The Burgess Shale

Wiwaxia corrugata

3D animation of Wiwaxia corrugata grazing on Morania confluens.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Class: Unranked clade halwaxiids (stem group molluscs)
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).

Species name: Wiwaxia corrugata
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:

Period:
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:

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

Waputikia ramosa

3D animation of Waputikia ramosa.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Class: Non applicable
Remarks:

No revisions of this alga have been published since its original description by Walcott (1919) and its affinities remain uncertain.

Species name: Waputikia ramosa
Described by: Walcott
Description date: 1919
Etymology:

Waputikia – from the Waputik Icefield, a glacier in Yoho National Park, east of the Burgess Shale.

ramosa – from the Latin ramosus, “full of branches,” in reference to the presence of clumps of branches.

Type Specimens: Syntypes –USNM35409, 35410, 35411 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:

This genus was described by Charles Walcott (1919) as a possible red alga. However, like all the algae from the Burgess Shale, it awaits a modern redescription.

Description:

Morphology:

Waputikia has a large central stem with wide branches at irregular intervals. The large branches divide dichotomously (into two), and the smaller tertiary or quaternary branches divide into much finer branches forming small terminal bush-like structures.

Abundance:

Waputikia is very rare and represents only 0.02% of the Walcott Quarry community (Caron and Jackson, 2008).

Maximum Size:
60 mm

Ecology:

Ecological Interpretations:

No attachment structure for this alga has been preserved but it probably lived attached to the sea floor.

References:

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

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

Other Links:

None

Wapkia grandis

3D animation of Wapkia elongata and other sponges (Choia ridleyiDiagoniella cyathiformisEiffelia globosaHazelia confertaPirania muricata, and Vauxia bellula) and Chancelloria eros a sponge-like form covered of star-shaped spines.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Class: Demospongia (Order: Monaxonida)
Remarks:

Wapkia is considered a primitive demosponge (Rigby, 1986). Demosponges, the same group that are harvested as bath sponges, represent the largest class of sponges today.

Species name: Wapkia grandis
Described by: Walcott
Description date: 1920
Etymology:

Wapkia – origin of name is unknown

grandis – from the Latin grandis, “large.” This name refers to the large size and complex skeleton of this sponge.

Type Specimens: Lectotype –USNM66458 (W. grandis), in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA. Holotype –ROM53544 (W. elongata), in the Royal Ontario Museum, Toronto, Canada.
Other species:

Burgess Shale and vicinity: W. elongata Rigby and Collins, 2004 from the Tulip Beds (S7) on Mount Stephen.

Other deposits: none.

Age & Localities:

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

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

History of Research:

Brief history of research:

Wapkia was described by Walcott in his initial description of the Burgess Shale sponges in 1920. The genus was re-examined by Rigby in 1986. Rigby and Collins (2004) also redescribed the genus and proposed a new species, W. elongata.

Description:

Morphology:

Wapkia is a large elongate or oval sponge with bundles of coarse and fine spicules aligned in long vertical columns and distinct horizontal bundles. The surface of the sponge is smooth and lacks any vertical or horizontal ridges. Spicules are straight and pointed at both ends (oxeas). The exact position of the various bundles of spicules in the skeleton is still uncertain, but it seems that the inner part of the skeleton is reticulate with horizontal wrinkles that are typical of the species and produced by horizontal bundles of spicules. The dermal layer is formed by bundles of oxeas up to 60 mm long which give a characteristic plumose aspect to this sponge. W. elongata is distinguished from W. grandis based on the overall shape of the sponge and different skeletal structures (varying distance between the horizontal spicule bundles).

Abundance:

Wapkia is rare and represents only 0.06% of the Walcott Quarry community (Caron and Jackson, 2008).

Maximum Size:
170 mm

Ecology:

Ecological Interpretations:

Wapkia would have lived attached to the sea floor. Particles of organic matter were extracted from the water as they passed through canals in the sponge’s wall.

References:

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

RIGBY, J. K. 1986. Sponges of the Burgess shale (Middle Cambrian), British Columbia. Palaeontographica Canadiana, 2: 105 p.

