Читать книгу Dinosaurs - Douglas Palmer - Страница 12

There are a number of reasons why animals, and even humans, fight one another. Disputes over food, territory and mates commonly lead to conflict, and dinosaurs were no exception to the rule. However, our understanding of dinosaur disputes is biased by what information we can recover from the fossil record and what can be inferred from general principles of animal behaviour.

Obviously, the main arena of conflict results from the predator–prey relationship between meat eaters and plant eaters. Predators have to be appropriately armed to catch and kill their prey and, as we have seen, this is primarily a matter of being able to detect the prey, surprise it and then catch it with claws or teeth. Inevitably, eggs, babies and juvenile dinosaurs would have been most vulnerable to predation. From the prey’s point of view, the matter is largely one of flight or fight – in other words, being able to run away or defend itself.

Some of the small plant-eating dinosaurs opted for the flight mechanism and were fleet of foot. The two-legged ornithomimids, for example, may have been able to run at speeds of up to 40kph (25mph). At the other end of the scale, giant sauropods, once grown up, were so big they would have been invulnerable. Medium-sized but heavy, slow plant eaters such as the ceratopsians, stegosaurs and ankylosaurs evolved a variety of types of armour and defensive weaponry. The ceratopsians are characterized by their helmet-like skulls with prominent rhino-like horns. The stegosaurs had plates and spikes along their back and tail, while the ankylosaurs had tough bony plates embedded in their skin as well as bone-crunching tail clubs. The same weaponry was probably also used by males when fighting one another in territorial disputes or over females. Some of the defensive weaponry that is not as structurally robust as it looks, such as the neck flanges and frills of the ceratopsians, may also have had other functions, such as for male display, signalling and species recognition.

Caption: A Repenomamus with a baby Psittacosaurus.

Medium-sized plant eaters that were neither fast movers nor well armoured developed other means of defending themselves against predators. The hadrosaurs, for example, were equipped with a variety of strange bony structures on their skulls, some of which may have been used to amplify calls to other members of the herd to warm against a nearby predator.

And, finally, we now know that dinosaurs did not have it all their own way. Recently, the fossil of a badger-sized mammal called Repenomamus has been found with the remains of a baby psittacosaur in its stomach cavity.

Caption:

Brachiosaurus, quite possibly too large for most predators.