The Burgess Shale

Media: Drawing

Amplectobelua stephenensis

Amplectobelua stephenensis (ROM 59492) – Holotype. Individual claw. Specimen length = 51 mm. Specimen wet – polarized light. Tulip Beds (S7) on Mount Stephen.

© Royal Ontario Museum. Photo: Jean-Bernard Caron

Taxonomy:

Kingdom: Drawing
Phylum: Drawing
Higher Taxonomic assignment: Dinocarida (Order: Radiodonta, stem group arthropods)
Species name: Amplectobelua stephenensis
Remarks:

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

Described by: Daley and Budd
Description date: 2010
Etymology:

Amplectobelua – from the Latin amplecto, “embrace,” and belua, “monster.”

stephenensis – from Mount Stephen (3,199 m), the mountain peak in Yoho National Park from which the specimens were collected. Named in 1886 for George Stephen, the first president of the Canadian Pacific Railway.

Type Specimens: Holotype –ROM59492 in the Royal Ontario Museum, Toronto, Canada.
Other species:

Burgess Shale and vicinity: none.

Other deposits: Amplectobelua symbrachiata from the Chengjiang Fauna in China.

Age & Localities:

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

The Tulip Beds (S7) on Mount Stephen.

History of Research:

Brief history of research:

The Chengjiang specimens of Amplectobelua were first described as “anomalocaridid animal 2” in Chen et al. (1994) and given a formal designation as Amplectobelua symbrachiata by Hou et al. (1995). The Burgess Shale genus Amplectobelua stephenensis was described by Daley and Budd (2010) from six specimens of isolated appendages in the Royal Ontario Museum collections.

Description:

Morphology:

Amplectobelua stephenensis is known from isolated appendages that have twelve segments, with paired ventral spines on the second to ninth segments. The appendages range in size from 2.8 cm to 5.1 cm. The nearest podomere has a pair of large spines that extend most of the length of the whole appendage. There are also paired dorsal spines on the three furthest segments, which are long and curved towards the end of the appendage. No full-body specimens of A. stephenensis have yet been found, but it may have a similar morphology to A. symbrachiata and Anomalocaris, with wide swimming flaps on a dorsoventrally flattened body and a head with circular mouth parts and eyes on stalks (Chen et al., 1994).

Abundance:

Six specimens of Amplectobelua have been described from a single locality, the Tulip Beds (S7), on Mount Stephen.

Maximum Size:
51 mm

Ecology:

Life habits: Drawing
Feeding strategies: Drawing
Ecological Interpretations:

Amplectobelua is considered a predator, based on the morphology of its frontal appendage. The wide range of mobility exhibited in the many-segmented appendage and the paired ventral spines means that they would have been ideal for gripping and manipulating prey items. The distal podomeres could be used to grasp prey with a scissor-like motion when brought into opposition against the proximal endites. Like other anomalocaridids, Amplectobelua has a streamlined body and would swim through the water column by undulating its lateral flaps to propel itself forward.

References:

CHEN, J. Y., L. RAMSKÖLD AND G. Q. ZHOU. 1994. Evidence for monophyly and arthropod affinity of Cambrian giant predators. Science, 264: 1304-1308.

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.

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.

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

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.

Other Links:

None

Marrella splendens

3D animation of Marrella splendens.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

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

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

Described by: Walcott
Description date: 1912
Etymology:

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

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

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

Burgess Shale and vicinity: none

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

Age & Localities:

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

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

History of Research:

Brief history of research:

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

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

Description:

Morphology:

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

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

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

Abundance:

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

Maximum Size:
25 mm

Ecology:

Life habits: Drawing
Feeding strategies: Drawing
Ecological Interpretations:

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

References:

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Other Links:

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

Leanchoilia superlata

3D animation of Leanchoilia superlata.

Animation by Phlesch Bubble © Royal Ontario Museum

Taxonomy:

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

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

Described by: Walcott
Description date: 1912
Etymology:

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

superlata – from the Latin superlata, “exaggerated.”

