Concavenator corcovatus: (Theropoda, Dinosauria) from Las Hoyas fossil site (Early Cretaceous, Cuenca, Spain): taphonomic, phylogenetic and morphofunctional analyses
Author
Cuesta Fidalgo, ElenaEntity
UAM. Departamento de BiologíaDate
2017-02-10Subjects
Dinosaurios - Tesis doctorales; Biología y Biomedicina / BiologíaNote
Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Biología. Fecha de lectura: 10-02-2017Esta tesis tiene embargado el acceso al texto completo hasta el 10-08-2018
Esta obra está bajo una licencia de Creative Commons Reconocimiento-NoComercial-SinObraDerivada 4.0 Internacional.
Abstract
Theropods are a widely taxonomically, paleobiogeographically and morphologically diverse
group that include the extant birds. The non-avian theropod record in the Iberian Peninsula
is represented by Portuguese taxa and some fragmentary remains in Spain. However, the two
taxa founded in Las Hoyas fossil site represent the most complete theropod inside the Iberian
Peninsula and Europe.
Las Hoyas fossil site is a Konservat-Lagerstätte that is reconstructed as a subtropical wetland
with a strong biannual seasonality. The fossils from Las Hoyas are characterized by their
completeness, articulation and preservation of soft-tissues and colour patterns. Two non-avian
theropods founded in this site, Pelecanimimus polyodon and Concavenator corcovatus, show these
preservation features, which allow to perform an exhaustive paleoecological analysis.
Concavenator is the most complete dinosaur founded in the locality and, also, it represents the
largest taxon preserved. Although its taphonomic features are coherent with the preservation
framework of the Las Hoyas wetland, its terrestrial condition and size are infrequent in the fossil
site, and thus, its presence raises issues about its processes of preservation. One of the aims
of the current PhD thesis is reconstructing the taphonomic history that affect to Concavenator
carcass. The methodology consists of several methods proposed in previous studies about the
archosaurian preservation in Las Hoyas fossil site. The taphonomic analysis shows that Concavenator
carcass suffered several processes as: early decay, dragging and slightly transport, rehydration
and, finally, entombing into the microbial mats developed in Las Hoyas pools. These processes
were consistent with the dynamic of the climate in Las Hoyas during the Lower Cretaceous.
Therefore, the results not only clarify the processes produced on Concavenator, but it also sheds
light on the understanding of mechanism acting in Konservat-Lagerstätten throughout the world.
The exquisite preservation of Concavenator allows to discern several anatomical features in the
skeleton and soft-tissues impressions. In this PhD thesis, these soft-tissues impressions have been
analysed and the results have determined a new conception of various anatomical structures,
such as the avian podotheca. This podotheca is consisting of three types of scales, similar to
those observed in the extant birds, plantar pads with an arthral disposition and corneous sheet
around the ungual phalanges. Moreover, the completeness of the skeleton has allowed to carry
out an exhaustive osteological description and phylogenetic analysis. Concavenator is a basal
member of Carcharodontosauridae and has several synapomorphies within the clade as the
lacrimal-postorbital contact or a peg-and-socket articulation between the ilium and ischium,
among others. This phylogenetic position of Concavenator has the best obtained support value
of branches until now.
Historically, carcharodontosaurids have been considered exclusively from Gondwana, however,
recent discoveries show several taxa throughout Laurasia. The European position of Concavenator
during the Early Cretaceous is key to understand the faunal interchanges between both continents.
Finally, two unusual and striking features are present in Concavenator, a series of bumps on the
ulnar shaft and hypertrophied neurapophyses of the posterior dorsal and anterior caudal vertebrae.
Both features have been analysed in the current thesis. The muscle reconstruction of the forearm
suggests that the bumps are not related to myological origin. Regarding the axial skeleton, the
unusual features of its vertebrae bestow stiffness during the locomotion and these features could
be related to the presence of an axial structure in the pelvic area. These results propose new
future research projects in order to determinate the functional morphology of both structures
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