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Sauropod dinosaur fauna of Late Cretaceous Kem Kem beds of Morocco:



From: Ben Creisler
bcreisler@gmail.com


A new paper:


Philip D. Mannion & Paul M. Barrett (2013)
Additions to the sauropod dinosaur fauna of the Cenomanian (early Late
Cretaceous) Kem Kem beds of Morocco: Palaeobiogeographical
implications of the mid-Cretaceous African sauropod fossil record.
Cretaceous Research 45: 49–59
http://dx.doi.org/10.1016/j.cretres.2013.07.007
http://www.sciencedirect.com/science/article/pii/S019566711300116X


Determining the relationships of mid-Late Cretaceous African taxa is
central to understanding the timing and resultant
palaeobiogeographical patterns of Gondwanan fragmentation. The early
Late Cretaceous (Cenomanian) Kem Kem beds of southeastern Morocco
preserve a diverse vertebrate fauna, including sauropod dinosaurs.
Sauropod material includes the holotype of the rebbachisaurid
diplodocoid Rebbachisaurus garasbae and fragmentary remains
representing indeterminate titanosauriforms and rebbachisaurids. Here,
we describe two new specimens from the Kem Kem beds. A dorsal neural
arch with complex internal pneumaticity is tentatively attributed to a
somphospondylan titanosauriform. A caudal vertebra possessing several
rebbachisaurid synapomorphies is excavated by a large and pervasive
lateral pneumatic foramen, a feature undocumented in other
rebbachisaurids. However, caudal vertebrae are currently unknown for
the sympatric R. garasbae, so this element could be referable to that
taxon or a second, previously unknown, rebbachisaurid species.
Interestingly, this new caudal vertebra displays a mosaic of features
otherwise restricted to limaysaurine or nigersaurine rebbachisaurids,
suggesting a placement basal to these clades, which is the position
usually recovered for R. garasbae in phylogenetic analyses. A review
of the mid-Cretaceous African sauropod fossil record removes the
Cretaceous record of dicraeosaurids from Africa, restricting this
clade to a single post-Jurassic occurrence in Argentina. All
diagnostic sauropod remains can be attributed to titanosauriforms or
rebbachisaurids. Whereas rebbachisaurids were seemingly restricted to
northwestern Africa and disappeared post-Cenomanian, titanosauriforms
were widespread across the African continent and survived until the
latest Cretaceous. The development of the mid-Cretaceous Trans-Saharan
Seaway might have acted as a dispersal barrier for rebbachisaurids and
other vertebrate groups. In contrast, titanosauriforms might have been
able to cross this barrier, but it is possible that they were also
unable to disperse, and that northwestern African titanosauriforms
were not closely related to taxa from the rest of the African
continent. New materials and a better understanding of titanosaur
interrelationships will be crucial in teasing these scenarios apart.