RIGBY, J. K. AND D. COLLINS. 2004. Sponges of the Middle Cambrian Burgess Shale and Stephen Formations, British Columbia. Royal Ontario Museum Contributions in Science (1): 155 p.

WALCOTT, C. D. 1920. Middle Cambrian Spongiae. Cambrian Geology and Paleontology IV. Smithsonian Miscellaneous Collections, 67(6): 261-365.

Other Links:

None

Pirania muricata

3D animation of Pirania muricata and other sponges (Choia ridleyi, Diagoniella cyathiformis, Eiffelia globosa, Hazelia conferta, Vauxia bellula, and Wapkia elongata) and Chancelloria eros a sponge-like form covered of star-shaped spines.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Class: Demospongea (Order: Monaxonida)
Remarks:

Pirania is considered a primitive demosponge (Rigby, 1986). Demosponges, the same group that are harvested as bath sponges, represent the largest class of sponges today.

Species name: Pirania muricata
Described by: Walcott
Description date: 1920
Etymology:

Pirania – from Mount Saint Piran (2,649 m), situated in the Bow River Valley in Banff National Park, Alberta. Samuel Allen named Mount St. Piran after the Patron Saint of Cornwall in 1894.

muricata – from the Latin muricatus, “pointed, or full of sharp points.” The name refers to the large pointed spicules extending out from the wall of the sponge.

Type Specimens: Lectotype –USNM66495 (erroneously referred as 66496 in Rigby, 1986), in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none

Other deposits: Pirania auraeum Botting, 2007 from the Lower Ordovician of Morocco (Botting, 2007); Pirania llanfawrensis Botting, 2004 from the Upper Ordovician of England (Botting, 2004).

Age & Localities:

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

The Walcott Quarry on Fossil Ridge. The Trilobite Beds and Tulip Beds (S7) on Mount Stephen and several smaller sites on Mount Field, Mount Stephen and Mount Odaray.

History of Research:

Brief history of research:

Pirania was first described by Walcott (1920). Rigby (1986) redescribed this sponge and concluded that the skeleton is composed of hexagonally arranged canals, large pointed spicules and tufts of small spicules. This sponge was also reviewed by Rigby and Collins based on new material collected by the Royal Ontario Museum (2004).

Description:

Morphology:

Pirania is a thick-walled cylindrical sponge that can have up to four branches. The skeleton of the sponge is composed of tufts of small spicules and has very distinctive long pointed spicules that emerge from the external wall. Long canals perforate the wall of the sponge to allow water flow through it. Branching occurs close to the base of the sponge.

Abundance:

Pirania is common in most Burgess Shale sites but comprises only 0.38% of the Walcott Quarry community (Caron and Jackson, 2008).

Maximum Size:
30 mm

Ecology:

Ecological Interpretations:

Pirania would have lived attached to the sea floor. Particles of organic matter were extracted from the water as they passed through canals in the sponge’s wall. The brachiopods Nisusia and Micromitra a range of other sponges and even juvenile chancelloriids are often found attached to the long spicules of this sponge, possibly to avoid higher turbidity levels near the seafloor.

References:

BOTTING, J. P. 2004. An exceptional Caradoc sponge fauna from the Llanfawr Quarries, Central Wales and phylogenetic implications. Journal of Systematic Paleontology, 2: 31-63.

BOTTING, J. P. 2007. ‘Cambrian’ demosponges in the Ordovician of Morocco: insights into the early evolutionary history of sponges. Geobios, 40: 737-748.

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

RIGBY, J. K. 1986. Sponges of the Burgess shale (Middle Cambrian), British Columbia. Palaeontographica canadiana, 2: 105 p.

RIGBY, J. K. AND D. COLLINS. 2004. Sponges of the Middle Cambrian Burgess Shale and Stephen Formations, British Columbia. Royal Ontario Museum Contributions in Science (1): 155 p.

WALCOTT, C. D. 1920. Middle Cambrian Spongiae. Cambrian Geology and Paleontology IV. Smithsonian Miscellaneous Collections, 67(6): 261-365.

Other Links:

None

Odaraia alata

3D animation of Odaraia alata.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Class: Unranked clade (stem group arthropods)
Remarks:

The affinity of Odaraia is uncertain because, while it was historically considered as a crustacean (Walcott, 1912; Briggs, 1981; Briggs and Fortey, 1989; Hou and Bergström, 1997; Wills et al., 1998), more recent studies have placed it in the upper stem lineage to the arthropods (Budd, 2002, 2008).

