late Maastrichtian critters

[Tom Holtz <tholtz@geochange.er.usgs.gov>]

>> Well, remember that by then the smallest dinosaur was probably Troodon,
>> or a close relative.
>> >> The largest mammal at the time was about the size of a cat
>> (and a small one at that).
>> There seems to have been no overlap in size at all, so the
>> largest surviving mammal was, perforce, smaller than the
>> smallest Late Maastricthian dinosaur.

>What evidence is there to support this?  It would seem, to me, to be
>mostly conjecture.

The evidence here is the fossils.  Perhaps a more acceptable rewording is
"the smallest KNOWN dinosaur" and the "largest KNOWN mammal".  To say there
was overlap in size between nonavian dinosaurs and mammals in the latest
Cretaceous is conjecture - it may be true, but the fossils haven't been
found yet which support it.

I might add to the "smallest late Maastrichtian dinosaur" list:
dromaeosaurids, oviraptorosaurs and maybe some hypsilophodontid are all
about the same size as Troodon.

                                
Thomas R. Holtz, Jr.                                   
tholtz@geochange.er.usgs.gov
Vertebrate Paleontologist in Exile                  Phone:      703-648-5280
U.S. Geological Survey                                FAX:      703-648-5420
Branch of Paleontology & Stratigraphy
MS 970 National Center
Reston, VA  22092
U.S.A.