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Small-sized sauropod trackways from China



Ben Creisler
bcreisler@gmail.com


A new paper:


Lida Xing, Martin G. Lockley, Matthew F. Bonnan, Daniel Marty, Hendrik
Klein, Yongqing Liu, Jianping Zhang, Hongwei Kuang, Michael E. Burns &
Nan Li (2015)
Late Jurassic–Early Cretaceous trackways of small-sized sauropods from
China: New discoveries, ichnotaxonomy and sauropod manus morphology.
Cretaceous Research 56: 470-481
doi:10.1016/j.cretres.2015.06.014
http://www.sciencedirect.com/science/article/pii/S0195667115300185

The growing database on sauropod tracksites, particularly from China,
raises questions about hypotheses that wide-gauge sauropod trackways
with low heteropody (Brontopodus) dominate the global sauropod track
record in the Cretaceous. It also raises questions about the
definition of narrow-, medium- and wide-gauge trackways and the
quality of preservation needed to use such labels reliably. A number
of Lower Cretaceous sauropod tracksites from China have yielded
trackways of small-sized sauropods with pronounced heteropody that
have been named Parabrontopodus. These co-occur with medium-sized to
large Brontopodus trackways giving rise to at least two possible
interpretations regarding sauropod trackmakers at these sites: 1)
trackways were left by two different, smaller narrow gauge and larger
wide gauge, taxonomic groups, 2) trackmakers belong to the same
taxonomic group and were narrow gauge when smaller and wide gauge when
larger, therefore not maintaining a constant gauge during ontogeny as
inferred from some assemblages. The presence of different taxonomic
groups is further evidence that narrow gauge trackmakers, previously
considered typical of the Jurassic, persisted into the Early
Cretaceous. This could be part of a regional trend in East Asia and
some other regions such as the Iberian peninsula in Europe, where
similar trackways have been found. Alternatively, this could reflect a
previously unrecognized global trend. More track and skeletal data are
needed to corroborate these hypotheses, because presently essential
parameters are missing.