Species name: Odaraia alata
Described by: Walcott
Description date: 1912
Etymology:

Odaraia – from Odaray Mountain (3,159 m) in Yoho Park, which was named by J. J. McArthur in 1887 from the Stoney First Nation Nakoda expression for “many waterfalls.”

alata – from the Latin ala, “wing,” referring to the wing-like fins of the tail.

Type Specimens: Lectotype –USNM57722 (O. alata) 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 and Raymond Quarries on Fossil Ridge.

History of Research:

Brief history of research:

Odaraia was first described by Walcott (1912), and was re-examined briefly by Simonetta and Delle Cave (1975). A major restudy of Odaraia was published by Briggs (1981), and it has since been included in several studies on arthropod evolution (Briggs and Fortey, 1989; Hou and Bergström, 1997; Wills et al. 1998; Budd, 2002). New morphological features of the gut and the head region were described by Butterfield (2002) and Budd (2008) respectively.

Description:

Morphology:

Much of the body of Odaraia is contained within a prominent bivalved carapace that, unusually, has its hinge line along the dorsal midline of the animal with the valves meeting on the ventral surface. The carapace forms a tube open at the front and back. The head protrudes from the front of this carapace tube, and consists of a small anterior plate, or sclerite, that bears a pair of large, spherical eyes on short stalks. On the head between the two large eyes are three small, highly reflective spots that have been interpreted as median eyes.

Behind the head, the body consisted of approximately 47 narrow segments, each bearing a pair of appendages. The appendages on the first two body segments are thin, segmented walking branches, but all appendages behind this are segmented and branch into two (biramous). These biramous appendages have a segmented inner branch that has a large spine at its base and splits into two walking branches distally, and an outer branch with filamentous blades. The tail or telson has three blades or flukes, two of which extend laterally and the third of which extends vertically. The gut is typically straight and has paired midgut glands.

Abundance:

Odaraia typically makes up less than 0.5% of the community in Walcott Quarry, from which over 200 specimens have been collected (Caron and Jackson, 2008). About a dozen specimens are known from Raymond Quarry.

Maximum Size:
150 mm

Ecology:

Ecological Interpretations:

The tubular carapace of Odaraia would have enclosed the ventral appendages, making it impossible for the animal to use its appendages for walking on the sea floor. It therefore seems to have swum through the water column by waving the inner segmented branches of its biramous appendages. The outer filamentous branches were likely used for respiration.

The large eyes and gut glands suggest that Odaraia was an active predator, seeking out floating or swimming organisms and sieving them out the water as the current passed through the tubular carapace. To minimize the drag created by its dorsal hinge, it is quite likely that Odaraia swam on its back, similar to the modern horseshoe crab. The large telson would have been used to stabilize the animal while swimming to prevent it from rolling, and to help with steering and braking.

References:

BRIGGS, D. E. G. 1981. The arthropod Odaraia alata Walcott, Middle Cambrian, Burgess Shale, British Columbia. Philosophical Transactions of the Royal Society of London B, 291: 541-582.

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

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

BUDD, G. E. 2008. Head structures in upper stem-group euarthropods. Palaeontology, 51: 561-573.

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

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

SIMONETTA, A. M. AND L. DELLE CAVE. 1975. The Cambrian non-trilobite arthropods from the Burgess shale of British Columbia: A study of their comparative morphology, taxonomy and evolutionary significance. Palaeontographia Italica, 69: 1-37.

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

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:

None

Nectocaris pteryx

3D animation of Nectocaris pteryx.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Class: Cephalopoda (stem group molluscs)
Remarks:

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

Species name: Nectocaris pteryx
Described by: Conway Morris
Description date: 1976
Etymology:

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

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

Type Specimens: Holotype –USNM198667 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none.

Other deposits: none.

Age & Localities:

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

The Walcott, Raymond and Collins Quarries on Fossil Ridge.

