Credit: Lund et al
A new dinosaur species with unique curved head-spikes has been discovered among fossils excavated in modern-day Utah.
The dinosaur, Machairoceratops cronusi, is a centrosaur – a sub-group within the family ceratops which lived around 77 million years ago in the southern part of what is now North America. It may have been six to eight metres long and weighed up to two tonnes.
Centrosaurs are characterised by their parrot-like beaks, enormous noses, facial horns and frills around their necks, which probably played a part in sexual selection.
It’s these adornments on the neck frill of Machairoceratops that singled it out as a species: it has two spikes that extend out the back of its frill and loop forward, as lead author Eric Lund, from the Ohio University Heritage College of Osteopathic Medicine, US, explains.
“Machairoceratops is unique in possessing two large, forward-curving spikes off of the back of the neck shield, each of which is marked by a peculiar sulcus or channel extending from the base of the spike to the tip, the function of which is currently unknown.”
The fossils were uncovered over two excavation seasons in the Wahweap Formation, a sediment stack in the Grand Staircase-Escalante National Monument, Utah. The formation is littered with fossils including sharks, fish, crocodiles, turtles and mammals, and contains the oldest evidence on record of ceratops dinosaurs.
This species is only the second dinosaur to be named from fossils among this formation after Diabloceratops eatoni was identified in 2010.
Fossilised evidence of dinosaurs is relatively slim from the lower part of North America during this time period when the continent was divided into east and west landmasses by a body of water. Researchers say the discovery narrows a four-million-year gap in the fossil record during this time period.
The findings, published in the journal PLOS One, will contribute to the broader understanding of the evolution of horned dinosaurs, and the diversity of a part of North America during the final years of the dinosaurs.