The Burgess Shale

Selkirkia columbia

3D animation of Selkirkia columbia.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Class: Unranked clade (stem group priapulids)
Remarks:

Selkirkia has been compared to the nemathelminth worms (Maas et al., 2007), but most analyses support a relationship with the priapulids at a stem-group level (Harvey et al., 2010; Wills, 1998).

Species name: Selkirkia columbia
Described by: Walcott
Description date: 1911
Etymology:

Selkirkia – from the Selkirk Mountains, a mountain range in southeastern British Columbia.

columbia – from British Columbia, where the Burgess Shale is located.

Type Specimens: Holotype –USNM57624 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none.

Other deposits: The genus Selkirkia ranges from the Lower to the Middle Cambrian and is represented by several species, including S. sinica from the Lower Cambrian Chengjiang Biota (Luo et al., 1999; Maas et al., 2007), S. pennsylvanica from the Lower Cambrian Kinzers Formation (Resser and Howell, 1938), Selkirkia sp. cf. and S. spencei from the Middle Cambrian Spence Shale of Utah (Resser, 1939; Conway Morris and Robison, 1986, 1988), and S. willoughbyi from the Middle Cambrian Marjum Formation of Utah (Conway Morris and Robison, 1986).

Age & Localities:

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

Burgess Shale and vicinity: The Walcott, Raymond and Collins Quarries on Fossil Ridge, and smaller localities on Mount Field and Mount Odaray. The Trilobite Beds, the Collins Quarry, the Tulip Beds (S7) and smaller localities on Mount Stephen.

Other deposits: The Middle Cambrian Spence Shale of Utah (Resser, 1939; Conway Morris and Robison, 1986, 1988).

History of Research:

Brief history of research:

Charles Walcott (1908) illustrated a single specimen of a simple tube that he named “Orthotheca major.” He interpreted the fossil as the tube of a polychaete worm, along with another famous species, “O. corrugata,” described by Matthew a decade earlier. O. corrugata is now referred to as Wiwaxia corrugata, which is not the tube of a worm but the scale of an armoured mollusc! The original specimen of “O. major” came from the Trilobite Beds on Mount Stephen, but it was not until the discovery of complete specimens from Fossil Ridge showing soft-bodied worms within the tubes that more details about this animal became available. Walcott (1911) created a new genus name Selkirkia to accommodate the new fossil material. In addition to the type species, S. major, he named two new species, S. gracilis and S. fragilis. In a revision of Walcott’s collections and other fossils discovered by the Geological Survey of Canada, Conway Morris (1977) synonymised Walcott’s three species into one that he called S. columbia, which is still in use today. S. columbia was described as a primitive priapulid worm (Conway Morris, 1977); later studies showed that it belongs to the priapulid stem group (Wills, 1998; Harvey et al., 2010).

Description:

Morphology:

Selkirkia lived in a tube and could reach up to 6 centimetres in length. The body of the worm itself is similar to most priapulids in having a trunk (which remained in the tube) and an anterior mouthpart that could be inverted into the trunk, called a proboscis. The proboscis has different series of spines along its length and is radially symmetrical. Small body extensions called papillae are present along the anterior part of the trunk and probably helped in anchoring the trunk in the tube. The gut is straight and the anus is terminal. The unmineralized tube is slightly tapered, open at both ends, and bears fine transverse lineations.

Abundance:

Selkirkia is the most abundant priapulid in the Walcott Quarry community, representing 2.7% of the entire community (Caron and Jackson, 2008); thousands of specimens are known, mostly isolated tubes.

Maximum Size:
60 mm

Ecology:

Ecological Interpretations:

The well developed proboscis and strong spines suggest a carnivorous feeding habit. Comparisons with modern tube-building priapulids suggest Selkirkia was capable of only limited movement, and spend most of the time buried vertically or at an angle to the sediment-water interface, where they might have “trap fed” on live prey. Empty tubes were often used as a substrate for other organisms to colonize, for example, brachiopods, sponges and primitive echinoderms (see Echmatocrinus).

References:

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

CONWAY MORRIS, S. AND R. A. ROBISON. 1986. Middle Cambrian priapulids and other soft-bodied fossils from Utah and Spain. The University of Kansas paleontological contributions, 117: 1-22.

CONWAY MORRIS, S. AND R. A. ROBISON. 1988. More soft-bodied animals and algae from the Middle Cambrian of Utah and British Columbia. University of Kansas Paleontological Contributions, Paper, 122: 23-48.

HARVEY, T. H. P., X. DONG AND P. C. J. DONOGHUE. 2010. Are palaeoscolecids ancestral ecdysozoans? Evolution & Development, 12(2): 177-200.

