Paleobiota of the Burgess Shale

Crown-group arthropods (euarthropods such as trilobites) and their stem-group relatives (such as radiodonts) are extremely diverse and some species are abundant in the Burgess Shale. Along with their earlier-diverging cousins, the "Lobopodians", they provide great information on early Panarthropod evolution.

Arthropods
Genus	Phylum	Higher taxon	Abundance	Notes	Images
Opabinia	Stem-group Arthropoda	Opabiniidae	3 specimens	An opabiniid stem-group arthropod. This animal had five stalked eyes, a set of swimming trunk appendages, and a proboscis tipped with a claw-like appendage.
Anomalocaris	Stem-group Arthropoda	Radiodonta		The largest radiodont from the Burgess shale, and the ecosystems apex predator. What it ate has been somewhat controversial due to the possible softness of its oral cone (mouthpart).
Hurdia	Stem-group Arthropoda	Radiodonta	69 specimens	A hurdiid radiodont that possessed a large frontal head sclerite. This animal is known from deposits in North America.
Peytoia	Stem-group Arthropoda	Radiodonta	108 specimens	A close relative of Hurdia that was originally named as a jellyfish, but was later recognized as the oral cone of the creature. This creature is also known from European deposits.
Stanleycaris	Stem-group Arthropoda	Radiodonta	268 specimens	A basal hurdiid radiodont known from a variety of Cambrian deposits in North America. Although looking more like anomalocaridid and amplectobeluid radiodonts, it has features that more closely align it with the hurdiids.
Cambroraster	Stem-group Arthropoda	Radiodonta	Hundreds of specimens	A unique looking hurdiid that bore a distinct horseshoe shaped head sclerite. This radiodont was first described in 2019, and was named after the fictional Millennium Falcon, which its dorsal carapace resembles.
Titanokorys	Stem-group Arthropoda	Radiodonta	12 specimens	The largest hurdiid from the shale, and one of the largest Cambrian animals (up to a foot long). This radiodont was originally thought to have been a giant specimen of Cambroraster until late 2021.
Amplectobelua	Stem-group Arthropoda	Radiodonta		Radiodont distinguished by its claw-shaped frontal appendages, another species A. symbrachiata, is known from China
Caryosyntrips	Stem-group Arthropoda	Radiodonta	Only known from isolated frontal appendages	A somewhat enigmatic radiodont that was characterized by their forward facing grasping appendages.
Waptia	Arthropoda	Order Hymenocarina	2.55% of the total number of organisms	A hymenocarine that possessed a shrimp-like body and is one of the earliest known examples of parental care in the fossil record.
Canadaspis	Arthropoda	Order Hymenocarina		A hymenocarine that is thought to have been benthic feeders that moved mainly by walking and possibly used its biramous appendages to stir mud in search of food. They have been placed within the Hymenocarina, which includes other bivalved Cambrian arthropods.
Fibulacaris	Arthropoda	Order Hymenocarina		A small, odarid hymenocarine that most likely swam in an inverted position in the water column. It most likely lived as a nektonic suspension feeder.
Balhuticaris	Arthropoda	Order Hymenocarina	11 known specimens from the Marble canyon	A large hymenocarine arthropod that most likely lived a mainly nektonic lifestyle. This creature had about 110 pairs of biramous limbs, the most of any Cambrian aged arthropod.
Loricicaris	Arthropoda	Order Hymenocarina		A hymenocarine with an elongated, spined abdomen. It was found in the Kicking Horse Shale Member of the shale
Odaraia	Arthropoda	Order Hymenocarina	217 specimens	A hymenocarine arthropod that bore a large pair of eyes at the front of its body, and may have had two smaller eyes in between. It had a tubular body with at least 45 pairs of biramous limbs, and its tail had three fins – two horizontal, one vertical – which were used to stabilise the animal as it swam on its back.	framess
Pakucaris	Arthropoda	Order Hymenocarina		A hymenocarine that ranged in length from 11.65 to 26.6 millimetres (0.459 to 1.047 in). The main bivalved carapace covers around 80% of the body, with the pygidium covering the remaining 20%.
Perspicaris	Arthropoda	Order Hymenocarina		Two named species are known from the Burgess Shale; Perspicaris dictynna and Perspicaris recondita, which differ in maximum size (66 millimetres (2.6 in) in P. recondita vs 29 millimetres (1.1 in) in P. dictynna), as well as proportions of the tail.
Nereocaris	Arthropoda	Order Hymenocarina		A large hymenocarine. This genus, including both species, is diagnosed by the presence of two lateral stalked eyes and one median eye, the possession of a laterally compressed bivalved carapace with hook-like elements, and a telson with a triangular medial process and a three-segmented elongate lateral process.
Tokummia		Hymenocarina		A hymenocarine known from the Marble canyon deposits that was one of the first animals that evolved claws. The genus name Tokummia named after Tokumm Creek which runs through the Marble Canyon. The species name katalepsis means Greek word for "seizing", "gasping" or "holding".
Branchiocaris		Hymenocarina		A hymenocarine that had a pair of short segmented tapered antennules with at least 20 segments, as well as a pair of claw appendages. It was likely an active swimmer, and used the claw appendages to bring food to the mouth.
Plenocaris		Hymenocarina		This hymenocarine was originally described as a species of Yohoia by Walcott in 1912, but was placed into its own genus in 1974.
Tuzoia	Arthropoda	Hymenocarina		A genus of large hymenocarine known from Early to Middle Cambrian marine environments from what is now North America, Australia, China, Europe and Siberia. The large, domed carapace reached lengths of 180 millimetres (7.1 in), making them amongst the largest known Cambrian arthropods.
Hymenocaris	Arthropoda	Hymenocarina		A Malacostracan arthropod that somewhat resembled a shrimp.
