Creatures: Grazers



Mega Zoom & Pan Image Zoomer image with id 0 does not exist!

Mega Zoom & Pan Image Viewer with preset id 0 does not exist!

Peronopsis columbiensis

Artistic reconstruction of Peronopsis columbiensis. Danielle Dufault © ROM

Taxonomy:

Kingdom: Grazers
Phylum: Grazers
Higher Taxonomic assignment: Artiopoda, Order: Agnostida
Species name: Peronopsis columbiensis
Remarks:

Owing to their distinctive appearance, agnostids have been classified either as trilobites, related to Eodiscina, or as stem group “crustaceans” (Müller and Walossek 1987; Cotton and Fortey 2005; Haug et al. 2009). The most recent phylogenetic analysis finds that agnostids form a grouping with trilobites, supported by shared features of the dorsal exoskeleton, such as mineralization, the expression of segmental boundaries, and the form of the thoracic joints (Moysiuk and Caron 2019). More taxonomically inclusive analyses will be needed to determine whether they belong inside or outside the group of true trilobites.

Described by: Rasetti
Description date: 1951
Etymology:

Peronopsis – From the Greek perone, “pin, brooch ” and opsis, “looking like.”

columbiensis – No etymology provided, but presumably in reference to the occurrence of the species in British Columbia, Canada.

Type Specimens: Holotype – USNM 116267; paratypes – USNM 116268-9; in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: P. montis

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

Age & Localities:

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

Mount Stephen, Mount Odaray, Marble Canyon.

History of Research:

Brief history of research:

Burgess Shale material was originally named Peronopsis columbiensis by Rasetti (1951). Naimark (2012) proposed to reassign the species to the genus Quadragnostus based on published images, but we maintain it here under Peronopsis pending taxonomic restudy of Burgess Shale specimens. Moysiuk and Caron (2019) recently described the appendages, digestive tract, and other soft tissues from exceptionally preserved specimens.

Description:

Morphology:

Adult dorsal exoskeletons reach about 20 mm in length. The semicircular cephalon has a narrow marginal rim around the front and sides and rounded genal angles. There are no dorsal eyes and no facial sutures. The narrow glabella comes to an ogival point, with no anterior median furrow; a transverse furrow crosses the glabella near its anterior. A pair of short genal spines are present. 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 and a pair of short, backwards-directed marginal spines posterolaterally. 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 is separated by a gap from the pygidial rim posteriorly, without a median furrow. A saddle-shaped hypostome is present ventrally, unfused to the headshield. Unmineralized anatomy: The head probably bears six pairs of appendages, including one pair of elongate sensory antennules, two pairs of appendages with oar-like outer branches, and probably three pairs of stout walking limbs with a row of club-like projections. Additional walking limbs were present beneath the thorax (2) and pygidium (probably 4). The digestive tract curves dorsally from the mouth before emitting two pairs of branching gut glands, the first of which is the largest and occupies much of the space below the headshield. Behind this, the cylindrical midgut extends back to the pygidium. The hindgut begins roughly below the pygidial tubercle, and narrows considerably before reaching the anus below the tip of the pygidial axis.

Abundance:

Specimens likely assignable to this species are very common at Tokumm Creek and in the upper levels of the Marble Canyon quarry, where it is the most abundant artiopodan (Nanglu et al. 2020). Peronopsis columbiensis also occurs in notable numbers at Mount Odaray, Mount Stephen, and a few smaller localities (Rasetti 1951).

Maximum Size:
About 20 mm.

Ecology:

Life habits: Grazers
Feeding strategies: Grazers
Ecological Interpretations:

The mode of life of agnostids has been extensively debated (Fortey and Owens 1999). With the oar-like appendages capable of protruding while the animal was partially enrolled, agnostids certainly appear well-adapted for swimming (Müller and Walossek 1987). Together with their occurrence in mass mortality beds with wide geographic range, this evidence has been proposed to support a pelagic lifestyle (Fortey 1985). However, most specimens at the Burgess Shale are found in unrolled position, suggesting they did not live permanently enrolled. Further, Peronopsis is sometimes found in groups, associated with the remains of other Burgess Shale organisms, where it was potentially feeding on carrion or bacterial films, providing evidence for a benthic habitat. The huge, branching gut glands in the head likely acted as a food storage organ, possibly enabling a feast-and-famine lifestyle. The club-like outgrowths on the walking legs may have functioned in respiration (Moysiuk and Caron 2019).

References:

  • COTTON, T. J. and FORTEY, R. A. 2005. Comparative morphology and relationships of the Agnostida. In KOENEMANN, S. and JENNER, R. (eds.) Crustacea and Arthropod Relationships, CRC Press, 95–136 pp.
  • FORTEY, R. A. 1985. Pelagic trilobites as an example of deducing the life habits of extinct arthropods. Earth and Environmental Science Transactions of The Royal Society of Edinburgh, 76: 219–230.
  • FORTEY, R. A. and OWENS, R. M. 1999. Feeding habits in trilobites. Palaeontology, 42: 429–465.
  • HAUG, J. T., MAAS, A. and WALOSZEK, D. 2009. †Henningsmoenicaris scutula, †Sandtorpia vestrogothiensis gen. et sp. nov. and heterochronic events in early crustacean evolution. Earth and Environmental Science Transactions of the Royal Society of Edinburgh, 100: 311–350.
  • MOYSIUK, J. and CARON, J.-B. 2019. Burgess Shale fossils shed light on the agnostid problem. Proceedings of the Royal Society B: Biological Sciences, 286: 20182314.
  • MÜLLER, K. J. and WALOSSEK, D. 1987. Morphology, ontogeny, and life habit of Agnostus pisiformis from the Upper Cambrian of Sweden. Fossils and Strata, 19: 1–124.
  • NAIMARK, E. B. 2012. Hundred species of the genus Peronopsis Hawle et Corda, 1847. Paleontological Journal, 46: 945–1057.
  • NANGLU, K., CARON, J.-B. and GAINES, R. R. 2020. The Burgess Shale paleocommunity with new insights from Marble Canyon, British Columbia. Paleobiology, 46: 58–81.
  • RASETTI, F. 1951. Middle Cambrian stratigraphy and faunas of the Canadian Rocky Mountains. Smithsonian Miscellaneous Collections, 116: 1–277.
Other Links:


Mega Zoom & Pan Image Zoomer image with id 0 does not exist!