LUO, H., S. HU, L. CHEN, S. ZHANG AND Y. TAO. 1999. Early Cambrian Chengjiang fauna from Kunming region, China. Yunnan Science and Technology Press, Kunming, 162 p.

MAAS, A., D. HUANG, J. CHEN, D. WALOSZEK AND A. BRAUN. 2007. Maotianshan-Shale nemathelminths – Morphology, biology, and the phylogeny of Nemathelminthes. Palaeogeography, Palaeoclimatology, Palaeoecology, 254(1-2): 288-306.

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

RESSER, C. E. 1939. The Spence Shale and its fauna. Smithsonian Miscellaneous Collections, 97(12):1-29.

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

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

WILLS, M. A. 1998. Cambrian and Recent disparity: the picture from priapulids. Paleobiology, 24(2): 177-199.

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Scolecofurca rara

Scolecofurca rara (GSC 45331) – Holotype (part and counterpart). Only known specimen of the species showing the pair tentacles in direct light (anterior to the right). Specimen length = 65 mm. Specimen wet – direct light (top), dry – polarized light (middle and bottom). Raymond Quarry.

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

Taxonomy:

Class: Unranked clade (stem group priapulids)
Remarks:

Scolecofurca belongs to the priapulid worm stem group (Harvey et al., 2010; Wills, 1998).

Species name: Scolecofurca rara
Described by: Conway Morris
Description date: 1977
Etymology:

Scolecofurca – from the Greek skolex, meaning “worm,” and the Latin furca, “fork,” in reference to the fork-like anterior of this worm.

rara – from the Latin rarus, “infrequent,” in reference to the rarity of the species.

Type Specimens: Holotype – GSC45331 in the Geological Survey of Canada, Ottawa, Canada.
Other species:

Burgess Shale and vicinity: none.

Other deposits: none.

Age & Localities:

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

The Raymond Quarry on Fossil Ridge.

History of Research:

Brief history of research:

This worm was described by Conway Morris in 1977 as a possible primitive priapulid. Later analyses showed that S. rara belongs to the priapulid stem group (Harvey et al., 2010; Wills, 1998).

Description:

Morphology:

Scolecofurca is known from a single incomplete specimen, which is estimated to have reached nine centimeters in total length. Like other priapulids, the body is divided into a proboscis and a trunk. The proboscis is fringed with small extensions called papillae, and tipped with a pair of conspicuous tentacles giving the appearance of a two-pronged fork. The trunk is annulated and the gut appears to be represented by a simple tube. Contrary to all the other species of priapulids from the Burgess Shale, this form does not have spines or hooks on the proboscis or body.

Abundance:

This species is known from a single specimen.

Maximum Size:
90 mm

Ecology:

Ecological Interpretations:

The general body-shape and presence of a proboscis suggests Scolecofurca was a burrower. The tentacles might have had a sensory function rather than being used for prey manipulation, but the mode of feeding of this species is unknown.

References:

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

HARVEY, T. H. P., X. DONG AND P. C. J. DONOGHUE. 2010. Are palaeoscolecids ancestral ecdysozoans? Evolution & Development, 12(2): 177-200.

WILLS, M. A. 1998. Cambrian and Recent disparity: the picture from priapulids. Paleobiology, 24(2): 177-199.

Other Links:

None

Scenella amii

3D animation of Scenella amii.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Class: Unranked clade (stem group molluscs)
Remarks:

Scenella is generally classified as a monoplacophoran mollusc (Knight, 1952; Runnegar and Jell, 1976). A position possibly ancestral to brachiopods (Dzik, 2010), or within the Cnidaria, has also been proposed (Babcock and Robison, 1988; Yochelson and Gil Cid, 1984).

Species name: Scenella amii
Described by: Matthew
Description date: 1902
Etymology:

Scenella – from the Greek word skene, “tent, or shelter,” in reference to its shape.

amii – after Marc Henri Ami from the Geological Survey of Canada.

Type Specimens: Holotype –ROM8048 in the Royal Ontario Museum, Toronto, ON, Canada.
Other species:

Burgess Shale and vicinity: none

Other deposits: Dozens of species are known from the Lower Cambrian to the Lower Ordovician.

Age & Localities:

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

The Walcott and Raymond Quarries on Fossil Ridge. The Trilobite Beds and smaller localities on Mount Stephen.

