The Burgess Shale

Media: 2D Model

Aysheaia pedunculata

Reconstruction of Aysheaia pedunculata.

© Marianne Collins

Taxonomy:

Kingdom: 2D Model
Phylum: 2D Model
Higher Taxonomic assignment: Xenusia (Order: Scleronychophora, stem group onychophorans)
Species name: Aysheaia pedunculata
Remarks:

Aysheaia is regarded as a member of the “lobopodans,” a group of vermiform Cambrian organisms possessing pairs of leg-like extensions of the body. The affinities of these animals are controversial; they have been placed at the base of a clade comprised of anomalocaridids and arthropods (Budd, 1996), or in a stem-group to modern onychophorans (Ramsköld and Chen, 1998).

Described by: Walcott
Description date: 1911
Etymology:

Aysheaia – after the nearby Aysha peak (since renamed Ayesha peak) in the Wapta icefield (3,065 m); original meaning unknown.

pedunculata – from the Latin pedunculus, “foot.”

Type Specimens: Holotype –USNM57655 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none

Other deposits: A.? prolata from the Middle Cambrian of Utah (Robison, 1985).

Age & Localities:

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

The Walcott Quarry on Fossil Ridge.

History of Research:

Brief history of research:

Walcott originally described Aysheaia as an annelid worm (Walcott, 1911). It was later re-described as a velvet worm (or a close relative) (Brues, 1923; Hutchinson, 1930; Walcott, 1931; Walton, 1927), although it lacked features such as jaws and slime glands. Its position remains a subject of debate, with a position in a new phylum being mooted (Tiegs and Manton, 1958). A morphological reinterpretation based on photographs (Delle Cave and Simonetta, 1975) prompted a detailed re-study of the fossil specimens (Whittington, 1978), and relationships were suggested with the water bears (tardigrades) (Bergström, 1978). Aysheaia is now grouped with close relatives in the class Xenusia (Liu et al., 2008), lobopods that fall on the arthropod stem lineage (Budd, 1996, 1998; Whittington, 1978).

Description:

Morphology:

Aysheaia is a worm-like animal, 1 to 6 cm in length and about 5 mm broad, bearing ten pairs of clawed, spiny limbs on the lower part of its body. It did not have a separate head, but a mouth occupied the very front of the body, accompanied by a pair of appendages and a circlet of bumps (papillae). The animal had a soft, flexible, non-mineralized cuticle, which had a corrugated, accordion-like form. Each stubby limb had ten corrugations, some of which bore a spiny projection. A suite of claws also adorned the end of each stub-foot. A faint line running down the axis of the organism is interpreted as its gut.

Abundance:

Aysheaia is rare in the Walcott Quarry representing less than 0.04% of the specimens counted in the community (Caron and Jackson, 2008).

Maximum Size:
60 mm

Ecology:

Life habits: 2D Model
Feeding strategies: 2D Model
Ecological Interpretations:

Aysheaia is frequently associated with the remains of sponges, and an ecological association has been posited. Whether Aysheaia used its spines to adhere to sponges while feeding on them, or whether it simply hid among sponges for protection from predators, is unclear.

References:

BERGSTRÖM, J. 1978. Morphology of fossil arthropods as a guide to phylogenetic relationships, p. 1-56 In A. P. Gupta (ed.), Arthropod Phylogeny. Van Nostrand Reinhold Co. New York.

BRUES, C. T. 1923. The geographical distribution of the Onychophora. American Naturalist, 57: 210-217.

BUDD, G. E. 1996. The morphology of Opabinia regalis and the reconstruction of the arthropod stem-group. Lethaia, 29: 1-14.

BUDD, G. E. 1998. Stem group arthropods from the Lower Cambrian Sirius Passet fauna of North Greenland, p. 125-138. In R. A. Fortey and R. H. Thomas (eds.), Arthropod relationships. Volume 55. Chapman & Hall, London.

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

DELLE CAVE, L. AND A. M. SIMONETTA. 1975. Notes on the morphology and taxonomic position of Aysheaia (Onycophora?) and of Skania (undetermined phylum). Monitore Zoologico Italiano, 9: 67-81.

HUTCHINSON, G. E. 1930. Restudy of some Burgess Shale fossils. Proceedings of the United States National Museum, 78(11): 59.

LIU, J., D. SHU, J. HAN, Z. ZHANG, AND X. ZHANG. 2008. Origin, diversification, and relationships of Cambrian lobopods. Gondwana Research, 14(1-2): 277-283.

ROBISON, R. A. 1985. Affinities of Aysheaia (Onychophora), with description of a new Cambrian species. Journal of Paleontology, 59(1): 226-235.

TIEGS, O. W. AND S. M. MANTON. 1958. The evolution of the Arthropoda. Biological Reviews, 33(3): 255-333.

WALCOTT, C. D. 1911. Middle Cambrian annelids. Smithsonian Miscellaneous Collections, 57(2): 109-144.

WALCOTT, C. D. 1931. Addenda to descriptions of Burgess Shale fossils. Smithsonian Miscellaneous Collections, 85(3): 1-46.

