Shamosuchus and Paralligator (Crocodyliformes, Cretaceous of Asia) review

[Ben Creisler <bcreisler@gmail.com>]

Ben Creisler
bcreisler@gmail.com


New in PLoS ONE:

Alan H. Turner (2015)
A Review of Shamosuchus and Paralligator (Crocodyliformes, Neosuchia)
from the Cretaceous of Asia.
PLoS ONE 10(2): e0118116.
doi:10.1371/journal.pone.0118116
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0118116


The crocodyliform Shamosuchus is known from numerous Late Cretaceous
localities in southern and eastern Mongolia and fragmentary remains
from Uzbekistan. Seven species of Shamosuchus have been named from six
localities in Mongolia and three in Uzbekistan. Six species originally
described as Paralligator were later referred to Shamosuchus. Only the
type species, Shamosuchus djadochtaensis has been examined in detail.
Many of the named species of Shamosuchus show striking similarity in
size and cranial morphology but most are based on partial remains
suggesting that the true species diversity is overestimated. A review
of all species referred to Shamosuchus recognizes three valid taxa:
Shamosuchus djadochtaensis, S. gradilifrons, and S. major. Shamosuchus
sungaricus, S. borealis, and S. karakalpakensis are nomena dubia,
whereas S. ancestralis, S. ulgicus, S. tersus, and S. ulanicus are
junior subjective synonyms of S. gradilifrons. Phylogenetic analysis
of 318 phenotypic characters recovers a Paralligatoridae clade
consisting of Shamosuchus, Rugosuchus, Batrachomimus, Glen Rose Form,
and Wannchampsus. Shamosuchus is non-monophyletic: S. djadochtaensis
is near the base of Paralligatoridae whereas S. gradilifrons + S.
major are the most deeply nested. The name Paralligator is resurrected
for this clade. Rugosuchus and Batrachomimus are sister taxa to
Paralligator. Paralligatoridae is closely related to Theriosuchus,
hylaeochampsids and a speciose Allodaposuchus clade, which together
are the sister group of Borealosuchus plus Crocodylia. These results
support the presence of a diverse clade in eastern Asia and western
North America throughout the Cretaceous with origins in the Late
Jurassic.