pygidium. In Kootenia, however, spines on the thoracic pleural tips and shorter and blunter, as are those around the margin of the pygidium; interpleural furrows on the pygidium are absent to very faint.

Unmineralized anatomy: based on evidence from just a few specimens, Kootenia burgessensis, like Olenoides serratus, had a pair of flexible, multi-jointed “antennae” followed by three pairs of biramous limbs on the cephalon. Pairs of similar biramous appendages were attached under each thoracic segment, with a smaller number under the pygidium. No specimens, however, show any evidence of posterior antenna-like cerci as in Olenoides.

Abundance:

Kootenia burgessensis is moderately common in the Walcott Quarry section on Fossil Ridge, as is Kootenia dawsoni in the Mount Stephen Trilobite Beds.

Maximum Size:
55 mm

Ecology:

Life habits: Drawing
Feeding strategies: Drawing
Ecological Interpretations:

Adult Kootenia burgessensis walked along the sea bed, possibly digging shallow furrows to locate small soft-bodied and weakly-shelled animals or carcasses. Kootenia could probably swim just above the sea bed for short distances. Tiny larvae and early juveniles probably swam and drifted in the water column.

References:

  • ARIA, C. (2022) The origin and early evolution of arthropods. Biological Reviews 97, 1786–1809.
  • ARIA, C., CARON, J.-B. & GAINES, R. (2015) A large new leanchoiliid from the Burgess Shale and the influence of inapplicable states on stem arthropod phylogeny. Palaeontology 58, 629–660.
  • COTTON, T.J. & BRADDY, S.J. (2004) The phylogeny of arachnomorph arthropods and the origin of the Chelicerata. Transactions of the Royal Society of Edinburgh-Earth Sciences 94, 169–193.
  • PATERSON, J.R. (2020) The trouble with trilobites: classification, phylogeny and the cryptogenesis problem. Geological Magazine 157, 35–46.
  • PATERSON, J.R., EDGECOMBE, G.D. & LEE, M.S.Y. (2019) Trilobite evolutionary rates constrain the duration of the Cambrian explosion. Proceedings of the National Academy of Sciences of the United States of America 116, 4394–4399.
  • 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, Vol. 5, Section IV:39-66.
  • MELZAK, A. AND S. R. WESTROP. 1994. Mid-Cambrian (Marjuman) trilobites from the Pika Formation, southern Canadian Rocky Mountains, Alberta. Canadian Journal of Earth Sciences, 31:969-985.
  • RASETTI, F. 1951. Middle Cambrian stratigraphy and faunas of the Canadian Rocky Mountains. Smithsonian Miscellaneous Collections, 116 (5): 1-277.
  • RESSER, C. E. 1942. Fifth contribution to nomenclature of Cambrian trilobites. Smithsonian Miscellaneous Collections, 101 (15): 1-58.
  • RESSER, C. E. 1942. Fifth contribution to nomenclature of Cambrian trilobites. Smithsonian Miscellaneous Collections, 101 (15): 1-58.
  • ROMINGER, C. 1887. Description of primordial fossils from Mount Stephens, N. W. Territory of Canada. Proceedings of the Academy of Natural Sciences of Philadelphia, 1887: 12-19.
  • SCHOLTZ, G. AND G. D. EDGECOMBE. 2006. The evolution of arthropod heads: reconciling morphological, developmental and palaeontological evidence. Development Genes and Evolution, 216: 395-415.
  • WALCOTT, C. 1889. Description of new genera and species of fossils from the Middle Cambrian. United States National Museum, Proceedings for 1888:441-446.
  • WALCOTT, C. D. 1908. Mount Stephen rocks and fossils. Canadian Alpine Journal, 1: 232-248.
  • WALCOTT, C. 1918. Cambrian Geology and Paleontology IV. Appendages of trilobites. Smithsonian Miscellaneous Collections, 67(4): 115-216.
  • WHITTINGTON, H. B. 1975. Trilobites with appendages from the Middle Cambrian, Burgess Shale, British Columbia. Fossils and Strata, No. 4: 97-136.
Other Links:

http://www.trilobites.info/ordcorynexochida.htm



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Hurdia victoria

3D animation of Hurdia victoria.

Animation by Phlesch Bubble © Royal Ontario Museum

Taxonomy:

Kingdom: Drawing
Phylum: Drawing
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: Drawing
Feeding strategies: Drawing
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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Elrathina cordillerae

Elrathina cordillerae (ROM 53273). Complete individual; a presumed carcass with free cheeks in place (coated with ammonium chloride sublimate to show details). Specimen length = 24 mm. Specimen dry – direct light. Mount Stephen Trilobite Beds on Mount Stephen.

