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Re: GRASS IN THE CRETACEOUS???



At 11:11 PM 12/14/98 -0500, Ray Stanford wrote:
>    Here's hoping one or more of you dinolisters can help me out by
carefully answering a question (one comment first, please):
>
>    COMMENT: Again and again I hear (even on this list) that grasses did
not develop until after the cretaceous was 'gone with the wind'. (Or, should
I say the BOOM!?)
>
>    QUESTION: Yet, in Philippe Taquet's wonderful, recent book, DINOSAUR
IMPRESSIONS [Cambridge University Press, 1998, ISBN 0 521 58372 1 hardback],
I read on page 47, first paragraph, "The first pollen grains from flowering
plants are known from the Barremian and Aptian deposits.  Among these
flowering plants are found the first grass-like plants..."

"There were Late Cretaceous marsh grasses, but ther is no evidence for
sod-forming dry-land grasses or their distinctive granular ped structures in
paleosols earlier than the middle Miocene"  Retallack, G.J. 1997.  Dinosaurs
and Dirt.  Dinfest International: 345-359.

In other words, the clade of grasses do appear in the Cretaceous, but these
were originally limited to wet waters.  Only long after the K-T boundary did
grasses become a major group of dry-land plants.  (Just as the group
Primatomorpha may date to the latest Cretaceous, but advanced primate groups
like hominoids don't appear until much later).

>    I want an accurate, up-to-date answer for a reason of my own; but,
ALONG ANOTHER AVENUE: If Taquet is right, might this offer artists rendering
at least Late Cretaceous scenes a freer hand at the ground cover?

Only when drawing marshes.  Grasslands were absent throughout the early
Cenozoic, too.

>    AN AFTER-THOUGHT: And, finally, if Taquet IS right, is there any artist
among us now sufficiently free of the need for 'political correctness' as to
be willing to produce a work (and dare publish it) with -- say -- Hadrosaurs
or Ceratopsians grazing grass?
>
>    Please don't flame me for that last question.  But, after all, the best
artists I've even come across seemed to have the attitude of, 'To hell with
political correctness!'

What "political"?  This is science were talking about!

It would be fine for Science Fiction, but it isn't supported by the facts.
Even within the Cenozoic, grazers are very rare until the middle Miocene
(earlier in South America), when grasslands begin to become abundant.  The
change in the teeth and jaw apparatus of Cenozoic mammals towards grazing
has long been a famous chapter in vertebrate paleontology.

To put it another way, the presence of the primitive primatomorph
_Purgatorius_ in the Hell Creek Formation isn't justification for drawing a
bunch of ourangutans or chimpanzees or australopithecines or university
faculty walking among the herds of _Triceratops_!  It that is what you want
for a painting, go ahead.

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:tholtz@geol.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661