It's called Hallucigenia because researchers have scratched their heads
over where it fits among life forms since its fossil was discovered in
the Burgess Shale of Canada's Rocky Mountains in the early 1970s...
A new study of the claws at the end of all those legs revealed... an oddity observed in at least one other place, the weird jaws of velvet worms, which, in the university's synopsis of the report, "are no more than legs modified for chewing."..
The finding is a big deal, said Javier Ortega-Hernandez, a co-author
of the study, because it turns what is known about the evolutionary tree
of arthropods -- spiders, crustaceans and insects -- on its head. "Most
gene-based studies suggest that arthropods and velvet worms are closely
related," Ortega-Hernandez said. But "our results indicate that
arthropods are actually closer to water bears," he said.
More at the
Washington Post. The full manuscript was published in
Nature.
To be fair, all arthropod jaws are also "legs modified for chewing" (I don't know about tardigrades mouthparts, though I would assume the same is true for them given no other information). Limbs, antennae, gills, and mouthparts are all appendages analogous to one another, just on different segments (the head has quite a few segments smushed together so as to be unrecognizable after early developmental stages).
ReplyDeleteThis is a very cool paper, though. They have really good support for the Tardigrade+Arthropod hypothesis on their cladogram. Original paper here: http://www.nature.com/nature/journal/vaop/ncurrent/full/nature13576.html
Thanks for the Nature link, which I've added to the post.
Delete