Mega Zoom & Pan Image Viewer with preset id 0 does not exist!

Wiwaxia corrugata

3D animation of Wiwaxia corrugata grazing on Morania confluens.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Kingdom: Grazers
Phylum: Grazers
Higher Taxonomic assignment: Unranked clade halwaxiids (stem group molluscs)
Species name: Wiwaxia corrugata
Remarks:

The relationship of Wiwaxia is hotly debated; its similarities to the molluscs have been highlighted (Conway Morris, 1985; Scheltema et al., 2003; Caron et al., 2006; Caron et al., 2007), but Matthew’s original view that it was related to the annelid worms (Matthew, 1899) still finds some adherents (Butterfield, 1990; Conway Morris and Peel, 1995; Butterfield, 2006; 2008). It is also possible that Wiwaxia branched off before the molluscs and annelids diverged (Eibye-Jacobsen, 2004). Wiwaxia has recently been placed in a group called the halwaxiids, along with the halkieriids, Orthrozanclus, and Odontogriphus (Conway Morris and Caron, 2007).

Described by: Matthew
Description date: 1899
Etymology:

Wiwaxia – from Wiwaxy Peaks (2,703 m) in Yoho National Park. The word wiwaxy is originally from the Stoney First Nation Nakoda language, meaning “windy.”

corrugata – from the Latin corrugis, “folded, or wrinkled,” in reference to the wrinkled aspect of the sclerites.

Type Specimens: Holotype –ROM8596 in the Royal Ontario Museum, Toronto, Canada.
Other species:

Burgess Shale and vicinity: none.

Other deposits: none described, although sclerites have been reported from a number of Middle Cambrian deposits extending from northern Canada (Butterfield, 1994) to China (Zhao et al., 1994).

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, Tulip Beds (S7) and Collins Quarry on Mount Stephen. Additional smaller localities are known on Mount Field and Mount Odaray.

History of Research:

Brief history of research:

In an early review of fossils collected from the Trilobite Beds on Mount Stephen by Walker, Canadian palaeontologist G. F. Matthew (1899) described several forms he thought represented tubes of various annelid worms, including one he named Orthotheca corrugata. At the time, Matthew did not know this particular fossil was only part of a much larger organism. It was only when Walcott (1911) discovered articulated and much better preserved specimens from the Phyllopod Bed that the morphology of this species became clearer. Walcott placed corrugata in his new genus Wiwaxia and interpreted it as a polychaete annelid worm (Walcott, 1911). The single best specimen of Walker’s “Orthotheca corrugata” remained unrecognized until it was “rediscovered” in the ROM collections in 1977.

Walcott’s interpretation was called into question in a comprehensive reassessment of the genus (Conway Morris, 1985), and Conway Morris’s link between Wiwaxia mouthparts and the molluscan radula was built upon by Scheltema et al. (2003) and Caron et al. (2006). Butterfield (1990), however, defended an annelid affinity mostly based on the study of individual sclerites, first at the crown-, and later at the stem-group level (Butterfield, 2003; 2006), but further work suggested that the evidence does not conclusively support a close relationship with annelids (Eibye-Jacobsen, 2004). A connection with the halkieriids was drawn early on (Bengtson and Morris, 1984; Conway Morris and Peel, 1995), and expanded more recently (Conway Morris and Caron, 2007).

Other studies have dealt more specifically with the ecology and taphonomy of this animal. The finely spaced patterning of ridges on the scale may have given Wiwaxia an iridescent aspect in life (Parker, 1998). Wiwaxia has proven useful in calculating the extent of decay in fossil assemblages (Caron and Jackson, 2006) and in reconstructing the longer term taphonomic processes responsible for the preservation of the Burgess Shale fossils (Butterfield et al., 2007).

Description:

Morphology:

Wiwaxia corrugata is a slug-like organism up to 5.5 cm in length almost entirely covered (except on the ventral surface) with an array of scale-like elements referred to as sclerites and spines. The body is roughly oval, and lacks evidence of segmentation. The body-covering sclerites are arranged in about 50 rows. In addition, two rows of 7–11 blade-like spines are present on the dorsal surface. Spines and sclerites were inserted directly into the body wall. Wiwaxia’s feeding apparatus consists of two (in rare cases three) toothed plates that have been compared to a molluscan radula or annelid jaws.

Abundance:

Wiwaxia is mostly known from the Walcott Quarry where it is relatively common, representing 0.9% of the specimens counted in the community (Caron and Jackson, 2008).

Maximum Size:
55 mm

Ecology:

Life habits: Grazers
Feeding strategies: Grazers
Ecological Interpretations:

The similarity of Wiwaxia’s feeding apparatus to that of Odontogriphus suggests that it too fed on the cyanobacterial Morania mats growing on the Cambrian sea floor. Its sclerite armour-plating and long spines, sometimes found broken, suggest that it was targeted by unidentified predators.

References:

BENGSTON, S. AND S. CONWAY MORRIS, 1984. A comparative study of Lower Cambrian Halkieria and Middle Cambrian Wiwaxia. Lethaia, 17:307-329.

