''Pambdelurion'' is an extinct genus of panarthropod from the

Cambrian The Cambrian Period ( ; sometimes symbolized Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million years ago ...

aged Sirius Passet site in northern

Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland ...

. Like the morphologically similar ''

Kerygmachela ''Kerygmachela kierkegaardi'' is a gilled lobopodian from the Cambrian Stage 3 aged Sirius Passet Lagerstätte in northern Greenland. Its anatomy strongly suggests that it, along with its relative ''Pambdelurion whittingtoni'', was a close rela ...

'' from the same locality, ''Pambdelurion'' is thought to be closely related to

arthropods Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and cuticle made of chitin, ...

, combining characteristics of " lobopodians" with those of primitive arthropods.

Description

''Pambdelurion'' was large for a Cambrian animal, and is estimated to have reached a length of . ''

Omnidens ''Omnidens amplus'', meaning "large all-tooth", is an extinct species of large Cambrian animal known only from a series of large mouth apparatus, originally mistaken as the mouthparts of anomalocaridids. When first named, it was interpreted as a ...

'', an organism from China that closely resembles ''Pambdelurion'' and may even be synonymous with it, reached even larger sizes, estimated to be based on the proportions of ''Pambdelurion''. The head of ''Pambdelurion'' bore a large pair of frontal appendages, homologous to the antennae of onychophorans and frontal appendages of radiodonts. These frontal appendages were weakly muscled and relatively soft, suggesting they may have served primarily as sensory organs, rather than for grasping prey. Between the appendages are a pair of clusters of three spines, which probably served a sensory function. Eyes have not been identified. On the ventral surface of the head was the mouth, which was an oral cone similar to that of other non-arthropod ecdysozoans. The body possessed eleven pairs of non-muscular, gill-bearing lateral flaps and eleven pairs of lobopodous legs ventral to the flaps. The body musculature was more similar to that of onychophorans than that of arthropods. The cuticle was unsclerotized. The anterior portion of the gut was a large, muscular pharynx, as in many other ecdysozoans. More posteriorly, the gut contained paired glands.

History of study

''Pambdelurion whittingtoni'' was named in 1997 by Graham E. Budd. The genus name comes from Greek ''pambdelyrion'' "all-loathsome" in reference to the fearsome appearance of the animal, and the species name honors the paleontologist

Harry B. Whittington Harry Blackmore Whittington FRS (24 March 1916 – 20 June 2010) was a British palaeontologist who made a major contribution to the study of fossils of the Burgess Shale and other Cambrian fauna. His works are largely responsible for the conce ...

Classification

''Pambdelurion'' is regarded as a member of Lobopodia, a

paraphyletic In taxonomy, a group is paraphyletic if it consists of the group's last common ancestor and most of its descendants, excluding a few monophyletic subgroups. The group is said to be paraphyletic ''with respect to'' the excluded subgroups. In ...

group of panarthropods that includes the ancestors of modern tardigrades,

onychophorans Onychophora (from grc, ονυχής, , "claws"; and , , "to carry"), commonly known as velvet worms (due to their velvety texture and somewhat wormlike appearance) or more ambiguously as peripatus (after the first described genus, '' Peripatus ...

, and

. It is more closely related to arthropods than to any other modern group, but it diverged from the arthropod lineage before the last common ancestor of all modern arthropods; as such, is a stem-group arthropod. ''Pambdelurion'' is part of a group of stem-arthropods known as the gilled lobopodians, which consists of lobopodians with gill-bearing lateral flaps and also includes ''

'' and '' Opabinia''. The gilled lobopodians are the closest relatives of the arthropods among lobopodians, and both the radiodonts and true arthropods are descended from a gilled lobopodian ancestor. ''

'', from the near-contemporaneous Maotianshan Shales of

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's List of countries and dependencies by population, most populous country, with a Population of China, population exceeding 1.4 billion, slig ...

, cannot be clearly distinguished from ''Pambdelurion'', and it is possible that they are synonymous. However, there is no evidence of gilled lobopodians like ''Pambdelurion'' in the Maotianshan Shales, so ''Omnidens'' may be the mouthparts of some other lobopodian, such as ''Megadictyon'' or ''Jianshanopodia''.

Paleobiology

''Pambdelurion'' was probably a predator, with a diet including arthropods. ''Pambdelurion'' was probably a benthic animal that lacked the ability to swim effectively.

Paleoecology

''Pambdelurion'' was one of the largest and most abundant organisms in the Sirius Passet biota.

References

Works cited

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External links

*Anomalocarid Homepag

* Palaeosbr>
Dinocarida Prehistoric arthropod genera Cambrian arthropods Sirius Passet fossils {{cambrian-animal-stub