Spectrovenator: Beast of the Week

 This week we will be showcasing a dinosaur with a particularly spooky name.  Check out Spectrovenator ragei!

Spectrovenator was a meat-eating dinosaur that lived in what is now Brazil during the early Cretaceous period, about 125 million years ago.  From snout to tail it only measured about 2.5 meters (8 feet) long.  It's genus name translates to "Ghost hunter" in reference to how it was found during the month of October (Halloween!) plus the fact that it was found serendipitously while paleontologists were excavating the bones of a larger dinosaur, called Tapuisaurus. Almost as if the Spectrovenator's bones were hiding...like a ghost.

Life reconstruction of Spectrovenator in watercolors by Christopher DiPiazza

Spectrovenator belonged to a group of theropod dinosaurs called ceratosaurs, known first appearing on the fossil record during the early Jurassic period, almost 200 million years ago, and persisted all the way to the end of the Cretaceous period, 66 million years ago.  Ceratosaurs were particularly diverse group of theropods, evolving a wide variety of shapes and sizes during the long time they existed on earth.  Spectrovenator was specifically part of the abelisaurid family of ceratosaurs, known for having extremely short snouts and tiny arms.  Their arms were so small, in fact, that they lacked the ability to use their fingers, which were reduced to mere stubs in most cases.  Later abelisaurids, like Carnotaurus, would lose the ability to bend their elbows, having small stumps for arms that could only swivel on one joint at the torso.  Spectrovenator was an earlier form of the abelisaurid group, appearing to be a somewhat transitional form between earlier Jurassic forms and later Late Cretaceous forms.  For instance, its snout was relatively short compared to most theropods, but not as short as the almost bulldog-like face of its later relatives, like Carnotaurus.

Spectrovenator had long, curved teeth that were serrated, like steak-knives on the anterior edge, ideal for slicing through meat.  Its lower jaw was relatively slender, implying it had a weaker bite force than its later relatives, possibly specializing in snatching smaller prey or slashing, rather than crushing or overpowering its prey.  The top of its skull, over the snout and eye sockets, possessed a rough texture, implying there could have been bony keratin there in life, possibly some sort of ornamentation for display.  

Skull of Spectrovenator from the paper by Zaher et. al. referenced below.

Spectrovenator also had relatively long and slender legs, implying it would have been a fast runner when alive.  This would have been helpful for a small predator for running down prey, and possibly escaping even larger meat-eaters it shared its environment with.  

References

Hendrickx, Christophe; Mateus, Octávio (2014). "Abelisauridae (Dinosauria: Theropoda) from the Late Jurassic of Portugal and dentition-based phylogeny as a contribution for the identification of isolated theropod teeth". Zootaxa. 3759: 1–74.

Senter, P. (2010). "Vestigial skeletal structures in dinosaurs". Journal of Zoology. 280 (1): 60–71.

Zaher, H.; Pol, D.; Navarro, B.A.; Delcourt, R.; Carvalho, A.B. (October 2020). "An Early Cretaceous theropod dinosaur from Brazil sheds light on the cranial evolution of the Abelisauridae" (PDF). Comptes Rendus Palevol. 19 (6): 101–115.