BUTTERFIELD, N. J. 1990. A reassessment of the enigmatic Burgess Shale fossil Wiwaxia corrugata (Matthew) and its relationship to the polychaete Canadia spinosa Walcott. Paleobiology: 287-303.

BUTTERFIELD, N. J. 1994. Burgess Shale-type fossils from a Lower Cambrian shallow-shelf sequence in northwestern Canada. Nature, 369(6480): 477-479.

BUTTERFIELD, N. J. 2003. Exceptional fossil preservation and the Cambrian Explosion. Integrative and Comparative Biology, 43:166-177.

BUTTERFIELD, N. J. 2006. Hooking some stem-group “worms”: fossil lophotrochozoans in the Burgess Shale. BioEssays, 28: 1161-1166.

BUTTERFIELD, N. J. 2008. An early Cambrian radula. Journal of Paleontology, 82(3): 543-554.

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., A. H. SCHELTEMA, C. SCHANDER AND D. RUDKIN, 2006. A soft-bodied mollusc with radula from the Middle Cambrian Burgess Shale. Nature, 442(7099): 159-163.

CARON, J.-B., A. H. SCHELTEMA, C. SCHANDER AND D. RUDKIN. 2007. Reply to Butterfield on stem-group “worms:” fossil lophotrochozoans in the Burgess Shale. BioEssays, 29:200-202.

CONWAY MORRIS, S. 1985. The Middle Cambrian metazoan Wiwaxia corrugata (Matthew) from the Burgess Shale and Ogygopsis Shale Shale, British Columbia, Canada. Philosophical Transactions of the Royal Society of London, Series B, 307(1134): 507-582.

CONWAY MORRIS, S. AND J.-B. CARON, 2007. Halwaxiids and the Early Evolution of the Lophotrochozoans. Science, 315(5816): 1255-1258.

CONWAY MORRIS, S. AND J. S. PEEL, 1995. Articulated halkieriids from the Lower Cambrian of North Greenland and their role in early protostome evolution. Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences, 347(1321): 305-358.

EIBYE-JACOBSEN, D. 2004. A reevaluation of Wiwaxia and the polychaetes of the Burgess Shale. Lethaia, 37(3): 317-335.

MATTHEW, G. F. 1899. Studies on Cambrian Faunas, No. 3. Upper Cambrian fauna, Mount Stephen, British Columbia. The trilobites and worms. Transactions of the Royal Society, 5: 39-66.

PARKER, A. R. 1998. Colour in Burgess Shale animals and the effect of light on evolution in the Cambrian. Proceedings of the Royal Society B: Biological Sciences, 265(1400): 967.

SCHELTEMA, A. H., K. KERTH AND A. M. KUZIRIAN, 2003. Original molluscan radula: Comparisons among Aplacophora, Polyplacophora, Gastropoda, and the Cambrian fossil Wiwaxia corrugata. Journal of Morphology, 257(2): 219-245.

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

ZHAO, Y.-l., Y. QIAN AND X.-S. LI, 1994. Wiwaxia from Early-Middle Cambrian Kaili Formation in Taijiang, Guizhou. Acta Palaeontologica Sinica, 33:359-366.

Other Links:

http://www.paleobiology.si.edu/burgess/wiwaxia.html



Mega Zoom & Pan Image Zoomer image with id 0 does not exist!

Mega Zoom & Pan Image Viewer with preset id 0 does not exist!

Scenella amii

3D animation of Scenella amii.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Kingdom: Grazers
Phylum: Grazers
Higher Taxonomic assignment: Unranked clade (stem group molluscs)
Species name: Scenella amii
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).

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:

Age:
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:

Life habits: Grazers
Feeding strategies: Grazers
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:

None



Mega Zoom & Pan Image Zoomer image with id 0 does not exist!

Mega Zoom & Pan Image Viewer with preset id 0 does not exist!

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:

Kingdom: Grazers
Phylum: Grazers
Higher Taxonomic assignment: Class Artiopoda, Order Agnostida
Species name: Ptychagnostus praecurrens
Remarks:

Owing to their distinctive appearance, agnostids have either been classified as trilobites, related to Eodiscina, or as stem group “crustaceans” (Müller and Walossek 1987; Cotton and Fortey 2005; Haug et al. 2009). The most recent phylogenetic analysis finds that agnostids form a grouping with trilobites, supported by shared features of the dorsal exoskeleton, such as mineralization, the expression of segmental boundaries, and the form of the thoracic joints (Moysiuk and Caron 2019). More taxonomically inclusive analyses will be needed to determine whether they belong inside or outside the group of true trilobites.

Described by: Westergård
Description date: 1936
Etymology:

Ptychagnostus – from the Greek ptychos, “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:

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

Most abundant in the Walcott Quarry on Fossil Ridge, but also present in most other localities.

History of Research:

Brief history of research:

Burgess Shale fossils assigned to this genus and species have been historically described under several name combinations. Originally, Rasetti (1951) described these as Triplagnostus burgessensis, but subsequently (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. Naimark and Pegel (2017) proposed to reassign the species to the genus Pentagnostus based on a study of Russian material, but we maintain it here under Ptychagnostus pending taxonomic restudy of Burgess Shale specimens. Moysiuk and Caron (2019) recently described the appendages, digestive tract, and other soft tissues from exceptionally preserved specimens.

