Paleontologists have announced the discovery of a new species in the tyrannosaurid dinosaur genus Labocania, based on a partial skeleton found in Coahuila, Mexico.
Labocania anomala. Image credit: Karkemish / CC BY-SA 3.0.
The newly-discovered dinosaur species lived in what is now Mexico during the Campanian age of the Cretaceous period, some 72.5 million years ago.
Named Labocania aguillonae, the ancient predator was at least 6.3 m (21 feet) in length — relatively small by tyrannosaur standards.
“Tyrannosaurs dominated as apex predators in the Late Cretaceous of western North America (Laramidia),” said Dr. Héctor Rivera-Sylva of the Museo del Desierto and Dr. Nicholas Longrich from the University of Bath.
“During the Cenomanian and Turonian ages (100 to 89 million years ago), tyrannosaurs were relatively small, unspecialized, and low in diversity.”
“By the Campanian age (83 million years ago), however, they had undergone a major radiation, diversifying and producing larger, more specialized forms.”
“The Labocania clade dominated southern Laramidia at a time when the north was dominated by daspletosaurins and albertosaurines,” they added.
“The high endemism seen in tyrannosaurids is remarkable, given that modern apex predators have large geographic ranges and hints that the diversity of carnivorous dinosaurs has been underestimated.”
The highly fragmentary and weathered partial skeleton of Labocania aguillonae was found in the upper part of the Cerro del Pueblo Formation at La Parrita, 54 km west of Saltillo, Coahuila, Mexico.
The dinosaur’s anatomy suggests it represents a tyrannosaurine, with affinities with Teratophoneini, and specifically Labocania anomala.
“Labocania aguillonae is closely related to Labocania anomala, Bistahieversor sealeyi, and Teratophoneus curriei,” the paleontologists said.
“It adds to the diversity of the Cerro del Pueblo Formation and shows that endemicity existed within tyrannosaurs in the Late Campanian, with distinct species and clades inhabiting the northern Great Plains in the north and the American Southwest and Mexico in the south.”
“Given the limited geographic sampling, many tyrannosaur species likely remain undiscovered.”
“Competition between species likely helped to enforce endemism among dinosaurs.”
“Why large dinosaurs seem to have such unusually high levels of endemism compared to modern mammals remains unclear.”
The discovery is described in a paper published this week in the journal Fossil Studies.
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Héctor E. Rivera-Sylva & Nicholas R. Longrich. 2024. A New Tyrant Dinosaur from the Late Campanian of Mexico Reveals a Tribe of Southern Tyrannosaurs. Foss. Stud 2 (4): 245-272; doi: 10.3390/fossils2040012