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

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

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

Age & Localities:

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

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

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

History of Research:

Brief history of research:

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

Description:

Morphology:

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

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

Abundance:

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

Maximum Size:
120 mm

Ecology:

Life habits: Drawing
Feeding strategies: Drawing
Ecological Interpretations:

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

References:

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

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

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

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

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

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

COTTON, T. J. AND S. J. BRADDY. 2004. The phylogeny of arachnomorph arthropods and the origin of the Chelicerata. Transactions of the Royal Society of Edinburgh: Earth Sciences, 94: 169-193.

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

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

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

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

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

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

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

Other Links:

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

Laggania cambria

Reconstruction of Laggania cambria.

© Marianne Collins

Taxonomy:

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

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

Described by: Walcott
Description date: 1911
Etymology:

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

cambria – from the Welsh Cambria meaning Wales.

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

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

Other deposits: none.

Age & Localities:

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

The Walcott Quarry on Fossil Ridge.

History of Research:

Brief history of research:

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

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

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

Description:

Morphology:

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

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

Abundance:

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

Maximum Size:
500 mm

Ecology:

Life habits: Drawing
Feeding strategies: Drawing
Ecological Interpretations:

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

References:

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

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

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

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

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

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

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

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

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

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

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

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

Other Links:

None

Waptia fieldensis

Reconstruction of Waptia fieldensis.

© MARIANNE COLLINS

Taxonomy:

Kingdom: Drawing
Phylum: Drawing
Higher Taxonomic assignment: Unranked clade (stem group arthropods)
Species name: Waptia fieldensis
Remarks:

It has been suggested that Waptia is closely related to Canadaspis and Perspicaris (Briggs and Fortey, 1989), with the group being allied to the crustaceans (Briggs, 1983; Wills et al., 1998; Briggs et al., 2008). However, some researchers argue instead that Waptia is at most a stem-lineage crustacean (Bergström and Hou, 2005), or perhaps even in the stem lineage to the arthropods (Hou and Bergström, 1997; Walossek and Müller, 1998).

Described by: Walcott
Description date: 1912
Etymology:

Waptia – from Wapta Mountain (2,778 m), just north of Fossil Ridge, in British Columbia, Canada, named after the Stoney First Nation Nakoda word “Wapta” meaning “running water.”

fieldensis – from Field, the mountain peak (2,643 m) and small town near Fossil Ridge, British Columbia, Canada. The name was given by William Cornelius Van Horne (General Manager of the Canadian Pacific Railway), to honor Cyrus West Field a promoter of the first telegraph cable across the Atlantic Ocean.

Type Specimens: Syntypes –USNM57681 andUSNM57682 (W. fieldensis) in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
Other species:

Burgess Shale and vicinity: none.

Other deposits: Waptia cf. fieldensis from the Spence Shale Member of the Langston Formation, Utah (Briggs et al. 2008).

Age & Localities:

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

The Walcott and Raymond Quarries on Fossil Ridge

History of Research:

Brief history of research:

Waptia was first described by Walcott (1912), who designated Waptia fieldensis as the type species of the type genus. Various authors have since commented on its affinities (e.g. Briggs, 1983; Briggs et al., 1994; Hou and Bergström, 1997; Walossek and Müller, 1998; Wills et al., 1998; Hou and Bergström, 2005). However, no detailed work on its morphology has since been completed. Despite this, specimens of Waptia cf. fieldensishave been described from the Spence Shale in Utah (Briggs et al., 2008), and Waptia has been compared to Pauloterminus spinodorsalis from the Sirius Passet biota in North Greenland (Taylor, 2002). Waptia-like specimens from southwest China (Li, 1975; Hou and Bergström, 1991) were at one point assigned to Waptia (Chen, 2004), but a re-examination of the specimens showed they were different enough to be assigned to their own genus, Chuandianella (Liu and Shu, 2004, 2008; Hou et al., 2009).

Description:

Morphology:

Waptia bears a bivalved head shield consisting of two roughly oval valves that narrow anteriorly and fold along a median line that functions as a hinge. Beneath this carapace, the head bears a pair of long, slender antennae and a pair of small eyes on stalks. Details of other head appendages cannot be seen due to compaction against the head and carapace. The body trunk is long and slender and bears ten pairs of appendages. The first four pairs of appendage are segmented walking limbs with terminal spines and setae on their back margin, and the next six pairs of appendages are segmented branches lined with setae (hair-like bristles) and bearing blade-shaped filaments. Behind these appendages there is an abdomen consisting of five elongated segments. The abdomen terminates in a forked tail that consists of two oval blades. The trace of a straight gut is apparent in some specimens, stretching from the head to the base of the forked tail.

