The Burgess Shale

Yawunik kootenayi

Yawunik kootenayi, ROMIP 64017

Taxonomy:

Kingdom: Unknown
Phylum: Unknown
Higher Taxonomic assignment: Megacheirans, Family Leanchoiliidae
Species name: Yawunik kootenayi
Remarks:

Yawunik is a representative of the megacheiran family Leanchoiliidae (Aria, Caron, & Gaines, 2015). Megacheirans are basal true arthropods with a frontal appendage pointing upward and made of multiple claws (the cheira, or “great appendage”). Megacheirans are generally considered to be among the first true arthropods (that is, arthropods with segmented bodies and appendages), and possibly the earliest representatives of the extended chelicerate lineage (Aria, 2022).

Described by: Aria, Caron and Gaines
Description date: 2015
Etymology:

Yawunik – Latinized spelling of Yawu?nik’, the fierce monster of the Ktunaxa First Nation’s creation story.

kootenayi – After the name Kootenay National Park, representing the area where the fossil was found, a territory previously inhabited by the Ktunaxa First Nation among others.

Type Specimens: Holotype ROMIP 62977, at the Royal Ontario Museum, Toronto, Canada
Other species:

Burgess Shale and vicinity: None
Other deposits: None

Age & Localities:

Age:
Middle Cambrian, Wuliuan stage, upper part of the Burgess Shale Formation (around 507 million years old).
Principal localities:

Marble Canyon, Kootenay National Park, British Columbia.

History of Research:

Brief history of research:

Along with Surusicaris elegans (Aria & Caron, 2015), Yawunik kootenayi is one of the first two arthropods described from the Marble Canyon locality of the Burgess Shale (Aria et al., 2015). The original study was based on 42 specimens from the 2012 Royal Ontario Museum expedition, the same year the new fossil deposit was found. Dozens more specimens have since been collected, making Yawunik one of the most abundant arthropods of the Marble Canyon quarry, next to Sidneyia (Nanglu, Caron, & Gaines, 2020). As the largest and one of the best preserved megacheiran arthropod, Yawunik has since been referenced in many studies.

Description:

Morphology:

Yawunik kootenayi was a large predator, stouter than its closest relatives. The body lacks any biomineralization. Like other leanchoiliid megacheirans, it is characterized by flagellate frontal appendages (cheirae) made of three long claws, and a body divided into two regions (tagmata): the cephalon, covered by a single shield, and the segmented trunk. At the front of the head, leanchoiliids bore a pair of large unstalked lateral eyes and a pair of smaller, mushroom-shaped median eyes. The megacheiran appendages were of similar simple morphology throughout the body, reflecting the typical arthropod biramous limb: sub-cylindrical basis with teeth for mastication (basipod), relatively strong walking legs (endopods), and paddle-like, semi-rigid flaps (exopods) fringed with lamellae. The tail is a single element called a telson, having the shape of spear’s tip (lanceolate).

Abundance:

Known through more than 180 specimens, Yawunik is one of the most abundant arthropods of Marble Canyon, and is also known from Tokumm Creek.

Maximum Size:
About 20 cm.

Ecology:

Life habits: Unknown
Feeding strategies: Unknown
Ecological Interpretations:

Like other leanchoiliid megacheirans the frontal appendages of Yawunik likely combined both sensing and grasping functions to detect and catch prey items. Food caught was brought under the body where it was rudimentarily masticated between the bases of limbs (basipods), before being channeled back to the mouth. As a leanchoiliid, Yawunik also had large glands atop its gut, presumably involved in digestion. The megacheiran body appendages, made of relatively strong walking legs (endopods) as well as paddle-like, semi-rigid flaps (exopods), would have allowed for both locomotion on the sea floor and swimming. The exopods likely served for gas exchanges (like breathing) as well, but recent studies showed that megacheirans and other Cambrian arthropods also possessed dedicated gills (Liu et al., 2021).

References:

  • 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.
  • 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.
  • Liu, Y., Edgecombe, G.D., Schmidt, M., Bond, A.D., Melzer, R.R., Zhai, D., Mai, H., Zhang, M. & Hou, X. (2021) Exites in Cambrian arthropods and homology of arthropod limb branches. Nature Communications 12, 4619.
  • Nanglu, K., Caron, J.-B. & Gaines, R.R. (2020) The Burgess Shale paleocommunity with new insights from Marble Canyon, British Columbia. Paleobiology 46, 58–81.
Other Links:

Misszhouia canadensis

Misszhouia canadensis, two specimens, ROMIP 65408

Taxonomy:

Kingdom: Unknown
Phylum: Unknown
Higher Taxonomic assignment: Subphylum Artiopoda (Hou & Bergström 1997), Class Nektaspida (Raymond 1920), Family Naraoiidae (Walcott 1912).
Species name: Misszhouia canadensis
Remarks:

Artiopoda is the clade including trilobites and their non-biomineralized relatives. The placement of Artiopoda relative to other arthropod groups, and particularly extant lineages, has been the subject of a long and ongoing debate (e.g. Aria et al. 2015; Paterson 2020). Misszhouia is the closest relative of Naraoia, together forming the family Naraoiidae, typified notably by having both cephalon and trunk forming smooth, articulating shields. Naraoiidae could be derived taxa among artiopodans (Mayers et al. 2019), but the internal relationships of Artiopoda have been difficult to resolve and continue to remain at odds between phylogenetic studies (e.g. Lerosey-Aubril et al. 2017; Moysiuk & Caron 2019).

Described by: Mayers, Aria and Caron
Description date: 2018
Etymology:

Misszhouia — in honour of Miss Guiqing Zhou, fossil preparator and technical assistant to Prof. Junyuan Chen from the Nanjing Institute of Geology and Palaeontology, Academia Sinica, China.

canadensis — from being discovered in Canada.

Type Specimens: dsfsdfdsfdsfdasf
Other species:

Holotype ROMIP 64408; paratypes ROMIP 64411, 64438, 64450, 64451, 64509, 64510, 64511, in the Royal Ontario Museum, Toronto, Canada.

Age & Localities:

Age:
Middle Cambrian, Wuliuan Stage, upper part of the Burgess Shale Formation (around 507 million years old)
Principal localities:

The Marble Canyon and Tokumm Creek areas of the Burgess Shale, British Columbia.

History of Research:

Brief history of research:

Chen and colleagues created the genus Misszhouia mostly based on the distinction that these individuals of “Naraoialongicaudata did not possess gut ramifications inside the head, compared to Naraoia species from the Chengjiang biota and Burgess Shale. The morphoanatomy and taxonomy of Naraoiidae from China were later thoroughly revised by Zhang and colleagues (2007). Misszhouia canadensis was one of the first taxa found on talus when the Marble Canyon outcrop was discovered in 2012 (Caron et al. 2014). Although these fossils do possess extensive digestive ramifications in the head, morphometric analyses of body shape showed that specimens from both Canada and China formed a genus distinct from Naraoia (Mayers et al. 2019). Morphometric data also allowed for the identification of putative sexual morphs (Zhang et al. 2007; Mayers et al. 2019).

Description:

Morphology:

As an artiopodan, Misszhouia possesses a flattened body divided into a circular cephalon and a trunk, a pair of sensory antennules, and robust walking limbs with masticatory gnathobases, oriented parallel to the ventral surface of the body. Both cephalon and trunk form single smooth shields articulating to one another. In the cephalon, the gut ramifies into extensive diverticula; it is completed by lateral extensions called caeca in the trunk. In addition to the frontal antennules, the head bears another three pairs of limbs. The trunk represents 65% of total body length, with at least 30 limb pairs. The appendages are likely similar to M. longicaudata, with an inner walking branch and an outer, rod-shaped respiratory branch bearing packed lamellae.

Abundance:

Misszhouia is relatively rare at the Marble Canyon Quarry proper, but can be common along Tokumm Creek sites (Mayers et al. 2019).

Maximum Size:
About 8 cm.

Ecology:

Life habits: Unknown
Feeding strategies: Unknown
Ecological Interpretations:

Misszhouia was construed to be a predator or scavenger based on the presence of long antennules and well-developed gnathobases (masticatory surfaces at the base of the limbs) (Chen et al. 1997). The absence of digestive ramifications in the head of the Burgess Shale species, compared to the one from Chengjiang, suggests either different diets or different frequencies of feeding (Mayers et al. 2019).

References:

  • ARIA, C., CARON, J.-B. and 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.
  • CARON, J.-B., GAINES, R. R., ARIA, C., MANGANO, M. G. and STRENG, M. 2014. A new phyllopod bed-like assemblage from the Burgess Shale of the Canadian Rockies. Nature Communications, 5.
  • CHEN, J. Y., EDGECOMBE, G. D. and RAMSKÖLD, L. 1997. Morphological and ecological disparity in naraoiids (Arthropoda) from the Early Cambrian Chengjiang fauna, China. Records of the Austalian Museum, 49, 1–24.
  • HOU, X. G. and BERGSTRÖM, J. 1997. Arthropods of the Lower Cambrian Chengjiang fauna, southwest China. Fossils and Strata, 45, 1–116.
  • LEROSEY-AUBRIL, R., ZHU, X. and ORTEGA-HERNÁNDEZ, J. 2017. The Vicissicaudata revisited – insights from a new aglaspidid arthropod with caudal appendages from the Furongian of China. Scientific Reports, 7, Article number: 11117.
  • MAYERS, B., ARIA, C. and CARON, J. B. 2019. Three new naraoiid species from the Burgess Shale, with a morphometric and phylogenetic reinvestigation of Naraoiidae. Palaeontology, 62, 19–50.
  • MOYSIUK, J. and CARON, J. B. 2019. Burgess Shale fossils shed light on the agnostid problem. Proc Biol Sci, 286, 20182314.
  • PATERSON, J. R. 2020. The trouble with trilobites: classification, phylogeny and the cryptogenesis problem. Geological Magazine, 157, 35–46.
  • RAYMOND, P. E. 1920. The appendages, anatomy and relationships of trilobites. Memoirs of the Connecticut Academy of Arts and Sciences, 7, 1–169.
  • WALCOTT, C. 1912. Cambrian Geology and Paleontology II. Middle Cambrian Branchiopoda, Malacostraca, Trilobita and Merostomata. Smithsonian Miscellaneous Collections, 57(6), 145–228.
  • ZHANG, X. L., SHU, D. G. and ERWIN, D. H. 2007. Cambrian naraoiids (Arthropoda): morphology, ontogeny, systematics, and evolutionary relationships. Journal of Paleontology, 81, 1–52.
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Pollingeria grandis

Pollingeria grandis (GSC 8362). Slab with several specimens. Specimen length (largest) = 15 mm. Specimen dry – polarized light. Walcott Quarry.

© GEOLOGICAL SURVEY OF CANADA. PHOTO: JEAN-BERNARD CARON

Taxonomy:

Kingdom: Unknown
Phylum: Unknown
Higher Taxonomic assignment: Non applicable
Species name: Pollingeria grandis
Remarks:

Pollingeria is one of the least understood Burgess Shale organisms, and its systematic status is unknown (Briggs and Conway Morris, 1986).

Described by: Walcott
Description date: 1911
Etymology:

Pollingeria – from Mount Pollinger (2,816 m), northwest of the Burgess Shale. The name was given after Joseph Pollinger (1873-1943).

grandis – from the Latin grandis, “big, large,” in reference to the purported large size of the fossils.

Type Specimens: Syntypes –USNM57639-57641 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, Bathyuriscus-Elrathina Zone (approximately 505 million years ago).
Principal localities:

The Walcott and Raymond Quarries on Fossil Ridge and smaller sites on Mount Field and Mount Stephen.

History of Research:

Brief history of research:

Pollingeria was first described by Walcott in a 1911 monograph dealing with various Burgess Shale worms. Walcott interpreted these fossils as the individual scales of a larger organism resembling Wiwaxia. However, this interpretation was doubted (Conway Morris, 1979), and firmly rejected after the restudy of Wiwaxia (Conway Morris, 1985). The affinities of Pollingeria have remained difficult to establish (Briggs and Conway Morris, 1986).

Description:

Morphology:

The shape of this fossil is ovoid but variable in details and most individuals range from 10 to 15 mm in length. A distinctive feature is a series of narrow tubular elements that are darker and often slightly raised; these are twisted and contorted and do not appear to be parts of a gut.

Abundance:

Pollingeria is locally very abundant with hundreds of specimens on some bedding surfaces. In the Walcott Quarry this species represents 5.83% of the specimens counted in the community (Caron and Jackson, 2008).

Maximum Size:
15 mm

Ecology:

Life habits: Unknown
Feeding strategies: Unknown
Ecological Interpretations:

Not enough is known about this organism to interpret its ecology.

References:

BRIGGS, D. E. G. AND S. CONWAY MORRIS. 1986. Problematica from the Middle Cambrian Burgess Shale of British Columbia, p. 167-183. In A. Hoffman and M. H. Nitecki (eds.), Problematic fossil taxa (Oxford Monographs on Geology and Geophysics No. 5). Oxford University Press & Clarendon Press, New York.

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

CONWAY MORRIS, S. 1979. The Burgess Shale (Middle Cambrian) fauna. Annual Review of Ecology and Systematics, 10(1): 327-349.

CONWAY MORRIS, S. 1985. The Middle Cambrian metazoan Wiwaxia corrugata (Matthew) from the Burgess Shale and Ogygopsis Shale Shale, British Columbia, Canada. Philosophical Transactions of the Royal Society of London, Series B, 307:507-582.

WALCOTT, C. 1911. Cambrian Geology and Paleontology II. Middle Cambrian annelids. Smithsonian Miscellaneous Collections, 57(5): 109-145.

Other Links:

None