Oolon Colluphid

I read (with some surprise) last night in the <a href="http://www.amazon.com/exec/obidos/ASIN/0521467861/internetinfidelsA/" target="_blank">The Cambridge Encyclopedia of Human Evolution</a> that the early primates, the carpolestids, are the best example of smooth gradual transitions in the primate fossil record. Given how good the hominid fossils are, this is something I’d like to see! Anyone know of more details / sites, preferably with nice pictures to show the cretinists?

Thanks, Oolon

Ergaster

I haven't done much in early primate evolution for a long time, but it appears that the Carpolestidae are part of the Order Plesiadapiformes, which are no longer considered to be primates. They are, however, probably a sister group to primates. They seem to retain some primitive primate-like characters, and people argued about their exact systematic placement for a long time, so no doubt you will encounter literature that does list them as a suborder of the order Primates and suggests that they are the earliest primates.

They were (whatever they were) and extremely diverse group, with plenty of genera and species in a number of families (see link for a list), and I think there are a couple of good evolutionary lineages within them. I haven't found pictures on the web, though; maybe someone else can do better.

<a href="http://members.tripod.com/cacajao/taxonomy_plesiadapiformes.html" target="_blank">http://members.tripod.com/cacajao/taxonomy_plesiadapiformes.html</a>

Anyway, the reference to the carpolestids probably refers to the strange premolar complex some of these creatures possessed, and there seems to be a fairly smooth sequence of fossils (from Elphidotarsius through Carpodaptes to Carpolestes that shows the development of the last premolar from a (relatively) small serrated blade to a very large, flat serrated blade (also involving the first molar). I couldn't find any pictures on the web.

Another good (and famous) example is the diagram in Gingerich 1976 (fig. 7) that shows the gradual change frm the genus Pelycodus to the genus Notharctus through time (see link below). Unfortunately this transition does not involve pictures, because it is documented by the change in size in the log-transformed area of the first molar through time.

<a href="http://www.cs.colorado.edu/~lindsay/creation/pelycodus.html" target="_blank">http://www.cs.colorado.edu/~lindsay/creation/pelycodus.html</a>

Hope this helps.

Ref: Gingerich PD 1976. Paleontology and phylogeny: patterns of evolution of the species level in the early Teriary mammals. American Journal of Science276:1-28.

[edited to add reference]

[ January 31, 2002: Message edited by: Ergaster ]</p>

Oolon Colluphid

Thanks Ergaster! I knew that if anyone could help it'd be you!

I think the gradual evolution bit was referring to teeth. (The CEHE does talk about the plesiadapiforms's are-they-aren't-they nature. I gather there's so little to go on that no-one's really sure. We're talking no more than bits of tooth and jaw again, aren't we?! )

While you're here, which book would you recommend on fossil primates/hominids? Both Klein and Fleagle have done good-sounding ones, but which (or another) is best for use in Evo/Cre discussions?

Cheers, Oolon

Ergaster

Well...yes and no: a lot of them are teeth and jaws, but IIRC there are some pretty good examples of skulls and postcranial material here and there. What I found most annoying was not the fragmentary nature of them, which in reality is no worse than that of the hominin fossil record, but their size. Many species are *really* small, so that you need a hand lens or microscope to make out the kind of tooth deatils that are relevant in primate evolutionary studies.

As far as a book that is useful for cre/evo debates? There isn't one--at least, I've never come across one that is better than any other for that purpose. The Talk Origin web pages are the best resource for that sort of thing, supplemented with the already-recommended books and the professional literature.