Description:

Morphology:

Adult dorsal exoskeletons reach about 10 mm in length. The semicircular cephalon has a narrow marginal rim around the front and sides and rounded 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. A saddle-shaped hypostome is present ventrally, unfused to the headshield. Unmineralized anatomy: The head probably bears six pairs of appendages, including one pair of elongate sensory antennules, two pairs of appendages with oar like outer branches, and probably three pairs of stout walking limbs with a row of club-like projections. Additional walking limbs were present beneath the thorax (2) and pygidium (probably 4). The digestive tract curves dorsally from the mouth before emitting two pairs of branching gut glands, the first of which is the largest and occupies much of the space below the headshield. Behind this, the cylindrical midgut extends back to the pygidium. The hindgut begins roughly below the pygidial tubercle, and narrows considerably before reaching the anus below the tip of the pygidial axis.

Abundance:

Very common in the Walcott Quarry on Fossil Ridge, where it is the most abundant artiopodan (Caron and Jackson 2008). Ptychagnostus also occurs in notable numbers at the Raymond Quarry, Mount Stephen, Tokumm Creek, the lower Marble Canyon Quarry and a few smaller localities (Caron et al. 2014; O’Brien and Caron 2016; Nanglu et al. 2020).

Maximum Size:
About 10 mm.

Ecology:

Life habits: Grazers
Feeding strategies: Grazers
Ecological Interpretations:

The mode of life of agnostids has been extensively debated (Fortey and Owens 1999). With the oar-like appendages capable of protruding while the animal was partially enrolled, agnostids certainly appear well-adapted for swimming (Müller and Walossek 1987). Together with their occurrence in mass mortality beds with wide geographic range, this evidence has been proposed to support a pelagic lifestyle (Fortey 1985). However, most specimens at the Burgess Shale are found in unrolled position, suggesting they did not live permanently enrolled. Further, Ptychagnostus is sometimes found in groups, associated with the remains of other Burgess Shale organisms, where it was potentially feeding on carrion or bacterial films, providing evidence for a benthic habitat. The huge, branching gut glands in the head likely acted as a food storage organ, enabling a feast-and-famine lifestyle. The club-like outgrowths on the walking legs may have functioned in respiration (Moysiuk and Caron 2019).

References:

  • CARON, J.-B. and JACKSON, D. A. 2008. Paleoecology of the Greater Phyllopod Bed community, Burgess Shale. Palaeogeography, Palaeoclimatology, Palaeoecology, 258: 222–256.
  • CARON, J.-B., GAINES, R. R., ARIA, C., MÁNGANO, M. G. and STRENG, M. 2014. A new phyllopod bed-like assemblage from the Burgess Shale of the Canadian Rockies. Nature communications, 5: 1–6.
  • COTTON, T. J. and FORTEY, R. A. 2005. Comparative morphology and relationships of the agnostida. In KOENEMANN, S. and JENNER, R. (eds.) Crustacea and Arthropod Relationships, CRC Press, 95–136 pp.
  • FORTEY, R. A. 1985. Pelagic trilobites as an example of deducing the life habits of extinct arthropods. Earth and Environmental Science Transactions of The Royal Society of Edinburgh, 76: 219–230.
  • FORTEY, R. A. and OWENS, R. M. 1999. Feeding habits in trilobites. Palaeontology, 42: 429–465.
  • HAUG, J. T., MAAS, A. and WALOSZEK, D. 2009. †Henningsmoenicaris scutula, †Sandtorpia vestrogothiensis gen. et sp. nov. and heterochronic events in early crustacean evolution. Earth and Environmental Science Transactions of the Royal Society of Edinburgh, 100: 311–350.
  • MOYSIUK, J. and CARON, J. B. 2019. Burgess Shale fossils shed light on the agnostid problem. Proceedings of the Royal Society B: Biological Sciences, 286: 20182314.
  • MÜLLER, K. J. and WALOSSEK, D. 1987. Morphology, ontogeny, and life habit of Agnostus pisiformis from the Upper Cambrian of Sweden. Fossils and Strata, 19: 1–124.
  • NAIMARK, E. B. and PEGEL, T. v. 2017. Revision of the Cambrian Agnostina (Trilobita?) from Russia. Paleontological Journal, 51: 1167–1248.
  • NANGLU, K., CARON, J.-B. and GAINES, R. R. 2020. The Burgess Shale paleocommunity with new insights from Marble Canyon, British Columbia. Paleobiology, 46: 58–81.
  • O’BRIEN, L. J. and CARON, J. B. 2016. Paleocommunity analysis of the Burgess Shale Tulip Beds, Mount Stephen, British Columbia: Comparison with the Walcott Quarry and implications for community variation in the Burgess Shale. Paleobiology, 42: 27–53.
  • PENG, S. and ROBISON, R. A. 2000. Agnostoid biostratigraphy across the middle-Upper Cambrian boundary in Hunan, China. Memoir ( The Paleontological Society ), 53: 1–104.
  • RASETTI, F. 1951. Middle Cambrian stratigraphy and faunas of the Canadian Rocky Mountains. Smithsonian Miscellaneous Collections, 116: 1–277.
  • RASETTI, F. 1967. Lower and Middle Cambrian trilobite faunas from the Taconic Sequence of New York. Smithsonian Miscellaneous Collections, 152: 1–112.
  • 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: 1–66.
Other Links:

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



Mega Zoom & Pan Image Zoomer image with id 0 does not exist!

Mega Zoom & Pan Image Viewer with preset id 0 does not exist!

Pagetia bootes

Pagetia bootes (ROM 60756). Complete individual. Specimen length = 4.5 mm. Specimen dry – direct light (left) and coated with ammonium chloride sublimate to show details (right). Walcott Quarry.

