Thagomizers and Proto-Thag

[PESELYG@LYNX.APSU.EDU]

If I have understood the recent postings correctly, the evidence for
Primates in the Cretaceous is limited to one tooth of problematical date
of a Purgatorius ceratops in Montana.  If this is Cretaceous in date,
is it safe to assume it would be from the very end of the Cretaceous
(i.e., Maastrichtian)?

How many thagomizeriferous stegosaurians were still around in the
Maastrichtian?  Weishampel et al., edd., _The Dinosauria_, in chapter
21 by Peter M. Galton on the Stegosauria has a table (21.1 on p. 450)
of Stegosauria.  The only stegosaur of Late Cretaceous date is
Dravidosaurus blanfordi from Tamil Nadu state, India, assigned to
the Coniacian (88.5 to 87.5 million years ago).  On p. 452 Galton
describes this as a small stegosaur from the Upper Cretaceous.
("...the tail spike has a uniquely expanded middle region.")
Elsewhere in the same volume, David B. Weishampel's chapter on
Dinosaurian Distribution (ch. 3), on page 130, lists both the
Dravidosaurus blanfordi and from elsewhere in Tamil Nadu state a
Stegosaurid indet. of Maastrichtian date.

Were stegosaurians pretty rare in the last 20 million years or so
of the Cretaceous (with uniquely expanded thagomizers or otherwise)?
It's a long way from Tamil Nadu to Montana.  Was Thag's forebear
pretty much safe from death by tail spike?


George Pesely
peselyg@lynx.apsu.edu