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Didactyl theropod tracks from Cretaceous Dinosaur Ridge in Colorado



Ben Creisler
bcreisler@gmail.com

A new paper:
(url is separated)

Martin G. Lockley, Lida Xing, Neffra A. Matthews & Brent H. Breithaupt (2016)
Didactyl raptor tracks from the Cretaceous, Plainview Sandstone at
Dinosaur Ridge.
Cretaceous Research 61: 161–168
doi:10.1016/j.cretres.2016.01.007
http: // www.sciencedirect.com/science/article/pii/S0195667116300076?np=y

Two natural casts of two-toed (didactyl) tracks from the Cretaceous
(Albian) Plainview Sandstone (Plainview Member) of the South Platte
Formation (Dakota Group) at Dinosaur Ridge, Colorado are attributed to
deinonychosaurian theropod dinosaurs and placed in the ichnogenus
Dromaeosauripus. This is both the first report of tracks from this
unit in the Dinosaur Ridge area and the first report of
deinonychosaurian tracks from Colorado. It is also only the third
report of this track type from North America. The rarity of tracks
from the Albian-aged, Plainview Sandstone (Dakota Group Sequence 2)
contrasts with their abundance in the upper (Cenomanian) part of the
overlying South Platte Formation (Dakota Group Sequence 3), which has
yielded more than 120 sites mostly in Colorado, giving rise to the
“Dinosaur Freeway” concept. As no deinonychosaurid tracks are known
from the sequence 3 part of the South Platte Formation, despite the
large vertebrate and invertebrate ichnological database available, it
is evident that the sparse vertebrate ichnofauna from the Plainview
Member (Sequence 2) is inherently different. This striking difference
in both track abundance and track type reflects differences in both
age and depositional environment. Based on the Albian age, and track
type, the Plainview tracks invite comparison with the ichnofaunas of
the Cedar Mountain Formation and not with those well-known from the
upper part of the South Platte Formation known as the Dinosaur
Freeway.