Abundance:

Waptia is common in the Burgess Shale, with over 1,400 specimens collected from the Walcott Quarry (Conway Morris, 1986; Caron and Jackson, 2008) and 70 specimens collected from the Raymond Quarry.

Maximum Size:
80 mm

Ecology:

Life habits: Drawing
Feeding strategies: Drawing
Ecological Interpretations:

Waptia lived on or near the sea floor and scavenged for food. It used its two types of appendages to both walk on the sea floor and to swim through the water column. The first four pairs of segmented walking limbs would have been used for balancing and moving around on the sea floor, and the animal could have propelled itself through the water column by waving the bladed filaments of the posterior six appendages. The tail flaps would have helped stabilize and steer Waptia while swimming. The bladed filament may also have had a use in gas exchange. The eyes and antennae were presumably used to sense the environment, and the head appendages would pick up food particles in the sediment and bring them to the mouth.

References:

BERGSTRÖM, J. AND X. HOU. 2005.Early Palaeozoic non-lamellipedian arthropods, p. 73-93. In S. Koenemann and R. A. Jenner (eds.), Crustaceans and Arthropod Relationships, Festschrift for Fredrick R. Schram. Taylor and Francis, Boca Raton, London, New York, Singapore.

BRIGGS, D. E. G. 1983. Affinities and early evolution of the Crustacea: The evidence of the Cambrian fossils, p. 1-22. In F. R. Schram (ed.), Crustacean Issues, Volume 1, Crustacean Phylogeny. Balkema, Rotterdam.

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

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.

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. 2004. The dawn of the animal world. Jiangsu Science and Technology Press. Nanjing.

CONWAY MORRIS, S. 1986. The community structure of the Middle Cambrian phyllopod bed (Burgess Shale). Palaeontology, 29: 423-467.

HOU, X. AND J. BERGTRÖM. 1991. The arthropods of the Lower Cambrian Chengjiang fauna, with relationships and evolutionary significance, 179-187. In A. Simonetta and S. Conway Morris (eds.), The early evolution of the Metazoa and the significance of problematic taxa. Cambridge University Press, Cambridge.

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

HOU, X., D. J. SIVETER, R. J. ALDRIDGE AND D. J. SIVETER. 2009. A new arthropod in chain-like associations from the Chengjiang lagerstätte (Lower Cambrian), Yunnan, China. Palaeontology, 52: 951-961.

LI, Y. 1975. On the Cambrian ostracods with new material from Sichuan, Yunnan and Shaanxi, China. Professional Papers on Stratigraphy & Palaeontology, 2: 37-72.

LI, H. AND D. SHU. 2004. New information on Chuandianella from the Lower Cambrian Chengjiang Fauna, Yunnan, China. Journal of Northwest University, 34: 453-456.

TAYLOR, R. S. 2002. A new bivalved arthropod from the Early Cambrian Sirius Passet fauna, North Greenland. Palaeontology, 45: 97-123.

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

WALOSSEK, D. AND K. J. MÜLLER. 1998. Early arthropod phylogeny in light of the Cambrian “Orsten” fossils, p. 185-231. In G. D. Edgecombe (ed.), Arthropod Fossils and Phylogeny. Columbian University Press, New York.

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

Other Links:

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

Tuzoia burgessensis

Outlines of Tuzoia canadensis (left), Tuzoia burgessensis (middle) and Tuzoia retifera (right).

© MARIANNE COLLINS

Taxonomy:

Kingdom: Drawing
Phylum: Drawing
Higher Taxonomic assignment: Unranked clade (stem group arthropods)
Species name: Tuzoia burgessensis
Remarks:

The affinity of Tuzoia is unknown because key information about its body structure and appendages is missing. It has been suggested that it is a crustacean (Briggs et al., 1994), specifically a phyllocarid (Lieberman, 2003). However, these affinities cannot be substantiated until further details of the morphology are revealed. Tuzoia shares similarities in carapace and eye structure with Isoxys (Vannier et al., 2007), another arthropod of uncertain affinity.

