Saturday, June 7, 2014

[Paleontology • 2014] Anthracosuchus balrogus • A New Blunt-snouted dyrosaurid (Crocodylomorpha, Mesoeucrocodylia) from the Palaeocene of Colombia

Titanoboa cerrejonensis and Anthracosuchus balrogus 

A new exceptionally brevirostrine dyrosaurid is described from the middle Palaeocene (58–60 million years ago) Cerrejón Formation, northeastern Colombia, based on four partial skulls and associated postcrania. This taxon is unique among dyrosaurids not only in skull shape, but also in having orbital tuberosities, and osteoderms that are dorsoventrally thick and unpitted, a trait otherwise unknown in Crocodylomorpha. Results from a cladistic analysis of Dyrosauridae suggest that the new taxon, together with Cretaceous–Palaeocene Chenanisuchus lateroculi from Africa and Cerrejonisuchus improcerus also from the Cerrejón Formation, are the most basal members of the family. Results from a biogeographic analysis indicate at least three independent dispersals of dyrosaurids from Africa to the New World occurred in the Late Cretaceous or early Palaeocene. Widely set orbits in the new taxon indicate a deviation from surface-based predation, characteristic of other dyrosaurids, to sub-surface predation, as in modern Gavialis. Tooth impressions found on turtle shells recovered from the same locality match well with teeth of the new taxon indicating possible predation. 

Keywords: Dyrosauridae, Crocodylomorpha, Palaeocene, Colombia, Cerrejón, biogeography

a new dyrosaurid crocodyliform has been named Anthracosuchus balrogus.

The specific epithet, balrogus, derives from the Balrog, the name of a ferocious fictional creature that appeared in J.R.R. Tolkien’s novel ‘The Lord of the Rings’ and dwelled deep in the middle-Earth ‘Mines of Moria.’

Anthracosuchus balrogus belongs to Dyrosauridae, a family of now-extinct crocodyliforms that lived from Late Cretaceous to the Eocene.

Originating in Africa, these crocodile-like reptiles swam across the Atlantic Ocean to South America about 75 million year ago. The family somehow survived the extinction event that wiped out the dinosaurs and persisted to become a top predator.

Four specimens of Anthracosuchus balrogus were unearthed in the Cerrejon coal mine, northern Colombia.

Alexander K. Hastings, Jonathan I. Bloch & Carlos A. Jaramillo. 2014. A New Blunt-snouted dyrosaurid, Anthracosuchus balrogus gen. et sp. nov. (Crocodylomorpha, Mesoeucrocodylia), from the Palaeocene of Colombia. Historical Biology: An International Journal of Paleobiology.