History of Research:

Brief history of research:

The limpet-like appearance of Scenella led to its original classification as a mollusc, initially as a pteropod, then as a gastropod (Walcott, 1886). The first fossils of this genus known from the Burgess Shale were collected from the Trilobite Beds on Mount Stephen. These were described as Metoptoma amii by Matthew (1902), but Walcott (1908) considered other specimens from the same locality (and from the Walcott Quarry) to belong to Scenella varians, an earlier named species. Resser (1938) recognized that both species were identical and proposed a new combination, Scenella amii. In the same publication, Resser named a second species from the Trilobite Beds S. columbiana; this was based on a single specimen, originally recognized as a brachiopod with possible spines (Walcott, 1912), and remains highly dubious.

Description:

Morphology:

Each cone-shaped fossil has the form of a flat disc with a central peak, here termed “shell.” Concentric rings surround this peak, and sometimes the shell is also corrugated. The shells are stretched along one axis, making them elliptical rather than circular.

The fossils are often preserved in dense clusters and are usually oriented point-up.

No soft tissue is ever found associated with Scenella. The shell was evidently mineralized as indicated by the three-dimensional preservation and the presence of small cracks suggesting brittleness.

Abundance:

Hundreds of specimens of S. amii are known in the Walcott Quarry (2.27% of the community, Caron and Jackson, 2008). Many of these are found in dense clusters on single slabs.

Maximum Size:
10 mm

Ecology:

Ecological Interpretations:

If a mollusc, Scenella would have been a creeping bottom-dweller, potentially a grazer.

References:

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

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

DZIK, J. 2010. Brachiopod identity of the alleged monoplacophoran ancestors of cephalopods. Malacologia, 52:97-113.

KNIGHT, J. B. 1952. Primitive fossil gastropods and their bearing on gastropod evolution. Smithsonian Miscellaneous Collections, 117(13): 1–56.

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, 4:107-112.

RASETTI, F. 1954. Internal shell structures in the Middle Cambrian gastropod Scenella and the problematic genus Stenothecoides. Journal of Paleontology, 28: 59-66.

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

Runnegar, B. AND P. A. JELL. 1976. Australian Middle Cambrian molluscs and their bearing on early molluscan evolution. Alcheringa: An Australasian Journal of Palaeontology, 1(2): 109-138.

WALCOTT, C. D. 1886. Second contribution to the studies on the Cambrian faunas of North America. Bulletin of the United States Geological Survey, (30): 11-356.

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

WALCOTT, C. 1912. Cambrian Brachiopoda. United States Geological Survey Monograph, 51: Part 1: 1-872, Part 872: 871-363.

YOCHELSON, E. L. AND D. GIL CID. 1984. Reevaluation of the systematic position of Scenella. Lethaia, 17: 331-340.

Other Links:

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Sarotrocercus oblita

Reconstruction of Sarotrocercus oblita.

© MARIANNE COLLINS

Taxonomy:

Class: Unranked clade (stem group arthropods)
Remarks:

The phylogenetic affinity of Sarotrocercus is uncertain because its morphology is too poorly known to make a definitive designation. Fryer (1998) suggested it was the most primitive of all arthropods, and it was placed within the Arachnomorpha by Cotton and Braddy (2004). Sarotrocercus has also been aligned with Megacheiran taxa such as Yohoia (e.g. Briggs and Fortey, 1989) and Leanchoilia (e.g., Wills et al. 1995; 1998).

Species name: Sarotrocercus oblita
Described by: Whittington
Description date: 1981
Etymology:

Sarotrocercus – from the Greek sarotes, “sweeper”, and kerkops, “a long tailed-monkey”, in reference to the feathery aspect of the tail.

oblita – from the Latin oblitus, “forgotten”, perhaps in reference to the fact that the few specimens of this species were described as part of another species.

Type Specimens: Holotype –USNM144890 (part) and UNSM 272171 (counterpart) in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none.

Other deposits: none.

Age & Localities:

Period:
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 genus Sarotrocercus was erected by Harry Whittington in 1981 based on seven specimens originally included within Molaria spinifera (Simonetta and Delle Cave, 1975). No further research has been performed on the fossil material since then, although Sarotrocercus has been included in many studies of arthropod relationships (e.g. Briggs and Fortey, 1989; Wills et al., 1995; Fryer, 1998).

Description:

Morphology:

Sarotrocercus has an oval body consisting of a head shield and nine overlapping trunk segments; a cylindrical posterior segment carries a relatively short, narrow spine ending in a fan-shape cluster of small spikes. The whole animal was about 1.5 cm long. Although the head shield was not very strongly developed, it did bear a pair of large, stalked eyes that poked out from beneath the margin, and a pair of jointed appendages. Each of the nine body segments bore a pair of lobate appendages, with comb-like fringes which might have functioned as gills.