Described by: Resser
Description date: 1929
Etymology:

Tuzoia – from Mount Tuzo, in the Valley of the Ten Peaks, named in 1907 after Henrietta Tuzo, who was the first to climb this mountain.

burgessensis – from Mount Burgess (2,599 m), a mountain peak in Yoho National Park. Mount Burgess. The name was given in 1886 by Otto Klotz, the Dominion topographical surveyor, after Alexander Burgess, a former Deputy Minister of the Department of the Interior.

Type Specimens: Holotypes –USNM80477b (T. burgessensis),USNM57720 (T. retifera),USNM80478b (T. canadensis) in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale: T. retifera and T. canadensis from the the Tuzoia layer above the Raymond Quarry, the Raymond and Walcott Quarries on Fossil Ridge, and other sites on Mount Field and Stanley Glacier. (See Vannier et al., 2007 for references).

Other deposits: T. guntheri from the Middle Cambrian Marjum and Pioche Formations of Utah and Nevada; T. bispinosa from the Middle Cambrian Kaili Formation of South China; T. polleni from the Lower Cambrian Eager Formation of British Columbia; and T. australisfrom the Lower Cambrian Emu Bay Shale of Australia as well as a number of poorly documented species from China. (See Vannier et al., 2007 for references).

Age & Localities:

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

The Walcott and Raymond Quarries, the Tuzoia layer above the Raymond Quarry and the Collins Quarry on Fossil Ridge. The Tulip Beds (S7) on Mount Stephen.

History of Research:

Brief history of research:

Tuzoia was first described by Charles Walcott (1912) based on a single carapace specimen from the Burgess Shale. He collected many more specimens after this publication that were later described in detail by Resser (1929). Resser designated ten different species of Tuzoia, including specimens from the Burgess Shale, the Eager Formation of British Columbia, the Kinzers Formation in Pennsylvania and the Tangshih Formation of China. Tuzoia was also described from other regions in the United States, including Utah (Robison and Richards, 1981) and Nevada (Lieberman, 2003), Australia (Glaessner, 1979), the Czech Republic (Chlupáč and Kordule, 2002), and other localities in China (Yuan and Zhao, 1999; Pan, 1957; Shu, 1990; Luo et al., 1999). At one point, there were over 20 described species of Tuzoia, all described from carapace morphology only, but a major redescription of all available material undertaken by Vannier et al., (2007) validated only 7 of these species. Vannier et al. (2007) also provided a more in-depth analysis of the morphology, including the first description of soft parts such as eyes, antennae and gut structures. The first description of frontal appendages in Tuzoia is documented in Caron et al. (2010).

Description:

Morphology:

The most prominent feature of Tuzoia is its large, bivalved carapace. The two dome-shaped carapace valves have convexly rounded ventral margins and are joined along a straight dorsal margin that extends at the front and back into pointed spines, or cardinal processes. There are two pairs of spines present in the mid-posterior and posteroventral locations of the carapace, and several smaller spikes may be present along the ventral margin. There are also spines along the dorsal margin, varying in number, size and orientation between species. A lateral ridge passes horizontally through the carapace, and is lined by frills in T. burgessensis. The carapaces are covered in a polygonal pattern. A pair of large, spherical eyes on stalks project forward from underneath the carapace, and a pair of thin antennae may also be present. The head bears a pair of robust frontal appendages with at least six segments each. In some specimens, a long, straight gut with digestive glands is preserved. Overall T. retifera and T. canadensis differ from T. burgessensis by having less and more spines respectively.

Abundance:

As the name suggests, the Tuzoia beds between the Raymond and Collins Quarries on Fossil Ridge yield abundant Tuzoia burgessensis specimens, with over 160 specimens found so far. T. burgessensis is also found rarely in Raymond Quarry, where T. retifera is more common, with 87 known specimens. Tuzoia is also found rarely in other sites on Mount Field and Mount Stephen.