Burgessia	Arthropoda	Unassigned	1383 specimens	Along with an uncertain placement in the arthropod family tree, Burgessia had a delicate structure below its round carapace. The largest individuals were only a little over four centimetres in length, and the smallest about half a centimetre from the front of the carapace to the tip of the rear spine.
Carnarvonia	Arthropoda	Unassigned		An arthropod of uncertain placement. Only known from a single bivalved carapace that bears veins.
Worthenella	Arthropoda	Family Kootenichelidae		An elongate arthropod of uncertain affinities, only known from a single specimen with 44 body segments with limbs.
Kootenichela	Arthropoda	Family Kootenichelidae		Kootenichela has appendages bound to the trunk are poorly sclerotised. It was approximately 4 centimetres (1.6 in) long. Most prominent are the claw-like, spinose cephalic appendages, which seem to suggest affinities with Megacheira, the "great appendage" arthropods. However, study in 2015 researchers could not confirm neither the head configuration nor the megacheiran interpretation of the anatomy. Kootenichela has been subsequently suggested to be a chimera of various arthropods such as a bivalved arthropod.
Liangshanella	Arthropoda	Bradoriida	6263 specimens	A bradoriid arthropod. 6263 specimens of Liangshanella are known from the Greater Phyllopod bed, where they are 11.9% of the community.
Marrella	Arthropoda	Marrellomorpha	over 15000 specimens	The most common organism of the Burgess Shale fauna. It was initially called the "Lace Crab" by Walcott, and was described more formally as an odd trilobite. In 1971, Whittington undertook a thorough redescription of the animal and, on the basis of its legs, gills and head appendages, concluded that it was neither a trilobite, nor a chelicerate, nor a crustacean. It carried a shield extending from its head over its gills. The brush-like appendages of its head probably swept food into its mouth. It is likely to have been an active swimmer with its swimming appendages used in a backstroke motion, with the large spines acting as stabilizers.
Skania	Arthropoda	Marrellomorpha?	a single specimen	A somewhat enigmatic arthropod that has been speculated to have belonged to the Marrellomorpha.
Primicaris	Arthropoda	Marrellomorpha?		An arthropod originally thought to have been a nektaspid, but is now considered a possible marrellomorph.
Emeraldella	Arthropoda	(unranked) Artiopoda	21 specimens	A vicissicaudatan arthropod that was aligned close to the trilobites. This creature had caudal flaps that are present on the terminal tergite, alongside an elongated spine.
Sidneyia	Arthropoda	(unranked) Artiopoda		Sidneyia was a large 13 centimeter (5.1 in) long predator of the Burgess Shale, and ate trilobites and hyolithids. It was named after Walcott's second son, Sidney.
Tegopelte	Arthropoda	(unranked) Artiopoda		A species of large (1 complete specimen was 27 cm) soft-bodied arthropod known from two specimens from the Burgess Shale. Trackways that may have been produced by this organism or a close relative are known from the Kicking Horse Shale, stratigraphically below its body fossil occurrences. It is currently classified as a concilitergan arthropod within the artiopoda.
Helmetia	Arthropoda	(unranked) Artiopoda		Another concilitergan arthropod. Fossils are both rare and poorly known; the genus was described by Walcott in 1918 and has not been reexamined, though it was briefly reviewed in the 1990s and has been included in a number of cladistic analyses. It has been lumped with the arachnomorphs. One analysis has resolved the Helmetiiida as a robust clade and the closest relatives of trilobites.
Molaria	Arthropoda	(unranked) Artiopoda	144 specimens	An artiopodan arthropod of uncertain affinity. The body of Molaria consisted of a head shield (cephalon), a trunk consisting of eight sections (tergites), and a telson, which included a short ventral spine and a long posterior spine.
Naraoia	Arthropoda	(unranked) Artiopoda		A nektaspid arthropod that belonged to the family Naraoiidae, that lived from the early Cambrian to the late Silurian period. The species are characterized by a large alimentary system and sideways oriented antennas. It reached small to average sizes (about 2-4.5 cm long).
Hanburia	Arthropoda	(unranked) Artiopoda	Four specimens	A trilobite possibly belonging to the family Dolichometopidae.
Kootenia	Arthropoda	(unranked) Artiopoda	118 specimens	A trilobite belonging to the family Dorypygidae. Its major characteristics are that of the closely related Olenoides, including medium size, a large glabella, and a medium-sized pygidium, but also a lack of the strong interpleural furrows on the pygidium that Olenoides has.
Ogygopsis	Arthropoda	(unranked) Artiopoda		A trilobite belonging to the family Dorypygidae. It is the most common fossil in the Mt. Stephen fossil beds there, but rare in other Cambrian faunas. Its major characteristics are a prominent glabella with eye ridges, lack of pleural spines, a large spineless pygidium about as long as the thorax or cephalon.	Reconstruction of Ogygopsis klotzi in the Burgess Shale
Olenoides	Arthropoda	(unranked) Artiopoda	213 specimens	Olenoides is an average size trilobite (up to 9 cm long), broadly oval in outline. Its cephalon is semi-circular. The glabella is parallel-sided, rounded at its front and almost reaches the anterior border. Narrow occular ridges curve backwards from the front of the glabella to the small, outwardly-bowed eyes. The librigenae narrow backward into straight, slender genal spines that reach as far as the third thorax segment. Thorax consists of seven segments that end in needle-like spines.
Oryctocephalus	Arthropoda	(unranked) Artiopoda	24 specimens	A trilobite belonging to the family Oryctocephalidae. This small- to medium-sized trilobite's major characteristics are prominent eye ridges, pleural spines, long genal spines, spines on the pygidium, and notably four furrows connecting pairs of pits on its glabella. Juvenile specimens have been found with only 5 or 6 thoracic segments and about one eighth of adult size, as well as about 2 mm wide.
