Tuesday 20 August 2013

Giant fossil Sea Snakes from the early Eocene of Morocco.

The Sea Snake Palaeophis maghrebianus was first described by Camille Arambourg from the early Eocene phosphate beds of Morocco in 1952, though like many fossil Snakes it has been known only from disarticulated vertebrae. This is due to the lightly mineralized, easily disarticulated skeletons of Snakes, which tends to result in fossil Snakes, where they are found at all, being poorly preserved and fragmentary.

In a paper published in the journal Palaeontology on 13 February 2013, a team of scientists led by Alexandra Houssaye of the Département Histoire de la Terre at the Muséum National d’Histoire Naturelle in Paris and the Steinmann Institut für Geologie, Paläontologie und Mineralogie at Universität Bonn describe several new specimens assigned to Palaeophis maghrebianus, including two incomplete skeletons, and inferences about the living animal made from these.

Partially articulated fossil Palaeophis maghrebianus from the Grand Daoui area in the Oulad Abdoun basin of Morocco. Hossaye et al. (2013).

These new specimens are considerably larger than the previous material, suggesting that Palaeophis maghrebianus may have been larger than any living Snake. The largest vertebrae from the new specimens are around 3.3 cm in length, compared to around 1.9 cm in a 5.9 m Reticulated Python (Python reticulatus). In addition the vertebrae show signs of a denser vascular network than that seen in either Green Anacondas (Eunectes murinus), which can reach 7 m, or Reticulated Pythons, which can reach 9 m, suggesting that Palaeophis maghrebianus was able to grow faster, and larger, than either of these Snakes.

Second specimen of Palaeophis maghrebianus from the Grand Daoui area in the Oulad Abdoun basin of Morocco. Hossaye et al. (2013).

In addition Palaeophis maghrebianus appears to be less flattened ventrally than modern Sea Snakes, and shows poor development of other adaptations to an aquatic lifestyle, suggesting that it was less well adapted to fully marine environments, probably living closer to shore and spending at least some of its time on land. The deposits where the fossils were found are interpreted as having been laid down in an estuarine or shallow marine environment, possibly with the presence of mangrove swamps.

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