© Royal Ontario Museum. Photo: Jean-Bernard Caron

Taxonomy:

Kingdom: Drawing
Phylum: Drawing
Higher Taxonomic assignment: Class Trilobita, Order Ptychopariida
Species name: Elrathina cordillerae
Remarks:

Trilobites are, by a large margin, the most diverse of extinct arthropod classes, encompassing more than 2000 species, although the biomineralization of their cuticle is likely largely responsible for their much better-known diversity. A recent probabilistic analysis of trilobite relationships suggests that many of the diagnostic traits used for the taxonomy of the main groups remain highly variable across lineages (Paterson, Edgecombe & Lee, 2019), which explains long-standing difficulties in resolving the trilobite evolutionary tree. The kinship of trilobites relative to other arthropod groups has been a historical dilemma also (Cotton & Braddy, 2004; Aria, Caron & Gaines, 2015; Paterson, 2020). Antennules and some other characters, on the one hand, would ally them with mandibulate arthropods (the Gnathomorpha or Antennulata hypothesis), while others would place them within the chelicerate lineage (the Arachnomorpha hypothesis). Recent phylogenetic results have brought increased support to Arachnomorpha, but there is still no consensus on the question (Aria, 2022).

Described by: Rominger
Description date: 1887
Etymology:

Elrathina – unspecified.

cordillerae – in reference to the Western Cordillera (Canadian Rocky Mountain ranges), derived from the Spanish cordilla, the diminutive of cuerda, meaning “cord.”

Type Specimens: Type status under review – UMMP 4883 (6 specimens), University of Michigan Museum of Paleontology, Ann Arbor, Michigan, USA.
Other species:

Burgess Shale and vicinity: Elrathina parallela, E. brevifrons, E. spinifera, and E. marginalis have been described from similar stratigraphic horizons at nearby sites on Mount Field, Mount Stephen, and Mount Odaray.

Other deposits: Other species of Elrathina have been reported from the Cambrian of North America and Greenland.

Age & Localities:

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

The Walcott Quarry on Fossil Ridge. The Trilobite Beds and additional localities on Mount Stephen.

History of Research:

Brief history of research:

E. cordillerae was originally described under the genus name Conocephalites in Rominger’s 1887 publication on trilobites from Mount Stephen. In 1888 Walcott reallocated the species to Ptychoparia where it remained until Charles Resser, Walcott’s former assistant at the United States National Museum, established the new replacement genus Elrathina (Resser, 1937). Other workers have subsequently suggested that Elrathina is indistinguishable from Ptychoparella (see Blaker and Peel, 1997).

Species of Elrathina, along with those of the corynexochid Bathyuriscus, were found to be very abundant in a narrow interval of Middle Cambrian rocks throughout western North America, forming the basis of the Bathyuriscus-Elrathina Zone erected by Charles Deiss (1940).

Description:

Morphology:

Hard parts: adult dorsal exoskeletons average about 2 cm long. The semicircular cephalon is about one-third the length of the entire dorsal shield, bordered by a well-defined narrow rim, and with rounded genal angles. Weak transverse eye ridges extend to the small eyes, which are located just forward of cephalic mid-length. The slightly anteriorly narrowing glabella is rounded in front and exhibits three pairs of shallow lateral furrows; the pre-glabellar field is about the same width as the narrow anterior rim. The long, tapering thorax with a narrow axial lobe contains between 17 and 19 straight-sided segments, flexed gently downwards a short distance from the rounded tips. The tiny elliptical pygidium usually features two segments.

Unmineralized anatomy: rare specimens from the Walcott Quarry on Fossil Ridge retain tantalizing evidence of soft parts, including a pair of slender uniramous antennae, followed by very delicate looking biramous limbs beneath the cephalon, thorax and pygidium. These and other individuals of E. cordillerae are occasionally associated with a dark stain adjacent to the exoskeleton, presumably representing fluidized decay products.

Abundance:

Relatively common on Fossil Ridge and locally very abundant in the Walcott Quarry, where it represents about 25% of all trilobites collected (Caron and Jackson, 2008).

Maximum Size:
28 mm

Ecology:

Life habits: Drawing
Feeding strategies: Drawing
Ecological Interpretations:

Like similar-looking ptychoparioid trilobites, E. cordillerae may be interpreted as a fully mobile, epibenthic deposit (particle) feeder adapted to very low oxygen levels.

References:

  • ARIA, C. (2022) The origin and early evolution of arthropods. Biological Reviews 97, 1786–1809.
  • ARIA, C., CARON, J.-B. & GAINES, R. (2015) A large new leanchoiliid from the Burgess Shale and the influence of inapplicable states on stem arthropod phylogeny. Palaeontology 58, 629–660.
  • BLAKER, M. R. AND J. S. PEEL. 1997. Lower Cambrian trilobites from North Greenland. Meddeleser om Grønland, Geoscience, 35, 145 p.
  • CARON, J.-B. AND D. A. JACKSON. 2008. Paleoecology of the Greater Phyllopod Bed community, Burgess Shale. Palaeogeography, Palaeoclimatology, Palaeoecology, 258: 222-256.
  • COTTON, T.J. & BRADDY, S.J. (2004) The phylogeny of arachnomorph arthropods and the origin of the Chelicerata. Transactions of the Royal Society of Edinburgh-Earth Sciences 94, 169–193.
  • DEISS, C. 1940. Lower and Middle Cambrian stratigraphy of southwestern Alberta and southeastern British Columbia. Bulletin of the Geological Society of America, 51: 731-794.
  • PATERSON, J.R. (2020) The trouble with trilobites: classification, phylogeny and the cryptogenesis problem. Geological Magazine 157, 35–46.
  • PATERSON, J.R., EDGECOMBE, G.D. & LEE, M.S.Y. (2019) Trilobite evolutionary rates constrain the duration of the Cambrian explosion. Proceedings of the National Academy of Sciences of the United States of America 116, 4394–4399.
  • RASETTI, F. 1951. Middle Cambrian stratigraphy and faunas of the Canadian Rocky Mountains. Smithsonian Miscellaneous Collections, 116 (5): 277 p.
  • RESSER, C. E. 1937. Third contribution to nomenclature of Cambrian trilobites. Smithsonian Miscellaneous Collections, 95(22): 29 p.
  • ROMINGER, C. 1887. Description of primordial fossils from Mount Stephens, N. W. Territory of Canada. Proceedings of the Academy of Natural Sciences of Philadelphia, 1887: 12-19.
  • RUDKIN, D. M. 1989. Trilobites with appendages from the Middle Cambrian Stephen Formation of British Columbia. 28th International Geological Congress, Washington, D.C. July 9-19, 1989. Abstracts: 2-729.
  • SCHOLTZ, G. AND G. D. EDGECOMBE. 2006. The evolution of arthropod heads: reconciling morphological, developmental and palaeontological evidence. Development Genes and Evolution, 216: 395-415.
  • WALCOTT, C. 1918. Cambrian Geology and Paleontology IV. Appendages of trilobites. Smithsonian Miscellaneous Collections, 67(4): 115-216.
  • WALCOTT, C. D. 1924. Cambrian and Lower Ozarkian trilobites. Smithsonian Miscellaneous Collections, 75(2): 53-60.
Other Links:

http://www.trilobites.info/ordptychopariida.htm

http://www.geological-supplies.com/burgess/abstracts/balint

http://gsa.confex.com/gsa/2008AM/finalprogram/abstract_149017.htm



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Caryosyntrips serratus

Caryosyntrips serratus (ROM 57161) – Holotype, part and counterpart. Individual claw. Specimen length = 78 mm. Specimen dry – direct light (top row), dry – polarized light (bottom row). Walcott Quarry.

© Royal Ontario Museum. Photo: Jean-Bernard Caron

Taxonomy:

Kingdom: Drawing
Phylum: Drawing
Higher Taxonomic assignment: Radiodonta?
Species name: Caryosyntrips serratus
Remarks:

Caryosyntrips was initially assigned to Radiodonta (Daley and Budd 2010), the group that includes Anomalocaris (Collins 1996), as the hardened appendages of these animals are typically the only remains that preserve. However, phylogenetic analyses (Vinther et al. 2014; Lerosey-Aubril and Pates 2018; Moysiuk and Caron 2021) have failed to resolve its precise relationship with radiodontans and a placement outside of this group remains possible.

Described by: Daley and Budd
Description date: 2010
Etymology:

Caryosyntrips – from the Greek karyon meaning “nut,” and syntrips, a mythical fiend who smashed pottery; thus, a nut smasher, referring to the nutcracker-like morphology of the paired appendages

serratus – from the Latin serratus, “saw-edged.”

Type Specimens: Holotype –ROM57161 in the Royal Ontario Museum, Toronto, Canada.
Other species:

Burgess Shale and vicinity: none

Other deposits: C. camurus from the Spence Shale Member of the Langston Formation and C. durus from the Wheeler Formation of Utah, U.S.A. A specimen identified as C. cf. camurus has also been recovered from the Valdemiedes Formation of Spain (Pates & Daley, 2017, but see Pates et al., 2018; Zhuravlev & Gámez Vintaned, 2018).

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. Also known from the Tulip Beds (S7) on Mount Stephen.

History of Research:

Brief history of research:

The Burgess Shale material was first noticed and illustrated as “Dinocarida A” in Caron (2005)), and formally designated as Caryosyntrips serratus by Daley and Budd (2010). Pates and Daley (2017) later revised the taxonomy and described new occurrences of the genus outside of the Burgess Shale.

Description:

Morphology:

This species is known from eleven isolated appendages from the Burgess Shale. Appendages are elongate and triangular in outline, with a length that ranges between 58 mm and 114 mm. Segmentation of the appendage is weakly developed due to partial fusion, but 14 podomeres (segments) can be distinguished. Each appendage is straight and rigid, with no movement occurring at the podomere boundaries. Each podomere has one thick, short spine on the inner margin, and several smaller spines on the outer margin, giving the latter a serrated appearance. The distal end of the appendage tapers to a point, and a single terminal spine is slightly curved. Most appendages are isolated, but a single paired specimen shows that the appendages were oriented with their thick spines in opposition. This particular specimen is loosely associated with other potential unidentifiable remains of the body of the animal.

Abundance:

Carysyntrips serratus is extremely rare. Most specimens (8) come from the Walcott Quarry.

