Wednesday 9 April 2014

A freshwater Coccolepidid Fish from the Late Jurassic of Patagonia.

In 1943 palaeontologist Alejandro Bordas described a number of fossil freshwater Fish from a location in the Río Chubut area of Argentine Patagonia, which he believed to have originated in the Cretaceous in a paper in the journal Physis. Since this time the date estimates of this locality has altered somewhat, and they are now believed to be of Late Jurassic origin, making them of particular interest, as Jurassic freshwater Fish are poorly represented in the fossil record. As well as Fish this site has produced Crocodiles, Dinosaurs and Temnospondyl Amphibians.

This site has yielded several specimens of a Coccolepidid Fish, a member of a group of extinct, non-Teleost Actinopterygian Fish thought to be related to the modern Acipenseriformes (Sturgeon and Paddlefish), which Boras placed in the genus Oligopleurus, which has been used by Louis Agassiz to describe similar Fish from the Solnhoffen Limestone, and gave them the specific name groeberi. These Fish have been moved to other genera twice since this time, as new specimens and data have become available.

In a paper published in the journal Palaeontologica Electronica on 30 January 2013, Adriana López-Arbarello of the Bayerische Staatssammlung für Paläontologie und Geologie in Munich and the Museo Paleontológico Egidio Feruglio in Trelew, Argentina, Emilia Sferco of the Laboratorio de Paleontología Evolutiva de Vertebrados at the Departamento de Geología at the Universidad de Buenos Aires and Oliver Rauhut, also of the Bayerische Staatssammlung für Paläontologie und Geologie, describe several new specimens of this fish, and redescribe the species on the basis of these.

Original specimens of the Coccolepidid Fish described by Boras as ‘Oligopleurus groeberi’ from the Río Chubut area of Argentine Patagonia. López-Arbarello et al.(2013).

Based upon these new specimens López-Arbarello et al. conclude that these Fish are sufficiently distinct to merit the erection of a separate genus to describe them, giving it the name Condorlepis, which derives from the village Cerro Cóndor, which is the closest settlement to the locality where the fish were found, and ‘lepis’, which is Greek for the scale of a Fish.

Condorlepis groeberi is a slender Coccolepidid Fish with small, tubercles covering the dermal bones on the roof of its skull, jaw and scales. Its body is deepest around the head, tapering towards the tail. It has a number of anatomical features seen in Acipenseriforme Fish, but not all of the features needed to assign a fish to this group are present, strongly supporting a close relationship between the Coccolepidids and Acipenseriformes.

One of the new specimens of Condorlepis groeberi. López-Arbarello et al.(2013).

See also…
 An Ichthyodectiform Fish from the Early Cretaceous of Queensland, Australia.

 A Flying Fish from the Middle Triassic of Guizhou Province, China.

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