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Metatheria (was Re: Declining pterosaur diversity)



----- Original Message -----
From: K and T Dykes
Sent: Monday, November 29, 2004 8:36 AM

Hi David,

<<"Ameridelphia" is the paraphyletic group that includes all not too basal (*Deltatheridium*, *Sinodelphys*, *Asiatherium*...) metatherians and excludes the Australian ones. A North American polydolopimorph, as well as a Cretaceous one, sounds very interesting, however!!! I would greatly appreciate the pdf...>>>>

[...]

In the terminolgy of the paper, they offer three Cretaceous polyodopimorphians from NAm: Hatcheritherium, Glasbius and Ectocentrocristus. (I managed to read about the centrocrista on upper molars without feeling the need to throw up due to bafflement. I must be making some progress.) They also produce some recycled formerly 'Alphadon' stuff, and transform it into three species of Nortedelphys; a Cretaceous herpetotheriid ameridelphian. Das pdf kommt.

Thanks, the pdf has arrived. K herpetotheriids may not be surprising... but what is surprising is the paper's approach to science. They are absolutely shameless about not doing practically any phylogenetic work in that paper, about erecting a full-blown Linnaean classification with tons of paraphyletic taxa that aren't even marked as such, and about drawing far-reaching conclusions from "the tooth, the whole tooth, and nothing but the tooth". I'll sometime write an Internet page on the problems with that paper. No, I can't show that any of their identifications of the fossils are wrong; but several, perhaps all, are extremely dubious. I tried to find out why one of the teeth is put into Polydolopimorphia -- that's based on one single character, on the exact arrangement of two cristae on that tooth. :-o :-o :-o
It's not mentioned when the paper was accepted by the journal. So I don't know if they can justify ignoring the impressive morphological phylogeny of Marsupialia by Horovitz, January 2004. They'd sorely need it.


<<Normally I'd say drop it at once, but... there's yet another SVP meeting abstract that proclaims the destruction of Pediomyidae, but doesn't tell how else those pesky little beasties -- sometimes considered the sistergroup of the South American + Australian metatheres -- are now arranged. Perhaps you should wait for the publication of that study.>>

I've only just picked Alphadelphia up.

In this paper, Alphadelphia, Ameridelphia and Australidelphia are three successive grades, of which the last just so happens to be holophyletic (an uninteresting side fact that isn't even mentioned), because it hasn't produced any descendants yet. Mentally, the paper belongs in the 60s.


The reorganisation certainly helped the structure of the directories, if nothing else.

It's meant to do just that (and nothing else). :-)