Maximum Size:
114 mm (appendage).

Ecology:

Life habits: Drawing
Feeding strategies: Drawing
Ecological Interpretations:

Caryosyntrips serratus is assumed to have had a similar mode of life to other radiodontans, meaning that it swam through the water column actively searching out prey. It has been suggested to have fed by moving the rigid appendages at their bases, bringing their medial spinous margins together in a scissor-like motion (Daley and Budd 2010). While some other radiodontans like Stanleycaris may have shared this general mode of functioning (Moysiuk and Caron 2021), the particularly rigid appendages of Caryosyntrips are uniquely specialized, arguing that this species was adapted to hard-shelled prey (Pates and Daley 2017).

References:

  • CARON, J.-B. 2005. Taphonomy and community analysis of the Middle Cambrian Greater Phyllopod Bed, Burgess Shale. PhD, University of Toronto, Toronto, 1–316pp.
  • 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. and BUDD, G. E. 2010. New anomalocaridid appendages from the Burgess Shale, Canada. Palaeontology, 53: 721–738.
  • LEROSEY-AUBRIL, R. and PATES, S. 2018. New suspension-feeding radiodont suggests evolution of microplanktivory in Cambrian macronekton. Nature Communications, 9: 3774.
  • MOYSIUK, J. and CARON, J.-B. 2021. Exceptional multifunctionality in the feeding apparatus of a mid-Cambrian radiodont. Paleobiology, 47: 704–724.
  • PATES, S. and DALEY, A. C. 2017. Caryosyntrips: a radiodontan from the Cambrian of Spain, USA and Canada. Papers in Palaeontology, 3: 461–470.
  • PATES, S. and 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.
  • VINTHER, J., STEIN, M., LONGRICH, N. R. and HARPER, D. A. T. 2014. A suspension-feeding anomalocarid from the Early Cambrian. Nature, 507: 496.
  • 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:

None



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Opabinia regalis

3D animation of Opabinia regalis.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Kingdom: Drawing
Phylum: Drawing
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: Drawing
Feeding strategies: Drawing
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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Olenoides serratus

3D animation of Olenoides serratus.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Kingdom: Drawing
Phylum: Drawing
Higher Taxonomic assignment: Class Trilobita, Order Corynexochida
Species name: Olenoides serratus
Remarks:

Trilobites are, by a large margin, the most diverse of extinct arthropod classes, encompassing more than 2000 species, although the biomineralization of their cuticle is likely largely responsible for their much better-known diversity. A recent probabilistic analysis of trilobite relationships suggests that many of the diagnostic traits used for the taxonomy of the main groups remain highly variable across lineages (Paterson, Edgecombe & Lee, 2019), which explains long-standing difficulties in resolving the trilobite evolutionary tree. The kinship of trilobites relative to other arthropod groups has been a historical dilemma also (Cotton & Braddy, 2004; Aria, Caron & Gaines, 2015; Paterson, 2020). Antennules and some other characters, on the one hand, would ally them with mandibulate arthropods (the Gnathomorpha or Antennulata hypothesis), while others would place them within the chelicerate lineage (the Arachnomorpha hypothesis). Recent phylogenetic results have brought increased support to Arachnomorpha, but there is still no consensus on the question (Aria, 2022).

Described by: Rominger
Description date: 1887
Etymology:

Olenoides – from Olenus, in Greek mythology a man who, along with his wife Lethaea, was turned to stone. Olenus was used for a trilobite genus name in 1827; the suffix –oides(“resembling”) was added later.

serratus – from the Latin serratus, “saw-shaped,” probably referring to the spinose margin of the pygidium.

Type Specimens: Type status under review – UMMP 4882 (11 specimens), University of Michigan Museum of Paleontology, Ann Arbor, Michigan, USA.
Other species:

Burgess Shale and vicinity: Kootenia dawsoni; Kootenia burgessensis. (Species of Kooteniaare no longer considered different enough from those in Olenoides to warrant placement in a separate genus, but Kootenia is retained here for ease of reference to historical literature).

Other deposits: species of Olenoides are widespread in the Cambrian of North America and Greenland, and have been recorded in Siberia, China, and elsewhere.

Age & Localities:

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

The Walcott Quarry on Fossil Ridge. The Trilobite Beds and other localities on Mount Stephen.

History of Research:

Brief history of research:

Olenoides serratus was among the first Burgess Shale animals to be named and described. The fossils used in Rominger’s original 1887 description were collected from the Mount Stephen Trilobite Beds in 1886. Rominger coined the name Ogygia serrata for this trilobite, illustrating one complete specimen in accompanying engravings. Following several intermediate changes, the name now in use was first published by Kobayashi in 1935. Spectacular appendage-bearing specimens discovered during Walcott’s Fossil Ridge excavations in 1910-1911 brought Olenoides serratus (then called Neolenus serratus) attention worldwide as one of the most anatomically complete trilobites known. This iconic Burgess Shale species has been thoroughly redescribed by Harry Whittington (1975, 1980), who also concluded that Nathorstia transitans (named by Walcott in 1912) was a “soft shell” moult stage of Olenoides serratus.