WALTON, L. B. 1927. The polychaete ancestry of the insects. American Naturalist, 61: 226-250.

WHITTINGTON, H. B. 1978. The lobopod animal Aysheaia pedunculata Walcott, Middle Cambrian, Burgess Shale, British Columbia. Philosophical Transactions of the Royal Society of London. B, Biological Sciences, 284(1000): 165-197.

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.

Other Links:

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

Nectocaris pteryx

3D animation of Nectocaris pteryx.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Kingdom: 2D Model
Phylum: 2D Model
Higher Taxonomic assignment: Cephalopoda (stem group molluscs)
Species name: Nectocaris pteryx
Remarks:

Nectocaris is regarded as an early stem-group mollusc close to the cephalopods. This stem-group also includes Vetustovermis from the Middle Cambrian Emu Bay Shale of Australia, and the Lower Cambrian Petalilium from the Chengjiang deposit in China (Smith and Caron, 2010).

Described by: Conway Morris
Description date: 1976
Etymology:

Nectocaris – from the Greek nekto, “swimming,” and the Latin caris, “shrimp,” based on its original interpretation as an arthropod.

pteryx – from the Greek pteryx, “fins,” in reference to the presence of fins.

Type Specimens: Holotype –USNM198667 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, Raymond and Collins Quarries on Fossil Ridge.

History of Research:

Brief history of research:

As with Odontogriphus, another Burgess Shale animal related to molluscs, Walcott collected the first specimen of Nectocaris between 1909 and 1924. The fossil was photographed by Walcott, and its print sat with the unidentified specimen in the Smithsonian collections until noticed and described by Simon Conway Morris in 1976. Due to the lateral compression of the fossil, his resulting reconstruction was laterally-oriented. The funnel, bent back over the front, resembled the head-shield of an arthropod, and yet the fin, folded along the top of the organism, looked much like the ray-bearing dorsal fin of a chordate. A chordate affinity was further suggested by the myomere-like appearance of the bars, and although Conway Morris did not offer a firm diagnosis, Simonetta (1988) promoted a chordate status (Insom et al., 1995).

Meanwhile, Glaessner had described Vetustovermis, based on an ill-preserved specimen from Australia’s Emu Bay Shale, and because of its segmented appearance he suggested an affinity with annelid worms (Glaessner, 1979). Other workers noted the similarity of some Chengjiang fossils to this specimen and described them as slug-like relatives of the molluscs (Chen et al., 2005). During this period, the Royal Ontario Museum had been collecting similar fossils, which Desmond Collins recognized as representatives of Nectocaris. These were eventually described as stem-group cephalopods (Smith and Caron, 2010). The relationships among members of this clade are difficult to determine, and it may require further fossil finds to establish their diversity and range. The absence of a shell in Nectocarisindicates that cephalopods, which were previously thought to have evolved later in the Cambrian from snail-like monoplacophorans, did not require a buoyant shell to start swimming, but derived their shell independently of other mollusc lineages.

Description:

Morphology:

The body of Nectocaris is kite-shaped and can reach up to 72 mm in length, including two flexible tentacles that extend forwards from the head, which also bears a pair of camera-type eyes on short stalks. A long, nozzle-like funnel originates under the base of the head. The main body has wide lateral fins with transverse bars; a large axial cavity contains paired gills.

Abundance:

Nectocaris is known from 90 specimens on Fossil Ridge, mostly from the Collins Quarry; it is rare or absent at most other Burgess Shale localities. Only two specimens, including the holotype, have been found in the Walcott Quarry.

Maximum Size:
72 mm

Ecology:

Life habits: 2D Model
Feeding strategies: 2D Model
Ecological Interpretations:

A free-swimming predator or scavenger, Nectocaris would have fed on small prey items with its prehensile tentacles in a similar fashion to squid today. Its primary mode of propulsion would have been in the flexing of its fins; it may have supplemented this by squirting water from its funnel. The funnel was also used to inhale and exhale water, which entered the animal’s body cavity to oxygenate the large internal gills.

References:

CHEN, J.-Y., D.-Y. HUANG AND D. J. BOTTJER. 2005. An Early Cambrian problematic fossil: Vetustovermis and its possible affinities. Proceedings of the Royal Society B: Biological Sciences, 272(1576): 2003-2007.

CONWAY MORRIS, S. 1976. Nectocaris pteryx, a new organism from the Middle Cambrian Burgess Shale of British Columbia. Neues Jahrbuch für Geologie und Paläontologie, Monatshefte, 12: 703-713.

GLAESSNER, M. F. 1979. Lower Cambrian Crustacea and annelid worms from Kangaroo Island, South Australia. Alcheringa, 3(1): 21-31.

INSOM, E. A. PUCCI AND A. M. SIMONETTA. 1995. Cambrian Protochordata, their origin and significance. Bollettino di Zoologia, 62(3): 243-252.

SIMONETTA, A. M. 1988. Is Nectocaris pteryx a chordate? Bollettino di Zoologia, 55(1-2): 63-68.

