Purranisaurus potens Rusconi, an enigmatic metriorhynchid from the Late Jurassic–Early Cretaceous of the Neuquén Basin
Authors:
Herrera et al
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.
On the morphoplogy and taxonomic status of Xinpusaurus kohi JIANG et al., 2004 (Diapsida: Thalattosauria) from the Upper Triassic of China
Author:
Maisch
Abstract:
Additional preparation has revealed new information on the cranium and the vertebral column of the type and only specimen of Xinpusaurus kohi JIANG et al., 2004, a thalattosaur from the Upper Triassic Xiaowa Formation of Guanling County (Guizhou, south-western China). The new data allow to supplement existing descriptions and to decide on some controversial points raised in recent discussions. Although the skeleton is almost complete, there is some reconstruction, which makes the low presacral vertebral number and the narrow proximal end of the femur, originally regarded as diagnostic characters, doubtful. All other diagnostic characters of the species are valid. Comparison to another thalattosaur species from the Xiaowa Formation, Xinpusaurus bamaolinensis, shows great similarities, but is limited due to its insufficient description. Hence, it cannot be excluded that X. kohi is a junior subjective synonym of X. bamaolinensis. However, the recent claim that X. kohi and X. bamaolinensis are synonyms of X. suni, the type species of the genus, is not supported by the new data. The description of X. bamaolinensis leaves many points unclear. Pending a re-description of that specimen that may allow for a more meaningful comparison, X. kohi should be allowed to stand.
The fossil of a sea reptile found two years ago in Alaska may be that of a previously unknown species, a scientist who was part of a team that discovered and excavated the remains said on Wednesday.
The creature, a kind of thalattosaur, swam in the ocean and crawled on land about 210 million years ago, said Pat Druckenmiller, a geologist and the earth-science curator of the University of Alaska's Museum of the North in Fairbanks.
"This does not look like anything else that's ever been discovered before," said Druckenmiller, who is studying the fossil.
The animal was 3 to 4 feet long with an extended tail to help propel it, an unusual skull and a very pointy beak, Druckenmiller said. It also had sharp teeth, but only at the back of its mouth.
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