Description:

Morphology:

Hard parts: adult dorsal exoskeletons may reach 9 cm long and are broadly oval in outline, with a semi-circular cephalon, a thorax of seven segments ending in spines, and a semi-circular pygidium with marginal spines. The cephalon, thorax and pygidium are of approximately equal length. The parallel-sided glabella is rounded in front and reaches almost to the anterior border. Thin eye ridges swing back from the front of the glabella to the small, outwardly-bowed eyes. The free cheeks narrow back into straight, slender genal spines reaching to the third pleurae. Tips of the pleurae also extend into needle-like spines. The spiny pygidium has six axial rings decreasing in size backwards; five pairs of marginal spines point rearward. The whole exoskeleton has a variably granulate outer surface with fine ridges and cusps near the margins.

Unmineralized anatomy: Olenoides serratus had a pair of flexible, multi-jointed cephalic “antennae.” Behind these, three pairs of biramous limbs were attached beneath the cephalon on either side of the mid-line. Each inner branch had a large spiny blade-shaped coxa and six spinose cylindrical podomeres that tapered away from the body, the last carrying three short “claws” at the tip. The outer limb branch was composed of many flat, overlapping filaments sweeping back from a long lobe, with a small oval, hair-fringed lobe at the outer end. Pairs of similar biramous appendages were attached under each thoracic segments; four to six pairs were attached under the pygidium, becoming shorter and more slender to the rear. Unique among all trilobites preserving limbs, Olenoides serratus also had a pair of antenna-like appendages (cerci; singular = cercus) emerging from under the pygidium behind the last biramous limbs.

Abundance:

Olenoides serratus is moderately common, especially at the Mount Stephen Trilobite Beds, where thousands of pieces and hundreds of partial to complete exoskeletons have been observed or collected. Olenoides is the largest and most conspicuous trilobite in the Walcott Quarry section on Fossil Ridge, where specimens with preserved appendages have been found.

Maximum Size:
90 mm

Ecology:

Life habits: Drawing
Feeding strategies: Drawing
Ecological Interpretations:

Adults of Olenoides serratus walked along the sea bed, possibly digging shallow furrows to locate small soft-bodied and weakly-shelled animals or carcasses. Prey items were shredded between the spiny limb bases and passed forward to the rear-facing mouth. Olenoides could probably swim just above sea bed for short distances. Some Olenoides fossils show unmistakable evidence of healed injuries, suggesting they may have been preyed upon, likely in their “soft-shell” growth phase, by larger arthropods such as Anomalocaris. Tiny larvae and early juveniles of Olenoides probably swam and drifted in the water column above the sea bed.

References:

  • ARIA, C. (2022) The origin and early evolution of arthropods. Biological Reviews 97, 1786–1809.
  • ARIA, C., CARON, J.-B. & GAINES, R. (2015) A large new leanchoiliid from the Burgess Shale and the influence of inapplicable states on stem arthropod phylogeny. Palaeontology 58, 629–660.
  • COTTON, T.J. & BRADDY, S.J. (2004) The phylogeny of arachnomorph arthropods and the origin of the Chelicerata. Transactions of the Royal Society of Edinburgh-Earth Sciences 94, 169–193.
  • KOBAYASHI, T. 1935. The Cambro-Ordovician formations and faunas of south Chosen. Paleontology, Part 3: Cambrian faunas of south Chosen with a special study on the Cambrian trilobite genera and families. Journal of the Faculty of Science, Imperial University of Tokyo, Section II. 4(2): 49-344.
  • PATERSON, J.R. (2020) The trouble with trilobites: classification, phylogeny and the cryptogenesis problem. Geological Magazine 157, 35–46.
  • PATERSON, J.R., EDGECOMBE, G.D. & LEE, M.S.Y. (2019) Trilobite evolutionary rates constrain the duration of the Cambrian explosion. Proceedings of the National Academy of Sciences of the United States of America 116, 4394–4399.
  • RASETTI, F. 1951. Middle Cambrian stratigraphy and faunas of the Canadian Rocky Mountains. Smithsonian Miscellaneous Collections, 116 (5): 1-277.
  • ROMINGER, C. 1887. Description of primordial fossils from Mount Stephens, N. W. Territory of Canada. Proceedings of the Academy of Natural Sciences of Philadelphia, 1887: 12-19.
  • SCHOLTZ, G. AND G. D. EDGECOMBE. 2006. The evolution of arthropod heads: reconciling morphological, developmental and palaeontological evidence. Development Genes and Evolution, 216: 395-415.
  • WALCOTT, C. D. 1912. Cambrian Geology and Paleontology, II. No. 6. – Middle Cambrian Branchiopoda, Malacostraca, Trilobita, and Merostomata. Smithsonian Miscellaneous Collections, 57(6): 145-228.
  • WHITTINGTON, H. B. 1975. Trilobites with appendages from the Middle Cambrian, Burgess Shale, British Columbia. Fossils and Strata, No. 4: 97-136.
  • WHITTINGTON, H. B. 1980. Exoskeleton, moult stage, appendage morphology, and habits of the Middle Cambrian trilobite Olenoides serratus. Palaeontology, 23: 171-204.
Other Links:

http://www.trilobites.info/ordcorynexochida.htm

http://www.trilobites.info/trilovent.htm

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

http://pakozoic.deviantart.com/art/Olenoides-serratus-3D-77550691



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Ogygopsis klotzi

Ogygopsis klotzi (figure 1) illustrated by Rominger (1887) as Ogygia klotzi.