SMITH, M. AND J.-B. CARON. 2010. Primitive soft-bodied cephalopods from the Cambrian. Nature, 465: 469-472.

Other Links:

http://www.nature.com/nature/journal/v465/n7297/full/nature09068.html

Naraoia compacta

Reconstruction of Naraoia compacta.

© MARIANNE COLLINS

Taxonomy:

Kingdom: 2D Model
Phylum: 2D Model
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: 2D Model
Feeding strategies: 2D Model
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

Amiskwia sagittiformis

Reconstruction of Amiskwia sagittiformis.

© Marianne Collins

Taxonomy:

Kingdom: 2D Model
Phylum: 2D Model
Higher Taxonomic assignment: Non applicable
Species name: Amiskwia sagittiformis
Remarks:

The phylogenetic position of Amiskwia is uncertain. Despite significant objections to its traditional interpretation as a chaetognath (Conway Morris, 1977; Owre and Bayer, 1962), some workers still hold this view (Butterfield, 1990). Nemertine (Owre and Bayer, 1962) and molluscan (Chen and Huang, 2002; Chen et al., 2005) affinities have also been suggested, but not substantiated.

Described by: Walcott
Description date: 1911
Etymology:

Amiskwia – from the Cree amiskwi, “beavertail,” a name given to various topographical features in Yoho National Park.

sagittiformis – from the Latin sagitta, “arrow,” and formis, “shape,” in reference to the general outline of the animal.

Type Specimens: Lectotype – UNSM 57644 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none.

Other deposits: A. sinica (Chen et al., 2002) from the Lower Cambrian Chengjiang deposits, Yunnan, China.

Age & Localities:

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

The Walcott Quarry on Fossil Ridge.

History of Research:

Brief history of research:

Described by Walcott in 1911, Amiskwia was originally interpreted as an arrow-worm (Walcott, 1911). Originally popular, this interpretation fell into disrepute after further studies (Conway Morris, 1977; Owre and Bayer, 1962), but it has more recently been reconsidered as a possible arrow-worm (Butterfield, 1990).

Description:

Morphology:

Amiskwia is a symmetrical, flattened worm. It bears a pair of lateral fins in addition to a paddle-like tail fin. A pair of small tentacles is situated on the bottom of its head, just in front of its mouth. The trace of a gut and other internal organs are preserved in the fossils.

Abundance:

A. saggitiformis is known from only a couple dozen specimens from the Walcott Quarry, comprising only 0.025% of the specimens counted (Caron and Jackson, 2008).

Maximum Size:
25 mm

Ecology:

Life habits: 2D Model
Feeding strategies: 2D Model
Ecological Interpretations:

The presence of fins demonstrates that Amiskwia was well adapted for swimming. Its rarity in the Burgess Shale suggests that it may have spent much of its time well above the sea bed, above the depth at which it could be caught in submarine mudslides.

References:

BUTTERFIELD, N. J. 1990. Organic preservation of non-mineralizing organisms and the Taphonomy of the Burgess Shale. Paleobiology, 16(3): 272-286.

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

CHEN, J.-Y. AND D.-Y. HUANG. 2002. A possible Lower Cambrian chaetognath (arrow worm). Science, 298(5591): 187.

CHEN, J.-Y., D.-Y. HUANG AND D. J. BOTTJER. 2005. An Early Cambrian problematic fossil: Vetustovermis and its possible affinities. Proceedings of the Royal Society B: Biological Sciences, 272(1576): 2003-2007.

CHEN, L., H. LUO, S. HU, J. YIN, Z. JIANG, Z. WU, F. LI AND A. CHEN. 2002. Early Cambrian Chengjiang fauna in Eastern Yunnan, China. Yunnan Science and Technology Press, Kunming, China, 199 p.

CONWAY MORRIS, S. 1977. A redescription of the Middle Cambrian worm Amiskwia sagittiformis Walcott from the Burgess Shale of British Columbia. Palaontologische Zeitschrift, 51(3): 271-287.

OWRE, H. B. AND F. M. BAYER. 1962. The systematic position of the Middle Cambrian fossil Amiskwia Walcott. Journal of Paleontology, 36(6): 1361-1363.

WALCOTT, C. D. 1911. Middle Cambrian annelids. Smithsonian Miscellaneous Collections, 57(2): 109-144.

Other Links:

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

Marrella splendens

3D animation of Marrella splendens.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Kingdom: 2D Model
Phylum: 2D Model
Higher Taxonomic assignment: Marrellomorpha (Order: Marrellida, stem group arthropods)
Species name: Marrella splendens
Remarks:

The affinity of Marrella is still somewhat uncertain. It has been grouped together with the Devonian taxa Mimetaster and Vachonisia from the Hunsrück Shale to form the Class Marrellomorpha (Beurlen, 1934; Strømer, 1944), but the placement of this class in arthropod evolution is unclear. It has been suggested to be at the base of a group of Lamellipedian arthropods, including trilobites and trilobite-like taxa, (Hou and Bergström, 1997), but has also been placed in the most basal position in the upper stem lineage arthropods (Briggs and Fortey, 1989; Wills et al., 1998).