Abundance:

S. oblita is rare in the Burgess Shale. It was originally described on the basis of 7 specimens (Whittington, 1981), and 28 further specimens have been recovered from the Walcott Quarry representing less than 0.1% of the community (Caron and Jackson, 2008).

Maximum Size:
16 mm

Ecology:

Ecological Interpretations:

The absence of walking limbs combined with an inferred flexibility of the body imply that the organism swam, probably in an inverted position, using its paddle-like appendages and long tail. Its rarity in the Burgess Shale suggests that it may have spent much time in the water column, thus avoiding submarine landslides that trapped animals living on the sea floor. The absence of sediment in its gut suggest that Sarotrocercus was a filter feeder (Briggs and Whittington, 1985; Whittington, 1981).

References:

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

BRIGGS, D. E. G. AND H. B. WHITTINGTON, 1985. Modes of life of arthropods from the Burgess Shale, British Columbia. Transactions of the Royal Society of Edinburgh. Earth Sciences, 76(2-3): 149-160.

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. AND S. J. BRADDY, 2004. The phylogeny of arachnomorph arthropods and the origin of the Chelicerata. Transactions of the Royal Society of Edinburgh, 94(03): 169-193.

FRYER, G. 1998. A defence of arthropod polyphyly, p. 23. In R. A. Fortey and R. H. Thomas (eds.), Arthropod relationships. Springer, London.

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.

WHITTINGTON, H. B. 1981. Rare arthropods from the Burgess Shale, Middle Cambrian, British Columbia. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences, 292(1060): 329-357.

WILLS, M. A., D. E. G. BRIGGS, R. A. FORTEY AND M. WILKINSON, 1995. The significance of fossils in understanding arthropod evolution. Verhandlungen den deutschen zoologischen Gesellschaft, 88: 203-216.

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:

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Ptychagnostus praecurrens

Ptychagnostus praecurrens (USNM 116212). Complete individual originally interpreted as the holotype of Triplagnostus burgessensis by Rasetti (1951). Specimen length = 8 mm. Specimen dry – direct light. Walcott Quarry.

© Smithsonian Institution – National Museum of Natural History. Photo: Jean-Bernard Caron

Taxonomy:

Class: Trilobita (Order: Agnostida)
Remarks:

Trilobites are extinct euarthropods, probably stem lineage representatives of the Mandibulata, which includes crustaceans, myriapods, and hexapods (Scholtz and Edgecombe, 2006).

Species name: Ptychagnostus praecurrens
Described by: Westergård
Description date: 1936
Etymology:

Ptychagnostus – from the Greek ptycho, “pleated” (some species have pleat-like furrows on the cephalon), and agnostos, for “unknown” or “unknowable.”

praecurrens – from the Latin prae, “before,” and currens, “to run,” in reference to the old age of this fossil

Type Specimens: Holotype – SGU611; in the Geological Survey of Sweden (Sveriges geologiska undersökning – SGU), Uppsala, Sweden (Westergård, 1936)
Other species:

Burgess Shale and vicinity: none.

Other deposits: other species occur throughout the world in Middle Cambrian rocks.

Age & Localities:

Period:
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:

Trilobites currently assigned to this genus and species have been described under several name combinations. Originally, Rasetti (1951) described it as Triplagnostus burgessensis, but subsequently (Rasetti, 1967) considered T. burgessensis to be a synonym of Ptychagnostus praecurrens (Westergård, 1936), a name retained by Peng and Robison (2000), despite numerous interim variations.

Description:

Morphology:

Hard parts: adult dorsal exoskeletons reach about 8 mm in length. The semicircular cephalon has a narrow marginal rim around the front and sides and sharply rounded the genal angles. There are no dorsal eyes and no facial sutures. The narrow glabella comes to an ogival point, with a median furrow extending across the short preglabellar field to the anterior margin; a transverse furrow crosses the glabella just in front of a low tubercle located behind the midpoint. Two short thoracic segments carry lateral nodes on the axial rings. A narrowly rimmed pygidium, the same size and general shape as the cephalon, has abruptly angled anterolateral corners. The pygidial axis is broader than the glabella, but of similar outline, with a median tubercle between two transverse furrows. The pointed tip of the axis reaches almost to the rim posteriorly, without a median furrow.

Unmineralized anatomy: not known

Abundance:

Very common in the Walcott Quarry on Fossil Ridge, where it is the most abundant trilobite (Caron and Jackson, 2008).

