WASHINGTON // Two dinosaurs unearthed in the western US states of Montana and Utah illustrate the exotic appearance some of these beasts developed towards the end of their reign.
Scientists on Wednesday announced the discovery of two species that provide new insights into an important group of lorry-sized, four-legged, plant-eating horned dinosaurs that roamed the landscape late in the Cretaceous Period.
Both dinosaurs were members of a group called ceratopsians, which included the well-known Triceratops, with parrot-like beaks to crop low-growing herbs and shrubs, a bony neck shield or frill, and forward-pointing facial horns.
Fossils of Machairoceratops cronusi, which lived about 77 million years ago, were found in Utah’s Grand Staircase-Escalante National Monument.
Machairoceratops, which was up to 8 metres long, had two large, forward-curving spikes protruding from the back of its shield, each marked by a peculiar groove extending from the base of the spike to the tip, said Eric Lund, a palaeontologist at Ohio University.
Machairoceratops also had two horns over its eyes and probably one over its nose, although the incomplete fossils did not show that.
Fossils of Spiclypeus shipporum, which lived about 76 million years ago, were found near the town of Winifred, Montana.
Spiclypeus, about 4.5 metres long, boasted brow horns that stuck out sideways rather than pointing forward, said Jordan Mallon, a palaeontologist at the Canadian Museum of Nature in Ottawa.
It had spikes at the back of its frill that pointed in different directions: some curling forwards and others projecting outwards, he said. “We think the horns and frills were probably used for display of some sort, either for sexual or species recognition,” Dr Mallon said.
This Spiclypeus was dubbed “Judith” because the fossils came from the Judith River rock formation.
Judith apparently lived a painful life. The upper bone in its left front leg bore signs of disease: arthritis near the shoulder joint and a hole near the elbow caused by a bone infection.
“I think Spiclypeus wins top prize for being the most aesthetically pleasing horned dinosaur, but that’s my bias talking,” Dr Mallon said.
“I think a visitor to the Late Cretaceous would have been immediately intimidated by standing in the shadow of Judith’s spiky skull, but then overcome with sympathy after noting the animal ambling about painfully on only three legs.”
The research was published in the journal PLOS ONE.
* Reuters