Described by: Walcott
Description date: 1912
Etymology:

Marrella – after Dr. John Marr, palaeontologist at Cambridge University and friend of Walcott.

splendens – from the Latin splendens, “beautiful, or brilliant.”

Type Specimens: Lectotype –USNM57674 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none

Other deposits: Marrella sp. from the Kaili Biota of southwest China (Zhao et al., 2003).

Age & Localities:

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

The Walcott and Raymond Quarries on Fossil Ridge. Smaller localities on Mount Field, the Tulip Beds (S7) on Mount Stephen and Mount Odaray.

History of Research:

Brief history of research:

Marrella was one of the first fossils found by Walcott, and sketches appear in his notebook as early as August 31st, 1909. Walcott informally named them “lace crabs” at the time. The next summer, on August 9, 1910, Walcott and son Stuart found the “lace crab beds” in situ, marking the discovery of the fossil-bearing beds of the Walcott Quarry of the Burgess Shale. Walcott (1912) formally described the “lace crabs” as Marrella splendens, but a reconstruction was not attempted until Raymond (1920).

Marrella was examined again by Simonetta (1962) and in a major study by Whittington (1971). New specimens collected by the Royal Ontario Museum allowed for the description of a specimen showing Marrella in the act of moulting (García-Bellido and Collins, 2004), and another re-description of the taxon (García-Bellido and Collins, 2006).

Description:

Morphology:

Marrella is a small arthropod with a wedge-shaped head shield bearing two pairs of prominent spines that project from the sides and posterodorsal margin and extend back along most of the length of the body. There is also a pair of smaller posteroventral spines. The head bears a pair of long, thin antennae with as many as 30 segments, and a pair of paddle-like appendages with six segments and numerous bushy setae along the edges.

Behind the head, the body consists of 26 segments that are small and subcircular, each bearing a pair of biramous appendages. The walking branch of this appendage has six segments, and the second branch is made of tapering gills with long, slim filaments that attach near the base of the legs. The last twelve body segments have conspicuous internal projections that form a net below the body.

The tail is minute and pointed. The stomach is located in the head near the ventral mouth, and the intestine stretches most of the length of the body. Dark stains found around the body are suggested to be the gut contents that were squeezed out during preservation. A small, triangular dorsal heart is located in the cephalic region and has arteries branching off from it.

Abundance:

Marrella is one of the most common species in the Burgess Shale. Over 25,000 specimens have been collected (García-Bellido and Collins, 2006), and it is the second most common arthropod species in Walcott Quarry, comprising 7.3% of the specimens counted (Caron and Jackson, 2008).

Maximum Size:
25 mm

Ecology:

Life habits: 2D Model
Feeding strategies: 2D Model
Ecological Interpretations:

Marrella was an active swimmer that moved just above the sea floor while deposit feeding. It could rest on the sea floor by standing on its body appendages. Swimming was achieved by undulating the second pair of paddle-like appendages on the head. Its antennae would be used to sense the environment and locate food items. The net of internal projections on the last twelve body segments would have been used to trap food particles located in water currents and to pass them along the underside of the animal. Food particles trapped in the net would be moved towards the mouth using the tips of the anterior legs.

References:

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

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

BEURLEN, K. 1934. Die Pygaspiden, eine neue Crustaceen – (Entomostraceen) – Gruppe aus den Mesosaurier führenden Iraty-Scichten Brasiliens. Paläontologische Zeitschrift, 16: 122-138.

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

GARCÍA-BELLIDO, D. AND D. H. COLLINS. 2004. Moulting arthropod caught in the act. Nature, 429: 40.

GARCÍA-BELLIDO, D. AND D. H. COLLINS. 2006. A new study of Marrella splendens(Arthropoda, Marrellomorpha) from the Middle Cambrian Burgess Shale, British Columbia, Canada. Canadian Journal of Earth Sciences, 43: 721-742.

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

RAYMOND, P. E. 1920. The appendages, anatomy, and relationships of trilobites. Memoirs of the Connecticut Academy of Arts and Sciences, 7: 1-169.

SIMONETTA, A. M. 1962. Note sugli artropodi non trilobiti della Burgess Shale, Cambriano Medio della Columbia Britannica (Canada). 1. contributo: 2. genere Marrella Walcott, 1912. Monitore Zoologico Italiano, 69: 172-185.

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

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

WHITTINGTON, H. B. 1971. Redescription of Marrella splendens (Trilobitoidea) from the Burgess Shale, Middle Cambrian, British Columbia. Bulletin of the Geological Survey of Canada, 209: 1-24.

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.

ZHAO, Y., J. YUAN, M. ZHU, X. YANG AND J. PENG. 2003. The occurrence of the genus Marrella (Trilobitoidea) in Asia. Progress in Natural Science, 13: 708-711.

Other Links:

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

Leanchoilia superlata

3D animation of Leanchoilia superlata.

