It often happens that animals move in herds, and we agree on this. In most cases, however, these groups are made up of animals of the same species, for obvious reasons: the possibility of finding a partner, the strength of the kinship ties, and also the fact that animals of the same species move at the same rhythm and at the same speed, facilitating movements. Yet it does not always go like this: mixed groups have their advantages, as shown by a series of fossil traces of dinosaurs that have been found in Canada and that belong to a mixed pack. The analysis of the tracks was published on Plos One.
Herbivores and carnivores in the same group
The traces of dinosaurs described in the study come from the State of Alberta, precisely in the Provincial Park dinosaurs, one of the richest fossiliferous sites in the world and the UNESCO heritage since 1979. Here, as told by the authors, the analyzes are usually made on “classic” fossils: the imprints of the dinosaurs, which are part of the category of Icnophossili, have always been studied less, also because of the conditions of fossilization of the area.
Those recently discoveries, however, are preserved very well, and contain surprises: a excavation of just 30 square meters has permeated to find 13 different footprints of five herbivorous dinosaurs, of the CeraTopsi group (the famous “cuckold”); Together with theirs, the footprints of what has been identified for the moment as an Akylosauro for the moment were also covered. A little further on, however, traces of two tyrannosaurids were also found. A puzzle of species that the authors of the study think they have solved.
Union makes strength
The main pack, according to the reconstruction, was made up of at least five specimens of ceilings, whose species has not yet been determined. Together with them two ankylosaurs traveled: the proximity and frequency of the footprints suggests that they constituted a unique group. The two tyrannosauri, on the other hand, were some distance from the pack: it is possible that they were keeping an eye on them, and that the herbivores were in a group to defend themselves better from any attacks.
On the other hand, a short distance from the tracks were found traces of a well of water: it is possible that the dinosaurs were actually going to drink, and that the tyrannosaurs were there by chance (or maybe the pack he felt safe, as well as thirsty). The indisputable fact remains that different species were traveling to the group: given the advantages that this leads to current herds (species different have different sensitivity to sounds, lights and colors, and collaborating have more chances to see a predator before this sees them) it is not difficult to imagine that they did it regularly.