Collinsovermis

Collinsovermis was discovered in 1983 by Desmond H. Collins, curator of invertebrate palaeontology at the Royal Ontario Museum, from an expedition at Mount Stephen at the Yoho National Park, British Columbia, Canada.[3] It was found among the Burgess Shale that belonged to the middle Cambrian period called Wuliuan, which is around 509 to 505 million years ago. In 1985, Collins presented the discovery before the Geological Society of America, and published the next year in a popular magazine Rotunda in an article "Paradise revisited." Avoiding the scientific nomenclature and systematic description, he referred to it as a "spiny animal with hairy legs."[4]

Diagram

Collinsovermis is 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,[3] and they are attached with fine curved spinules in about 20 pairs arranged in a V (chevron)-shaped stripe. These limbs are also covered in fine setae, and end with a terminal claw. The eight posterior lobopods are stout and smooth, and each with a terminal curved claw. There are pairs of spines matching to each pair of lobopods (on each body segment or somite) on its back, which were likely served a defensive function. The spines are larger at the middle region of the body and taper towards both ends.[2]

The general body appearance resembles that of Luolishania longicruris (discovered in 1989 in China[7]), which is but smaller and with more posterior lobopods.[8] The head is rounded, small, covered with sclerite (exoskeleton) and has a mouth at its front.[2] Such external body sclerites are also present L. longicruris[8] but absent in other closely related luolishaniid lobopods such as Collinsium (discovered in 2015 from China,[9] popularly known as "Hairy Collins's monster"[10][11]) and Acinocricus (discovered in 1988 from Utah, US[12]). The head also bears a pair of antennae-like projections.[2] Collinsovermis is regarded as characteristically most closely related to Acinocricus, with the major differences being large size (up to 10 cm long), five pairs of anterior legs, absence of sclerites and presence of numerous rows of back spines in the latter.[13][14][2]

Like other "luolishaniid" lobopodians, Collinsovermis is thought to have been a sessile suspension feeder, using the posterior pairs of limbs to anchor itself to a substrate, while using its spinose anterior appendages to catch small food particles.[2]