Animation by Phlesch Bubble © Royal Ontario Museum

Taxonomy:

Kingdom: 2D Model
Phylum: 2D Model
Higher Taxonomic assignment: Megacheira (Order: Leanchoiliida, stem group arthropods)
Species name: Leanchoilia superlata
Remarks:

The phylogenetic position of Leanchoilia is controversial. Some studies align it with the arachnomorphs, a group including trilobites and chelicerates (Wills et al., 1998; Cotton and Braddy, 2004), while others group Leanchoilia with Alalcomenaeus, Yohoia and Isoxys together in the Megacheira, the “great appendage” arthropods (Hou and Bergström 1997). Megacheirans have been suggested to either be stem-lineage chelicerates (Chen et al., 2004; Edgecombe, 2010), or the stem-lineage euarthropods (Budd, 2002).

Described by: Walcott
Description date: 1912
Etymology:

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

superlata – from the Latin superlata, “exaggerated.”

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

Burgess Shale and vicinity: L. persephone from Walcott Quarry and Raymond Quarry on Fossil Ridge, as well as other sites on Mount Stephen and Mount Field; L. protagonia from the Walcott Quarry.

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

Age & Localities:

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

Burgess Shale and vicinity: The Walcott and Raymond Quarries, Fossil Ridge. Additional localities are known on Mount Field and Mount Stephen – Tulip Beds (S7).

Other deposits: L. superlata,, from the Middle Cambrian of Utah (Briggs et al., 2008).

History of Research:

Brief history of research:

Leanchoilia superlata was first described by Walcott in 1912, and later revised by Simonetta (1970), who added the second and third species L. persephone and L. protagonia. L. superlata was later restudied in detail by Bruton and Whittington (1983) and García-Bellido and Collins (2007), who included in their study an analysis of L. persephone. The three-dimensionally preserved gut of Leanchoilia was analyzed by Butterfield (2002). A more detailed description of L. protagonia was provided by Briggs et al. (2008) who also identified L. superlata from the Cambrian sediments of Utah.

Description:

Morphology:

The body is convex in cross section and is widest in the posterior part of the trunk. The largest animal recorded is 12 cm long, including appendages. The head shield has a pointed anterior with a distinct upward-curving snout. The lateral edges of the head shield are serrated with short spines. The head bears a pair of frontal appendages, often referred to as “great appendages,” each consisting of three branches terminating in long flexible flagella, followed by two pairs of appendages that are segmented and branch into two (biramous), with large and flat outer gill blades. Two pairs of simple eyes are present below the head shield and the mouth was positioned just behind the base of the great appendages.

The trunk is composed of 11 segments with two dorsal angular peaks (or carinae) along the midline. The trunk also appears serrated, with each segment having short spines along the edges. Each segment bears one pair of biramous appendages similar to the ones on the head. The inner branch of the limb attaches to a small coxa with no spines and has small elongate spines along its podomeres, with the last terminating in small claws. The telson is triangular and is fringed on both sides with 11 long and straight lateral spines. Serially repeated three dimensional structures along the body have been interpreted as mid-gut glands preserved in phosphate. L. persephone and L. protagonia lack a frontal snout and have shorter great appendages, with the latter having an elongate telson with six pairs of long spines. L. persephone and L. superlata have been interpreted as potential sexual variants (see García-Bellido and Collins, 2007)

Abundance:

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

Maximum Size:
120 mm

Ecology:

Life habits: 2D Model
Feeding strategies: 2D Model
Ecological Interpretations:

The large gill branches could have been used for respiration as well as for swimming. The lack of strong sclerotization of the limbs and strong hinge joints suggest that this animal was not adapted for walking. The flagellae of the great appendages are thought to be sensory organs. The great appendages would have presumably folded backwards below the trunk while the animal was swimming, and pointed forwards when the animal was resting or feeding. The distal claws and the leg branches could have been used to dig through the superficial level of the mud and to bring particulate matter or small prey items towards the mouth. More recently, the presence of mid-gut glands, eyes, and spines along the limbs have also been interpreted as potential evidence for scavenging or predatory habits. The animal would have probably swum just above the sea bottom in search of food.

References:

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

BRUTON, D. L. AND H. B. WHITTINGTON. 1983. Emeraldella and Leanchoilia, Two arthropods from the Burgess Shale, Middle Cambrian, British Columbia. Philosophical Transactions of the Royal Society of London, Series B, 300: 553-582.

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

BUTTERFIELD, N. J. 2002. Leanchoilia guts and the interpretation of three-dimensional structures in Burgess Shale-type fossils. Paleobiology, 28: 155-171.

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

CHEN, J. Y., D. WALOSZEK AND A. MAAS. 2004. A new ‘great-appendage’ arthropod from the Lower Cambrian of China and homology of chelicerate chelicerae and raptorial antero-ventral appendages. Lethaia, 37: 3-20.

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. 2010. Arthropod phylogeny: An overview from the perspectives of morphology, molecular data and the fossil record. Arthropod Structure and Development, 39: 74-87.