© ROYAL ONTARIO MUSEUM. PHOTOS: JEAN-BERNARD CARON

Taxonomy:

Kingdom: Grazers
Phylum: Grazers
Higher Taxonomic assignment: Artiopoda, Order Agnostida
Species name: Pagetia bootes
Remarks:

Pagetia is a member of Agnostida, small arthropods characterized by a pygidium (tail plate) similar in size and shape to the head and only two or three thoracic segments in adults. Unlike some other agnostids, Pagetia has dorsal eyes and moulting sutures. In this respect, its morphology is intermediate between that of presumably more derived agnostids (e.g. Peronopsis) and other trilobites (Cotton and Fortey 2005). A phylogenetic analysis recovered the group including Pagetia and related species to have been one of the first to branch off among trilobites (Paterson et al. 2019).

Described by: Walcott
Description date: 1916
Etymology:

Genus – unspecified, presumably from Paget Peak (2565 m) in Yoho National Park, named for the Very Reverend Dean Paget, founding member of the Alpine Club of Canada, who made the first recorded ascent in 1904.

species – unspecified, probably from the Greek Boötes meaning herdsman or ploughman; name of a northern constellation.

Type Specimens: Syntypes (P. bootes) – USNM 62855-61; Holotype (P. walcotti) – USNM 146310; in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: P. walcotti Rasetti, 1966.

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

Age & Localities:

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

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

History of Research:

Brief history of research:

Pagetia bootes was first named by Walcott (1916). Öpik was the first to recognize the hypostome (1952). Rasetti later provided the first detailed description (1966). The species has been featured in numerous works discussing trilobite biogeography, biostratigraphy, and phylogeny, e.g. (Rasetti 1951, 1952; Cotton and Fortey 2005; Paterson et al. 2019). Chatterton and colleagues described several Burgess Shale specimens preserved within Selkirkia tubes (2003).

Description:

Morphology:

Adult dorsal exoskeletons reach about 10 mm in length (including the pygidial spine). The semicircular cephalon has a narrow marginal rim around the front and sides and acute genal angles. The border is divided perpendicularly by a series of shallow furrows. The cephalon laterally bears a pair of proparian moulting sutures and compound eyes, connected to the axis by narrow, arcing eye ridges. The eyes of Pagetia and related genera are structurally unique among trilobites, having relatively few lenses separated by gaps (Jell 1975). The narrow glabella comes to an ogival point, with a median furrow extending across the short preglabellar field to the anterior margin. Faint traces of segmentation are visible on the glabella. The occipital lobe at the posterior or the cephalic axis emits an elongate spine, directed posteriad. The thorax contains two short segments with pleural furrows. A narrowly rimmed pygidium, the same size and general shape as the cephalon, has abruptly angled anterolateral corners. The pygidial axis shows six well-developed segments. The first five each bear a median tubercle while the terminal segment emits a long spine, directed posteriad. An elongate, convex hypostome is present ventrally, unfused to the headshield. Appendages are unknown.

Abundance:

P. bootes is very common in the Walcott Quarry. It is the third most common trilobite with at least 1000 specimens observed (Caron and Jackson, 2008), prompting Rasetti (1951) to define the “Pagetia bootes faunule” as the conventional shelly fossil assemblage associated with the exceptionally preserved soft-bodied biota. The co-occurring P. walcotti is very rare.

Maximum Size:
About 10 mm.

Ecology:

Life habits: Grazers
Feeding strategies: Grazers
Ecological Interpretations:

The mode of life of agnostids has been extensively debated (Fortey and Owens 1999). Their small size, degenerate eyes, adaptations for enrollment, and wide geographic occurrence have been proposed to support a pelagic lifestyle (Jell 1975; Fortey 1985). However, most specimens at the Burgess Shale are found in unrolled position, suggesting they did not live permanently enrolled. Further, Pagetia is sometimes found in groups, occasionally entombed inside the tubes of Selkirkia, which suggests the animal was spending at least part of its life cycle near the benthos (Chatterton et al. 2003; Lin and Yuan 2009). Due to the absence of appendage preservation, less is known about the mode of life of Pagetia than other Burgess Shale agnostids (Moysiuk and Caron 2019).

References:

  • CHATTERTON, B. D. E., COLLINS, D. H. and LUDVIGSEN, R. 2003. Cryptic behaviour in trilobites: Cambrian and Silurian examples from Canada, and other related occurrences. Special Papers in Palaeontology, 70: 157–173.
  • COTTON, T. J. and FORTEY, R. A. 2005. Comparative morphology and relationships of the Agnostida. In KOENEMANN, S. and JENNER, R. (eds.) Crustacea and Arthropod Relationships, CRC Press, 95–136 pp.
  • FORTEY, R. A. 1985. Pelagic trilobites as an example of deducing the life habits of extinct arthropods. Earth and Environmental Science Transactions of The Royal Society of Edinburgh, 76: 219–230.
  • FORTEY, R. A. and OWENS, R. M. 1999. Feeding habits in trilobites. Palaeontology, 42: 429–465.
  • JELL, P. A. 1975. The abathochroal eye of Pagetia, a new type of trilobite eye. Fossils and Strata, 4: 33–43.
  • LIN, J. P. and YUAN, J. L. 2009. Reassessment of the mode of life of Pagetia Walcott, 1916 (Trilobita: Eodiscidae) based on a cluster of intact exuviae from the Kaili Formation (Cambrian) of Guizhou, China. Lethaia, 42: 67–73.
  • MOYSIUK, J. and CARON, J.-B. 2019. Burgess Shale fossils shed light on the agnostid problem. Proceedings of the Royal Society B: Biological Sciences, 286: 20182314.
  • NANGLU, K., CARON, J.-B. and GAINES, R. R. 2020. The Burgess Shale paleocommunity with new insights from Marble Canyon, British Columbia. Paleobiology, 46: 58–81.
  • ÖPIK, A. A. 1952. The hypostoma of Pagetia. Journal of Paleontology, 26: 272–274.
  • PATERSON, J. R., EDGECOMBE, G. D. and LEE, M. S. Y. 2019. Trilobite evolutionary rates constrain the duration of the Cambrian explosion. Proceedings of the National Academy of Sciences of the United States of America, 116: 4394–4399.
  • RASETTI, F. 1951. Middle Cambrian stratigraphy and faunas of the Canadian Rocky Mountains. Smithsonian Miscellaneous Collections, 116: 1–277.
  • RASETTI, F. 1952. Revision of the North American trilobites of the family Eodiscidae. Journal of Paleontology, 26: 434–451.
  • RASETTI, F. 1966. Revision of the North American species of the Cambrian Trilobite genus Pagetia. Journal of Paleontology, 40: 502–511.
  • WALCOTT, C. D. 1916. Cambrian geology and paleontology, III, No. 5; Cambrian trilobites. Smithsonian Miscellaneous Collections, 64: 303–456.
Other Links:

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

2D reconstruction – see: http://www.trilobites.info/galagnostida.htm



Mega Zoom & Pan Image Zoomer image with id 0 does not exist!

Mega Zoom & Pan Image Viewer with preset id 0 does not exist!

Orthrozanclus reburrus

Taxonomy:

3D animation of Orthrozanclus reburrus.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Kingdom: Grazers
Phylum: Grazers
Higher Taxonomic assignment: Unranked clade halwaxiids (stem group molluscs)
Species name: Orthrozanclus reburrus
Remarks:

The classification of this animal remains ambiguous but is thought to belong to the halwaxiids, a group including Wiwaxia and halkierids (Conway Morris and Caron, 2007). Two alternative positions were proposed for the halwaxiids, as either stem-group lophotrochozoans (a group which includes molluscs, annelids, and brachiopods) or as stem-group molluscs (see also Sigwart and Sutton, 2007).

Described by: Conway Morris and Caron
Description date: 2007
Etymology:

Orthrozanclus – from the Greek orthros, “dawn,” referring to its ancestral position, and zanclon, “sickle-like,” in reference to its long sclerites.

reburrus – from the Latin reburrus, “with bristling hair,” in reference to its hairy appearance.

Type Specimens: Holotype –ROM57197 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 Quarry on Fossil Ridge.

History of Research:

Brief history of research:

Two specimens were collected by Walcott but were never described. Between 1994 and 2000, the Royal Ontario Museum collected nine additional specimens from the Walcott Quarry. These were recognized as an unknown sclerite-bearing animal (Type C, Caron and Jackson 2006) allowing for a formal description of this new species (Conway Morris and Caron, 2007).

Description:

Morphology:

Specimens vary from 6 mm to 11.3 mm in length. The ventral side is flat, whereas the dorsal surface is rounded in cross-section, bearing three zones of sclerites and one anterior shell. A set of relatively small sclerites is present around the margins of the body. These appear flat and slightly curved in one direction. Above this marginal set is a second set of much longer sclerites that seem to originate from a narrow zone along the entire length of the body. These are circular in cross section, appear to have a larger base, and tend to be curved and pointing upwards; they are probably hollow and bear one or two ridges. The presence of kinked sclerites suggests a lack of mineralization. A third set of much smaller sclerites covers the convex dorsal side of the body, but these are not clearly preserved. The shell, which was presumably mineralized, is triangular in outline with the pointed end towards the front. Fine striations along the shell are probably growth lines, indicating that growth occurred from the front to the back.

Abundance:

Very rare; all 11 known specimens come from the Walcott Quarry only, where it represents a tiny fraction of the community (0.02%) (Caron and Jackson, 2008).

Maximum Size:
11 mm

Ecology:

Life habits: Grazers
Feeding strategies: Grazers
Ecological Interpretations:

Orthrozanclus is similar in overall aspect and probably in ecology to the better known Wiwaxia corrugata.Orthrozanclus, like Wiwaxia, was probably herbivorous and would have crept along the seafloor in search for food.

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. AND J.-B. CARON. 2007. Halwaxiids and the early evolution of the lophotrochozoans. Science, 315: 1255-1258.

SIGWART, J. D. AND M. D. SUTTON. 2007. Deep molluscan phylogeny: synthesis of palaeontological and neontological data. Proceedings of the Royal Society B: Biological Sciences, 274: 2413-2419.

Other Links:

http://www.sciencemag.org/content/315/5816/1255



Mega Zoom & Pan Image Zoomer image with id 0 does not exist!

Mega Zoom & Pan Image Viewer with preset id 0 does not exist!

Odontogriphus omalus

3D animation of Odontogriphus omalus.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Kingdom: Grazers
Phylum: Grazers
Higher Taxonomic assignment: Unranked clade halwaxiids (stem group molluscs)
Species name: Odontogriphus omalus
Remarks:

Odontogriphus is an early stem-group mollusc (Caron et al., 2006; Sigwart and Sutton, 2007), or a stem-group to the lophotrochozoans, a group which includes molluscs, annelids, and brachiopods (Conway Morris and Caron, 2007). A relationship to annelids (Butterfield, 2006) has been suggested, but appears less likely (Caron et al., 2007).

Described by: Conway Morris
Description date: 1976
Etymology:

Odontogriphus – from the Greek odontos, “tooth,” and griphos, “puzzle, or riddle,” in reference to its uncertain affinities.

omalus – from the Greek homalos, “flat,” in reference to the animal’s flattened shape.

Type Specimens: Holotype –USNM196169 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 Quarry on Fossil Ridge and the Tulip Beds (S7) on Mount Stephen.

