Fossilized Teeth Highlight Theropod Dinosaur Diversity in Prehistoric East Sussex | Sci.News
Several groups of meat-eating dinosaurs — tyrannosaurs, spinosaurs and members of the Velociraptor family — stalked what is now the Bexhill-on-Sea region in East Sussex, England, approximately 135 million years ago (Early Cretaceous epoch), according to new research.
An Early Cretaceous floodplain in southeastern England, 135 million years ago: a spinosaur (center) takes over the carcass of an ornithopod, much to the annoyance of the smaller tyrannosaurs (left) and dromaeosaurids (bottom right). Image credit: Anthony Hutchings.
“Meat-eating dinosaurs are rare in the Cretaceous sediments of southern England,” said Dr. Chris Barker, a paleontologist at the University of Southampton.
“Usually, Isle of Wight dinosaurs attract most of our attention. Much less is known about the older Cretaceous specimens recovered from sites on the mainland.”
In the research, Dr. Barker and colleagues examined an assemblage of theropod teeth from the Wadhurst Clay Formation, mostly collected from the Ashdown Brickworks locality near Bexhill, East Sussex.
Theropod teeth are complex, and vary in size, shape, and in the anatomy of their serrated edges.
The authors used several techniques to analyze the fossils, including phylogenetic, discriminant and machine learning methods.
“Dinosaur teeth are tough fossils and are usually preserved more frequently than bone. For that reason, they’re often crucial when we want to reconstruct the diversity of an ecosystem,” Dr. Barker said.
“Rigorous methods exist that can help identify teeth with high accuracy.”
“Our results suggest the presence of spinosaurs, mid-sized tyrannosaurs and tiny dromaeosaurs — Velociraptor-like theropods — in these deposits.”
Theropod teeth from the Wadhurst Clay Formation. Scale bar – 10 mm. Image credit: Barker et al., doi: 10.1002/spp2.1604.
The discovery of tyrannosaurs is particularly notable, since the group hasn’t previously been identified in sediments of this age and region.
These tyrannosaurs would have been around a third of the size of their famous cousin Tyrannosaurus rex, and likely hunted small dinosaurs and other reptiles in their floodplain habitat.
“Assigning isolated teeth to theropod groups can be challenging, especially as many features evolve independently amongst different lineages,” said Lucy Handford, a Ph.D. student at the University of York.
“This is why we employed various methods to help refine our findings, leading to more confident classifications.”
“It’s highly likely that reassessment of theropod teeth in museum stores elsewhere will bring up additional discoveries.”
“Southern England has an exceptionally good record of Cretaceous dinosaurs, and various sediment layers here are globally unique in terms of geological age and the fossils they contain,” said Dr. Darren Naish, a paleontologist at the University of Southampton.
“These East Sussex dinosaurs are older than those from the better-known Cretaceous sediments of the Isle of Wight, and are mysterious and poorly known by comparison.”
“We’ve hoped for decades to find out which theropod groups lived here, so the conclusions of our new study are really exciting.”
The findings appear in the journal Papers in Palaeontology.
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Chris T. Barker et al. 2024. Theropod dinosaur diversity of the lower English Wealden: analysis of a tooth-based fauna from the Wadhurst Clay Formation (Lower Cretaceous: Valanginian) via phylogenetic, discriminant and machine learning methods. Papers in Palaeontology 10 (6): e1604; doi: 10.1002/spp2.1604
