Homalocephale calathocercos -Maryanska et Osmolska 1974- cast of the skull
Archosauria: Ornithischia: Pachycephalosauria: Homalocephaliidae
Locality: Omnogov, Gobi Desert, southern Mongolia
Age: Late Cretaceous (Late Campanian-Early Maastrichtian), 74 million years ago
Meaning of the name; "even-head"
Homalocephale calathocercos is a pachycephalosaurid, literally 'thickheads'.
The top of their skulls were 3 to 4 inches thick- solid bone usefully protecting
a walnut-sized brain. This thickening of the skull would allow these
animals to act like the modern sheep and goats where the males compete for females by
head-butting. Other indications that
these dinosaurs head-butted can be seen in the stiff spinal column.
This made it robust enough for the forces applied when contact occurred.
The angle of articulation of the skull
and the neck vertebrae (which puts the head in just the right position) makes butting
safe and not a back-breaking exercise. These dinosaurs had tiny teeth
ideal for shredding plant material. Pachycephalosaurids may have
had a lifestyle very like that of modern deer and goats and even may have
congregated in small herds.