History of Research:

Brief history of research:

Walcott collected the first specimen between 1909 and 1924 but it remained unstudied for more than half a century. Conway Morris “rediscovered” the part and counterpart of this specimen in different sections of the Walcott collection and described it in 1976 as Odontogriphus omalus. The affinities of Odontogriphus remained uncertain until the Royal Ontario Museum discovered 189 new specimens between 1990 and 2000, allowing for a thorough redescription of the animal (Caron et al., 2006).

Description:

Morphology:

This entirely soft-bodied animal is ovoid and dorsoventrally compressed, reaching up to 125 mm in length and 43 mm in width. The front and back are semicircular in outline and of similar size. The mouth is ventral with a radula composed of two primary tooth rows. A muscular foot extends from behind the mouth to the posterior part of the animal and is surrounded by gills (or ctenidia), except at the front. The dorsal surface is smooth and does not bear any shells, spines or plates. Internally, a large stomach is preserved with a narrow and straight intestine ending in a sub-terminal anus.

Abundance:

Most specimens come from the Walcott Quarry, where Odontogriphus represents 0.42% of the community (Caron and Jackson, 2008). A single specimen comes from Mount Stephen (S7 locality).

Maximum Size:
125 mm

Ecology:

Life habits: Grazers
Feeding strategies: Grazers
Ecological Interpretations:

The presence of a radula suggests that Odontogriphus was a grazer, using its teeth to rasp and ingest food. Locomotory waves within the large foot would have enabled the animal to crawl along the surface of the mud. Odontogriphus might have fed on benthic, sheet-like masses of the cyanobacterium Morania, since fossils of both are often found associated in the same layers.

References:

BUTTERFIELD, N. J. 2006. Hooking some stem-group “worms”: fossil lophotrochozoans in the Burgess Shale. BioEssays, 28: 1161-1166.

CARON, J.-B., A. H. SCHELTEMA, C. SCHANDER AND D. RUDKIN. 2006. A soft-bodied mollusc with radula from the Middle Cambrian Burgess Shale. Nature, 442: 159-163.

CARON, J.-B., A. H. SCHELTEMA, C. SCHANDER AND D. RUDKIN. 2007. Reply to Butterfield on stem-group “worms:” fossil lophotrochozoans in the Burgess Shale. BioEssays, 29: 200-202.

CONWAY MORRIS, S. 1976. A new Cambrian lophophorate from the Burgess Shale of British Columbia. Palaeontology, 19: 199-222.

SIGWART, J. D. AND M. D. SUTTON. 2007. Deep molluscan phylogeny: synthesis of palaeontological and neontological data. Proceedings of the Royal Society B: Biological Sciences, 274: 2413-2419.

Other Links:

http://www.nature.com/nature/journal/v442/n7099/full/nature04894.html



Mega Zoom & Pan Image Zoomer image with id 0 does not exist!

Mega Zoom & Pan Image Viewer with preset id 0 does not exist!

Aysheaia pedunculata

Reconstruction of Aysheaia pedunculata.

© Marianne Collins

Taxonomy:

Kingdom: Grazers
Phylum: Grazers
Higher Taxonomic assignment: None
Species name: Aysheaia pedunculata
Remarks:

Aysheaia is one of a variety of lobopodian taxa from the Cambrian, which are early members of the lineage that gave rise to arthropods, and whose only modern survivors are onychophorans (velvet worms) and tardigrades (water bears). Lobopodians characteristically have annulated, unjointed bodies and bear soft limbs after which they are called: the lobopods. Although the finding is not consensual, the type of claws and orientation of rear limbs suggest that Aysheaia could be the earliest member of the water bear lineage.

Described by: Walcott
Description date: 1911
Etymology:

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

species – 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, Wuliuan stage, Burgess Shale Formation (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; Walton 1927; Hutchinson 1930; Walcott 1931), although it lacked features such as jaws and slime glands. Certain authors advocated a position in its own phylum (Tiegs & Manton 1958). A morphological reinterpretation based on photographs (Delle Cave & Simonetta 1975) prompted a detailed re-study of the fossil specimens (Whittington 1978), and relationships were suggested with the water bears (tardigrades) (Bergström 1978). Although some more recent phylogenetic approaches resolve Aysheaia as a basal lobopodian (Smith & Ortega-Hernandez 2014; Yang et al. 2015), other find support for a more derived affinity and a close relationship with tardigrades (Caron & Aria 2017, 2020).

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. The terminal pair of limbs was oriented towards the front of the animal. 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: Grazers
Feeding strategies: Grazers
Ecological Interpretations:

Aysheaia is frequently associated with the remains of sponges, and an ecological association has been posited. Considering recent evidence that other lobopodians lived anchored to a substrate for suspension-feeding (Caron & Aria 2017), it is possible that Aysheaia also used sponges as substrate for its lifestyle, although the animal lacked the morphological specializations of a suspension feeder, and more likely grazed or predated walking on their surface.

References:

