Australia: The Land Where Time Began

A biography of the Australian continent 

Dinosaur Behaviour - Social Activities

According to the author1 organised groups are not formed by terrestrial reptiles, though they are often formed by birds and mammals. Examples are lion prides and deer herds, though most big cats are solitary, coming together only to breed. Evidence of herd forming behaviour of dinosaurs has been found in the bone beds that that can contain up to tens of thousands of individuals of a number of species and smaller beds that contain only a single species. The author1  suggests some of these bone accumulations can be attributed to death traps that accumulated individuals over long periods or times of drought when many individuals would have been compelled to gather at remaining waterholes where they ate out all the vegetation in an increasing zone around water source until they starved to death, as can be seen in Africa at the present where this occurs in times of drought.

There are also bone accumulations that have been attributed to many animals succumbing to sudden events such as falling volcanic ash, flash floods, or as can be seen when the African herbivores are making their regular seasonal migration to better feeding grounds. When they need to cross rivers there are often a number that drown or are taken by the crocodiles that gather at known crossing points at such times. Mass deaths could also be caused by dune slides. Some of these bone beds suggest the existence of very large herds made up of large herbivores such as hadrosaurs and ceratopsids.

Bone accumulations consisting of a number of a single species of  theropod in association with the skeleton of a prey species has been suggested to support the idea that predatory dinosaurs sometimes hunted in packs. According to the author1 it is not always easy to explain how so many theropods died at the same time while feeding on a carcass. He suggest that in such cases it is probable that the skeletons of the theropods were those that were killed by others of their species in fights over feeding privileges. This still occurs when large carnivorous mammals compete over a kill.

The author1 describes dinosaur trackways as 'the closest thing we have to motion pictures of the behaviour of fossil animals'. Among the trackways of a diverse assortment of dinosaurs a significant portion are of solitary dinosaurs, which the author1 suggests indicate that the dinosaur making the track was not part of a larger group. The trackways also display multiple tracks of a single species of a wide variety of dinosaurs that follow the same path close together. He suggests that in some such cases it is possible that the conditions at the site of the trackway at the time of deposition forced the dinosaurs to follow such paths, as would occur at if they were following a shoreline. In such cases it is not necessary for them to be travelling as a cohesive group, it could be that solitary dinosaurs also travelled along the shoreline. It is often common to see these parallel trackways crisscrossed  by the racks of other dinosaurs that appear to have been free to travel in other directions. He suggests that the many parallel trackways are evidence that many species, both herbivores and carnivores, of various sizes often formed collectives that moved as pods, flocks, packs and herds.

The author1 suggests that the degree of sophistication of dinosaur groups was probably at a similar level of sophistication as schools of fish, though not as developed as is seen in herds and packs of mammals. He also suggest that the trackways of sauropods that have been claimed to show juveniles being surrounded by protective adults have not been supported by study of the trackways. He also thinks it is unlikely that packs of theropods used advanced tactics such as those attributed to packs of canids and prides of lions.


Sources & Further reading

  1. Paul, Gregory S., 2010, The Princeton Field guide to Dinosaurs, Princeton University Press.


Author: M. H. Monroe
Last updated 28/01/2012 




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