Couple More New Papers

["Jerry D. Harris" <jharris@dixie.edu>]

Hi Again -

   A few more papers of interest to the group:

Gates, T. A. 2005. The Late Jurassic Cleveland-Lloyd Dinosaur Quarry as a 
drought-induced assemblage. Palaios 20:363-375.

   ABSTRACT:  A comprehensive taphonomic analysis has yielded a novel 
interpretation for one of the most famous dinosaur quarries in the world. 
The Cleveland-Lloyd Dinosaur Quarry (CLDQ) traditionally has been 
interpreted as an attritional predator trap. This scenario is based largely 
on a remarkable 3:1 predator:prey ratio, dominated by the remains of the 
theropod _Allosaurus fragilis_. This study addresses the taphonomy of CLDQ 
by combining analyses of fossils and entombing sediments along with putative 
modern analogues.

Thousands of bones have been excavated from CLDQ, representing at least 70 
individual dinosaurs from a minimum of nine genera. The fossils occur in a 
1-m-thick fine-grained calcareous mudstone interpreted as a floodplain 
ephemeral-pond deposit. The bones show minimal carnivore modification and 
surface weathering, whereas approximately 1/3 of the elements studied 
possess pre-depositional fractures and evidence of abrasion. The vast 
majority of elements are found horizontal to subhorizontal, without a 
preferred long-axis orientation. The demographic profile of the CLDQ 
dinosaur assemblage appears to be highly skewed toward subadult individuals.

Numerous lines of evidence question the traditional predator-trap 
hypothesis. Of the alternatives, catastrophic drought appears to be most 
consistent with available data. Evidence includes a large assemblage of 
animals in a low-energy ephemeral-pond depositional setting and geologic and 
biologic evidence of desiccation. Additional support comes from modern 
drought analogues that frequently result in mass-death assemblages of large 
vertebrates. Climatic interpretations during Late Jurassic times are 
consistent with a semiarid environment characterized by periodic drought 
conditions.



Colson, M. C., Colson, R. O., and Nellermoe, R. 2004. Stratigraphy and 
depositional environments of the upper Fox Hills and lower Hell Creek 
formations at the Concordia Hadrosaur Site in northwestern South Dakota. 
Rocky Mountain Geology 39:93-111.

   ABSTRACT: Many of the dinosaur-bearing bone beds in the Hell Creek 
Formation of the Dakotas and Montana involve multiple species preserved in 
the upper Hell Creek Formation. In contrast, the Concordia Hadrosaur Site is 
monospecific with respect to dinosaurian taxa and is situated in the lower 
Hell Creek Formation in a lithostratigraphic unit we associate with the 
Little Beaver Creek Member. This member consists of organic-rich sandstones, 
siltstones, and claystones that are distinctive within the Hell Creek 
Formation based on their uniformly fine grain size, purplish color, and 
presence of highly lignitic shale rather than coal. Similar lignitic 
deposits occur at other marine-terrestrial boundaries of the Fox Hills-Hell 
Creek Formations in the Little Missouri and Missouri River valleys.
The bone bed at the Concordia Hadrosaur Site (CHS) is associated with an 
extensive coastal swamp rather than a localized fluvial subenvironment such 
as river channel, floodplain, or abandoned channel. The bone bed itself lies 
at the transition from an extensive swamp (represented by highly organic 
mudstones) to a more fluvially dominated, distributary environment 
characterized by variegated mudstones, siltstones, and channel sandstones.
The thirty meters of exposed section at the Concordia site include the top 
of the Fox Hills Formation and lower parts of the Hell Creek Formation. We 
identify marine silts, muds, and sands, coastal dune sands, coastal swamp 
muds and silts, and fluvial sands and silts. The sediments are indicative of 
the marine-terrestrial transition from upper shoreface and foreshore 
environments to a complex system of coastal dunes, swamps, and distributary 
channels that formed during the progradation of the Hell Creek sediments 
into the Cretaceous Fox Hills seaway. Locally, grain size and organic 
fraction varied due to differences in the proximity to distributary 
channels, supply of organic material, and water depth.
Despite the concentration of bones dominated by a single species in the CHS 
bone bed, the high clay fraction of the bone bed matrix, combined with the 
fact that the lowest part of the bone bed has the greatest clay fraction, 
indicates that the bones were not introduced by way of a high-energy, 
catastrophic event, such as a flood. Rather, the bones accumulated in an 
area of quiet standing water. Although preliminary examination of the bones 
is consistent with this depositional interpretation, it does not necessarily 
provide direct support for it.



Yuan, C., Zhang, H., Li, M., and Ji, X. 2005. Discovery of a Middle Jurassic 
fossil tadpole from Daohugou region, Ningcheng, Inner Mongolia, China. Acta 
Geologica Sinica 78:145-148.

       Just what it sounds like.  Again, this is NOT the English Edition of 
this journal.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Jerry D. Harris
Director of Paleontology
Dixie State College
Science Building
225 South 700 East
St. George, UT  84770
Phone: (435) 652-7758
Fax: (435) 656-4022
E-mail: jharris@dixie.edu
and     dinogami@hotmail.com
http://cactus.dixie.edu/jharris/

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