Dinosaur fossils belonging to T. rex cousins found in Morocco

These T. rex relatives had tiny bulldog-like snouts and significantly shorter arms. 
Mrigakshi Dixit
Fossils have been found of several types of abelisaur showing the diversity of dinosaurs in Morocco at the end of the Cretaceous period.
Fossils have been found of several types of abelisaur showing the diversity of dinosaurs in Morocco at the end of the Cretaceous period.

Andrey Atuchin 

Paleontologists uncovered two new species related to Tyrannosaurus rex in Morocco that lived during the late Cretaceous period, just before the massive asteroid wiped out the dinosaurs.

Like T. rex, these relatives had tiny bulldog-like snouts and significantly shorter arms. 

These newly discovered species are members of the Abelisauridae, a carnivorous dinosaur family that ruled parts of the southern hemisphere some 66 million years ago.  

As per the official release from the University of Bath, these new species of dinosaurs were “counterparts” to the tyrannosaurs of the Northern Hemisphere.

Both newly found species have yet to be named. 

Examination of fossil remains

One species' fossil remnants contain a foot bone, indicating that the creature was around eight feet (two and a half meters) long. 

The second new species' remains consist of a shin bone, implying that the dinosaur grew to be about 15 feet (five meters) long.

The two new species coexisted with Chenanisaurus barbaricus, a considerably bigger abelisaur. 

According to the official statement, the findings imply that dinosaurs were diversified in Africa right before their terrible mass extinction by a massive asteroid at the end of the Cretaceous period 66 million years ago. 

The mass extinction wiped out 90 percent of all living species, including mosasaurs, plesiosaurs, pterosaurs, and ammonites. The impact crater on the Yucatan peninsula serves as proof of this global extinction. 

The authors highlight that a massive asteroid impact has been connected to the extinction of these majestic dinosaurs; however, it has been suggested that dinosaurs were already in decline. 

“The end of the Cretaceous in western North America definitely seems to become less diverse at the end. But that’s just one small part of the world. It’s not clear that you can generalize from the dinosaurs of Wyoming and Montana to the whole world,” said Nick Longrich, from the Milner Centre for Evolution at the university, who led the study, in an official release. 

“It also grew colder near the end, so it might not be surprising if dinosaurs at higher latitudes became less diverse. But we don’t know much about dinosaurs from lower latitudes,” added Longrich. 

The diverse dinosaur fossil site 

The fossilized bones of the two dinosaur species were discovered in Morocco's Sidi Daoui and Sidi Chennane, on the outskirts of Casablanca. 

The area is known for being a treasure trove of various dinosaur fossils from the late Cretaceous period, which signaled the end of the dinosaur era.  

Digging at this location often yields fossils of various new species from the lost ancient world.

“What’s surprising here is that these are marine beds. It’s a shallow, tropical sea full of plesiosaurs, mosasaurs, and sharks. It’s not exactly a place you’d expect to find a lot of dinosaurs. But we’re finding them,” said Longrich. 

Previously, fossil specimens of five distinct dinosaur species — a tiny duckbill dinosaur dubbed Ajnabia, a long-necked titanosaur, and the huge abelisaur Chenanisaurus — were discovered at this location. 

Longrich added: “We have other fossils as well, but they’re currently under study. So we can’t say much about them at the moment, except that this was an amazingly diverse dinosaur fauna.”

The details of the new species have been reported in the journal Cretaceous Research

Study abstract:

The end of the Cretaceous saw the evolution of endemic dinosaur faunas on different landmasses, driven by continental fragmentation. Understanding the evolution of these biogeographic patterns is important for understanding the evolution of Mesozoic ecosystems. However, the faunas of the southern land masses remain understudied relative to the intensively sampled dinosaur faunas of western North America and Asia. In particular, the latest Cretaceous of Africa remains largely unknown, with only a handful of taxa reported so far, including titanosaurian sauropods, the lambeosaurine Ajnabia odysseus, and the large abelisaurid theropod Chenanisaurus barbaricus. We report two new abelisaurid fossils from the upper Maastrichtian phosphates of the Ouled Abdoun Basin, in northern Morocco. The first is the tibia of a medium-sized abelisaurid from Sidi Chennane, with an estimated length of ∼5 m. The tibia has a strongly hooked cnemial crest resembling that of the South American Quilmesaurus and Aucasaurus. The highly rugose bone texture suggest the animal was mature, rather than a juvenile of the larger Chenanisaurus. The second is a small right second metatarsal from Sidi Daoui. The metatarsal measures 190 mm in length, suggesting a small animal, ∼2.6 m in length.

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