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Re: Rép : Post–K-Pg Radiation of Placentals -- open access!!!

David Marjanovic <david.marjanovic@gmx.at> wrote:

> In particular, *P. coombsi* is known only from "the tooth, the whole tooth,
> and nothing but the tooth", so its affinities are difficult to evaluate.

Reminds me of _Tingamarra_, the Australian "condylarth" (or not).

> As its name indicates, it was immediately thought to be "the first
> ungulate".

Not far wrong, based on the phylogeny presented in the Science paper,
where _Protungulatum_ is given as the most basal euungulate.

> Warning: mammalologists are usually happy to refer isolated tarsals to taxa
> otherwise known only from isolated teeth if they have the expected size. The
> relationship between tooth size and the sizes of various tarsal bones is
> apparently well known and fairly constant, so this is less scary than it
> sounds like; but there are bound to be occasions where this practice puts
> the LOL in mammalology.

Very true; but in the case of _Protungulatum donnae_, the tarsals
(initially referred by Szalay and Decker, 1974) are usually considered
part of the hypodigm

> The dryolestidan *Henkelotherium* was also arboreal or scansorial. But I
> don't think dryolestidans are known from before the Middle, perhaps even
> Late, Jurassic.

Good point.  I didn't mean to imply that the only arboreal Mesozoic
mammals were therians.  The gliding _Volaticotherium (lately regarded
as a eutriconodont) was also arboreal, and _Argentoconodon_ (a
putative close relative) might also have been an arboreal glider.  The
synapsid _Suminia_ is inferred to have been arboreal much earlier
(Late Permian).  But the early diversification of metatherians and
eutherians may well be linked to scansorial/arboreal adaptation.