[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Nothosaurus marchicus from Triassic of the Netherlands

Ben Creisler

A new advance online paper:

Nicole Klein , Dennis F. A. E. Voeten, Jos Lankamp, Remco Bleeker,
Oliver J. Sichelschmidt, Marco Liebrand, Dennis C. Nieweg & P. Martin
Sander (2015)
Postcranial material of Nothosaurus marchicus from the Lower
Muschelkalk (Anisian) of Winterswijk, The Netherlands, with remarks on
swimming styles and taphonomy.
Paläontologische Zeitschrift (advance online publication)
DOI: 10.1007/s12542-015-0273-5

The postcranial morphology of Nothosaurus from Winterswijk is
described on the basis of three partially preserved skeletons. Because
of the association with a diagnostic cranium, two of these can be
confidently assigned to N. marchicus. Preserved humeri are recognized
as morphotype II, which confirms the relationship between this humeral
morphotype and N. marchicus. The occurrence of an additional nothosaur
taxon in the Lower Muschelkalk, strong sexual dimorphism, or a broader
size range of N. marchicus is evidenced again. The postcranial
morphology of Nothosaurus is compared to published and new data on the
basal pistosauroid (cf. Cymatosaurus) from the same locality. Numerous
shared morphological characters of N. marchicus, Nothosaurus sp., and
the basal pistosauroid from Winterswijk hamper assignment of isolated
bones, which is presently only possible if a combination of features
on multiple bones from a single individual can be assessed.
Ontogenetic stage of the described skeletons is discussed as well.
Differences between N. marchicus, the basal pistosauroid, and the
morphologically similar, but smaller pachypleurosaur A. heterodontus
are mainly related to the morphologies of the humerus, ulna, and the
clavicle-interclavicle complex, and thereby indicate different modes
of locomotion i.e., swimming styles. The pachypleurosaur and the basal
pistosauroid were most likely anguilliform swimmers, whereas
Nothosaurus also employed its forelimbs during swimming (paraxial
swimming). Taphonomical observations on material of the Winterswijk
locality indicate the presence of scavengers, although most
disarticulated skeletons were transported by water and decayed and
disintegrated in shallow water.