Parkaspis	Arthropoda	(unranked) Artiopoda		A trilobite belonging to the family Zacanthoididae.
Zacanthoides	Arthropoda	(unranked) Artiopoda		A trilobite belonging to the family Zacanthoididae. It was a nektobenthic predatory carnivore. Its major characteristics are a slender exoskeleton with 9 thoracic segments, pleurae with long spines, additional spines on the axial rings, and a pygidium that is considerably smaller than its cephalon.
Ptychagnostus	Arthropoda	(unranked) Artiopoda		Several agnostid artiopods (usually considered trilobites).
Peronopsis	Arthropoda	(unranked) Artiopoda
Pagetia	Arthropoda	(unranked) Artiopoda	1022 specimens
Chancia	Arthropoda	(unranked) Artiopoda		A trilobite belonging to the family Alokistocaridae. Chancia was a particle feeder. Its major characteristics are a normal glabella but an enlarged cephalon due to a pre-glabellar field in front of the glabella, as well as developed eye ridges, medium-sized genal spines, and an extremely small pygidium.
Ehmaniella	Arthropoda	(unranked) Artiopoda	392 specimens	A trilobite. Ehmaniellas major characteristics are a wide cranidium, heavy eye ridges, longitudinal striae on the pre-glabellar area, and a small pygidium with few segments.
Elrathia	Arthropoda	(unranked) Artiopoda	1950 specimens	A genus of trilobite belonging to Ptychopariacea. E. kingii is one of the most common trilobite fossils in the USA. It is locally found in extremely high concentrations within the Wheeler Formation in the U.S. state of Utah. E. kingii has been considered the most recognizable trilobite. Commercial quarries extract E. kingii in prolific numbers, with just one commercial collector estimating 1.5 million specimens extracted in a 20-year career.
Elrathina				A genus of trilobite belonging to Ptychopariacea.
Spencella	Arthropoda	(unranked) Artiopoda		A trilobite belonging to the family Ptychopariidae.
Habelia	Arthropoda	Chelicerata	54 specimens	While previously enigmatic, a 2017 redescription found that Habelia formed a clade (Habeliida) with Sanctacaris, Utahcaris, Wisangocaris and Messorocaris as a stem-group to Chelicerata. Habelia is thought to have been durophagous, feeding on hard shelled organisms.
Sanctacaris	Arthropoda	Chelicerata		A member of the clade Habeliida, related to chelicerates. Sanctacaris was only first described in 1981. It possessed a large flat tail, suggesting it was a good swimmer, a group of six appendages in each side of its body, and a very streamlined head.
Mollisonia	Arthropoda	Chelicerata	21 specimens	An extinct genus of Cambrian arthropod. An observation published in 2019 suggests this genus is a basal chelicerate, closer to crown group Chelicerata than members of Habeliida.
Thelxiope	Arthropoda	stem-groupChelicerate		A relative of Mollisonia that possessed a long spine that protruded out of its posterior.
Leanchoilia	Arthropoda	Megacheira	55 specimens	A megacheiran arthropod. Leanchoilia is distinguished from other arthropods by its arms. They split into three appendages, probably to find food, as they lack the spiny characteristic of predators.
Yohoia	Arthropoda	Megacheira	711 specimens	Yohoia was a streamlined megacheiran that had around 20 segments. It has been compared to modern mantis shrimp, where It had two four-fingered hands, and may have preyed on trilobites, smashing or spearing them with its fingers.
Actaeus	Arthropoda	Megacheira	A single specimen	A megacheiran arthropod containing the single species Actaeus armatus. It is known from a single specimen recovered from the Burgess Shale, and it may be poorly preserved specimen of Alalcomenaeus.[2] The specimen is over 6 cm long and has a body consisting of a head shield, 11 body tergites, and a terminal plate.
Alalcomenaeus	Arthropoda	Megacheira	300 specimens	One of the most widespread and longest-surviving arthropod genera of the Early and Middle Cambrian. Its large eyes and the long flagella on its great appendages, combined with its large feeding apparatus and the spines on its inner limb branches, are more consistent with a predatory lifestyle, and the most recent interpretation has it feeding on organisms that lived on or in the surface of the sea floor.
Yawunik	Arthropoda	Megacheira		Yawunik is named after a primordial sea monster in Ktunaxa mythology. Compared to Leanchoilia, it beard teeth on great appendages, which suggest that have enhanced its ability to grasp prey.
Isoxys	Arthropoda	Family Isoxyidae		A basal bivalved arthropod, member of the family Isoxyidae. It had a pair of large spherical eyes (which are the most commonly preserved feature of the soft-bodied anatomy), and two large appendages It is possible that these appendages are homologous to the great appendages of radiodonts and megacheirans.
Surusicaris	Arthropoda	Family Isoxyidae	A single specimen	A close relative of Isoxys from the Burgess shale. The only known specimen (ROM 62976), has a roughly semicircular bivalved carapace, which is approximately 1.49 centimetres (0.59 in) long and 0.89 centimetres (0.35 in) tall. The head has a pair of rounded eyes, and a pair of upward-curling segmented frontal appendages with at least five segments, the second, third and fourth of which bear a spine, with three long spines and at least one short spine on the fifth and terminal segment. It alongside Isoxys are considered basal stem-group arthropods.
Sarotrocercus	Arthropoda	Not applicable	7 specimens	An arthropod of uncertain affinities. In the original description, Sarotrocercus had been interpreted as a pelagic, nektonic animal that swam freely on its back, moving perhaps through movements of the trunk appendages and the action of its long tail tuft. However, based on the redescription by Haug et al. 2011, Sarotrocercus may had been benthic or at least swimming close to the seafloor, as the robust head appendages rather suggest a grasping or raking function.

