Fossilized teeth provide new insights into dinosaurs in South China

BEIJING -- Four large dinosaur teeth unearthed in Guangdong province have been confirmed by Chinese scientists to be from the Tyrannosauroidea group dating back 70 million to 66 million years ago, making it the southernmost fossil evidence of this taxon in China.

The four teeth can be traced back to the Maastrichtian stage, the most recent phase of the Late Cretaceous period. Three of these specimens were discovered in 2010 in the city of Sihui by an amateur fossil enthusiast who later donated them to a local museum. The other tooth was found at a construction site in the provincial capital Guangzhou in 2020 by one researcher and is currently housed in the collection of Sun Yat-sen University.

The three teeth discovered in Sihui were remarkably well-preserved, boasting crowns exceeding 6 cm in length, and the tooth fragment found in Guangzhou is 3.3 cm long. However, all four fossils exhibited similar morphological characteristics, including gently serrated edges and smooth enamel.

These features are consistent with those of Tyrannosauroidea teeth and distinguish them from those observed in other large carnivorous dinosaurs, according to a research article recently published in the international journal Cretaceous Research.

Lead author Xing Lida, an associate professor at China University of Geosciences (Beijing), said that Tyrannosauroidea is a bipedal predatory dinosaur exhibiting significant variations in body size, making it the dominant group during the middle and late Cretaceous period. The Tyrannosaurus rex, measuring over 12 meters in length, represents the largest and most renowned species within the Tyrannosauroidea.

However, compared with other Tyrannosauroidea teeth found in China, the sizes of the four fossils are small.

The research team is facing difficulties in accurately estimating the body lengths of the teeth owners due to the inability to pinpoint the exact locations of the teeth in the mouth.

A conservative estimate suggests that the teeth owners measure at least five to six meters in length, according to Wang Donghao, a member of the research team at China University of Geosciences (Beijing).

The lack of records of large carnivorous dinosaur fossils in South China has been addressed with the fossil teeth discovery, which "fills a prominent ecological gap for the region and expands the confirmed range of the tyrannosauroids," the researchers noted in the study.

Together with previous records of fossilized dinosaur eggs found in the region, the discovery of the teeth also suggests that a variety of dinosaur species thrived in southern China before the mass extinction at the end of the Cretaceous period, Xing said.