What are dyrosaurs?

March 11th, 2013
Posted by: Whiting,Evan T

Dyrosaurs* (or more specifically dyrosaurid crocodyliforms) are relatives of modern crocodylians that superficially look very similar to their living cousins. Dyrosaurs first appeared in the Late Cretaceous Period during the Mesozoic Era (the so-called “age of dinosaurs”) about 70 million years ago, and persisted into the Cenozoic Era until approximately 35 million years ago. Most dyrosaurs were marine animals with long snouts used for catching fish in ancient oceans. However, some of the Cerrejón dyrosaurs differ from this typical anatomical and ecological pattern, possessing much blunter snouts used for eating prey items such as turtles and living entirely in freshwater. These unique members of the dyrosaur family are characterized by shortened snouts and a decreased (or completely absent) reliance on saltwater environments, which could help explain why this group survived the great K-T Extinction 65 million years ago that wiped out all non-avian dinosaurs and a number of other prominent reptile groups on land and in the seas. Ongoing research will hopefully shed more light on the unique paleoecologies and adaptations of the Cerrejón dyrosaurs, so keep your eyes peeled for new and exciting studies on these incredible animals!

*Note the spelling of this group (DYRosaurs) compared to a very different group of animals with a similar name (DRYosaurs). Dryosaurs are plant-eating ornithischian dinosaurs that lived during the Late Jurassic Period of the Mesozoic Era and are completely unrelated to dyrosaurs. A tiny misspelling can therefore make a BIG difference, as switching just two letters around in this case can mean the difference between a crocodile relative and a small, bipedal dinosaur!

If you’d like to learn more about dyrosaurs, here are a few suggested scientific publications worth checking out:

Jouve, S., B. Bouya, and M. Amaghzaz. 2008. A long‐snouted dyrosaurid (Crocodyliformes, Mesoeucrocodylia) from the Paleocene of Morocco: Phylogenetic and palaeobiogeographic implications. Palaeontology 51(2):281-294.

Hastings, A. K., J. I. Bloch, E. A. Cadena, and C. A. Jaramillo. 2010. A new small short-snouted dyrosaurid (Crocodylomorpha, Mesoeucrocodylia) from the Paleocene of Northeastern Colombia. Journal of Vertebrate Paleontology 30(1):139-162.

Hastings, A. K., J. I. Bloch, and C. A. Jaramillo. 2011. A new longirostrine dyrosaurid (Crocodylomorpha, Mesoeucrocodylia) from the Paleocene of north‐eastern Colombia: biogeographic and behavioural implications for New‐World Dyrosauridae. Palaeontology 54(5):1095-1116.