History of Research:

Brief history of research:

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

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

Description:

Morphology:

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

Abundance:

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

Maximum Size:
72 mm

Ecology:

Ecological Interpretations:

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

References:

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

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

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

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

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

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

Other Links:

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

Anomalocaris canadensis

3D animation of Anomalocaris canadensis.

Animation by Phlesch Bubble © Royal Ontario Museum

Taxonomy:

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

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

Species name: Anomalocaris canadensis
Described by: Whiteaves
Description date: 1892
Etymology:

Anomalocaris – from the Greek anomoios, “unlike,” and the Latin caris, “crab” or “shrimp,” thus, “unlike other shrimp.”

canadensis – from Canada, the country where the Burgess Shale is located.

Type Specimens: Lectotype – GSC3418 in the Geological Survey of Canada, Ottawa, Canada.
Other species:

Burgess Shale and vicinity: none.

Other deposits: A. pennsylvanica from the Early Cambrian Kinzers Formation in Pennsylvania (Resser, 1929); A. saron (Hou et al., 1995) from the Early Cambrian Chengjiang biota; A. briggsi (Nedin, 1995) from the Early Cambrian Emu Bay Shale of Australia.

Age & Localities:

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

The Collins, Raymond and Walcott Quarries on Fossil Ridge. The Trilobite Beds, Tulip Beds (S7) and the Collins Quarry on Mount Stephen. Additional localities on Mount Field, Mount Stephen, near Stanley Glacier and in the Early Cambrian Cranbrook Shale, Eager Formation, British Columbia.

History of Research:

Brief history of research:

Anomalocaris has a complex history of description because parts of its body were described in isolation before it was realized they all belonged to the same animal. The frontal appendage of Anomalocaris was described by Whiteaves (1892) as the body of a shrimp. The mouth parts were described by Walcott (1911) as a jellyfish called Peytoia nathorsti. A full body anomalocaridid specimen was originally described as the sea cucumber Laggania cambria (Walcott, 1911), and re-examined by Conway Morris (1978) who concluded it was a superimposition of the “jellyfish” Peytoia nathorsti on top of a sponge. Henriksen (1928) attached Anomalocaris to the carapace of Tuzoia, but Briggs (1979) suggested instead that it was the appendage of an unknown arthropod, an idea that turned out to be correct.

In the early 1980s, Harry Whittington was preparing an unidentified Burgess Shale fossil from the Geological Survey of Canada by chipping away layers of rock to reveal underlying structures, when he solved the mystery of Anomalocaris‘s identity. Much to his surprise, Whittington uncovered two Anomalocaris “shrimp” attached to the head region of a large body, which also had the “jellyfish” Peytoia as the mouth apparatus. Similar preparations of other fossils from the Smithsonian Institution in Washington DC revealed the same general morphology, including the Laggania cambria specimen Conway Morris (1978) thought to be the superimposition of the Peytoia jellyfish on a sponge, which was actually a second species of Anomalocaris. Thus, Whittington and Briggs (1985) were able to describe two species: Anomalocaris canadensis, which had a pair of the typical Anomalocaris appendages, and Anomalocaris nathorsti, which has a different type of frontal appendage and includes the original specimen of Laggania cambria. Bergström (1986) re-examined the morphology and affinity of Anomalocaris and suggested it had similarities to the arthropods.

Collecting at the Burgess Shale by the Royal Ontario Museum in the early 1990s led to the discovery of several complete specimens, which Collins (1996) used to reconstruct Anomalocaris canadensis with greater accuracy. This led to a name change of Anomalocaris nathorsti to Laggania cambria. Anomalocaris has since been the subject of many studies discussing its affinity (e.g., Hou et al., 1995; Chen et al., 2004; Daley et al., 2009), ecology (e.g., Rudkin, 1979; Nedin, 1999) and functional morphology (e.g., Usami, 2006).

Description:

Morphology:

Anomalocaris is a bilaterally symmetrical and dorsoventrally flattened animal with a non-mineralized exoskeleton. It has a segmented trunk, with at least 11 lateral swimming flaps bearing gills, and a prominent tailfan, which consists of three pairs of prominent fins that extend upward from the body. Paired gut glands are associated with the body segments in some specimens. The head region bears one pair of anterior appendages, two eyes on stalks, and a ventrally oriented circular mouth apparatus with many spiny plates. The frontal appendages are elongated and have 14 segments, each with a pair of sharp spikes projecting from the ventral surface. The stalked eyes are dorsal and relatively large. The ventral mouth apparatus has 32 rectangular plates, four large and 28 small, arranged in a circle, with sharp spines pointing into a square central opening. The most complete Anomalocaris specimen is 25 cm in length, although individual fragments suggest individuals could reach a larger size, perhaps up to 100 cm.