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Taxonomy:

Kingdom: Drawing
Phylum: Drawing
Higher Taxonomic assignment: Class Trilobita, Order Corynexochida
Species name: Ogygopsis klotzi
Remarks:

Trilobites are, by a large margin, the most diverse of extinct arthropod classes, encompassing more than 2000 species, although the biomineralization of their cuticle is likely largely responsible for their much better-known diversity. A recent probabilistic analysis of trilobite relationships suggests that many of the diagnostic traits used for the taxonomy of the main groups remain highly variable across lineages (Paterson, Edgecombe & Lee, 2019), which explains long-standing difficulties in resolving the trilobite evolutionary tree. The kinship of trilobites relative to other arthropod groups has been a historical dilemma also (Cotton & Braddy, 2004; Aria, Caron & Gaines, 2015; Paterson, 2020). Antennules and some other characters, on the one hand, would ally them with mandibulate arthropods (the Gnathomorpha or Antennulata hypothesis), while others would place them within the chelicerate lineage (the Arachnomorpha hypothesis). Recent phylogenetic results have brought increased support to Arachnomorpha, but there is still no consensus on the question (Aria, 2022).

Described by: Rominger
Description date: 1887
Etymology:

Ogygopsis – from Ogygia, in Greek mythology, the 7th daughter of Amphion and Niobe; Ogygia was first used as a trilobite genus name in 1817.

klotzi – after Otto Klotz, the Dominion topographical surveyor who provided the fossils for Rominger’s study and description.

Type Specimens: Holotype (K. burgessensis) – USNM65511 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA (Resser, 1942); Type status under review – (K. dawsoni), University of Michigan Museum of Paleontology, Ann Arbor, Michigan, USA.
Other species:

Burgess Shale and vicinity: Ogygopsis spinulosa Rasetti, 1951, from the slightly older Cathedral Formation on Mount Stephen.

Other deposits: species of Ogygopsis have now been described from elsewhere in the Cambrian of North America, as well as in Greenland and Siberia.

Age & Localities:

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

The Trilobite Beds and smaller localities on Mount Stephen.

History of Research:

Brief history of research:

Ogygopsis klotzi was first described in the same 1887 publication as several other important Mount Stephen trilobites. Rominger named the largest and most abundant species after Klotz, placing it in the genus Ogygia. The following year, Charles Walcott questioned this assignment, and in 1889 proposed the new genus name Ogygopsis. For decades afterwards, Ogygopsis was thought to be unique to the Mount Stephen Trilobite Beds, where it is the most conspicuous fossil on the mountain slope. In fact, Walcott designated the occurrence as the “Ogygopsis shale” in 1908, and subsequently named the Burgess Shale as its geographic equivalent (although Ogygopsis itself has never been found on Fossil Ridge!)

Description:

Morphology:

Hard parts: adult dorsal exoskeletons may be up to 13 cm long and are elongate oval in outline, with a large crescentic cephalon, a thorax of eight segments ending pointed blade-like tips, and a large semi-circular pygidium without spines. The glabella is long and barrel-shaped, smoothly rounded in front, reaching almost to the anterior border. Thin eye ridges angle back from near the front of the glabella to long narrow eyes located opposite glabellar mid-length. Free cheeks extend back into straight, short genal spines. The large pygidium has 9 axial rings decreasing in size backwards, followed by a terminal piece; 8 or 9 pairs of pygidial ribs become progressively shorter and more backwardly directed. The whole exoskeleton is mostly smooth externally, with fine ridges parallel to the margins; free cheeks and posterior fixed cheeks may show a distinctive pattern of fine anastomosing (interlinking) ridges.

Unmineralized anatomy: only a very few specimens of Ogygopsis klotzi are known with preserved evidence of limbs, but these show that there was a pair of flexible, multi-jointed antennae on the cephalon (Hofmann and Parsley, 1966).

Abundance:

Ogygopsis klotzi is extraordinarily abundant at the Mount Stephen Trilobite Beds, where it is the most common fossil encountered (Rudkin, 1996; 2009), but it does not occur on Fossil Ridge. The vast majority of more-or-less complete specimens lack free cheeks, and many paleontologists have interpreted these as moulted individuals.

