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Concavenator (theropod) had avian-type podotheca



Ben Creisler
bcreisler@gmail.com


A new paper:

Elena Cuesta, Ignacio Díaz-Martínez, Francisco Ortega & José L. Sanz (2015)
Did all theropods have chicken-like feet? First evidence of a
non-avian dinosaur podotheca.
Cretaceous Research 56: 53–59
doi:10.1016/j.cretres.2015.03.008
http://www.sciencedirect.com/science/article/pii/S0195667115000373

Highlights

We describe the first evidence of a podotheca in the dinosaur fossil record.
Concavenator supports the presence of the avian podotheca for the
Theropoda clade.
The arthral condition is primitive in Theropoda.
The ichnological record could be interpreted based on the new evidence.

Abstract

The podotheca is the structure of scales covering the foot in extant
birds. It is usually assumed that this structure is present in the
whole clade of theropod dinosaurs; however, the knowledge of the
origin of the podotheca is based on scarce direct evidence and its
point of emergence within Theropoda is ambiguous. Here we discuss the
relatively complete and well preserved podotheca of the basal
tetanurae Concavenator corcovatus, which allows the description of its
structure and its osteological correlation. We describe the skin
pattern around the autopod of Concavenator and we compare it with
available fossil skin impressions and the skin of extant crocodiles
and birds. These scale impressions present a similar pattern to those
observed in the autopod of avian theropods, so our results suggest
that Concavenator have a bird-like podotheca. On the other hand, there
is a current debate about the ichnological–osteological correlation in
dinosaurs, derived from the lack of knowledge about the position of
the phalanges in relation to the plantar pads of the podotheca. We
describe, in Concavenator, an arthral condition of the position of the
plantar pads. This condition would be the basal condition in the
tetanurans and, thus, the ichnological record could be interpreted
with an additional criterion. The autopod of Concavenator provides the
first evidence of this type of structure in a non-avian theropod and
it sheds light on the origin and distribution of this structure in the
theropod large lineage.