Abundance:

The Anomalocaris frontal appendage is extremely common at the Mount Stephen Trilobite Beds, and several hundred specimens of isolated frontal appendages and mouth parts have been collected from Mount Stephen and the Raymond Quarry on Fossil Ridge. These parts are relatively rare at Walcott Quarry, where fewer than 50 specimens are known (Caron and Jackson, 2008). Several dozen disarticulated assemblages and five complete body specimens are known from the Raymond Quarry.

Maximum Size:
1000 mm

Ecology:

Ecological Interpretations:

The streamlined body would have been ideal for swimming. Undulatory movements of the lateral flaps propelled the animal through the water column and might have also served in gill ventilation. While swimming, Anomalocaris‘s frontal appendages would hang below the body, but it would thrust its head and appendages forward 180° to attack prey as needed.

A predatory lifestyle is suggested by the large eyes, frontal appendages with spines, gut glands, and spiny mouth apparatus. The circular mouth part is unique in the animal kingdom. It seems unlikely that it was used to bite prey by bringing lateral plates into opposition, rather, it grasped objects either by pivoting the plates outwards or contracting them inward. It has been suggested that Anomalocaris may have preyed on trilobites because some Cambrian trilobites have round or W-shaped healed wounds, interpreted as bite marks (Rudkin, 1979), and large fecal pellets composed of trilobite parts have been found in the Cambrian rock record; anamalocaridids are the only known animals large enough to have produced such pellets. The anomalocaridids could have fed by grasping one end of the trilobite in the mouth apparatus and rocking the other end back and forth with the frontal appendages until the exoskeleton cracked (Nedin, 1999). However, the unmineralized mouth apparatus of Anomalocaris would have probably been too weak to penetrate the calcified shell of trilobites in this manner, and the mouth parts do not show any sign of breakage or wear. Thus, Anomalocaris may have been feeding on soft-bodied organisms including on freshly moulted “soft-shell” trilobites (Rudkin, 2009).

References:

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

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

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.

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

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

DALEY, A. C., 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.

HENRIKSEN, K. L. 1928. Critical notes upon some Cambrian arthropods described from Charles D. Walcott. Videnskabelige Meddelelser fra Dansk Naturhistorisk Forening: Khobenhavn, 86: 1-20.

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.

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

RESSER, C. E. 1929. New Lower and Middle Cambrian Crustacea. Proceedings of the United States National Museum, 76: 1-18.

RUDKIN, D. M. 1979. Healed injuries in Ogygosis klotzi (Trilobita) from the Middle Cambrian of British Columbia. Royal Ontario Museum, Life Sciences Occasional Paper, 32: 1-8.

RUDKIN, D. M. 2009. The Mount Stephen Trilobite Beds, pp. 90-102. In J.-B. Caron and D. Rudkin (eds.), A Burgess Shale Primer – History, Geology, and Research Highlights. The Burgess Shale Consortium, Toronto.

USAMI, Y. 2006. Theoretical study on the body form and swimming pattern of Anomalocaris based on hydrodynamic simulation. Journal of Theoretical Biology, 238: 11-17.

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

WHITEAVES, J. F. 1892. Description of a new genus and species of phyllocarid Crustacea from the Middle Cambrian of Mount Stephen, B.C. Canadian Record of Science, 5: 205-208.

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

Other Links:

Marrella splendens

3D animation of Marrella splendens.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Class: Marrellomorpha (Order: Marrellida, stem group arthropods)
Remarks:

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

Species name: Marrella splendens
Described by: Walcott
Description date: 1912
Etymology:

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

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

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

Burgess Shale and vicinity: none

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

Age & Localities:

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

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

History of Research:

Brief history of research:

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

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

Description:

Morphology:

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

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

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

Abundance:

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

Maximum Size:
25 mm

Ecology:

Ecological Interpretations:

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

References:

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

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

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

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

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

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

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

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

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

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

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

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

WILLS, M. A., D. E. G. BRIGGS, R. A. FORTEY, M. WILKINSON AND P. H. A. SNEATH. 1998. An arthropod phylogeny based on fossil and recent taxa, p. 33-105. In G. D. Edgecombe (ed.), Arthropod fossils and phylogeny. Columbia University Press, New York.