Maximum Size:
130 mm

Ecology:

Life habits: Drawing
Feeding strategies: Drawing
Ecological Interpretations:

The shape and size of Ogygopsis klotzi adults suggest that they walked along the sea bed. Because Ogygopsis occurs in such enormous numbers, it is hard to imagine it as a predator/scavenger, like Olenoides. It may instead have consumed much smaller organic particles in unusual environments. Obvious healed injuries have been described on a number of Ogygopsis specimens; some of these may be evidence of predation on freshly moulted “soft-shell” trilobites by larger arthropods such as Anomalocaris (Rudkin, 1979; 2009). The tiny larval stages and early juveniles of Ogygopsis probably swam and drifted in the water column above the sea bed.

References:

  • ARIA, C. (2022) The origin and early evolution of arthropods. Biological Reviews 97, 1786–1809.
  • ARIA, C., CARON, J.-B. & GAINES, R. (2015) A large new leanchoiliid from the Burgess Shale and the influence of inapplicable states on stem arthropod phylogeny. Palaeontology 58, 629–660.
  • COTTON, T.J. & BRADDY, S.J. (2004) The phylogeny of arachnomorph arthropods and the origin of the Chelicerata. Transactions of the Royal Society of Edinburgh-Earth Sciences 94, 169–193.
  • HOFFMAN, H. J. AND R. L. PARSLEY. 1966. Antennae of Ogygopsis. Journal of Paleontology, 40: 209-211.
  • PATERSON, J.R. (2020) The trouble with trilobites: classification, phylogeny and the cryptogenesis problem. Geological Magazine 157, 35–46.
  • PATERSON, J.R., EDGECOMBE, G.D. & LEE, M.S.Y. (2019) Trilobite evolutionary rates constrain the duration of the Cambrian explosion. Proceedings of the National Academy of Sciences of the United States of America 116, 4394–4399.
  • RASETTI, F. 1951. Middle Cambrian stratigraphy and faunas of the Canadian Rocky Mountains. Smithsonian Miscellaneous Collections, 116 (5): 1-277.
  • ROMINGER, C. 1887. Description of primordial fossils from Mount Stephens, N. W. Territory of Canada. Proceedings of the Academy of Natural Sciences of Philadelphia, 1887: 12-19.
  • RUDKIN, D. M. 1979. Healed injuries in Ogygopsis klotzi (Trilobita) from the Middle Cambrian of British Columbia. Royal Ontario Museum, Life Sciences Occasional Paper, 32: 1-8.
  • RUDKIN, D. M. 1996. The Trilobite Beds of Mount Stephen, Yoho National Park, p. 59-68. InR. Ludvigsen (ed.), Life in Stone – A Natural History of British Columbia’s Fossils. UBC Press, Vancouver.
  • RUDKIN, D. M. 2009. The Mount Stephen Trilobite Beds, p. 90-102. In J.-B. Caron and D. Rudkin (eds.), A Burgess Shale Primer – History, Geology, and Research Highlights. The Burgess Shale Consortium, Toronto.
  • SCHOLTZ, G. AND G. D. EDGECOMBE. 2006. The evolution of arthropod heads: reconciling morphological, developmental and palaeontological evidence. Development Genes and Evolution, 216: 395-415.
  • WALCOTT, C. D. 1908. Mount Stephen rocks and fossils. Canadian Alpine Journal, 1: 232-248.
  • WHITTINGTON, H. B. 1975. Trilobites with appendages from the Middle Cambrian, Burgess Shale, British Columbia. Fossils and Strata, No. 4: 97-136.
Other Links:

http://www.trilobites.info/ordcorynexochida.htm

http://www.trilobites.info/trilovent.htm



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Naraoia compacta

Reconstruction of Naraoia compacta.

© MARIANNE COLLINS

Taxonomy:

Kingdom: Drawing
Phylum: Drawing
Higher Taxonomic assignment: Unranked clade (stem group arthropods)
Species name: Naraoia compacta
Remarks:

Naraoia is usually compared to the trilobites, but its exact relationships are uncertain (Whittington, 1977). The naraoiids and other trilobite-like arthropods, sometimes referred to as Trilobitoidea, can be grouped together with the trilobites to form the Lamellipedians (Hou and Bergström, 1997; Wills et al. 1998; Edgecombe and Ramsköld, 1999). This group has been variously placed in the upper stem lineage of the arthropods (Budd, 2002), or in the stem lineage of either the mandibulates (Scholtz and Edgecombe, 2006) or the chelicerates (Cotton and Braddy, 2004).

Described by: Walcott
Description date: 1912
Etymology:

Naraoia – from Narao Lakes, near Kicking Horse Pass in Yoho Park, British Columbia. From the Stoney First Nation Nakoda word Narao, meaning “hit in the stomach,” which likely refers to James Hector, who was kicked by a horse while travelling up the Kicking Horse River in 1858.

compacta – from the Latin compactus, “joined together.”

Type Specimens: Lectotype –USNM57687 (N. compacta) and holotypesUSNM83946 (N. spinifer) andUSNM189210 (N. halia) in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: N. spinifer (Walcott, 1931); N. halia (Simonetta and Delle Cave, 1975) from the Walcott Quarry, Burgess Shale.

