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Ophthalmosaurian ichthyosaurs from Middle Jurassic of Argentina

From: Ben Creisler

A new online paper:

Marta S. Fernández and Marianella Talevi (2013)
Ophthalmosaurian (Ichthyosauria) records from the Aalenian–Bajocian of
Patagonia (Argentina): an overview.
Geological Magazine (advance online publication)
DOI: http://dx.doi.org/10.1017/S0016756813000058

The oldest ophthalmosaurian records worldwide have been recovered from
the Aalenian–Bajocian boundary of the Neuquén Basin in Central-West
Argentina (Mendoza and Neuquén provinces). Although scarce, they
document a poorly known period in the evolutionary history of
parvipelvian ichthyosaurs. In this contribution we present updated
information on these fossils, including a phylogenetic analysis, and a
redescription of ‘Stenopterygius grandis’ Cabrera, 1939. Patagonian
ichthyosaur occurrences indicate that during the Bajocian the Neuquén
Basin palaeogulf, on the southern margins of the Palaeopacific Ocean,
was inhabited by at least three morphologically discrete taxa: the
slender Stenopterygius cayi, robust ophthalmosaurian Mollesaurus
periallus and another indeterminate ichthyosaurian. Rib bone tissue
structure indicates that rib cages of Bajocian ichthyosaurs included
forms with dense rib microstructure (Mollesaurus) and forms with an
‘osteoporotic-like’ pattern (Stenopterygius cayi).