GSA Dinosaur Fieldtrip.

[dis@gj.net]

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 American?s 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.