Two enormous heads arrayed with horns are the first striking images of a pair of newly discovered dinosaur species announced today.
The ornate heads belong to Kosmoceratops richardsoni and the Utahceratops gettyi, two species of dinosaur found in southern Utah's Grand-Staircase-Escalante National Monument .
The research team describe them in the online journal PLoS ONE.
Both Kosmoceratops and Utahceratops were plant-eating inhabitants of the 'long lost continent' of Laramidia about 76 million years ago, says Dr Eric Roberts, one of the scientists involved in the discovery, who is now based at James Cook University in Townsville.
"The two dinosaurs are relatives of the famous Triceratops but they are about 10 million years older," says Roberts.
He says it's particularly exciting because they are among the first of many dinosaur discoveries being made in the region.
"The area we're working in is yielding a whole slew of other dinosaurs as well," says Roberts. "This pair is from a whole amazing range of discoveries, from other dinosaurs to other mammals."
The two new dinosaurs have a much more elaborate array of horns than the more familiar Triceratops, with the smaller of the two, Kosmoceratops, baring 15 of different shapes and sizes.
It is the most ornate dinosaur head yet discovered ('kosmos' is Greek for ornate). The discoverers speculate that rather than being used for fighting, the horns may have been for decoration and advantage in courtship displays, as well as to deter mating rivals.
The Utahceratops doesn't have so many horns, but is distinguished with a massive head - its skull measuring 2.3 metres long. It is said to resemble a giant rhino with a supersized head.
A world of dinosaurs
The continent of Laramidia was a landmass approximately the size of Australia that existed during the Late Cretaceous Period - 99.6 to 65.5 million years ago. It formed when a large inland sea divided what is now North America into Laramidia (western half) and Appalachia (eastern half).
The northern part of Laramidia - present day Montana and Alberta - is a rich source of dinosaur discoveries - including the Triceratops and the infamous Tyrannosaurus rex. Dinosaur fossils have been found as far south as Texas and New Mexico.
Palaeontologists have only been studying the fossils of the 1.9 million-acre Grand Staircase-Escalante National Monument of the southern region for a decade, but believe it still holds a rich source of new discoveries.
"The surprising find is that what we're finding is that it turns out that a lot of the different dinosaurs are very closely related in age. This was a relatively large landmass, but to have all these different dinosaurs living in relatively the same age is amazing," says Roberts.
The next step is to work out how so many different dinosaurs co-existed at the same time in a relatively restricted region.
"It's really quite incredible that we're seeing this large number of different taxa living apparently at the same time. It is something that starts to prompt some interesting ecological and environmental questions."