Paleontologists identify 12 new dinosaur teeth in the formation of Nenjiang in China

A recent study by Keifeng Yu and his colleagues, published in ACTA Geologica Sinicadescribes the discovery and identification of 12 new dinosaurs of the formation of Nenjiang from the upper Cretaceous. Cretaceous dinosaurs have been identified as five different taxa, including tyrannosaurids, dromaeosaurins, véloiraptorines, Hadrosauroïdes and Titanosaures.

In addition to providing information on the previously identified dinosaurs of the Songliao basin, three new ones have been identified, extending the paleogeographic range of these taxa.

According to Dr. Wenhao Wu, one of the paleontologists involved in the study, the Songliao basin was chosen for the study due to the possibility that many dinosaur fossils are probably not discovered.

Dr. Wu is developing, “the Songliao basin, one of the largest continental sedimentary basins of the Mesozoic of East Asia, welcomes a continuous sequence of continental strata of the upper Cretaceous. This makes it an exceptional location to study the continental climate change in Cretaceous, paleoenvironal and associated biote.

“However, the fossil dinosaurs’ files in the Songliao basin are relatively rare. The remains of previously documented dinosaurs come mainly from the quarter -update (Cenomanian) quarter formatia, leaving a significant gap in the fossil record for the layers of the upper Cretaceous of the basin.

“On the other hand, abundant fossils of dinosaurs of the upper Cretaceous have been discovered in regions such as Mongolia and North America.

The 12 fossils of dinosaurs which were part of the study were found in a thin layer, only about 10 cm thick. Although representing isolated teeth, they could only be identified with taxa, not species.

“Among vertebrates, mammals can often be identified in terms of gender or species according to dental characteristics due to their complex dental structures. On the other hand, the teeth of dinosaurs and other vertebrate groups, whose morphology is relatively simple, have different groups within the same family with very similar dental forms.

Four of the teeth were identified as belonging to carnivorous theropods. Among these, two belonged to Tyrannosauridae and were identified on the basis of their unique combination of dental characteristics, including their high robust appearance with chisel-type denticles.

The two remaining teeth have been identified as Dromaeosaruinae and Velociraptorinae, a subfamily in Dromaeosaurinae.

While the Dromaeosaurides have been recovered in Nong’an, China, the tooth of the Nenjiang Bei’an site is located more than 500 km northeast and considerably extends the known range of taxa in China.

Likewise, the Veloceraptorid tooth is the first to be discovered in the formation of Nenjiang.

The majority of teeth came from herbivorous sauropods. The geographic distribution of the Sauropods strongly depended on the temperature, preferring warmer climates compared to theropods.

On the northern continents, the Sauropods are mainly in warmer altitudes, with a few exceptions near fossils found at higher altitudes.

Three of these Sauropods teeth belonged to Titanosauria. These teeth are unique not only to be the first of this taxon to be found in the formation of Nenjiang, but also for having been found in the Songliao basin, which is located at a relatively high altitude and prolongs the most northern presence of Titanosaurs at the Campanian era.

The five remaining teeth belonged to various Hadrosauridae individuals. During the evolution of the Hadrosaurides, there was a simplification in their teeth. Their dental crowns have become narrower, the main ridge moved to a more central location, and the accessory ridges have decreased from four to one or not.

The teeth found by Yu and his colleagues all had a slightly off -center crest and only one or two small accessory ridges. This indicated that these teeth belonged to non -hadrosaurid Hadrosauroids.

Hadrosauroids were initially an abundant and diversified group, found through the old continents of Laurasia and certain regions of Gondwana. However, primitive Hadrosauroids experienced a significant decrease in the number at the end of the Cretaceous period.

Specimens of non -hadrosaurid Hadrosauroids had never been found before in the Songliao basin.

However, the discovery of these teeth expands our understanding of the distribution and the evolutionary trajectory of these dinosaurs at the beginning of the Campanian.

© 2025 Science X Network