GARCÍA-BELLIDO, D. C. AND D. COLLINS. 2007. Reassessment of the genus Leanchoilia (Arthropoda, Arachnomorpha) from the middle Cambrian Burgess Shale, British Columbia, Canada. Palaeontology, 50: 693-709.

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

LIU, Y., X.-G. HOU, AND J. BERGSTRÖM. 2007. Chengjiang arthropod Leanchoilia illecebrosa (Hou, 1987) reconsidered. Gff, 129: 263-272.

SIMONETTA, A. M. 1970. Studies on non trilobite arthropods of the Burgess Shale (Middle Cambrian). Palaeontographia Italica, 66 (New series 36): 35-45.

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

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.

Other Links:

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

Lingulella waptaensis

Reconstruction of Lingulella waptaensis.

© Marianne Collins

Taxonomy:

Kingdom: 2D Model
Phylum: 2D Model
Higher Taxonomic assignment: Lingulata (Order: Lingulida)
Species name: Lingulella waptaensis
Remarks:

Lingulella belongs within the Family Obolidae.

Described by: Walcott
Description date: 1924
Etymology:

Lingulella – from the Latin lingua, “tongue,” and ellus, “diminutive.”

waptaensis – from Wapta Moutain (2,778 m), just north of the Walcott Quarry, in British Columbia, Canada.

Type Specimens: Syntypes –USNM69822-69824 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

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

Other deposits: Hundreds of species have been assigned to the genus Lingulella.

Age & Localities:

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

The Walcott Quarry on Fossil Ridge.

History of Research:

Brief history of research:

Lingulella waptaensis was only cursorily described by Walcott (1924). At least another possible related form is known from the Trilobite Beds – originally described as Lingulella mcconnelli (Walcott, 1889; Matthew, 1902) and later renamed Obolus mconnelli (Walcott, 1908, 1912). Sutton et al. (2000) revised the diagnosis of Lingulella, restricting the concept of what had become a ‘trashcan’ genus for any similar elongate forms (called “obolids”). Consequently, many of the hundreds of species assigned to Lingulella no longer fit the diagnosis. As such, ‘Lingulella’ waptaensis needs to be re-examined to determine whether it conforms to the current concept of the genus. Shell structures and the first specimens with pedicles preserved have recently been described from the Burgess Shale (Pettersson et al., 2010).

Description:

Morphology:

Lingulella waptaensis is elongate and suboval in outline. The valves are weakly biconvex and smooth with the exception of growth lines. The visceral areas are weakly impressed to the interior of the shell and difficult to study in details. The pedicle is slender and protrudes between the valves. It is at least three times the length of the valves and is often twisted and wrinkled. The shell was originally mineralized.

Abundance:

Lingulella waptaensis is known from several hundred specimens in the Walcott Quarry but overall represents a small fraction of the fauna (<0.7%) (Caron and Jackson, 2008)

Maximum Size:
10 mm

Ecology:

Life habits: 2D Model
Feeding strategies: 2D Model
Ecological Interpretations:

Like another comparable brachiopod from the Burgess Shale, Acanthotretella spinosa, the long, thin pedicle and overall shell shape of Lingulella waptaensis probably precludes an infaunal habit. The pedicle was likely able to maintain the shell in an upright position well above the sediment-water interface. Extraction of food particles from the water would have been possible thanks to a filter-feeding apparatus (located between the shells) called a lophophore.

References:

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

MATTHEW, G. F. 1902. Notes on Cambrian Faunas: Cambrian Brachiopoda and Mollusca of Mt. Stephen, B.C. with the description of a new species of Metoptoma. Transactions of the Royal Society of Canada, 4: 93-112.

PETTERSSON, S., L. E. HOLMER AND J.-B. CARON. 2010. First record of a pediculate linguloid from the Middle Cambrian Burgess Shale. Acta Zoologica, 91: 150-162.

SUTTON, M. D., M. G. BASSET AND L. CHERNS. 2000. The type species of Lingulella (Cambrian Brachiopoda). Journal of Paleontology, 74: 426-438.

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

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

WALCOTT, C. D. 1924. Cambrian and Ozarkian Brachioda. Cambrian Geology and Paleontology IV. Smithsonian Miscellaneous Collections, 67: 477-554.

Other Links:

http://onlinelibrary.wiley.com/doi/10.1111/j.1463-6395.2009.00394.x/abstract

Laggania cambria

Reconstruction of Laggania cambria.

© Marianne Collins

Taxonomy:

Kingdom: 2D Model
Phylum: 2D Model
Higher Taxonomic assignment: Dinocarida (Order: Radiodonta, stem group arthropods)
Species name: Laggania cambria
Remarks:

Laggania is an anomalocaridid. Anomalocaridids have been variously regarded as basal stem-lineage euarthropods (e.g., Daley et al., 2009), basal members of the arthropod group Chelicerata (e.g., Chen et al., 2004), and as a sister group to the arthropods (e.g., Hou et al., 2006).

Described by: Walcott
Description date: 1911
Etymology:

Laggania – from Laggan, the name given to a now defunct railway station on the Canadian Pacific Railway in Banff National Park, now known as Lake Louise Village. The name Laggan comes from a location of a 1655 battle in the Great Glen of Scotland.

cambria – from the Welsh Cambria meaning Wales.