Lobopodians, a grouping of worm-like panarthropods from which arthropods arose, were present in the shale.

Lobopodians
Genus	Higher Taxa	Abundance	Notes	Images
Hallucigenia	Hallucigeniidae	109 specimens	A spined lobopodian. This creature is one of the more iconic taxa from the shale. The generic name reflects the type species' unusual appearance and eccentric history of study; when it was erected as a genus, H. sparsa was reconstructed as an enigmatic animal upside down and back to front. Hallucigenia was later recognized as a lobopodian, a grade of Paleozoic panarthropods from which the velvet worms, water bears, and arthropods arose.
Aysheaia	Protonychophora	20 specimens	Aysheaia has ten body segments, each of which has a pair of spiked, annulate legs. The animal is segmented, and looks somewhat like a bloated caterpillar with a few spines added on — including six finger-like projections around the mouth and two grasping legs on the "head". Each leg has a subterminal row of about six curved claws. No jaw apparatus is evident. A pair of legs marks the posterior end of the body, unlike in onychophorans where the anus projects posteriad; this may be an adaptation to the terrestrial habit.
Ovatiovermis	Luolishaniidae		A suspension-feeding lobopodian. Ovatiovermis had nine pairs of lobopods. The first two pairs were elongate and had approximately 20 pairs of spines on each lobopod, with a bifid claw at each tip. The third to sixth pairs of lobopods were shorter and their paired spines were much smaller. On these four pairs of lobopods the spines were only large near the tip. The last three pairs of lobopods did not have the paired spines, showing that these spines were used for filter-feeding.
Collinsovermis	Luolishaniidae		A luolishaniid. Heavily armored, it was probably a suspension feeder. It was originally nicknamed the "Collins Monster". It was a tiny worm-like soft bodied animal measuring about 3 cm long with multiple pairs of stump legs called lobopods. It bears 14 pairs of lobopods, which are closely attached to the main body unlike in other lobopodians. The anterior six pairs are unusual in that they are much longer than the posterior pairs or typical lobopod.

Sponges (Porifera) were extremely diverse in the shale, with many of them belonging to the class Demospongiae.[1][3]

