London: A scientist at Britain's University of Bath has identified a rare fossil of a dog-sized horned dinosaur from eastern North America -- also called the 'lost continent' of Appalachia.
About 66-100 million years ago, North America was split in two continents by a shallow sea called the Western Interior Seaway. Dinosaurs living in the western continent, called Laramidia, were similar to those found in Asia.
But few fossils of animals from Appalachia have been found because these areas were densely vegetated, making it difficult to discover and excavate fossils.
Nick Longrich, from the Milner Centre for Evolution based in the University of Bath's Department of Biology and Biochemistry, studied a fragment of a jaw bone kept in the Peabody Museum at Yale University. It turned out to be a member of the horned dinosaurs -- the Ceratopsia.
"Just as many animals and plants found in Australia today are quite different to those found in other parts of the world, it seems that animals in the eastern part of North America in the late Cretaceous period evolved in a completely different way to those found in the western part of what is now North America due to a long period of isolation," Longrich said.
"This adds to the theory that these two land masses were separated by a stretch of water, stopping animals from moving between them, causing the animals in Appalachia to evolve in a completely different direction, resulting in some pretty weird looking dinosaurs," Longrich added.
Ceratopsia was a group of plant-eating horned dinosaurs and the fossil studied by Longrich comes from a smaller cousin of the better known Triceratops, the leptoceratopsids. It was about the size of a large dog.
"Studying fossils from this period, when the sea levels were very high and the landmasses across the Earth were very fragmented, is like looking at several independent experiments in dinosaur evolution," Longrich said.
During late Cretaceous period (66-100 million years ago), many land masses -- eastern North America, Europe, Africa, South America, India, and Australia -- were isolated by water.
"Each one of these island continents would have evolved its own unique dinosaurs -- so there are probably many more species out there to find," Longrich added.
His study, published in the journal Cretaceous Research, highlights it as the first fossil from a ceratopsian dinosaur identified from the late Cretaceous period of eastern North America.