Siamraptor suwati is a predatory dinosaur that lived 120 million years ago

Reconstruction of Siamraptor suwati with the bones available (Image courtesy Chokchaloemwong et al, doi: 10.1371/journal.pone.0222489)
Reconstruction of Siamraptor suwati with the bones available (Image courtesy Chokchaloemwong et al, doi: 10.1371/journal.pone.0222489)

An article published in the journal “PLOS ONE” reports the identification of a new species of dinosaur that lived in today’s Thailand around 120 million years ago, in the Cretaceous period, which was named Siamraptor suwati. It belongs to the group of carcharodontosaurian, in turn part of the larger group of allosaurs, carnivorous dinosaurs that were super-predators in their ecosystems. This new species, like its closest relatives, had teeth similar to those of sharks and can provide information on the global spread of these dinosaurs.

Carcharodontosaurians (Carcharodontosauria) were among the major predators during most of the Cretaceous period. Over the decades their classification has been modified following the discovery of new fossils that led to redefining the relationships between various genera. A team of researchers added a new species to that group after examining some bones discovered in a campaign of excavations in Thailand that went on between 2007 and 2009.

A partial skull and other bones discovered in the Khok Kruat Formation were attributed to at least four specimens of a species that was previously unknown by the team led by Dr. Duangsuda Chokchaloemwong of the Nakhon Ratchasima Rajabhat University. The characteristics of those fossils convinced the researchers that it was a carcharodontosaurian quite different from those known to create a new genus. They named the species Siamraptor suwati and, despite the limited amount of bones discovered, it’s the most complete of a dinosaur in that group.

Various characteristics of Siamraptor suwati have been deduced based on those of other species of carcharodontosaurians. Probably its length was almost 8 meters and it had to be fast and fierce when it hunted its prey. The dinosaurs of that group had teeth similar to those of sharks, sharp as knives, but in the discovered fossils attributed to the new species only very few teeth were found.

The importance of the discovery of Siamraptor suwati lies in the fact that the examination of the fossils discovered indicates that it represented one of the oldest evolutionary diversifications with respect to the rest of its group. It’s also the first species of carcharodontosaurian discovered in south-east Asia but other fossils belonging to that group dating back more or less to the same period have been discovered in Europe and Africa. This confirms that at the beginning of the Cretaceous period those dinosaurs were already widespread and that they were already having considerable success. Allosaurs belonging to other groups were also widespread in the world, even in Asia.

The history of allosaurs is known much better in its final part. Before the great extinction that eliminated all non-avian dinosaurs, allosaurs were already in decay and at that point other dinosaurs like the famous T. rex had become dominant. Findings like that of Siamraptor suwati are important to understand the beginning of that story and confirm that in today’s Thailand there are very interesting fossils.

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