A fossil soft-bodied lobopodian has been found in Carboniferous strata in Illinois.
Lobopodians (“lobe-footed”) are soft-bodied worm-like animals with cylindrical legs that are well known from the Cambrian explosion. The best-known fossils were from Sweden, although members have been found in the Burgess Shale in Canada. The taxonomy of these classic Cambrian-explosion animals has been confusing; some evolutionists think they are related to modern tardigrades (water bears) or were ancestral to arthropods. Paleontologists had thought they died out in the middle Cambrian, but now, an exquisitely-preserved fossil has been found in Carboniferous rock in Illinois. This one is not related to onycophorans. Current Biology reported,1
Lobopodians, a nonmonophyletic assemblage of worm-shaped soft-bodied animals most closely related to arthropods, show two major morphotypes: long-legged and short-legged forms. The morphotype with stubby, conical legs has a long evolutionary history, from the early Cambrian through the Carboniferous, including the living onychophorans and tardigrades. Species with tubular lobopods exceeding the body diameter have been reported exclusively from the Cambrian; the three-dimensionally preserved Orstenotubulus evamuellerae from the uppermost middle Cambrian “Orsten” (Sweden) is the youngest long-legged lobopodian reported thus far. Here we describe a new long-legged lobopodian, Carbotubulus waloszeki gen. et sp. nov., from Mazon Creek, Illinois, USA (∼296 million years ago). This first post-Cambrian long-legged lobopodian extends the range of this morphotype by about 200 million years. The three-dimensionally preserved specimen differs significantly from the associated short-legged form Ilyodes inopinata, of which we also present new head details. The discovery of a Carboniferous long-legged lobopodian provides a more striking example of the long-term survival of Cambrian morphotypes than, for example, the occurrence of a Burgess Shale-type biota in the Ordovician of Morocco and dampens the effect of any major extinction of taxa at the end of the middle Cambrian….
Continue Reading on crev.info