The dinosaurs, known as pachycephalosaurs - meaning "thick-headed lizards", have long puzzled paleontologists who wondered why the heads of these dinosaurs looked to have built-in football helmets.
"While neither group has a bowling ball-like structure on top of its head, the head-slapping behaviour of crocodiles and the face-pecking observed in a variety of birds suggest that 'using your head' is not unique to pachycephalosaurs and domes likely evolved in response to such behaviour," he said.
Consider the plates on Stegosaurus and the domed skulls of pachycephalosaurs
. Scientists have proposed various explanations for these and other bizarre body features of dinosaurs.
They found that the bony anatomy of some pachycephalosaur
domes were better at protecting the brain than in any modern head butter.
They compared them to dozens of fossils from related species found in Canada and Montana before confirming that the fossils represented a new genus of pachycephalosaur
, a group of bipedal, thick-skulled dinosaurs.
Over the last 14 years, over a dozen species have been found in the area, including the duck-billed hadrosaurs, armored ankylosaurs and the dome-headed pachycephalosaurs
(2000): The fossil record, systematics and evolution of pachycephalosaurs
and ceratopsians from Asia.
The plates on Stegosaurus and the fleshy, domed skulls on pachycephalosaurs
could certainly have been for recognition, but not the kind of recognition cited in the article comparing it to teen fashion ("Just for Frills?" SN: 8/13/05, p.
Tyrannosaurids are one of many dinosaur groups that exhibited trans-Laurasian (or at least Asian and North American) distributions during the Late Cretaceous; others include ceratopsians, hadrosaurs, and pachycephalosaurs
(e.g., Sereno, 2000; Upchurch et al., 2002).
In contrast, small herbivores (ankylosaurs and pachycephalosaurs
), carnivorous dinosaurs (tyrannosaurs and coelurosaurs), and enormous herbivores without advanced chewing abilities (sauropods) remained relatively stable or even slightly increased in biodiversity.
Recent studies have revealed extreme changes in the skulls of pachycephalosaurs
, tyrannosaurs and other dinosaurs that died out about 65 million years ago in North America.