Type Specimens: Holotype –USNM57555 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: A possible new species from the Tulip Beds (S7) on Mount Stephen (Daley and Budd, 2010).

Other deposits: none.

Age & Localities:

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

The Walcott Quarry on Fossil Ridge.

History of Research:

Brief history of research:

The anomalocaridids, including Laggania, have a complex history of description, because parts of their bodies were preserved in isolation from each other, resulting in the body part fossils being given their own generic names before they were identified as different parts of the same animal. The name Laggania cambria was first applied to a single specimen of a “sea cucumber” (Walcott, 1911a), which was later re-described as a superimposition of the “jellyfish” Peytoia nathorsti on top of a sponge (Conway Morris, 1978). The frontal appendages of Laggania were first described as “Appendage F”, the feeding appendages of the arthropod Sidneyia (Walcott, 1911b), but they were later removed from that genus and described as the appendage of an unknown arthropod (Briggs, 1979).

A critical revelation was made by Harry Whittington early in the 1980s when he discovered the basic body plan of the anomalocaridids by preparing specimens of Anomalocaris and Laggania. He revealed that the anomalocaridids had the “jellyfish” Peytoia as a mouth part and a pair of large frontal appendages at the front of the head. Whittington and Briggs (1985) first described Laggania under the name Anomalocaris nathorsti. Bergström (1986) re-described some aspects of the morphology of the anomalocaridids.

The discovery of several more complete specimens during Royal Ontario Museum fieldwork in the 1990s allowed Collins (1996) to reconstruct the genus Anomalocaris with greater accuracy. This led to a reversal of names from Anomalocaris nathorsti to Laggania cambria. Laggania has since been the subject of many studies discussing anomalocaridid affinity (e.g., Hou et al., 1995; Chen et al., 2004; Daley et al., 2009).

Description:

Morphology:

The body of Laggania consists of a posterior body region with a series of lateral swimming flaps, and a head region with circular mouth parts, a pair of frontal appendages, two large eyes, and a head shield. Full body specimens are no longer than 15 cm in length, but isolated parts suggest that body lengths could be much longer, perhaps up to 50 cm. The frontal appendages have eleven robust segments with short dorsal and lateral spines and five elongated ventral spines.

A pair of these appendages is found on the ventral surface of the head, flanking the mouth parts. They consist of 32 rectangular plates, four large and 28 small, arranged in a circle with sharp spines pointing into a square central opening. The large, oval eyes are located on either side of the head, and a thin carapace shield covers the dorsal head region. The trunk of Laggania has a central region of eleven segments bearing rows of gills, and elongated, wide swimming flaps extending out to either side. The body trunk is tapering, and ends in a blunt tail.

Abundance:

Ten whole-body specimens of Laggania and dozens of isolated frontal appendages are known from the Walcott Quarry on Fossil Ridge.

Maximum Size:
500 mm

Ecology:

Life habits: 2D Model
Feeding strategies: 2D Model
Ecological Interpretations:

Laggania was an active swimmer, as indicated by the lack of walking limbs and the presence of numerous gills. It probably propelled itself through the water column by undulating its swimming flaps along the sides of its body. The large eyes, sharp mouth parts and spiny appendages would have made Laggania a formidable predator. It may have used its frontal appendages as a sieve to sift prey out from the sediment or entangle swimming prey and sweep them towards its mouth parts. The mouth parts likely operated by pivoting the plates outwards and contracting them inward to bring prey further into the mouth. Like other anomalocaridids, Laggania probably ingested mostly soft-bodied prey. It swam through the water column just above the sea floor, using its large eyes to seek out prey.

References:

BERGSTRÖM, J. 1986. Opabinia and Anomalocaris, unique Cambrian ‘arthropods’. Lethaia, 19: 241-46.

BRIGGS, D. E. G. 1979. Anomalocaris, the largest known Cambrian arthropod. Palaeontology, 22: 631-663.

CHEN, J. Y., D. WALOSZEK AND A. MAAS. 2004. A new ‘great-appendage’ arthropod from the Lower Cambrian of China and homology of chelicerate chelicerae and raptorial antero-ventral appendages. Lethaia, 37: 3-20.

COLLINS, D. 1996. The “evolution” of Anomalocaris and its classification in the arthropod class Dinocarida (nov) and order Radiodonta (nov). Journal of Paleontology, 70: 280-293.

CONWAY MORRIS, S. 1978. Laggania cambria Walcott: a composite fossil. Journal of Paleontology, 52: 126-131.

DALEY, A. C. AND G. E. BUDD. 2010. New anomalocaridid appendages from the Burgess Shale, Canada. Palaeontology, 53: 721-738.

DALEY, A. C., G. E. BUDD, J. B. CARON, G. D. EDGECOMBE AND D. COLLINS. 2009. The Burgess Shale anomalocaridid Hurdia and its significance for early euarthropod evolution. Science, 323: 1597-1600.