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

Other Links:

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

Marpolia spissa

3D animation of Marpolia spissa.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Class: Cyanophyceae (Order: Oscillatoriales?)
Remarks:

Walcott (1919) considered this species to be a cyanobacterium, but Walton suggested a relationship to red algae instead (Walton, 1923). More recent studies concurred with Walcott’s original interpretation (Conway Morris and Robison, 1988).

Species name: Marpolia spissa
Described by: Walcott
Description date: 1919
Etymology:

Marpolia – from Mount Marpole (2,997 m), a peak located near the Burgess Shale, northwest of Emerald Lake in Yoho National Park.

spissa – from the Latin spissus, “crowded,” in reference to the bush-like aspect of this cyanobacteria.

Type Specimens: Lectotype –USNM35403 (M. spissa); holotype –USNM35412 (M. aequalis) in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: M. aequalis Walcott 1919 from the Trilobite Beds on Mount Stephen (known from a single specimen).

Other deposits: Marpolia (possibly represented by different species) is common in various Cambrian exceptional fossil deposits, in particular from the Middle Cambrian Spence Shale and Wheeler Formation in Utah (Conway Morris and Robison, 1988) and the Middle Cambrian Kaili Formation in China (Yang et al., 2001).

Age & Localities:

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

The Walcott Quarry on Fossil Ridge, the Tulip Beds (S7) on Mount Stephen, and other smaller localities on Mount Field, Mount Stephen and Monarch Cirque.

History of Research:

Brief history of research:

Walcott described Marpolia in 1919 and named two species from the Burgess Shale, M. spissa from the Walcott Quarry and M. aequalis from the Trilobite Beds. M. spissa was compared to the modern Oscillatorialesin an unpublished thesis (Satterthwait, 1976), an interpretation followed by Conway Morris and Robison (1988) based on the study of fossil material from various Utah deposits. M. spissa is commonly found in thin sections (Mankiewicz, 1992) and can be isolated by acid maceration (Butterfield, 1990). A recent taphonomic study demonstrated that the preservation style of Marpolia is similar to other Burgess Shale organisms (Butterfield et al., 2007).

Description:

Morphology:

Marpolia forms dense tufts up to 5 cm in length composed of numerous filaments. Filaments tend to branch near the base of the tuft. Each filament averages about 40 microns in width. Filaments are composed of an outer sheath and one to four strands of inner cells. Each cell is about 2 microns in length. M. aequalis has a central stem and stronger branching structures than M. spissa.

Abundance:

Estimating the abundance of Marpolia is difficult since some bedding planes have large tangled masses of this cyanobacterium, and many could represent fragments of the same colony. M. spissa is rare and represents only 0.07% of the Walcott Quarry community (Caron and Jackson, 2008).

Maximum Size:
50 mm

Ecology:

Ecological Interpretations:

The absence of an attachment structure suggests that Marpolia may have been free-living, floating in large masses (i.e., planktonic). It may have attached to other floating objects as free-living cyanobacteria do today. It is also possible that the lack of attachment structure is taphonomic (a structure that is lost during deposition), due to detachment from the sediment during transport (caused by having been swept up in mud flows) prior to burial.

References:

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

BUTTERFIELD, N. J., U. BALTHASAR AND L. WILSON. 2007. Fossil diagenesis in the Burgess Shale. Palaeontology, 50: 537-543.

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 R. A. ROBISON. 1988. More soft-bodied animals from the Middle Cambrian of Utah and British Columbia. University of Kansas Paleontological Contributions, 122 p.

MANKIEWICZ, C. 1992. Obruchevella and other microfossils in the Burgess Shale: preservation and affinity. Journal of Paleontology, 66: 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. D. 1919. Middle Cambrian Algae. Cambrian Geology and Paleontology IV. Smithsonian Miscellaneous Collections, 67(5): 217-260.