Porifera
Genus	Class	Abundance	Notes	Images
Capsospongia	Demospongiae	3 specimens	A middle Cambrian sponge genus known from 3 specimens in the Burgess shale. It has a narrow base, and consists of bulging rings which get wider further up the sponge, resulting in a conical shape. Its open top was presumably used to expel water that had passed through the sponge cells and been filtered for nutrients.
Choia	Demospongiae	127 specimens	A genus of demosponge ranging from the Cambrian until the Lower Ordovician periods. Fossils of Choia have been found in the Burgess Shale in British Columbia; the Maotianshan shales of China; the Wheeler Shale in Utah; and the Lower Ordovician Fezouata formation. It was first described in 1920 by Charles Doolittle Walcott.
Crumillospongia	Demospongiae	49 specimens	A genus of middle Cambrian sponges known from the Burgess Shale and other localities from the Lower and Middle Cambrian. Its name is derived from the Latin crumilla ("money purse") and spongia ("sponge"), a reflection of its similarity to a small leathery money purse.
Diagoniella	Hexactinellida	128 specimens of	A genus of sponge known from the Burgess Shale. This sponge formed a conical shape, with a diagonally arranged skeleton.
Eiffelia	Stem-group Hexactinellida	60 specimens	A genus of sponges known from the Burgess Shale as well as several Early Cambrian small shelly fossil deposits. It is named after Eiffel Peak, which was itself named after the Eiffel Tower. It was first described in 1920 by Charles Doolittle Walcott. It belongs in the Hexactinellid stem group. Eiffelia generally have star-shaped six-rayed spicules, with rays diverging at 60°, occasionally with a seventh ray perpendicular to the other six.
Eiffelospongia	Stem-group Hexactinellida		A genus of sponge known from the Mount Stephen Trilobite Beds. It had a small ovoid shape, with a hairy-like root tuft.
Falospongia	Demospongiae	5 specimens	A genus of sponge made up of radiating fronds, known from the Burgess Shale. Irived from the Latin fala ("scaffold") and spongia ("sponge"), referring to the open framework of the skeleton. It superficially resembles Haplistion but is monaxial.
Fieldospongia	Demospongiae	5 specimens	A genus of demosponge. Described in 1920 as Tuponia bellilineata by Walcott in his monograph on sponges from the Burgess Shale. The only known specimen purportedly came from the Mount Whyte Formation.
Halichondrites	Demospongiae	7 specimens	A genus of sea sponge. It had an elongated, cone-like structure, with long spicules.
Hamptonia	Demospongiae	48 specimens	A genus of sea sponge. It is known from the Middle Cambrian Burgess Shale and the Lower Ordovician Fezouata formation. It was first described in 1920 by Charles Walcott.
Hamptoniella	Demospongiae		A three dimensional sponge that was filled with many canals.
Hazelia	Demospongiae		A genus of spicular demosponge known from the Burgess Shale, the Marjum formation of Utah, and possibly Chengjiang. It was described by Charles Walcott in 1920. Its tracts are mainly radial and anastomose to form an irregular skeleton. Its oxeas form a fine net in the skin of the sponge. It is one of the more common sponges of the shale.
Leptomitella			A genus of demosponge.
Leptomitus	Demospongiae	138 specimens	A genus of demosponge known from the Burgess Shale. Its name is derived from the Greek lept ("slender") and mitos ("thread"), referring to the overall shape of the sponge.
Petaloptyon	Hexactinellida	A few specimens	A goblet-shaped hexactinellid sponge known from rare fragments from the Burgess Shale. The fragments show the living animal had a stalk, and had panels with a lattice pattern.
Pirania	Demospongiae	198 specimens	A genus of sea sponge known from the Burgess Shale and the Fezouata formation. It is named after Mount St. Piran, a mountain situated in the Bow River Valley in Banff National Park, Alberta. It was first described in 1920 by Charles Walcott.
Protoprisma	Demospongiae		This creature was a glass sponge that had long, prismatic branches.
Protospongia	Hexactinellida	102 specimens	A genus of hexactinellid sponge. Many other sponges from Ordovician and Devonian deposits are placed in this genus due to the architecture of their spicules resembling that of Protospongia.
Stephenospongia	Hexactinellida	1 specimen	A genus of sponge known from a single specimen in the Trilobite beds of the Burgess Shale. Its body had numerous conspicuous holes.
Takakkawia	Demospongiae	1377 specimens	A genus of sponge in the order Protomonaxonida and the family Takakkawiidae. It reached around 4 cm in height, and its structure consisted of four columns of multi-rayed, organic spicules (perhaps originally calcareous or siliceous) that align to form flanges. The spicules form blade-like structures, ornamented with concentric rings. It was named after Takakkaw Falls, which marks the start of the trail to Fossil Ridge.
Ulospongiella	Demospongiae		A genus of sponge known only from the Burgess Shale deposit. It contains only one species, Ulospongiella ancyla. The generic name is derived from the Greek words oulus ("wooly" or "curly") and spongia ("sponge"), referring to the curled or curved spicules forming the skeleton. The specific name, ancyla, is from the Greek ankylos ("bent" or "hooked"), also referring to the curved spicules.
Vauxia	Demospongiae		A genus of demosponge that had a distinctive branching mode of growth. Vauxia had a skeleton of spongin (flexible organic material) common to modern day sponges. Much like Choia and other sponges, Vauxia fed by extracting nutrients from the water. Vauxia is named after Mount Vaux, a mountain in Yoho National Park.
Wapkia	Demospongiae	32 specimens	A genus of sea sponge with radial sclerites, known from the Burgess Shale. It was first described in 1920 by Charles Walcott.

Ctenophores, also known as comb jellies, are rare in the shale, but three genera are known from the site.[4][5]

Ctenophora
Genus	Abundance	Notes	Images
Ctenorhabdotus	5 specimens	This ctenophore had rows of cilia to help it swim in the water column. It had around 24 comb rows on its body, around three times as more than extant comb jellies.
Fasciculus		This stem-group ctenophore lived around 515 to 505 million years ago. It had two rows of long and short comb rows, a feature not seen in the fossil record or among modern species.
Xanioascus		This ctenophore had 24 comb rows - in contrast to all modern forms which have only 8, and was described in 1996 by Simon Conway Morris.

Many of the Hemichordates from the shale have either remained enigmatic, or were once classified under other groupings.[6][7]

Hemichordata
Genus	Class	Abundance	Notes	Images
Chaunograptus	Graptolithina?	11 specimens	This enigmatic hemichordate has been interpreted as a possible graptolite.
Gyaltsenglossus		33 specimens	A hemichordate.
Oesia	incertae sedis	1147 specimens	This common, enigmatic worm-like organism has been interpreted as either a chaetognath, or some kind of hemichordate. Some fossils have been found in Margaretia, which is a mysterious fossil that has been found to possibly represent some kind of organic tube that this hemichordate used as a nest.
Yuknessia	Pterobranchia	23 specimens	This colonial pterobranch (a grouping of filter feeding hemichordates that live in tubes on the ocean floor) was originally interpreted as a green algae.
Dalyia	Pterobranchia?	37 specimens	A possible pterobranch.
Spartobranchus			An acorn worm. It is similar to the modern representatives of the family Harrimaniidae, distinguished by branching fiber tubes. It is a believed predecessor of Pterobranchia, but this species is intermediate between these two classes. Studies show that these tubes were lost in the line leading to modern acorn worm, but remained in the graptolites.