Maximum Size:
10 mm

Ecology:

Ecological Interpretations:

Adult agnostine trilobites have often been regarded as pelagic organisms that swam or drifted in the water column. Evidence now suggests that most were members of the mobile benthic epifauna, possibly micrograzers or particle feeders, preferentially occupying colder, deeper, offshore waters.

References:

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

PENG, S. C. AND ROBISON, R. A. 2000. Agnostoid biostratigraphy across the middle-upper Cambrian boundary in Hunan, China. Paleontological Society Memoir, no. 53 (supplement to Journal of Paleontology), 74(4), 104 pp.

RASETTI, F. 1951. Middle Cambrian stratigraphy and faunas of the Canadian Rocky Mountains. Smithsonian Miscellaneous Collections, 116(5): 277 pp.

RASETTI, F. 1967. Lower and Middle Cambrian trilobite faunas from the Taconic Sequence of New York. Smithsonian Miscellaneous Collections, 152(4): 112 pp.

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.

WESTERGÅRD, A. H. 1936. Paradoxides oelandicus beds of Oland: with the account of a diamond boring through the Cambrian at Mossberga. Sveriges Geologiska Undersökning. Series C, no. 394, Årsbok 30, no. 1: 1-66.

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Isoxys acutangulus

3D animation of Isoxys carinatus.

Animation by Phlesch Bubble © Royal Ontario Museum

Taxonomy:

Class: Unranked clade (stem group arthropods)
Remarks:

The affinity of Isoxys is uncertain because for a long time it was known only from empty carapaces. Recent descriptions of soft parts show that the frontal appendage is similar to that of some megacheiran, or “great appendage,” taxa such as Leanchoilia, Alalcomenaeus, and Yohoia (Vannier et al., 2009; García-Bellido et al., 2009a). The affinity of Megacheira as a whole is uncertain, but it has been suggested that they either sit within the stem-lineage to the euarthropods (Budd, 2002) or they are stem-lineage chelicerates (Chen et al., 2004; Edgecombe, 2010).

Species name: Isoxys acutangulus
Described by: Walcott
Description date: 1908
Etymology:

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

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

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

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

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

Age & Localities:

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

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

History of Research:

Brief history of research:

Walcott gave the name Isoxys to specimens from the lower Cambrian Chilhowee Group of Tennessee, USA, in 1890. He then later designated the first species from the Trilobite Beds on Mount Stephen, Anomalocaris? acutangulus (Walcott, 1908), although he placed it erroneously in the genus Anomalocaris. Simonetta and Delle Cave (1975) renamed it Isoxys acutangulus and discovered a second Burgess Shale species, I. longissimus. The original designations were based on carapaces only, making research on the ecology and affinity of Isoxys difficult. Soft parts have recently been described from the Burgess Shale taxa (Vannier et al. 2009, García-Bellido et al. 2009a).

Description:

Morphology:

The most prominent feature of Isoxys is the non-mineralized carapace, which ranged in length from 1 cm to almost 4 cm, and covered most of the body. It was folded to give two equal hemispherical valves, and had pronounced spines at the front and back. A pair of bulbous, spherical eyes protrudes forward and laterally from under the carapace. They are attached to the head by very short stalks. A pair of frontal appendages that are segmented and non-branching (uniramous) is adjacent to the eyes. The flexible appendages are curved with a serrated outline and five segments in total, including a basal part, three segments with stout outgrowths, and a pointed terminal segment.

The trunk of the body has 13 pairs of evenly spaced appendages that are segmented and branch into two (biramous), with slender, unsegmented walking limbs and large, paddle-like flaps fringed with long setae. The telson has a pair of lateral flaps. A cylindrical gut passes from the head to the ventral terminus of the telson, and is lined by paired, lobate gut glands. I. longissimus is distinguished from I. acutangulus by the presence of extremely long spines and an elongated body shape.

Abundance:

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

Maximum Size:
40 mm

Ecology:

Ecological Interpretations:

The streamlined body, thin carapace, and the presence of large paddle-shaped flaps in the appendages all suggest that Isoxys was a free-swimming animal. The spines and wide telson would have been use for steering and stability in the water column. A predatory lifestyle is indicated by the large eyes, frontal appendage, and gut glands. Isoxys would have swum just above the sea floor, seeking out prey in the water column and at the sediment-water interface.

References:

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

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.

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.

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

GARCÍA-BELLIDO, D. C., J. VANNIER AND D. COLLINS. 2009a. Soft-part preservation in two species of the arthropod Isoxys from the middle Cambrian Burgess Shale of British Columbia, Canada. Acta Palaeontologica Polonica, 54: 699-712.