Maximum Size:
180 mm

Ecology:

Life habits: Drawing
Feeding strategies: Drawing
Ecological Interpretations:

Tuzoia is suggested to be free-swimming animal, based mainly on the morphology of the carapace. The midposterior and posteroventral spines probably acted as a keel to provide directional stability to the animal while swimming, and the lateral ridge may have allowed directional control to improve the streamlining of the animal while preventing sinking. The reticulate pattern of the carapace is interpreted as a way of strengthening the carapace without adding so much weight that the animal would be unable to swim. Spines and the lateral ridge may also have provided protection from predation. The eyes had a wide field of vision, further suggesting that Tuzoia was a swimmer. The antennae would have been used to sense the environment, and the frontal appendages could have been used to obtain food.

References:

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

CARON, J. B,. R. R. GAINES, M. G. MÁNGANO, M. STRENG AND A. C. DALEY. 2010. A new Burgess Shale-type assemblage from the “thin” Stephen Formation of the southern Canadian Rockies. Geology, 38: 811-814.

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

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

LIEBERMAN, B. S. 2003. A new soft-bodied fauna: the Pioche Formation of Nevada. Journal of Paleontology, 77(4): 674-690.

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

PAN, K. 1975. On the discovery of Homopoda from South China. Palaeontologica Sincia, 5: 523-526.

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

ROBISON, R. A. AND B. C. RICHARDS. 1981. Larger bivalve arthropods from the Middle Cambrian of Utah. The University of Kansas Paleontological Contributions, 106: 1-28.

SHU, D. 1990. Cambrian and Lower Ordovician Bradoriida from Zhejiang, Hunan and Shaanxi Provinces. Northwest University Press, Xian.

VANNIER, J., J. B. CARON, J. YUAN, D. E. G. BRIGGS, D. COLLINS, Y. ZHAO AND M. ZHU. Tuzoia: Morphology and lifestyle of a large bivalved arthropod of the Cambrian seas. Journal of Paleontology, 81: 445-471.

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

YUAN, J. AND Y. ZHAO. 1999. Tuzoia (bivalved arthropods) from the Lower-Middle Cambrian Kaili Formation of Taijiang, Guizhou. Palaeontologica Sinica, 38, supplement: 88-93.

Other Links:

http://www.bioone.org/doi/abs/10.1666/pleo05070.1

Perspicaris dictynna

Outlines of Perspicaris dictynna (top right) and Perspicaris recondita (bottom) approximately to scale.

© MARIANNE COLLINS

Taxonomy:

Kingdom: Drawing
Phylum: Drawing
Higher Taxonomic assignment: Unranked clade (stem group arthropods)
Species name: Perspicaris dictynna
Remarks:

Perspicaris is closely related to Canadaspis, but the phylogenetic position of this group is debated, with most considering them to be phyllocarid crustaceans (Briggs, 1977; Briggs and Fortey, 1989; Wills et al. 1998). However, a basal position within the stem-lineage euarthropods has also been proposed (Budd, 2002).

Described by: Simonetta and Delle Cave
Description date: 1975
Etymology:

Perspicaris – from the Latin perspicax, “sharp-sighted,” and caris, “crab, or shrimp,” thus, a sharp-sighted shrimp.

dictynna – from Dictynna, an alternate name for the Cretan goddess Britomartis, who was caught in a fisherman’s net when she threw herself into the sea to escape the pursuit of King Minos.

Type Specimens: Holotypes –USNM189280 (P. dictynna) andUSNM114255 (P. recondita) in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: P. recondita from Walcott Quarry, Fossil Ridge.

Other deposits: ?P. dilatus and ?P. ellipsopelta from the Wheeler, Pioche, Marjum and Bloomington Formations of Utah and Nevada (Robison and Richards, 1981; Lieberman, 2003).

Age & Localities:

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

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

History of Research:

Brief history of research:

Specimens of Perspicaris were first described by Walcott (1912) as Hymenocaris and then moved to several species of Canadaspis, including C. dictynna, by Simonetta and Delle Cave (1975). A major re-examination of the material by Briggs (1977) led him to erect the new genus Perspicaris and designate the two Burgess Shale species. Perspicaris has been included in several studies of arthropod relationships (e.g. Briggs and Fortey, 1989; Wills et al. 1998; Budd, 2002).

