The carnivorous dinosaurs avoided competing with each other for their preys and distributed them according to their species, according to a study published today in the Proceedings of the Royal Society of London.
This clever distribution of food resources may explain the glut of fossils of predators found in deposits in Morocco and Niger. The calcium contained in the fossil remains was what allowed a group of French researchers to determine the dietary preferences of carnivorous dinosaurs.
The research carried out in the Lyon geology laboratory is based on the question of coexistence among so many carnivores in North Africa, an area in which herbivores were inferior in number. Specifically, the scientists measured the proportions of different calcium isotopes contained in fossil footprints, such as tooth enamel or fish scales.
The samples were taken in the region of Gadoufaoua in the north of Niger, where the remains are 120 million years old, and Kem Kem in Morocco, where the remains reach 100 million years.
To achieve the reconstruction of the food chains, the experts compared the isotopic composition of potential prey as herbivores with that of predator teeth. Indeed, in In vertebrates, calcium comes almost exclusively from food. Comparing the isotopic composition of potential prey (fish, herbivores) with that of carnivore teeth can therefore produce an overall picture of ecosystem-wide dietary habits.
The data obtained show similar food preferences in the two deposits: some large carnivorous dinosaurs (abelisaurids and carcharodontosaurids) preferentially hunt terrestrial prey such as herbivorous dinosaurs, others (spinosaurs) were piscivorous; the regime of the giant crocodile sarcosuchus was intermediate, consisting of terrestrial and aquatic prey. Thus, the different predators avoided competition thanks to a subtle sharing of food resources.
In addition, they observed that in some cases both aquatic and terrestrial preys were part of the diet of some dinosaurs, such as the giant crocodile sarcosuchus.