GARCÍA-BELLIDO, D. C., J. R. PATERSON, G. D. EDGECOMBE, J. B. JAGO, J. G. GEHLING AND M. S. Y. LEE. 2009b. The bivavled arthropods Isoxys and Tuzoia with soft-part preservation from the lower Cambrian Emu Bay Shale Lagerstätte (Kangaroo Island, Australia). Palaeontology, 52: 1221-1241.

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.

STEIN, M., J. S. PEEL, D. J. SIVETER AND M. WILLIAMS. 2010. Isoxys (Arthropoda) with preserved soft anatomy from the Sirius Passet Lagerstätte, lower Cambrian of North Greenland. 2010. Lethaia, 43: 258-265.

VANNIER, J. AND J.-Y. CHEN. 2000. The Early Cambrian colonization of pelagic niches exemplified by Isoxys (Arthropoda). Lethaia, 35: 107-120.

VANNIER, J., D. C. GARCÍA-BELLIDO, S. X. HU AND A. L. CHEN. 2009. Arthropod visual predators in the early pelagic ecosystem: evidence from the Burgess Shale and Chengjiang biotas. Proceedings of the Royal Society of London Series B, 276: 2567-2574.

WALCOTT, C. D. 1890. The fauna of the Lower Cambrian or Olenellus Zone. Reports of the U.S. Geological Survey, 10: 509-763.

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

WILLIAM, M., D. J. SIVETER AND J. S. PEEL. 1996. Isoxys (Arthropoda) from the early Cambrian Sirius Passet Lagerstätte, North Greenland. Journal of Paleontology, 70: 947-954.

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Insolicorypha psygma

Insolicorypha psygma (USNM 198712) – Holotype, part and counterpart. Only known specimen showing the purported head (top) surrounded by a dark stain (probably representing decay fluids), setae, and gut trace. Specimen length = 12 mm. Specimen dry – polarized light (both images). Walcott Quarry.

© Smithsonian Institution – National Museum of Natural History. Photos: Jean-Bernard Caron

Taxonomy:

Class: Unranked clade (stem group polychaetes)
Remarks:

The single specimen (perhaps incomplete, Eibye-Jacobsen, 2004) of this species is too poorly known to allow detailed studies of its affinities.

Species name: Insolicorypha psygma
Described by: Conway Morris
Description date: 1979
Etymology:

Insolicorypha – from the Latin insolitus, “unusual,” and the Greek koryphe, “head,” thus, “unusual head.”

psygma – from the Greek psygma, “fan,” in reference to the fan-like arrangement of the worm’s bristles.

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:

Period:
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:

Only a single specimen is known. This was originally interpreted by Conway Morris (1979) as a complete animal with an abnormal head. Eibye-Jacobsen (2004) later suggested that the specimen represented just the rear part of the animal, and that the ragged edge of the torn body wall formed the illusion of a head.

Description:

Morphology:

This tiny worm (12 mm long) had at least 19 segments, each bearing a pair of lateral projections called parapodia. On the first and perhaps second segment the parapodia are simple (uniramous), while all the other segments have biramous parapodia (divided into two sections of unequal lengths). In the third segment through to the last segment, parapodia support two main bundles of setae, the notosetae (on the upper branch) and the neurosetae (on the lower branch). The notosetae are short while the neurosetae are much longer. The branch bearing the neurosetae has three (two dorsal) and one ventral cirri (representing sensory of secretory organs) and is much longer. The purported front end of the animal has an elongate projection (prostomium) divided into two main sections.

Abundance:

Only a single specimen of Insolicorypha is known and comes from the Walcott Quarry.

Maximum Size:
12 mm

Ecology:

Ecological Interpretations:

Insolicorypha probably had a similar mode of life to modern swimming annelids which also have sensory cirri, but the rarity of this species makes it impossible to conclude exactly how the animal fed. The fans of bristles are clear adaptations to swimming, which may contribute to the organism’s rarity in the Burgess Shale, which primarily preserves bottom-dwelling species.

References:

CONWAY MORRIS, S. 1979. Middle Cambrian Polychaetes from the Burgess Shale of British Columbia. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences, 285: 227-274.

EIBYE-JACOBSEN, D. 2004. A reevaluation of Wiwaxia and the polychaetes of the Burgess Shale. Lethaia, 37: 317-335.

Other Links:

None

Hurdia victoria

3D animation of Hurdia victoria.

