A partially preserved femur from the Kem Kem beds of Morocco has revealed the size of a large-bodied theropod dinosaur called abelisaur.
An artist’s drawing of the abelisaur. Image credit: Davide Bonadonna / Imperial College London.
Abelisaurs (Abelisauridae) were a group of meat-eating dinosaurs, characterized by very small forelimbs, a short deep face, small razor sharp teeth, and powerful muscular hind limbs.
Paleontologists suspect these ancient predators were also covered in fluffy feathers.
The abelisaur in the current study lived around 95 million years ago (Cretaceous period) in what is now North Africa, which at that time was a lush savannah criss-crossed by rivers and mangrove swamps.
“This ancient tropical world would have provided the abelisaur with an ideal habitat for hunting aquatic animals like turtles, crocodiles, large fish and other dinosaurs,” said Alfio Alessandro Chiarenza from Imperial College London and Andrea Cau from the University of Bologna’s Geological and Paleontological Museum.
Abelisaur femur. Abbreviations: gt – greater trochanter; iMie – insertion for the M. iliofemoralis externus; fn – femoral neck; s – shallow sulcus. Scale bars – 5 cm. Image credit: Alfio Alessandro Chiarenza / Andrea Cau.
By studying the fossilized dinosaur bone from Morocco, the paleontologists deduced that this abelisaur may have been 29.5 feet (9 m) long and weighed about 2,000 kg.
“Fossilized femora are useful for paleontologists to study because they can determine the overall size of a dinosaur,” the scientists explained.
“This is because femora are attached to the thigh and tail muscles and have scars, or bumps, which tell scientists where the ligaments and muscles were attached to the bone and how big those muscles and ligaments would have been.”
“Smaller abelisaur fossils have been previously found by paleontologists, but this find shows how truly huge these flesh eating predators had become,” said Chiarenza, who is the lead author of a paper in the journal Peer J.
“Their appearance may have looked a bit odd as they were probably covered in feathers with tiny, useless forelimbs, but make no mistake they were fearsome killers in their time.”
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Chiarenza A.A. & Cau A. 2016. A large abelisaurid (Dinosauria, Theropoda) from Morocco and comments on the Cenomanian theropods from North Africa. PeerJ 4: e1754; doi: 10.7717/peerj.1754
