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Purranisaurus (metriorhynchid from Argentina) described



Ben Creisler
bcreisler@gmail.com


A new online paper:



Yanina Herrera, Zulma Gasparini & Marta S. Fernández (2015)
Purranisaurus potens Rusconi, an enigmatic metriorhynchid from the
Late Jurassic–Early Cretaceous of the Neuquén Basin.
Journal of Vertebrate Paleontology (advance online publication)
DOI:10.1080/02724634.2014.904790
http://www.tandfonline.com/doi/full/10.1080/02724634.2014.904790#abstract


The Tithonian record from northwestern Patagonia (Neuquén Basin)
documents a complete succession of lower, middle, and late Tithonian
marine reptiles. From the late Tithonian–early Berriasian of
Patagonia, three marine crocodyliforms have been recorded: Dakosaurus
andiniensis, Cricosaurus araucanensis, and Purranisaurus potens.
Although P. potens includes the first metriorhynchid skull described
from Patagonia, no detailed description and/or illustrations have been
published. Since the mid-20th century, several authors have discussed
the validity of P. potens. Recent preparation of the type material
allowed a detailed description as well as exploration of its
phylogenetic relationships. We consider P. potens as a valid taxon
characterized by a unique combination of characters, such as medial
and posterolateral processes of the frontal forming an angle of 60°;
supratemporal fossae reaching the minimum interorbital distance, with
the dorsal margin of the supratemporal arch being slightly concave in
lateral view; thin bony lamina projecting from the lateral and medial
alveolar margins of the maxilla; occipital surface ventral to
occipital condyle parallel to transverse plane of skull;
well-developed crest that extends along the entire height of the
supraoccipital; and orbital process of the quadrate very conspicuous
and acute, horizontal, and without bony attachment. Phylogenetic
analysis recovers P. potens as deeply nested within Geosaurini and,
contrary to previous proposals, not closely related to
'Metriorhynchus' casamiquelai and 'M.' westermanni. Internal
relationships within Geosaurini are unresolved. Purranisaurus, as a
monotypic genus, is restricted to the late Tithonian–early Berriasian.

http://zoobank.org/urn:lsid:zoobank.org:pub:CDB288F2-087C-4E19-A897-8AB94BD60EC2