Animation by Phlesch Bubble © Royal Ontario Museum

Taxonomy:

Class: Dinocarida (Order: Radiodonta, stem group arthropods)
Remarks:

Hurdia is an anomalocaridid, and is usually considered to represent either a basal stem-lineage euarthropod (e.g. Daley et al., 2009), a member of the crown-group arthropods (e.g. Chen et al., 2004), or a sister group to the arthropods (Hou et al., 2006).

Species name: Hurdia victoria
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 Utah (Wheeler Formation) (Briggs et al., 2008), the Jince Formation in the Czech Republic (Chlupáč and Kordule 2002) and the Shuijingtuo Formation in Hubei Province, China (Cui and Huo, 1990) and possibly Nevada (Lieberman, 2003).

Age & Localities:

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

History of Research:

Brief history of research:

Hurdia is a relative newcomer to the anomalocaridids. Although isolated parts of its body 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 phyllopod arthropod (Rolfe, 1962). Hurdia’s frontal appendages were first described by Walcott (1911a) 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 anomalocaridids, the mouth parts were first described as the jellyfish Peytoia nathorsti (Walcott, 1911b). When Whittington and Briggs (1985) discovered the first whole body specimens of Anomalocaris, the mouth part identity of Peytoia was recognized and “Appendage F” was determined to be the frontal appendage of Anomalocaris nathorsti (later renamed Laggania cambria by Collins (1996). When describing 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 anomalocaridid, which also had an “Appendage F” pair and a frontal carapace structure 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 three distinct morphologies, two of which belongs to the Hurdia animal (known from two species, victoria and triangulata) and one to Laggania cambria.

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-mineralized carapaces consisting of one dorsal triangular H-element (previously called Hurdia) and two lateral subrectangular P-elements (or Proboscicaris). This complex is hollow and open ventrally. It attaches near the anterior margin of the head and protrudes 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 dorsal-lateral notches in the overlapping posterior corners of the H- and P-elements.

Mouth parts 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 inner 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 dorsal spines and seven elongated ventral spines. The posterior half of the body consists of a series of seven to nine reversely imbricated lateral lobes that extend ventrally into triangular flaps. Dorsal surfaces of the lateral lobes are covered in a series of elongated blades interpreted to be gill structures. The body terminates abruptly in two rounded lobes, and lacks a tailfan. Complete specimens are up to 20 cm in length, although disarticulated fragments may suggest a larger body size up to 50 cm long. Hurdia triangulata differs from Hurdia victoria by having a wider and shorter H-element.

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:
500 mm

Ecology:

Ecological Interpretations:

Hurdia was likely nektonic, since there are no trunk limbs for walking, and the numerous gills suggest an active swimming lifestyle. The animal propelled itself through the water column by waving its lateral lobes and gills. The large eyes, prominent appendages and spiny mouth parts suggest that Hurdia actively sought out moving prey items. Although the function of the frontal carapace remains unknown, it may have played a role in prey capture. If Hurdia were swimming just above the sea floor, it could have used the tip of its frontal carapace to stir up sediment and dislodge prey items, which would then be trapped beneath its frontal carapace. Prey items were funneled towards the mouth by a sweeping motion of the long ventral blades of the frontal appendages, which formed a rigid net or cage. Like other anomalocaridids, Hurdia likely ingested soft-bodied prey.

References:

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

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

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.

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.

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.

CUI, Z. AND S. HUO. 1990. New discoveries of Lower Cambrian crustacean fossils from Western Hubei. Acta Palaeontologica Sinica, 29: 321-330.

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.

LIEBERMAN, B. S. 2003. A new soft-bodied fauna: The Pioche Formation of Nevada. Journal of Paleontology, 77: 674-690.

ROLFE, W. D. I. 1962. Two new arthropod carapaces from the Burgess Shale (Middle Cambrian) of Canada. Breviora Museum of Comparative Zoology, 60: 1-9.

WALCOTT, C. D. 1911a. Middle Cambrian Merostomata. Cambrian Geology and Paleontology II. Smithsonian Miscellaneous Collections, 57: 17-40.

WALCOTT, C. D. 1911b. Middle Cambrian holothurians and medusae. Cambrian Geology and Paleontology II. Smithsonian Miscellaneous Collections, 57: 41-68.

WALCOTT, C. D. 1912. Middle Cambrian Branchiopoda, Malacostraca, Trilobita and Merostomata. Smithsonian Miscellaneous Collections, 57: 145-228.

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

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Haplophrentis carinatus

3D animation of Haplophrentis carinatus.