A number of different Annelid worms are known from the shale.[8][9]

Annelids
Genus	Phylum	Class	Abundance	Notes	Images
Burgessochaeta	Annelida	Polychaeta	189 specimens	A bristle worm that used tentacles to feel for food. It had 24 segments, each carrying a pair of appendages used for propulsion. is thought to have been a decomposer or scavenger on organic material. Specimens have been found from both continental slope and deep-water environments, indicating that this was a widespread animal.
Canadia	Annelida	Polychaeta	28 specimens	A genus of annelid worm. The animal's most notable feature is the many notosetae (rigid setae extending from dorsal branches of notopodia) along the back of the animal that are characteristic of polychaete worms. It would have had the ability to creep along the seafloor using the ventral counterpart of the notopodia, which are termed neuropodia.
Insolicorypha	Annelida	Polychaeta		a genus of polychaetes known from the Burgess Shale. A single specimen of Insolicorypha is known from the Greater Phyllopod bed. This creature is the rarest polychaete from the shale.
Peronochaeta	Annelida	Polychaeta	19 specimens	a genus of annelid. 19 specimens of Peronochaeta are known from the Greater Phyllopod bed, where they constitute < 0.1% of the community.
Stephenoscolex	Annelida	Polychaeta	150 specimens	A slender bristle worm that was covered in a large number of tiny bristles. Stephenoscolex contributes 0.29% of the total faunal community.
Kootenayscolex	Annelida	non-applicable	Over 500 specimens	An annelid worm. It appears to have been an aquatic worm with about 56 bristles on each of up to 25 segments, serving to propel it through mud or water.
Ursactis	Annelida	non-applicable	Over 580 specimens	An annelid worm.

Various stem-group priapulids are known from the Burgess Shale.

Priapulids
Genus	Phylum	Class	Abundance	Notes	Images
Ancalagon	Priapulida (?)	Archaeopriapulida	2 specimens	An extinct priapulid worm. This worm averaged around 6 centimeters in length. Its proboscis was armed with circum-oral hooks at the anterior. There were about 10 of these hooks, with all of them being equal in size.
Fieldia	Priapulida (?)	Archaeopriapulida	18 specimens	This priapulid was originally interpreted as an arthropod; its trunk bears a dense covering of spines. It most likely fed on sea-floor mud, evidenced by the frequent presence of sediments preserved in its gut.
Louisella	Priapulida (?)	Archaeopriapulida	48 specimens	A genus of priapulid worm. It was originally described by Charles Walcott in 1911 as a holothurian echinoderm. It's also been interpreted as an annelid and a sipunculan, (neither on particularly compelling grounds) and a pripaulid.
Ottoia	Priapulida (?)	Archaeopriapulida	At least 1000 specimens	This priapulid is the most common worm of the Burgess shale. Ottoia was a burrower that hunted prey with its eversible proboscis. It also appears to have scavenged on dead organisms.
Scolecofurca	Priapulida (?)	Stem-group	1 specimen	The only known species in the genus, Scolecofurca rara was first described by Conway Morris in 1977 as a possible primitive priapulid, but later shown to belong to the priapulid stem group. Scolecofura's single fossil specimen is 6.5 centimeters in length. The fossil displays a proboscis, which bore two 3 millimeter tentacles at the anterior. The tentacles most likely would have functioned for sensory purposes rather than for feeding.
Selkirkia	Priapulida (?)	Archaeopriapulida	142 specimens	A genus of predatory, tubicolous priapulid worm. Many burrows of this worm have been found in the shale, but many of them (up to 80%) have been found empty without the worms in them.

The molluscs of the Burgess shale are diverse in body shapes, the ecological niches they filled, and their enigmatic qualities.[10]

Mollusca
Genus	Phylum	Class	Abundance	Notes	Images
Odontogriphus	Mollusca (?)		221 specimens	A bilaterian animal that had a flat, oval shaped body. This creature possessed a rasping tongue covered in multiple rows of teeth. Due to this feature resembling a radula, this creature is thought to represent a basal mollusk.
Oikozetetes	Animalia	incertae sedis		An enigmatic shelled fossil that is possibly thought to represent a halkieriid, which have been considered early mollusks.
Orthrozanclus	Mollusca			A two centimeter sized mollusk that was covered in a wide array of spines. This creature's name means "Dawn scythe". While this animal's placement is somewhat controversial, it has been aligned with the halkieriids.
Scenella	Mollusca	Superfamily Scenelloidea	1206 specimens	A disk shaped mollusk that is somewhat enigmatic, and has been placed in a number of different groups (Gastropoda, Helcionelloida, or Monoplacophora). This mollusk is common in the shale, where they are often found in dense clusters.
Wiwaxia	Mollusca?		464 complete specimens	This animal possessed a set of carbonaceous scales and spines that protected it from predators. It resembled Orthrozanclus in appearance, but its placement in mollusca is still debated.

