Three fossilized teeth from a previously unknown species of non-tyrannosaurid tyrannosauroid dinosaur have been unearthed in northeastern Thailand by a team of paleontologists from Kasetsart University, Mahasarakham University and Sirindhorn Museum.
Paleoenvironmental reconstruction of the Late Jurassic Phu Kradung Formation of northeastern Thailand. Image credit: Chatcharin Somboon.
“Tyrannosauroidea is a clade of theropods, including well-known carnivorous dinosaurs such as Tyrannosaurus rex from the Late Cretaceous of North America,” said Dr. Chatchalerm Ketwetsuriya of Kasetsart University and colleagues.
“They primarily inhabited in the supercontinent Laurasia throughout the Middle Jurassic to Late Cretaceous.”
“The earliest-known members of Tyrannosauroidea have been discovered in the Middle Jurassic of Europe and Asia, suggesting the origin of this theropod group within Eurasia.”
“Tyrannosauroids were distributed from the Late Jurassic to the Late Cretaceous of Asia, with most Asian tyrannosaurs found in China and Mongolia.”
The three isolated teeth of a tyrannosauroid dinosaur examined by the team were recovered from the Phu Noi locality, Kham Muang district, Kalasin province, northeastern Thailand.
The specimens date back to the Tithonian age of the Jurassic period, about 145 million years ago.
Isolated teeth of basal tyrannosauroid dinosaur from the Phu Noi locality, Thailand. Image credit: Chowchuvech et al.
“The Phu Noi locality is renowned as one of the most prolific Mesozoic vertebrate deposits in Southeast Asia,” the paleontologists said.
“Numerous species have been unearthed from this site, including freshwater sharks, ray-finned fishes, lungfishes, amphibians, turtles, crocodyliforms, pterosaurs, and dinosaurs.”
“Within the Phu Noi locality, three dinosaur species have been identified, comprising a metriacanthosaurid theropod, a mamenchisaurid sauropod, and the basal neornithischians Minimocursor phunoiensis.”
“Three of those theropod teeth from the Phu Noi locality show unique dental features that can be distinguished from previous discovered metriacanthosaurid theropod, including the lateral teeth with mesiolingual twisted mesial carinae extending above the cervix line and braided enamel surface texture,” they added.
“Morphological examination along with cladistics and morphometric analyses show that these isolated teeth exhibit the synapomorphies of basal tyrannosauroids, closely related to Guanlong wucaii and Proceratosaurus bradleyi from the Jurassic period.”
“This discovery notes the first report of Tyrannosauroidea in the Jurassic of Southeast Asia and contributes to the knowledge paleoecology of the lower Phu Kradung Formation, as well as paleobiogeo-graphical distribution of tyrannosauroids during the Late Jurassic,” they concluded.
“Furthermore, this study sheds light on the possibility to finding new Thai dinosaur species in future excavations and studies.”
The study was published in the journal Tropical Natural History.
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W. Chowchuvech et al. 2024. The First Occurrence of a Basal Tyrannosauroid in Southeast Asia: Dental Evidence from the Upper Jurassic of Northeastern Thailand. Tropical Natural History 24 (1): 84-95
