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Ant hills, Cretaceous mammals, and Purgatorious



> And undergrad or grad students at Yale can earn some lab 
>time (and
>maybe some cash) picking Mesozoic mammal teeth out of anthills (a long
>story...)).
>

Which is worth expanding on.  Mound-building ants are highly effective at
collecting detritus that is within a very narrow size-range.  Small
fossils, such as mammal teeth, mammal jaws, lizard jaws, fish teeth, are
roughly of the same size as the sand and granules that the ants
collect, and these fossils get picked up by the ants and hauled back
to the mound. As a result, tiny fossils (almost impossible to
find _in situ_), can get highly concentrated within the mound.

Picking microfossils out of anthill sand is fun...
for the first half-hour.


>  Members of the Ungulata and the
>Primatomorpha have been identified in the early Late K and latest K
>(respectively), but these don't closely resemble the modern forms, and 
>why should they?  

Van Valen and Sloan, in 1965, found the single molar of Purgatorius
ceratops n. sp. in latest Cretaceous seds.  Unless new Cretaceous
material has been found since, that molar is still all we have of
Mesozoic primatomorpha (which may be plesiadapiforms).

Didn't the authors (or others) later express some concern that perhaps the
"occurrence" of P. ceratops is a result of washing-screen contamination?
(apparently, previously the washing screen was used to screen seds from
the Paleocene Tullock Fm., which contains P. unio).

If anything new (after 1965) has come up regarding the Cret. primatomorph
issue, I would like to hear more.


Earlier dicussions regarding Purgatorious ("Purgie") can be found
in the Dinosaur-list archives.
                       
                       <pb>

--
                 Phil Bigelow
                 bh162@scn.org