Carnotaurusi were the cheetahs of the Late Cretaceous, instead of relying on massive jaws or teeth they were built for speed. Capturing prey with partial binocular vision, it had vestigial arms, a long neck, large tail muscles, and scutes similar to an iguanas‘. On its skull were twin horns, while other abelisaurs like rajasaurus and majungasaurus sported a singular horn.
Large for an abelisaur, carnotaurus had advanced features and size reaching 9 meters, 2 tons, and speeds of 35 mph. Although lightly built, its short snout, serrated teeth, robust neck, and highly kinetic skull would have let it inflict wounds on even large prey such as sauropods like a club. Animals with cranial kinesis include sharks and snakes who can strike without deflecting prey and simultaneously begin feeding, as with an elastic skull chewing is optional. Mobbing with numerous attacks, its unhinged lower jaw meant it could gouge holes and devour large chunks without killing its victim; feasting on it alive, a sauropod would be merely a moving buffet.
All abelisaurs had compacted arms, some with fused fingers, and ornate skulls. Abelisauridae meaning “Abel’s lizards” were neotheropods found on the prehistoric supercontinent of Gondwana 66- 170 million years ago.
Chasmosauri were apparently Canadian, discovered in Alberta from 75-76 million years ago they don purely ornamental head gear attached with up to 24 spikes. They vary greatly between individuals causing controversy among once valid species and such as in the case of triceratops vs torosaurus, genus. Interestingly enough, a nearly complete juvenile specimen and as well as skin impressions were also found, perhaps belonging to chasmosaurus.
“Chasm lizards” shared their habitat with centrosaurs in the Campanian age where earth’s climate was warmer and dinosaur diversity exploded. They were larger than most buffaloes at 1-2 tons and 4-5 meters in length and traveled in herds in tens or hundreds as many individuals have been found deposited together in fossil sites.