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Palaeontologists have announced the discovery of a duck-billed dinosaur unlike any discovered before, giving insight into their evolution.
The duck-billed platypus might look odd to us today, but hundreds of millions of years ago there existed a duck-billed dinosaur. Now, researchers from the US and Spain have announced the discovery of a new genus and species named Aquilarhinus palimentus, with an aquiline nose and wide lower jaw shaped like two trowels side by side.
Bones of the dinosaur were first uncovered in the 1980s in rock layers at a place called Rattlesnake Mountain. Badly weathered, the remains were stuck together, making them impossible to study. In the 1990s an arched nasal crest was identified, thought to be distinctive of the hadrosaurid Gryposaurus.
However, it was not until this recent research – published to the Journal of Systematic Palaeontology – that researchers discovered the specimen was more ancient than Gryposaurus and the two major groups of duck-billed dinosaurs.
An illustration of Aquilarhinus palimentus. Image: ICRA Art
Important discovery
“This new animal is one of the more primitive hadrosaurids known and can therefore help us to understand how and why the ornamentation on their heads evolved, as well as where the group initially evolved and migrated from,” said lead author Dr Albert Prieto-Márquez from the Institut Català de Paleontologia Miquel Crusafont, near Barcelona. “Its existence adds another piece of evidence to the growing hypothesis, still up in the air, that the group began in the south-eastern area of the US.”
While sounding strange, duck-billed dinosaurs – also known as hadrosaurids – were actually the most common herbivorous dinosaurs at the end of the Mesozoic Era.
Across the species, these dinosaurs had a jaw that met in a U-shape to support a cupped beak for cropping plants. While some beaks were broader than others, Aquilarhinus palimentus is the first to show a significantly different shape. Instead, the lower jaw of this newly discovered species met in a strange W-shape to create a wide, flattened scoop.
Dating to approximately 80m years ago, this dinosaur does not fit in with the main group of duck-billed dinosaurs known as Saurolophidae. The fact it is older suggests there might have been a greater number of lineages than previously recognised, and that they evolved before the great radiation that gave rise to the bewildering array of unadorned, solid and hollow-crested forms.
