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Dakota Group tracks and other new stuff



From: Ben Creisler
bh480@scn.org

A few new items:

Reiji Kukihara & Martin G. Lockley (2011)
Fossil footprints from the Dakota Group (Cretaceous), John Martin
Reservoir, Bent County, Colorado: new insights into the paleoecology of the
Dinosaur Freeway.
Cretaceous Research (advanced online publication)
doi:10.1016/j.cretres.2011.09.013
http://www.sciencedirect.com/science/article/pii/S0195667111001352

Abstract
The John Martin Reservoir tracksites from the Dakota Group of Bent County,
in southeastern Colorado form part of the mid Cretaceous Dinosaur Freeway
characterized by abundant ornithopod footprints (Caririchnium). Over 350
tracks (331 Caririchnium, 1 Magnoavipes, 22 crocodiles, and a few
pterosaurs) were discovered at 10 new tracksites. All tracks were found as
natural casts, including Caririchnium trackways that were still in situ,
parallel and regularly spaced, suggesting gregarious behavior. Most
crocodile tracks are swimming tracks that consist of three or four scratch
marks also with parallel orientations in many cases. A few pterosaur tracks
consist of pes footprints and scratch marks suggesting swimming or floating
activity in shallow water. This is the first pterosaur evidence from the
Dakota Group. The Caririchnium size structure from John Martin Reservoir is
consistent with the size structure tendency of the whole Dinosaur Freeway,
which shows larger track size in the north. This tendency could be
interpreted as evidence for more than one ornithopod species spread out
across the Dinosaur Freeway. The alternative, that there was one ornithopod
species that migrated north and south seasonally is less likely. The John
Martin paleoecosystem is interpreted from the track evidence as a
well-vegetated coastal plain environment with many ornithopods and a few
theropods on land, crocodiles in the water, and pterosaurs in the skies and
on the water.

++++
Andreas T. Matzke and Michael W. Maisch (2011)
The first aetosaurid archosaur from the Trossingen Plateosaurus Quarry
(Upper Triassic, Germany).
Neues Jahrbuch für Geologie und Paläontologie ? Abhandlungen (advance
online publication)
DOI: 10.1127/0077-7749/2011/0203
http://www.ingentaconnect.com/content/schweiz/njbgeol/pre-prints/0203

Two associated cervical paramedian osteoderms and one isolated paramedian
osteoderm of an aetosaur from the famous Trossingen Plateosaurus Quarry are
described. They represent the first evidence of aetosaurs from Trossingen
as well as the stratigraphically youngest remains of this group from
Germany. Therefore, the Trossingen assemblage consists now of four species
level taxa. Hitherto only three species level taxa were known from this
quarry. Plateosaurus longiceps and Proganochelys quenstedti from complete
specimens as well as one tooth of cf. Liliensternus. The finds indicate
that more small- to medium-sized taxa may be present in the Trossingen
Quarry. 

++++
Photo of possible new type of pterosaur:
http://www.donaukurier.de/_/tools/picview.html?_CMELEM=2154775 photo

Article about discovery (in German):

http://www.donaukurier.de/nachrichten/bayern/Muehlheim-wochennl372011-Ein-Ja
hrhundertfund;art155371,2472945





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