Many of the brachiopods from the site are members of the class Lingulata.[8][11]

Brachiopoda
Genus	Class	Abundance	Notes	Images
Acanthotretella	Lingulata	0.05% of the entire fauna	Acanthotretella was a brachiopod of the class Lingulata. Most of the specimens of the genus were found within Walcott quarry, but it is one of the more rare brachiopods found in the site with it accounting for only 0.05% of the entire fauna. It reached a maximum size of around 8 mm in length. Like most brachiopods, it was a suspension feeder, but uniquely it attached itself to the seabed with a long pedicle.
Acrothyra	Lingulata	253 specimens	A species of gregarious brachiopod. It was originally described by Walcott in 1924. It had a short pedicle, and most likely lived in groups with one another and fliter fed with their lophophores.
Diraphora	Rhynchonellata	664 specimens	An early rhynchonellatid brachiopod that had rigid appearance to its shell.
Dictyonina	Paterinata		A brachiopod belonging to the extinct order Paterinida.
Lingulella	Lingulata	346 specimens	A genus of phosphatic-shelled brachiopod. It is known from the Burgess Shale to the Upper Ordovician Bromide Formation in North America. Some specimens of the brachiopod preserve the pedicle intact, which is normally rare in the fossil record. This brachiopod is thought to have been a generalist, as it appears consistently common throughout the strata of the Burgess Shale.
Linnarssonia	Lingulata		A brachiopod belonging to the family Acrotretidae.
Micromitra	Paterinata	160 specimens	This genus is the most ornamented of the Burgess Shale brachiopods. This creature reached a size of around 10 mm in length. Many specimens of Micromitra have been found attached to the sponge Pirania, suggesting an epibenthic lifestyle for this brachiopod. This creature had a large amount of bristles (setae) that extended far beyond the rim of the shell.
Nisusia	Kutorginata	133 specimens	An early rhynchonelliform brachiopod. Nisusias pedicle emerged from between its valves, as displayed by silicified material of N. sulcate, though it still has an opening at the apex of the pedicle valve.
Paterina	Paterinata	18 specimens	A brachiopod that shows prominent growth lines on its fossils. They are very rare in the Phyllopod bed, with it only making up 0.03% of the community.

A wide variety of cnidarians like scyphozoans and conulariids are known from this site.[12][4]

Cnidaria
Genus	Class	Abundance	Notes	Images
Byronia	Scyphozoa?(Order Byroniida)		Byronia is thought to represent the polyp stage of a scyphozoan cnidarian that built narrow, chitinous tubes (theca) that were attached to the substrate by a disc. How this animal fed is unknown, but compared to other coexisting genera like Cambrorhytium, it is thought to have been a carnivore or a suspension feeder. It is thought to be closely related to coronatid scyphozoans. It was first described back in 1899.
Cambrorhytium	Staurozoa	350 specimens	An enigmatic animal that was first described in 1908, and has been classified under a number of different groups. Currently it is thought to possibly represent a staurozoan cnidarian, more specifically a conulariid. It has also been interpreted as a cnidarian polyp of some description. The other possible affinity is with the hyolithid lophophorates.
Mackenzia	Actiniaria	14 specimens	An elongated bag-like animal. It has been found attached directly to hard surfaces, such as brachiopod shells. Mackenzia is thought to be a cnidarian and appears most similar to modern sea anemones. Mackenzia was originally described by Charles Walcott in 1911 as a holothurian echinoderm.
Burgessomedusa			A free swimming medusa, likely either a stem group to Cubozoa or Acraspeda (the clade containing Staurozoa, Cubozoa and Scyphozoa).[13]
Sphenothallus sp.	Staurozoa		A problematic genus lately attributed to the holdfasts of conulariids. It was very widespread in paleozoic environments, and has been found attached to other fossils. Sphenothallus is represented in the Mount Stephen trilobite beds (which are a part of the Burgess Shale), where it co-occurs with the coexisting organisms Cambrorhythium and Byronia.
Thaumaptilon	incertae sedis		Thaumaptilon is a genus of feather shaped animal from the shale which some authors have compared to members of the Ediacaran biota, which went extinct long before the Burgess shale was deposited. More specifically, it has been compared to the Ediacaran organism Charnia. It got up to 20 cm long, and attached itself to the sea floor with a holdfast. One side of its surface was covered in spots, which might have been zooids.
Tubulella	stem-group		A stem-group cnidarian that lived in a slender, conical tube. This creature was most likely related to scyphozoans.

The echinoderms of the shale represent extinct groups distantly related to extant groups.[4]

Echinodermata
Genus	Class	Abundance	Notes	Images
Gogia	Eocrinoidea	Six specimens	This echinoderm was a primitive member of the eocrinoid group (which despite the name weren't closely related to crinoids). This creature had a plated body that formed a "bowling pin" shape.
Lyracystis	Eocrinoidea		This echinoderm was another eocrinoid, and a close relative of Gogia. This creatures arms formed a shape similar to a lyre.
Walcottidiscus	Edrioasteroidea	16 specimens	This echinoderm is one of the earliest confirmed members of the edrioasteroidea, a grouping of pentagonally shaped echinoderms.

Chordates are very rare in the shale, but the two that are known are possibly being very important in the study of these creatures earlier evolution.[14]

Chordata
Genus	Abundance	Notes	Images
Metaspriggina	around 100 specimens mainly from Marble canyon[15]	A genus of animal that is considered to represent a primitive chordate, possibly transitional between cephalochordates and the earliest vertebrates, albeit this has been questioned because it seems to possess most of the characteristics attributed to craniates. It lacked fins and it had a weakly developed cranium, but it did possess two well-developed upward-facing eyes with nostrils behind them.
Pikaia		A basal chordate described in 1911 by Walcott as an annelid worm, and in 1979 by Harry B. Whittington and Simon Conway Morris as a chordate. It became the "most famous early chordate fossil." Probably descended from an even earlier chordate based on fossil material from China, Pikaia swam through the Cambrian oceans like a modern fish. Originally thought to be the most primitive chordate, it had two lobe-like appendages on its head unlike vertebrates.

