Saturday, 19 March 2011

Dinosaurs on the beach

The Ilha de Cajual, in the north of Brazil, is today a tranquil, restful, place. 95 million years ago it was a little more, shall we say, lively, with pterosaurs, giant turtles, and a 14 meter long, 7 tonne crocodile running towards you on it's hind legs!

Just recently researchers at the Universidade Federal do Rio de Janeiro have been displaying fossils of Oxalaia quilombensis, the largest animal of it's type ever found in Brazil. Actually, it wasn't really a crocodile, but a spinosaurid, a type of reptile with a huge crocodile like head that could walk on it's hind legs with a distinctive "sail" on it's back.

So what was life like for Sr. Oxalaia? Well, like most spinosaurids he probably spent most of his time in water - believe it or you can tell this by oxygen isotope analysis of their bones. His skull is characteristic of a predator of fish and small animals, not large prey, and in fact most Spinosaurids tend to be found with fish fossils The need for lots of small meals suggests he was probably quite an active hunter. The sail is a bit of a mystery though, some people say it helped spinosaurids control their temperature, some say it was for display, like a peacocks tail. Could be both of course.

A typical spinosaurid skull

Why "Oxalaia quilombensis"? Well, quilombensis refers to the quilombo, a group of runaway African slaves who were once established on the Isha de Cajual. And Oxalaia is named after Oxalá , one of the highest gods of the Yoruba religion, which started in Africa and spread to the Americas. This African motif is actually very appropriate as the spinosaurids originated there - north Africa and Brazil have so many reptile and fresh water fish fossils in common from this period that there must once have been a land bridge between the two. Oxalaia had plenty of cousins in Africa.

If you would like to know more,
Oxalaia quilombensis is properly described in...

Kellner, Alexander W.A.; Sergio A.K. Azevedeo, Elaine B. Machado, Luciana B. Carvalho and Deise D.R. Henriques (2011). "A new dinosaur (Theropoda, Spinosauridae) from the Cretaceous (Cenomanian) Alcântara Formation, Cajual Island, Brazil". Anais da Academia Brasileira de Ciências 83 (1): 99-108.

1 comment:

Anonymous said...

Very interesting!