Id this extinct South American hoofed critter

[Earl_Snake-Hips_Tucker]

@Lemur866

Essentially, all of these groups were probably already distinct back in the Cretaceous, but gross morphologically they weren’t that different from each other–they were all little mousy-shrewy thingies. Some of those mousy-shrewies were the ancestors of artiodactyls, but the artiodactyl ancestors didn’t particularly look artiodactyly.

And thanks for these comments. I hadn’t actually thought of itthat way, that the various mammal “lines” had already diverged in the Cretaceous, but, being that were still underfoot to the big lizards, that they weren’t nearly as morphologically dissimilar to each other as their descendants today, and in most cases not even remotely similar to their descendants.

[Darwin_s_Finch]

@Polycarp

Aside from the fact that stegosaurs survived in India well into the Cretaceous while going extinct everywhere else, I don’t know of any unique Indian forms.

If you are referring to Dravidosaurus, the extremely fragmentary material upon which it was based was found to instead be a form of pliosaur, back in 1996. There are currently no definitively known Late Cretaceous stegosaurs.

[Lemur866]

@Darwin_s_Finch

If you are referring to Dravidosaurus, the extremely fragmentary material upon which it was based was found to instead be a form of pliosaur, back in 1996. There are currently no definitively known Late Cretaceous stegosaurs.

[Polycarp]

@Darwin_s_Finch

If you are referring to Dravidosaurus, the extremely fragmentary material upon which it was based was found to instead be a form of pliosaur, back in 1996. There are currently no definitively known Late Cretaceous stegosaurs.

That’s exactly what I meant, and I’ve never seen any reports on this (not doubting your word of course; that’s a lot more my limited access to good palaeontological reports than anything else). Got a link, preferably not totally technical, I can look at?

[Darwin_s_Finch]

There’s a lot of sketchy stuff on the interwebs (largely because the material itself is somewhat sketchy), but the following sites all seem to go for the “not a stegosaur” option:

Wikipedia link
Dinosaur Mailing List archive
The Plesiosaur Site (little more than a blurb, but its presence on this site at all says something :p)
DinoData link

In print, I checked my copy of Dinosaurs: The Encyclopedia, Supplement 1, and found the following as well:

Regarding a taxon originally described as an Indian stegosaur, Chatterjee and Rudra (1996) visited the site (Kossmaticeras theobaldianum Zone, Trichinopoly Group) which yielded the only remains thus far collected of Dravidosaurus blandordi, there finding only fragmentary material belonging to plesiosaurs. Reexamining the holotype (GSI SR PAL 1, a fragmentary skeleton) of this type species, Chatterjee and Rundra found nothing pertaining to the supposed stegosaurian plates and skull as claimed by the species’ authors, Yadagiri and Ayysami (1979). Instead, they found “highly weathered limb and girdle elements that may belong to plesiosaurs.”

At this point, then, the remains and locale seem to indicate “plesiosaur” rather than “stegosaur” (or pliosaur, for that matter…my oops), though nothing is necessarily definitive at this point. The best one can really say is that Dravidosaurus is currently a nomen dubium, and the fossils may or may not be a plesiosaur, and that the notable stegosaurian traits (plates + skull) seem to be absent. Since Chatterjee and Rudna are the most recent to publish anything on the specimen, their papers (see the DML archive link above for the actual references) represent the current status of the beastie.

[Colibri]

@Lemur866

It’s just that South American mammals are such a striking example of convergency. They’ve got convergent evolution for everything, even for stuff we don’t have anymore. Australia’s marsupials are a very distant second place.

I’m currently working on an exhibition on the Great American Biotic Interchange, which will also feature some examples of convergence. We’ll be comparing fossils of rhinos and toxodonts, horses and Thoatherium, and Smilodon and Thylacosmilus.

I never hear anything about weird Indian fossils, yet India was also an island continent for something like 40 million years.

Some recent controversial evidence suggests that the condylarth ancestral ungulates could have originated in India.