Saurosuchus: Beast of the Week

This week we will be checking out an amazing giant predator that was a neighbor to (and likely hunted) the earliest dinosaurs.  Make way for Saurosuchus galilei!

Saurosuchus was a meat-eating reptile that lived during the late Triassic period, about 231 million years ago, in what is now Argentina.  From snout to tail an adult would have measured about eighteen feet long, but some estimate this beast may have been able to grow even larger.  The genus name, Saurosuchus, translates to "Lizard Crocodile".   

Saurosuchus overpoweriing the early dinosaur, Herrerasaurus.  Watercolor reconstruction by Christopher DiPiazza.

Despite its appearance, Saurosuchus was not a dinosaur.  Rather, it was part part of a group of reptiles that was more closely related to modern crocodilians than to dinosaurs, called prestosuchidae.  Prestosuchids shared common ancestors with other pseudosuchians (broad group that includes modern crocodilians) like the poposauroids (like Shuvosaurus) and the rauisuchians (like Postosuchus). Prestosuchids were generally large land predators that usually walked on all fours and had fully erect posture with regards to their limbs, rather than a more sprawling posture, like modern lizards, or semi-sprawling, like modern crocodilians.  

Saurosuchus had a large robust skull with long, curved, serrated teeth, ideal for slashing through meat.  It had pronounced ridges on the back of its skull, implying there were large muscles attached there in life, and its neck vertebrae were relatively short and robust, which would have been an adaptation for absorbing impacts and strain in life.  This implies Saurosuchus was likely using its jaws and neck for rough activities, like overpowering struggling prey and/or forcefully dismantling carcasses as it ate.  

Saurosuchus skeletal mount on display at the Mori Arts Gallery in Japan.

Saurosuchus likely walked on all fours most of the time but probably could have reared up on its hind legs or even ran and walked short distances as a biped.  It also had rows of small bony plates, called osteoderms, running down the length of most of its body.  These may have been an adaptation for protecting the animal from bites from members of its own species, like chainmail armor, if there was any kind of intraspecies combat or cannibalism.  They also could have helped camouflage the animal better by breaking up its shape, or could have simply been for display.  (or maybe a combination of more than one of those things for all we know)

Saurosuchus was the largest and most powerful known predator from its environment, and likely could have hunted every other animal it coexisted with during its time on the planet.  Its kind would eventually go extinct and make way for more derived pseudosuchians, like the rauisuchians, and after that, dinosaurs.  

References 

Alcober, O. (2000). "Redescription of the skull of Saurosuchus galilei (Archosauria: Rauisuchidae)". Journal of Vertebrate Paleontology. 20 (2): 302–316.

Nesbitt, S.J. (2011). "The early evolution of archosaurs: relationships and the origin of major clades" (PDF). Bulletin of the American Museum of Natural History. 352: 1–292. 

Reig, O. A. (1959). "Primeros datos descriptivos sobre nuevos arcosaurios del Triásico de Ischigualasto (San Juan, Argentina)". Revista de la Asociación Geológica Argentina. 13(4): 257–27.

Sill, W. D. (1974). "The anatomy of Saurosuchus galilei and the relationships of the rauisuchid thecodonts". Bulletin of the Museum of Comparative Zoology. 146: 317–362.

Trotteyn, M.J.; Desojo, J.; Alcober, O. (2011). "Nuevo material postcraneano de Saurosuchus galilei (Archosauria: Crurotarsi) del Triásico Superior del centro-oeste de Argentina". Ameghiniana. 48 (1): 13–27.