GSA Dino Field Trip.

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Date
This announcement is cross-posted from the vrtpaleo. list.

Norm MacLeod

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To All;

This is to announce that in association with the Annual Geological
Society of America meeting to be held Oct. 20-23, 1997 in Salt Lake
City, Utah, there will be a post meeting field trip to examine many of
the new mid-Cretaceous dinosaur sites in eastern Utah.

Fieldtrip 31;

Lower-Middle Cretaceous Dinosaur Faunas of the Central Colorado Plateau:
A Key to understanding 35 million years of Tectonics, Sedimentology,
Evolution, and Biogeography. Friday Oct. 24 - Sunday Oct. 26.

$240.00 includes hotels in Price and Moab, Utah; lunches, and
transportation.

There will be 12 stops over the 3 days and several of the dinosaur
quarries will be actively undergoing excavation during the fieldtrip. We
will visit sites in the area of the San Rafael Swell and around Arches
National Park.
Collections of these dinosaurs will be availible for examination in
Price, Utah.

I have attached a copy of the Abstract from the guidebook (87 manuscript
pages and 37 figures) to be published in a volume of BYU Geology Studies
this fall in time for participants to get a reprint.

This is going to be a great fieldtrip to visit many important new
localities. For more info contact myself or GSA at:

http://www.geosociety.org

Jim Kirkland
Dinamation Int'l Society

Lower to Middle Cretaceous Dinosaur Faunas of  the Central Colorado
Plateau: A Key to
Understanding 35 Million Years of  Tectonics, Sedimentology, Evolution and
Biogeography

James I. Kirkland, Dinamation International Society, 550 Jurassic
Court, Fruita, CO 81521
with

Brooks Britt, Museum of Western Colorado; Donald L. Burge,
College of Eastern Utah, Prehistoric Museum; Ken Carpenter,
Denver Museum of Natural History; Richard Cifelli, Oklahoma
Museum of Natural History; Frank DeCourten, Sierra College;
Jeffrey Eaton, Weber State University; Steve Hasiotis, University
of Colorado; Tim Lawton; New Mexico State University


Abstract

	Three distinct dinosaur faunas separated by unconformities
representing about 10 my each are present in the Cedar Mountain
Formation of east-central Utah. These biostratigraphic
relationships compliment the lithostratigraphic relationships
present in the Cedar Mountain Formation resulting in the
recognition of five members to be recognized. These members are a
basal Buckhorn Conglomerate and four new members defined herein.
In ascending order these are the Yellow Cat Member, Poison Strip
Sandstone, Ruby Ranch Member, and Mussentuchit Member.
 	The Buckhorn Conglomerate is a trough cross-bedded pebble
conglomerate present at the base of the Cedar Mountain Formation
on the west and north sides of the San Rafael Swell. It is
unfossiliferous. The oldest fauna preserved is in the largely
fine grained deposits of basal Yellow Cat Member east of the San
Rafael Swell. The dinosaurs include abundant polacanthids, cf.
Polacanthus n. gen., Iguanodon ottingeri, a sail-backed
iguanodontid (= I. ottingeri ?), camarasaurid and titanosaurid
sauropods, a small maniraptoran theropod, cf. Ornitholestes n.
gen., and the giant dromaeosaurid Utahraptor ostrommaysorum.  The
ankylosaurs, iguanodontids, and sauropods indicate close temporal
and geographic ties to the Barremian of Europe.
	The cliff forming Poison Strip Sandstone outcrops across
central Utah east of the San Rafael Swell. Dinosaurs present in
this member are limited to the nodosaurid ankylosaur Sauropelta,
and isolated theropod and sauropod bones. The overlying Ruby
Ranch Member is characterized by largely illitic mudstones and an
abundance of calcareous nodules. It preserves a dinosaur fauna
including the nodosaurid Sauropelta, the primitive iguanodontian
Tenontosaurus?, sauropods assigned to Pleurocoelus, dromaeosaurid
teeth, an unidentified large theropod, and Acrocanthosaurus.
This fauna compares well with those documented from the Cloverly
Formation, Arundel Formation, and Trinity Group characteristic of
North Americanís apparently endemic Aptian-Albian dinosaur fauna.
	A sharp break from carbonate nodule bearing, non-smectitic
strata to carbonaceous, highly smectitic strata marks the base of
the Mussentuchit Member in the western San Rafael Swell region.
It is dated as spanning the Albian/Cenomanian boundary based on
palynology and radiometric dates. This youngest dinosaur fauna
includes a small nodosaurid, cf. Pawpawsaurus n. gen., a small
ornithopod, a primitive lambeosaurid hadrosaur, ceratopsian
teeth, pachycephalosaur teeth, tiny sauropod teeth, a
dromaeosaurid, cf. Richardoestesia teeth, cf. Paronychodon teeth,
and an early tyrannosaurid.  This dinosaur fauna is remarkably
similar to those of the Campanian and Maastrichtian of western
North America.  As the most likely ancestors of the
tyrannosaurid, hadrosaur and ceratopsian are from the Early
Cretaceous of Asia, the dramatic shift to faunas typical of the
North American Late Cretaceous is interpreted to result from
opening migration corridors to and from Asia through Alaska at
the end of the Early Cretaceous, when migration to eastern North
America was still possible. The middle to upper Cenomanian Dakota
Formation preserves a dinosaur fauna much like that of the
Mussentuchit fauna with the notable absence of sauropods.
	The fossil record in east-central Utah indicates that a
Barremian iguanodont-polacanthid fauna with European affinities
predating common flowering plants was replaced by an Aptian-
middle Albian Tenontosaurus-Pleurocoelus fauna, perhaps
representing an impoverished recovery fauna following a Early
Cretaceous extinction event (endemic to North America). In turn,
this was followed by a latest Albian-earliest Cenomanian
hadrosaur dominated fauna with Asian affinities when flowering
plants were co-dominant, which continued until the end of the
Cretaceous.











___________________________________________________________________

Dr. Norman MacLeod
Micropalaeontological Research
N.MacLeod@nhm.ac.uk (E-mail)

Department of Palaeontology, The Natural History Museum,
Cromwell Road, London, SW7 5BD

Office Phone: 0171-938-9006
Dept. FAX: 0171-938-9277
E-mail: N.MacLeod@nhm.ac.uk
___________________________________________________________________