New species of shark discovered in Argentina!

Researchers from Buenos Aires have discovered an exciting array of fossilised selachian teeth, including a new species.

The fossilised teeth were collected from the Calafate Formation in Argentina and were discovered during the preparation of another fossil of a very large elasmosaurid plesiosaur. After conducting a thorough analysis of squaliform phylogeny and evolution, the authors were able to ascertain that some of the teeth discovered had never been described before and comprised a new species of the genus Protosqualus: Protosqualus argentinensis.  

Images of fossilised P. argentinensis teeth. Image courtesy of Sergio Bogan at Fundación de Historia Natural Félix de Azara Departamento de Ciencias Naturales y Antropología CEBBAD - Universidad Maimónides

The exciting news doesn't end there, however. Not only did the authors describe a new species, but this is also the first time any member of the genus Protosqualus has been discovered in South America. Previous examples of this genus have been noted from Russia, Australia and India and it has been suggested that this species would have had an anti-tropical distribution which is supported by the findings here.

The authors also discovered teeth belonging to the previously described Hexanchiform Notidanodon dentatus. Whilst today most Hexanchiform species are extinct, were it alive today Notidanodon dentatus would have a handful of living relatives in the cowsharks and frilled sharks. Interestingly previous examples of this extinct species have also been found in association with an elasmosaurid plesiosaur suggesting that this species may have been a scavenger opportunistically taking advantage of these marine reptiles.

Fossilised N. dentatus teeth. Image courtesy of Sergio Bogan at Fundación de Historia Natural Félix de Azara Departamento de Ciencias Naturales y Antropología CEBBAD - Universidad Maimónides

What's even more exciting (yes - there's more!) is the placement of these species. As noted in the paper, the Northern Patagonian fossil record is dominated by Lamniform (living species of which would include mackerel sharks like the Great White) and ray teeth, whilst the Southern Patagonia fossil record is comprised of cold water species suggesting that there was little species overlap in the late Cretaceous oceans around South America.

Whilst these species may be long extinct, piecing together their life history from the fossil record will help us to understand modern day sharks better and provides insight into how the prehistoric oceans may have looked.

Sergio Bogan, Federico L. Agnolin & Fernando E. Novas (2016) New selachian records from the Upper Cretaceous of southern Patagonia: paleobiogeographical implications and the description of a new taxon, Journal of Vertebrate Paleontology http://www.tandfonline.com/doi/full/10.1080/02724634.2016.1105235