Other deposits: N. longicaudata and spinosa (Zhang and Hou, 1985) from the Early Cambrian Chengjiang biota of South China, of which N. longicaudata was later placed in its own genus, Misszhouia (Chen et al., 1997); Possible specimens of Naraoia have been found at the Lower Cambrian Emu Bay Shale in Australia (Nedin, 1999). Unlike most Burgess Shale arthropods, Naraoia has also been found in rocks younger than the Cambrian, in the Late Silurian Bertie Formation of Southern Ontario (Caron et al., 2004).

Age & Localities:

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

The Walcott and Raymond Quarries on Fossil Ridge. The Trilobite Beds on Mt. Stephen, Tulip Beds (S7) and Collins Quarry as well as other smaller localities on Mount Stephen.

History of Research:

Brief history of research:

The first description of Naraoia was N. compacta by Walcott (1912), who later described a second specimen, N. spinifer (1931). Simonetta and Delle Cave (1975) re-examined the specimens and designated the new species N. halia and N. pammon. A major redescription of all Burgess Shale material was undertaken by Whittington (1977), and N. compactaspecimens from the Marjum Formation in Utah and the Gibson Formation in Idaho were described by Robison (1984), both of whom synonymized N. halia and N. pammon with N. compacta. However, a major restudy of the naraoiids by Zhang et al. (2007) concluded that N. halia is actually a valid species.

Description:

Morphology:

Naraoia consists of two dorsal shields with a convex axial region, including a roughly square head shield and an elongated body shield. A pair of long, multi-jointed antennae emerges from beneath the head shield. Behind the antennae are four pairs of cephalic appendages and 14 pairs of trunk appendages. All these appendages are segmented and branch into two (biramous), with a spiny walking limb made up of seven segments, and a filamentous branch consisting of a thin shaft bearing many lamellae (flexible and elongated plate-like elements). The basal segment of the biramous appendage is composed of a large, spiny plate.

Internal structures of Naraoia are well preserved, with the most conspicuous feature being the complexly branched gut glands visible on the cephalic shield. The gut passes along the whole length of the body, with paired gut glands visible in the anterior half.

Abundance:

Hundreds of specimens of Naraoia are known from the Walcott Quarry, where they make up about 0.74% of the community (Caron and Jackson, 2008). Naraoia is rare in all the other known localities.

Maximum Size:
40 mm

Ecology:

Life habits: Drawing
Feeding strategies: Drawing
Ecological Interpretations:

Naraoia likely spent much of its time walking on the sea floor, since the rigidity of its appendages would only allow for limited periods of swimming. It would have sensed its environment, including food items, using its antennae. Naraoia used the segmented walking limbs of its biramous appendages for walking and for manipulating food items, which were crushed and moved towards the mouth using the spiny basal plate. The filamentous branches of the biramous limb were used for gas exchange and to propel the animal through the water during short burst of swimming. The large gut glands and spiny appendages suggest that Naraoia was a predator or scavenger. Specimens with healed injuries suggest that Naraoia was also a prey item for other larger predators.

References:

BUDD, G. E. 2002. A palaeontological solution to the arthropod head problem. Nature, 417: 271-275.

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., D. M. RUDKIN AND S. MILLIKEN. 2004. A new Late Silurian (Pridolian) naraoiid (Euarthropoda: Nektaspida) from the Bertie Formation of southern Ontario, Canada – delayed fallout from the Cambrian explosion. Journal of Paleontology, 78: 1138-1145.

CHEN, J. G. D. EDGECOMBE AND L. RAMSKöLD. 1997. Morphological and ecological disparity in naraoiids (Arthropoda) from the Early Cambrian Chengjiang fauna, China. Records of the Australian Museum, 49: 1-24.

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. Journal of Paleontology, 73: 263-287.

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

NEDIN, C. 1999. Anomalocaris predation on nonmineralized and mineralized trilobites. Geology, 27: 987-990.

ROBISON, R. B. 1984. New occurrence of the unusual trilobite Naraoia from the Cambrian of Idaho and Utah. University of Kansa Paleontological Contribution, 112: 1-8.

SCHOLTZ, G. AND G. D. EDGECOMBE. 2006. The evolution of arthropod heads: reconciling morphological, developmental and palaeontological evidence. Development Genes and Evolution, 216: 395-415.

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.

WALCOTT, C. D. 1931. Addenda to descriptions of Burgess Shale fossils. Smithsonian Miscellaneous Collections, 85: 1-46.

WHITTINGTON, H. B. 1977. The Middle Cambrian trilobite Naraoia, Burgess Shale, British Columbia. Philosophical Transactions of the Royal Society of London, B, 280: 409-443.

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, p. 33-105. In G. D. Edgecombe (ed.), Arthropod fossils and phylogeny. Columbia University Press, New York.

ZHANG, W. AND X. HOU. 1985. Preliminary notes on the occurrence of the unusual trilobite Naraoia in Asia. Acta Palaeontologica Sinica, 24: 591-595.

ZHANG, X., D. SHU AND D. H. ERWIN. 2007. Cambrian naraoiids (Arthropoda): Morphology, ontogeny, systematics and evolutionary relationships. Journal of Paleontology, 81:1-52.

Other Links:

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