WALTON, J. 1923. On the structure of a Middle Cambrian alga from British Columbia (Marpolia spissa Walcott). Proceedings of the Cambridge Philosophical Society-Biological Sciences, 1: 59-62.

YANG, R., J. MAO, Y. ZHAO, X. CHEN AND X. YANG. 2001. Branching macroalgal fossils of the Early-Middle Cambrian Kaili Formation from Taijiang, Guizhou Province, China. Acta Geologica Sinica, 75: 433-440.

Other Links:

None

Margaretia dorus

3D animation of Margaretia dorus.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Class: Bryopsidophyceae (Order: Bryopsidales)
Remarks:

Walcott (1919) considered this species to be a green alga, but also noted some similarities with alcyonarian corals (closely related to the sea pens). Studies of specimens from the Burgess Shale and Utah suggest affinities with the modern green alga Caulerpa(Satterthwait, 1976; Conway Morris and Robison, 1988).

Species name: Margaretia dorus
Described by: Walcott
Description date: 1931
Etymology:

Margaretia – unspecified; possibly from the Greek margarites, “pearl,” in reference to the rounded structures present along the tegument.

dorus – unspecified; possibly from the Greek dora, “skin,” in reference to the skin-like tegument of this algae.

Type Specimens: Holotype –USNM83922 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none.

Other deposits: M. chamblessi from the Lower Cambrian Latham Shale of southeastern California (Waggoner and Hagadorn, 2004).

Age & Localities:

Period:
Upper Lower Cambrian, Olenellus Zone to the upper Middle Cambrian, Ptychagnostus punctuosus Zone.
Principal localities:

Burgess Shale and vicinity: The Walcott, Raymond and Collins Quarries on Fossil Ridge. The Trilobite Beds, Collins Quarry and smaller sites on Mount Stephen. Mount Odaray and Stanley Glacier.

Other deposits: M. dorus is known from several Cambrian deposits in particular from the Middle Cambrian Spence Shale and Marjum Formation in Utah (Conway Morris and Robison, 1988).

History of Research:

Brief history of research:

Walcott collected about 70 specimens of this new species from the Burgess Shale. It is only after his death that this material was formally published by his assistant Charles Resser in 1931. This species was compared to the modern green alga Caulerpa in an unpublished thesis (Satterthwait, 1976) an interpretation followed by Conway Morris and Robison (1988) based on the study of well preserved material from several Utah deposits. No revisions of this alga using specimens from the Burgess Shale have been published since its original description by Walcott (1931).

Description:

Morphology:

This alga is the largest known in the Burgess Shale. It is composed of single or dichotomous (divided into two) tubular axes which are erect and are connected perpendicularly to simple root-like elements called rhizomes. The tubular axes do not vary in width and can reach at least 40 cm in length. The distal ends were rounded. The surfaces are covered with small protuberances of similar size and shape called papillae. These papillae are organized in a spiral pattern. Papillae are visible along the margins of the fossils, but when preserved perpendicularly, they tend to split off at their base giving the impression of holes along the stems. Contrary to Walcott’s initial assessment, Margaretia is not a “thin membranous perforated sheet.” The rhizomes are usually smaller in diameter than the stems and tend to have irregular undulations but no papillae.

Abundance:

Margaretia is present in many sites but is usually rare. No specimens of this alga were found in the Walcott Quarry community out of 52,620 specimen observed (Caron and Jackson, 2008).

Maximum Size:
400 mm

Ecology:

Ecological Interpretations:

Margaretia lived attached to the sea floor via its rhizomes, with its fronds floating above it in the water. The presence of mostly fragmentary specimens in many fossil deposits suggests this alga could have been transported from nearby environments.

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 R. A. ROBISON. 1988. More soft-bodied animals from the Middle Cambrian of Utah and British Columbia. University of Kansas Paleontological Contributions, 122 p.

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

WAGGONER, B. AND J. W. HAGADORN. 2004. An unmineralized alga from the Lower Cambrian of California, USA. Neus Jahrbuch fur Geologie und Palaontologie-Abhandlungen, 231: 67-83.

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

Other Links:

None