As before, you can get three points for the best answer, two points for second-best and one point for third best. And remember, the best answer will not necessarily be the first with the most accurate identification.
Update: Identity now available here. Figure from Bardashev et al. (2002).
It's part of a good old-fashioned evolutionary tree showing the evolution of the diagnostic feature "24", which is a... ummm... crikey. When points are involved you get mean. The white bit at the top looks like some sort of a tooth. Or a tooth-comb. Is it from a fish? Or even from a vertebrate...? Help!
ReplyDeleteOK - this is a shot in the dark - but I think this might be the tooth of a gastropodan radula. Best I can do...
ReplyDeleteConodont
ReplyDeleteNeognathodus, or Gondolella perhaps, its been awhile.
ReplyDeleteI salvage a microscopic crumb of pride from the fact that it's not a vertebrate, at least.
ReplyDeleteAs Al K said: they're conodonts, so they ARE vertebrates!
ReplyDeleteSo, the figure is variation on a conodont sp. fossil within a rock strata denoted by the dots? (I am sooo grubbing for points on an organism I know nothing about :)
ReplyDeleteIt is an inferred evolutionary lineage of P-elements of some type of euconodont, possibly of the Ozarkodinid family. You can tell they are P-elements (the single pair of elements at the back of a conodont apparatus)because they have a broad palmate region with a verticle blade and denticulated structure sticking out at one end. Wether or not they are vertebrates is still a little controversial, in any case they are definately chordates (not ecdysozoans - yay!)
ReplyDeleteChordate I'm happy with, but for now I'm going to stick with the old-school concept that vertebrates possess vertebrae. If you're not happy with that (which puts you ever so slightly closer, conceptually, to the hagfish than I personally feel comfortable with...) then I'll settle for an invertebrate vertebrate, and wrestle with that paradox in my own time! Oh but the joys of discovering conodonts, which didn't even have a body last time I looked!
ReplyDeleteTotally would not have recognized that as a conodont.
ReplyDeleteTrying very hard for the points here, the elements are of the carminiplanate type which refers to the forms with the platform part of the element is compressed into a a pair of lophs, one on each side of the main blade (I'm struggling along without the most rudimentary knowledge of conodont terminology). The best match I could find was Siphonodella (family Polygnathidae) from the Carboniferous but it wasn't very convincing. That's the very best I can do without completely dropping all work duties.
ReplyDeleteI haven't forgotten this post, don't worry, but I have to delay the follow-on post for now (technical issues). Adam Yates is clearly in the lead at present!
ReplyDeleteOh, and in regard to...
ReplyDeleteChordate I'm happy with, but for now I'm going to stick with the old-school concept that vertebrates possess vertebrae.
It is quite possible that conodonts did have vertebrae, at least to the degree that lampreys have vertebrae. Definite preserved arcualia have not been identified in conodonts, but they have also not been preserved in some stem-lampreys that undoubtedly had them. The preservation potential of cartilaginous arcualia is low, even in some cases were other soft tissue has been preserved. Some authors have even suggested that conodonts may be more closely related to gnathostomes than are lampreys; this isn't a consensus, but then in this corner of phylospace there is no consensus.
Molecular data, meanwhile, continue to support a lamprey + hagfish clade to the exclusion of other craniates, which would imply that the 'non-vertebrate' features of hagfish are actually derived losses rather than retained plesiomorphies.
So I guess that's a Nul Points then. Bah! This contest is rigged. Rigged I tell you!
ReplyDeleteMind you I've had a great time discovering the genius of the Palaeos website - the conodont pages are laugh-out-loud - and I've also experienced the horror of watching slo-mo videos of a hagfish engulfing its prey. Stuff of nightmares. Brrrr.
ReplyDeleteSo - are you going to enlighten us...? and give us an ecdysozoan next, pretty please?