  • BERGSTRÖM, J. 1978. Morphology of fossil arthropods as a guide to phylogenetic relationships. In Arthropod Phylogeny, Van Nostrand Reinhold Co., New York, 1–56 pp.
  • BRUES, C. 1923. The geographical distribution of the Onychophora. American Naturalist, 57, 210–217.
  • CARON, J. and ARIA, C. 2020. The Collins’ monster, a spinous suspension‐feeding lobopodian from the Cambrian Burgess Shale of British Columbia. Palaeontology, 63, 979–994.
  • CARON, J.-B. and ARIA, C. 2017. Cambrian suspension-feeding lobopodians and the early radiation of panarthropods. BMC Evolutionary Biology, 17, 29.
  • DELLE CAVE, L. and SIMONETTA, A. M. 1975. Notes on the morphology and taxonomic position of Aysheaia (Onycophora?) and of Skania (undetermined phylum). Monitore Zoologico Italiano, (N.S.), 67–81.
  • HUTCHINSON, G. E. 1930. Restudy of some Burgess Shale fossils. Proceedings of the United States National Museum, 78, 59.
  • SMITH, M. R. and ORTEGA-HERNANDEZ, J. 2014. Hallucigenia’s onychophoran-like claws and the case for Tactopoda. Nature, 514, 363–366.
  • TIEGS, O. W. and MANTON, S. M. 1958. The evolution of the Arthropoda. Biological Reviews, 33, 255–333.
  • WALCOTT, C. 1911. Cambrian Geology and Paleontology II. Middle Cambrian annelids. Smithsonian Miscellaneous Collections, 57(5), 109–145.
  • WALCOTT, C. 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, 284, 165–197.
  • YANG, J., ORTEGA-HERNANDEZ, J., GERBER, S., BUTTERFIELD, N. J., HOU, J., LAN, T. and ZHANG, X. 2015. A superarmored lobopodian from the Cambrian of China and early disparity in the evolution of Onychophora. Proceedings of the National Academy of Sciences of the United States of America, 112, 8678–8683.
Other Links:


Mega Zoom & Pan Image Zoomer image with id 0 does not exist!

Mega Zoom & Pan Image Viewer with preset id 0 does not exist!

Morania confluens

3D animation of Morania confluens (being grazed by Wiwaxia corrugata).

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Kingdom: Grazers
Phylum: Grazers
Higher Taxonomic assignment: Cyanophyceae (Order: Nostocales?)
Species name: Morania confluens
Remarks:

Walcott (1919) considered Morania to be related to the modern cyanobacteria Nostoc. No revisions to the affinities of this cyanobacterium have been published since.

Described by: Walcott
Description date: 1919
Etymology:

Morania – from Moraine Lake (1,885 m), in Banff National Park.

confluens – from the Latin fluere, “flow or stream,” and the prefix con, “together.” The name refers to the abundance of this species.

Type Specimens: Syntypes–USNM35378-35390, 35398 (M. confluens); USMN 35391, 35392 (M. costellifera);USNM35393 (M. elongata);USNM35394 (M. fragmenta);USNM35395 – 35397, 35401 (M.? globosa);USNM57718 (M. parasitica);USNM35402 (M.? reticulata) in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: M. costellifera Walcott, 1919; M. elongata Walcott, 1919; M. fragmenta Walcott, 1919; M.? globosa Walcott, 1919; M. parasitica Walcott, 1919; M.? reticulata Walcott, 1919, all from the Walcott Quarry.

Other deposits: M.? antiqua Fenton and Fenton, 1937 from the middle Proterozoic Altyn Limestone of Montana and the Little Dal Group, Mackenzie Mountains (see Hofmann and Aitken, 1979).

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 described Morania, erecting eight species, in a 1919 paper along with Burgess Shale algae, comparing the genus to the extant cyanobacteria Nostoc. Walcott included thin sections and details of the microstructures of M. confluens showing that it was formed of tangled strings of pyrite. Satterthwait (1976) studied specimens of M. confluens from the Geological Survey of Canada collections as part of her PhD thesis and broadly agreed with Walcott’s original interpretations, in particular regarding a position within the Nostocaceae. Sattertwhait’s work has not been published but she suggested that many species erected by Walcott might not be valid and could represent parts of more complex algae. Mankiewicz (1992) re-observed Walcott’s thin sections and confirmed the presence of Morania in several samples. Rigby (1986) identified M.? frondosa Walcott 1919, as a sponge and reassigned it to a new genus (see Crumillospongia frondosa).

Description:

Morphology:

Morania ranges in shape from spherical to sheet-like. The sheet-like form M. confluens is by far the most common species. Specimens typically range in length between 1 to more than 13 centimeters. The sheets are characteristically perforated, with holes up to 3 centimeters in diameter. The shape, size, number and distribution of holes are highly variable. Thin sections show that the microstructure of M. confluens is represented by a tangle mass of filaments called trichomes. These filaments have a beadlike structure with little spheroids of pyrite ranging 3 to 7 micrometers in diameter, and originally interpreted by Walcott as defining cellular structures.

Abundance:

Estimating the abundance of Morania is difficult since some bedding planes have large tangled masses of this cyanobacterium, and many could represent fragments of the same colony. Morania is very common in the Walcott Quarry and represents 4.9% of the community (Caron and Jackson, 2008).

Maximum Size:
130 mm

Ecology:

Life habits: Grazers
Feeding strategies: Grazers
Ecological Interpretations:

Caron and Jackson (2006) suggested that Morania covered large areas of the benthos and might have provided a stable substrate and food source for benthic animals, in particular for a number of grazers, like Odontogriphus and Wiwaxia.

References:

CARON, J.-B. AND D. A. JACKSON. 2006. Taphonomy of the Greater Phyllopod Bed Community, Burgess Shale. Palaios, 21: 451-465.

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

HOFMANN, H. J. AND J. D. AITKEN. 1979. Precambrian biota from the Little Dal Group, Mackenzie Mountains, northwestern Canada. Canadian Journal of Earth Sciences, 16: 150-166.

MANKIEWICZ, C. 1992. Obruchevella and other microfossils in the Burgess Shale: preservation and affinity. Journal of Paleontology, 66(5): 717-729.

SATTERTHWAIT, D. F. 1976. Paleobiology and Paleoecology of Middle Cambrian Algae from Western North America. Unpublished PhD thesis, California, Los Angeles, 120 p.

WALCOTT, C. 1919. Cambrian Geology and Paleontology IV. Middle Cambrian Algae. Smithsonian Miscellaneous Collections, 67(5): 217-260.

Other Links:

None