An extinct group of sponge-like animals covered in hollow spines

Incertae sedis
Genus	Phylum	Class	Abundance	Notes	Images
Chancelloria	non-applicable	Chancelloriidae	178 specimens	Superficially, this animal resembles a sea sponge, covered in spine-like sclerites. However it is a member of the extinct group Chancelloriidae, whose relationhip to other animals are unclear.
Archiasterella	non-applicable	Chancelloriidae		A genus of chancellorid known from the Burgess Shale and earlier deposits, and originally described as Chancelloria by Walcott. The species may represent form taxa rather than true species.
Allonnia	non-applicable	Chancelloriidae		A genus of chancelloriid.

Cyanobacteria are photosynthesizers, and would have been important in the shale.[16][17]

Cyanobacteria
Genus	Phylum	Class	Abundance	Notes	Images
Marpolia	Nostocales	non-applicable	40 specimens	This genus has been interpreted as a cyanobacterium, but also resembles the modern cladophoran green algae. It is known from the Middle Cambrian Burgess shale and Early Cambrian deposits from the Czech Republic. It consists of a dense mass of entangled, twisted filaments. It may have been free-floating or grown on other objects, although there is no evidence of attachment structures.
Morania	Cyanobacteria	Cyanophyceae	2580 specimens	A genus of cyanobacterium preserved as carbonaceous films. it is present throughout the shale, with thousands of specimens being known. It formed filamentous sheets, and resembles the modern cyanobacterium Nostoc. It would have had a role in binding the sediment together, and would have been a food source for such organisms as Odontogriphus and Wiwaxia.

Red algae are found in the shale, with three genera being known.[18][4]

This section documents organisms from the shale whose taxonomic affinities are not fully understood,[19][20] or who do not fit into any of the above groups.

Incertae sedis
Genus	Phylum	Class	Abundance	Notes	Images
Banffia	Vetulicolia	Heteromorphida	hundreds of fossils	This bizarre deuterostome animal was a member of the Vetulicolia, whose placement in the tree of life has remained controversial.
Dinomischus	non-applicable	non-applicable	13 specimens	This cup shaped creature has been in the center of debate since its description in 1977. It sat on the ocean floor with a long stalk, and a small holdfast and was a filter feeder. Recent studies have suggested that it is likely stem-group ctenophoran.[21]
Echmatocrinus	Animalia	non-applicable	5 specimens	This animal resembles a crinoid or an octocoral in appearance. It had a crown of seven-nine tentacles. This organism lived a solitary lifestyle, although juveniles are sometimes attached to (or budding from) adults.
Eldonia	Deuterostoma	Unranked Cambroernida	224 specimens	A soft bodied, disk shaped animal. Currently it is thought to have been a cambroernid, but that groups taxonomic relationships have not been resolved yet.
Herpetogaster	Deuterostoma	Unranked Cambroernida	6 specimens	A genus of cambroernid animal. It is most likely to have fed by snaring either small prey or edible particles in the tentacles and bringing the tentacles to the mouth. This animal secured itself to hard surfaces by using an extensible stolon that emerged from the body at about the ninth segment and secured the animal. It is often found secured to the sponge Vauxia.
Nectocaris	Lophotrochozoa (?)	Family Nectocarididae	Mainly rare, mostly found in the Collins Quarry	A squid like-predator that is rare in the shale. Has been controversially suggested to be a cephalopod, but this is rejected by most scholars. This animal had a kite shaped body, and a single pair of tentacles. It was originally considered some kind of arthropod hence its name meaning (Swimming shrimp).
Pollingeria	Animalia	non-applicable	3080 specimens	This problematic genus is worm-like in appearance, and is long and thin. Originally it was thought that these fossils represented the chaetae of polychaete worms. More recently, it has been assumed that each individual "chip" represents an entire organism. In the photo, Panels 7, 8 and 9 depict Pollingeria.
Portalia	Animalia	non-applicable		This creature is one of the many Burgess shale organisms that Walcott interpreted as a sea cucumber. More recently it has been suggested to have been a sponge.
Scathascolex	Animalia	Palaeoscolecida		A priapulid-like palaeoscolecid worm
Priscansermarinus	Animalia	non-applicable Arthropoda?		This enigmatic creature was first interpreted as a lepadomorph barnacle. This would push back the origins of this crustacean group by another 200 or so million years. Recently its status as a barnacle, or even an arthropod in general has been questioned.
Siphusauctum	Animalia	non-applicable		An enigmatic filter feeding animal. It lived by attaching itself to the substrate by a holdfast, it had a tulip-shaped body, called a calyx, into which it actively pumped water that entered through pores and filtered out and digested organic contents. It grew to a length of only about 20 cm (7.9 in). Recent studies have suggested it to be a stem-group ctenophore.
Haplophrentis	Lophotrochozoa	Hyolithia	186 specimens	Haplophrentis was a hyolith, a grouping of strange, conical shelled invertebrates that lived throughout the Paleozoic. This animal was a filter feeder, using its lophophore to extract organic matter from passing seawater. The soft bodied fossils of this genus were important in establishing hyoliths as possible members of the lophophorata alongside brachiopods and bryozoans.
Fuxianospira				A filamentous fossil considered either to represent an alga or a coprolite.
Tontoia	Unknown	Unknown		Initially suggested to represent an external mould of an arthropod exoskeleton, but it currently considered a nomen dubium, and it is unclear as to whether it is even an arthropod at all.