Description:

Morphology:

Perspicaris had a bivalved carapace, with prominent eyes and an abdomen that extends beyond the carapace. The valves of the carapace were suboval with an anterior taper, and attached to each other along a straight hinge line. Immediately behind the large, oval eyes with stalks, which projected forward from the bivalved carapace, there was a pair of stout, segmented antennae. The body trunk consisted of ten thorax segments, bearing flattened appendage flaps, followed by seven abdomen segments, and a forked tail. The trace of the gut is sometimes preserved due to sediment infill. P. dictynna is distinguished from P. recondita by having a more elongated and spiny tail, with P. dictynna being smaller (maximum length 2.9 cm) than P. recondita (maximum length 6.6 cm).

Abundance:

P. dictynna and P. recondita are relatively common in the Walcott Quarry (<0.1% of the community, Caron and Jackson, 2008).

Maximum Size:
29 mm

Ecology:

Life habits: Drawing
Feeding strategies: Drawing
Ecological Interpretations:

The large eyes and flap-like appendages (with no walking branch) suggest that Perspicarisswam in the water column. The delicate antennae were likely sensory, as opposed to being used to manipulate food items. The sediment-filled gut in some specimens indicates that Perspicaris may have been a deposit feeder, but the large eyes could also indicate that it was a scavenger or even a predator.

References:

BRIGGS, D. E. G. 1977. Bivalved arthropods from the Cambrian Burgess Shale of British Columbia. Palaeontology, 20: 596-612.

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.

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

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

ROBISON, R. A. AND B. C. RICHARDS. 1981. Larger bivalve arthropods from the Middle Cambrian of Utah. The University of Kansas Paleontological Contributions, 106: 1-28.

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

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

Other Links:

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

Dalyia racemata

Sketch of Dalyia racemata.

© Marianne Collins

Taxonomy:

Kingdom: Drawing
Phylum: Drawing
Higher Taxonomic assignment: Non applicable
Species name: Dalyia racemata
Remarks:

No revisions of the affinities of this alga have been published since its original description.

Described by: Walcott
Description date: 1919
Etymology:

Dalyia from Mount Daly (3,152 m), a mountain northeast of Fossil Ridge, just at the border between British Columbia and Alberta. The name was originally given by mountaineer Professor Charles E. Fay to honour Judge Charles P. Daly (1816-1899), president of the American Geographical Society (1864-1899).

racemata – from the Latin racemus, “the stalk of a cluster,” referring to the shape of the alga.

Type Specimens: Syntypes –USNM35415-35418 (D. racemata); Holotype –USNM35414 (D. nitens) in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: Dalyia nitens Walcott 1919 from the Walcott Quarry.

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 Trilobite Beds on Mount Stephen.

History of Research:

Brief history of research:

Walcott (1919) described D. racemata and D. nitens, but the latter was based on only one specimen and may not be a separate species. The validity of this genus is also questionable and it is likely that Dalyia represents only the distal branches of Yuknessia. Walcott’s proposed affinity of Dalyia with the rhodophytes (red algae) was briefly questioned in an unpublished thesis (Satterthwait, 1976). However, the relationships of all Burgess Shale algae await thorough restudy and redescription.

Description:

Morphology:

This form is composed of a central axis, from which emerge almost perpendicular, slender, straight branching stems that terminate in whorls of short branchlets, not exceeding five in number. The surface of the stems is generally smooth, but transverse lines in some specimens give a jointed appearance, which Walcott likened to the modern rhodophyte Halurus equisetifolius. The central axes are 0.4 to 0.6 cm in diameter and the largest specimens found reach up to 4 cm in height.

Abundance:

Dalyia is very rare and represents only 0.07% of the Walcott Quarry community (Caron and Jackson, 2008).

Maximum Size:
40 mm

Ecology:

Life habits: Drawing
Feeding strategies: Drawing
Ecological Interpretations:

The mode of life of this alga is uncertain. Its rigidity suggests it was attached to the sea floor within the photic zone, rather than free floating.

References:

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

Other Links:

None