HOU, X., J. BERGSTRÖM AND P. AHLBERG. 1995. Anomalocaris and other large animals in the Lower Cambrian Chengjiang fauna of Southwest China. GFF, 117: 163-183.

HOU, X., J. BERGSTRÖM AND Y. JIE. 2006. Distinguishing anomalocaridids from arthropods and priapulids. Geological Journal, 41: 259-269.

WALCOTT, C. D. 1911a. Middle Cambrian holothurians and medusae. Cambrian geology and paleontology II. Smithsonian Miscellaneous Collections, 57: 41-68.

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

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

Other Links:

None

Herpetogaster collinsi

3D animation of Herpetogaster collinsi.

Animation by Phlesch Bubble © Royal Ontario Museum

Taxonomy:

Kingdom: 2D Model
Phylum: 2D Model
Higher Taxonomic assignment: Unranked clade Cambroernida (stem group ambulacrarians)
Species name: Herpetogaster collinsi
Remarks:

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

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

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

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

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

Burgess Shale and vicinity: none.

Other deposits: none.

Age & Localities:

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

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

History of Research:

Brief history of research:

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

Description:

Morphology:

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

Abundance:

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

Maximum Size:
48 mm

Ecology:

Life habits: 2D Model
Feeding strategies: 2D Model
Ecological Interpretations:

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

References:

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

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

Other Links:

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

Helmetia expansa

Reconstruction of Helmetia expansa.

© Marianne Collins

Taxonomy:

Kingdom: 2D Model
Phylum: 2D Model
Higher Taxonomic assignment: Unranked clade (stem group arthropods)
Species name: Helmetia expansa
Remarks:

Helmetia is extremely rare and poorly known, so its phylogenetic affinity is uncertain. Some researchers have suggested it may be aligned with the arachnomorphs, as a sister group to the trilobites (Edgecombe and Ramsköld, 1999; Cotton and Braddy, 2004). If this is confirmed, Helmetia probably represents a stem group of the Mandibulata, which includes crustaceans, myriapods, and hexapods (Scholtz and Edgecombe, 2006).

Described by: Walcott
Description date: 1918
Etymology:

Helmetia – from Helmet Mountain (3,138 m) in Kootenay National Park, named by Joseph Scattergood in 1900 because of the helmet shape of the peak.

expansa – from the Latin expansa, “spread out or wide,” referring to the broad body.

Type Specimens: Lectotype –USNM83952 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none.

Other deposits: Helmetia? fastigata from the Jince Formation in the Czech Republic (Chlupáč and Kordule 2002).

Age & Localities:

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

The Walcott and Raymond Quarries on Fossil Ridge

History of Research:

Brief history of research:

Helmetia expansa was first described by Walcott in 1918, and has not been re-examined since, except for brief reviews by Conway Morris et al. (1992) and Briggs et al. (1994). It has been included in several phylogenetic analyses of the arachnomorphs (e.g. Edgecombe and Ramsköld, 1999; Cotton and Braddy, 2004).

Description:

Morphology:

The most complete specimen of Helmetia is approximately 19 cm long and has a broad, flat and thin dorsal exoskeleton. The body consists of a head shield, six thoracic segments, and a large tail shield. The head shield has a concave frontal margin with two prominent spines at each corner. An oval structure with two large spots sits in the center of the head shield anterior margin. Two eyes are preserved as reflective spots behind the oval structure on either side. The six body segments are relatively thin but broad, and have a single spine projecting from their back corners. The tail shield tapers rapidly to a point, with two posteriorly-directed spines on the sides. The central region of the body has paired reflective muscle attachment scars near the anterior, and a series of large filamentous structures.

Abundance:

Helmetia expansa is extremely rare at the Walcott Quarry and the Raymond Quarry.

Maximum Size:
190 mm

Ecology:

Life habits: 2D Model
Feeding strategies: 2D Model
Ecological Interpretations:

Helmetia was likely free-swimming, as indicated by the lack of walking limbs, the flat carapace and the presence of filamentous appendages. The shape of the carapace might have limited sinking, but the body is not streamlined, suggesting it was a slow swimmer. It is unlikely that it actively pursued swimming prey, because there are no apparent appendages or other modifications for predation or scavenging. It may have been a suspension feeder.

References:

BRIGGS, D. E. G., D. H. ERWIN AND F. J. COLLIER. 1994. The fossils of the Burgess Shale. Smithsonian Institution Press, Washington D. C.

CHLUPÁČ, I. AND V. KORDULE. 2002. Arthropods of Burgess Shale type from the Middle Cambrian of Bohemia (Czech Republic). Bulletin of the Czech Geological Survey, 77: 167-182.

CONWAY MORRIS, S., H. B. WHITTINGTON, D. E. G. BRIGGS, C. P. HUGHES. AND D. L. BRUTON. 1992. Atlas of the Burgess Shale. Palaeontological Association, London.

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.

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. 1918. Geological explorations in the Canadian Rockies. Explorations and fieldwork of the Smithsonian Institution in 1917. Smithsonian Miscellaneous Collections, 68: 4-20.

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