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Dinosaur track assemblage from Lower Cretaceous of China with new ichnospecies Caririchnium liucixini (ornithischian)



Ben Creisler
bcreisler@gmail.com

A new paper:

Lida Xing, Martin G. Lockley, Daniel Marty, Hendrik Klein, Geng Yang,
Jianping Zhang, Guangzhao Peng, Yong Ye, W. Scott Persons IV, Xianya
Yin & Ting Xu (2016)
A diverse saurischian (theropod–sauropod) dominated footprint
assemblage from the Lower Cretaceous Jiaguan Formation in the Sichuan
Basin, southwestern China: A new ornithischian ichnotaxon, pterosaur
tracks and an unusual sauropod walking pattern.
Cretaceous Research 60: 176–193
doi:10.1016/j.cretres.2015.12.005
http://www.sciencedirect.com/science/article/pii/S0195667115301294

A sample of fallen blocks of fluvial sandstone from the Lower
Cretaceous Jiaguan Formation of Sichuan Province yielded an assemblage
of dinosaur and pterosaur tracks preserved as natural impressions and
casts. Collectively the assemblage reveals 132 tracks representing at
least 30 trackways of tridactyl and didactyl theropods, sauropods,
ornithopods and pterosaurs. Ichnotaxonomically, the trackways of small
tridactyl theropods (pes lengths 7–18 cm) are indeterminable, whereas
the trackway of a small didactyl dromaeosaur (pes length up to 7.5 cm)
is tentatively assigned to cf. Velociraptorichnus. The sauropod
trackways are assigned to cf. Brontopodus based on the medium to
nearly wide-gauge pattern. Other characteristics are the U-shaped
manus and strong heteropody. One sauropod trackway shows a peculiar
pattern with a lack of left manus imprints, and an unusual position
and rotation of right manus imprints. Different scenarios and
explanations for this phenomenon are discussed. Ornithopod trackways
are the most abundant in the sample and characterized by pes imprints
of a small biped that are assigned here to the new ichnospecies
Caririchnium liucixini. It is characterized by an unusual broad shape
and weak mesaxony. Bivariate analysis of different Caririchnium
ichnospecies reveals increasing mesaxony toward the larger forms, a
trend that is the reverse of typical theropod ichnotaxa, where large
imprints have weak mesaxony. Three isolated, small pterosaur tracks
(two manus, one pes) are visible on a single surface. They show strong
similarities to the widespread ichnogenus Pteraichnus. This is the
ninth report of tetrapod tracks from the Jiaguan Formation in recent
years and represents one of the most diverse assemblages recorded to
date. It is also rare evidence of typical didactyl dromaeosaur tracks
and the co-occurrence of sauropod and ornithopod tracks in a fluvial
depositional environment representing arid climate conditions.