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Mid-Jurassic theropod tracks from Southwest China



From: Ben Creisler
bcreisler@gmail.com

A new online paper:


Li-Da Xing, Martin G. Lockley, Zhong-Dong Li, Hendrik Klein, Jian-Ping
Zhang, Gerard D. Gierliński, Yong Ye, W. Scott Persons Iv & Long Zhou
(2012)
Middle Jurassic theropod trackways from the Panxi region, Southwest
China and a consideration of their geologic age.
Palaeoworld (advance online publication)
doi: http://dx.doi.org/10.1016/j.palwor.2012.11.002
http://www.sciencedirect.com/science/article/pii/S1871174X12000625?v=s5


Theropod footprints from the Middle Jurassic Xincun Formation in the
Panxi region (Sichuan Province, Southwest China) show strong
similarities to the ichnogenus Kayentapus. They are characterized by
slender digits, wide digit divarication, and a characteristic pad
configuration that is different from other Jurassic theropod
ichnotaxa. At the Shansong tracksite, three trackways are present,
each consisting of four consecutive tracks (stride and pes lengths up
to 200 cm and 36 cm, respectively). The speed of the trackmakers has
been calculated with values between 1.1 and 1.4 m/sec. The assemblage
is a further document of a Middle Jurassic occurrence of this
morphotype that is basically known from the Lower Jurassic deposits
elsewhere. This could be due to peculiarities of theropod communities
in this region, reflecting a different paleobiogeographic distribution
pattern in the Middle Jurassic. Biostratigraphically, ostracods lend
support to a Middle Jurassic age of the trackbearing unit. This
corresponds partly with data from the Shangshaximiao Formation that is
considered to be of Middle Jurassic age based on ostracods but Late
Jurassic age based on vertebrate skeletons. The ichnological record
and the presence of Kayentapus-like footprints in both units support a
Lower–Middle Jurassic age.