North Greenland's Sirius Passet site, which dates back to the Cambrian period, is home to the extinct panarthropod genus Pambdelurion. Pambdelurion, like the morphologically similar Kerygmachela from the same site, is believed to be closely linked to arthropods, sharing traits with primitive arthropods and "lobopodians" in particular.
Description
Pambdelurion is thought to have reached a length of 55 centimeters (22 in), making it a huge animal for a Cambrian-age animal. Omnidens, a creature from China that strongly resembles Pambdelurion and may perhaps be identical with it, reached much bigger sizes, estimated to be 1.5 meters (4.9 ft) based on the proportions of Pambdelurion. Similar to the antennae of onychophorans and frontal appendages of radiodonts, the head of Pambdelurion included a sizable pair of frontal appendages. The fact that these frontal appendages were comparatively soft and had weak muscles suggests that their primary function may have been as sensing organs rather than for catching prey. There are two clusters of three spines located between the appendages, which most likely had a sensory purpose. No name has been given to the eyes. The mouth was an oral cone on the ventral side of the head, resembling the oral cones of other non-arthropod ecdysozoans. Eleven pairs of lobopodous legs were located ventral to the non-muscular, gill-bearing lateral flaps on the body. The musculature of the body was more akin to that of onychophorans than arthropods. There was an unsclerotized cuticle. Like many other ecdysozoans, it had a wide, muscular pharynx as the front region of its stomach. There were paired glands in the intestines located farther behind.
History of Study
Graham E. Budd gave Pambdelurion Whittingtoni its name in 1997. Given the animal's terrifying look, the genus name, Pambdelurion, means "all-loathsome" in Greek. The specific name, Harry B. Whittington, is in honor of the paleontologist. The holotype is MGUH 24508.
Classification
Being the progenitors of current tardigrades, onychophorans, and arthropods, Pambdelurion is considered a member of Lobopodia, a paraphyletic group of panarthropods. It is more closely linked to other current groups than to arthropods, yet it is a stem-group arthropod since it split off from the arthropod lineage before the last common ancestor of all modern arthropods. Pambdelurion belongs to a class of stem-arthropods called the gilled lobopodians, which also includes Kerygmachela and Opabinia. These lobopodians have lateral flaps that carry gills. The radiodonts and real arthropods are both descended from a gilled lobopodian ancestor, and the gilled lobopodians are the closest lobopodians cousins to the arthropods. The Chinese Maotianshan Shales are home to Omnidens, which is difficult to differentiate from Pambdelurion; in fact, the two may be interchangeable. But since the Maotianshan Shales do not appear to include any gilled lobopodians like Pambdelurion, Omnidens could perhaps represent the mouthparts of another lobopodian, such Megadictyon or Jianshanopodia.
Paleobiology
It is likely that Pambdelurion was a predator that consumed arthropods. Pambdelurion was most likely a benthic organism with poor swimming prowess.
Paleoecology
Among the biggest and most prevalent creatures in the Sirius Passet biota was the Pambdelurion.
Reconstruction of Pambdelurion by Junnn11.
Sources[1]