Animation by Phlesch Bubble © Royal Ontario Museum

Taxonomy:

Class: Hyolitha (Order: Hyolithida, stem group molluscs)
Remarks:

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

Species name: Haplophrentis carinatus
Described by: Matthew
Description date: 1899
Etymology:

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

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

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

Burgess Shale and vicinity: none

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

Age & Localities:

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

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

History of Research:

Brief history of research:

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

Description:

Morphology:

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

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

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

Abundance:

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

Maximum Size:
40 mm

Ecology:

Ecological Interpretations:

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

References:

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

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

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

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

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

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

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

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

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

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Hanburia gloriosa

Hanburia gloriosa (ROM 48468). Complete individual (external mold). Specimen length = 26 mm Specimen coated with ammonium chloride sublimate to show details. Trilobite Beds on Mount Stephen.

© Royal Ontario Museum. Photo: Jean-Bernard Caron

Taxonomy:

Class: Trilobita (Order: Corynexochida?)
Remarks:

Trilobites are extinct euarthropods, probably stem lineage representatives of the Mandibulata, which includes crustaceans, myriapods, and hexapods (Scholtz and Edgecombe, 2006).

Species name: Hanburia gloriosa
Described by: Walcott
Description date: 1916
Etymology:

Hanburia – unspecified, but probably after Hanbury Peak or Hanbury Glacier in the Canadian Rockies, in turn named for David T. Hanbury (1864-1910), a British explorer of the Canadian Northwest Territories.

gloriosa – from the Latin gloriosus, meaning “glorious” or “boastful,” perhaps in allusion to the unusual cephalic morphology of this rare species.

Type Specimens: Lectotype –USNM61724, in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none.

Other deposits: none.

Age & Localities:

Period:
Middle Cambrian, Glossopleura to Bathyuriscus-Elrathina Zones (approximately 505 million years ago).
Principal localities:

The Walcott Quarry on Fossil Ridge. The Tulip Beds (S7) and smaller localities on Mount Stephen.

History of Research:

Brief history of research:

Walcott’s three original specimens of Hanburia gloriosa were found over the course of five years of quarrying the Phyllopod Bed on Fossil Ridge (Walcott, 1916); two more from this locality are also in theUSNMcollections. A singleUSNMspecimen was later found by Charles Resser, supposedly from the “Ogygopsis shale” on Mount Stephen (Rasetti, 1951), but this is almost certainly an error. Harry Whittington reassessed this odd trilobite in 1998.

Description:

Morphology:

Hard parts: the few known specimens of Hanburia gloriosa range in length from 4 mm (for a juvenile stage) to 35 mm. Dorsal shields are broadly ovate to subcircular in outline and all specimens are considerably flattened by compression of the thin exoskeleton. The cephalon is semicircular with a weak, shallow border furrow along the posterior and lateral margins, fading out towards the anterior corners of the glabella. The glabella in small specimens expands forwards and shows two pairs of faint bulbous lateral lobes; in larger specimens, the glabella is parallel-sided and the lobes are subdued. There are no apparent eyes located laterally on the cephalon, and there is no sign of dorsal facial suture. In these two features, Hanburia is unique among the non-agnostoid trilobites of the Burgess Shale.

Whittington (1998) has suggested that the facial suture might run along the outside edge of the cephalon, or ventrally, crossing to the dorsal side only at the genal angles, which in all specimens appear to be rounded. Larger individuals show six or seven segments in the comparatively short thorax, and a single known (presumed) juvenile stage shows four; the distal tips of the pleurae are rounded. The semicircular pygidium lacks a defined border, and is approximately the same width and length as the cephalon. Seven or eight axial rings and a terminal piece make up the pygidial axis, which ends short of the posterior margin. Eight or nine pairs of well-marked pygidial pleurae radiate out and back from the axis.

Unmineralized anatomy: not known

Abundance:

Very rare in all the Burgess Shale localities.

Maximum Size:
35 mm

Ecology:

Ecological Interpretations:

Due to its unusual cephalic morphology (i.e., no dorsal sutures or lateral compound eyes), rarity, and unique occurrence only in the Burgess Shale, Hanburia gloriosa remains an ecological enigma. Other “blind” Cambrian trilobites with somewhat similar morphologies have been interpreted as inhabiting deeper waters, perhaps below the photic zone (Whittington, 1998).

References:

RASETTI, F. 1951. Middle Cambrian stratigraphy and faunas of the Canadian Rocky Mountains. Smithsonian Miscellaneous Collections, 116 (5): 1-277.

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. 1916. Smithsonian Miscellaneous Collections, 64(3): 157-258.

WHITTINGTON, H. B. 1998. Hanburia gloriosa: rare trilobite from the Middle Cambrian, Stephen Formation, British Columbia, Canada. Journal of Paleontology, 72: 673-677.

Other Links:

None