Massive and monstrous – but still not a clumsy stalker: Contrary to previous assumptions, the mysterious Anteosaurus was apparently a rather nimble predator from the era before the dinosaurs. This emerges from a reconstruction of nerve structures using CT scans of a fossil skull. The carnivore, about the size of a rhinoceros, therefore had adaptations to a brisk movement compared to its relatives. That way he could catch up with quick prey, say the researchers.
Fossil finds in southern Africa have made it known for some time that a seemingly monstrous creature lived there 265 to 260 million years ago: a massive skull with massive jaws
and long fangs clearly identify Anteosaurus magnificus as a carnivore. Its other features assign it to the reptile family of the Dinocephalia, which in turn formed a subgroup of the Therapsids. Similar to the later dinosaurs, the various herbivorous and carnivorous representatives of the Dinocephalia ruled the Permian landscapes. During the mass extinction of 251 million before this line of Therapsids died out completely – about 30 million years before the first dinosaurs entered the stage of evolution.
A clumsy ambulance hunter?
For the representatives of the Dinocephalia a robust looking skull with horn structures and humps was typical, which suggests that at least some species have used their massive heads as battering rams in intra-species fights. In addition, the bones of the Dinocephalia are usually thick and dense – this also applies to Anteosaurus. Due to the massive skeletal structure, it was previously assumed that it was a rather sluggish animal that may have caught its prey by surprise. Some scientists also suspected that Anteosaurus lurked in the water – much like a crocodile. But so far the behavior has remained unclear, because the actual performance of the musculoskeletal system can only be assessed with difficulty from the fossils.
But as the researchers around Julien Benoit from the University of Witwatersrand report, so-called paleoneurological clues now enable conclusions to be drawn about the behavior of the primeval predator. As part of their study, they analyzed the skull of an Anteosaurus magnificus from the South African Karoo region using X-ray microtomography. This enabled them to depict the inside of the skull in exceptional detail for the first time. They then used the recordings to develop a digital 3D model of the skull, which in turn enabled conclusions to be drawn about the internal structures that had long since disappeared. In this way, the paleontologists were able to reconstruct certain brain structures as well as the area of the inner ear and the organ of equilibrium. Similar results were already available in the case of other representatives of the Dinocephalia and so it was possible to show what peculiarities there were in Anteosaurus.
Paleoneurological evidence of speed
As the scientists report, the skull model shows that the robber, despite his knobbly head, was probably not a “battering ram” like some of his dinocephalia relatives. In contrast to these, it did not have the typical skull features that absorb the pressure when heads hit each other. During the reconstruction of the former internal structures it became clear that the balance organ of Anteosaurus was significantly larger than that of its closest relatives and other known carnivores of its era. As the researchers explain, this suggests that the predator was able to move faster than its prey and competitors.
They found a further indication of an agile way of movement in the characteristics of certain brain structures, which are also reflected in the skull model. These are regions that are known to be associated with body coordination and eye movements. As the researchers report, their characteristics were similar to those of agile predators such as cats and the velociraptors of the dinosaur era. This is a further indication of a persecution behavior when hunting Anteosaurus, say the scientists.
As Benoit sums up, it becomes apparent overall: “Although Anteosaurus lived 200 million years before the famous Tyrannosaurus rex, he was definitely not a ‘primitive’ being, but apparently also a very effective predator”. Her colleague Ashley Kruger from the Natural History Museum in Stockholm adds: “The examinations of the Anteosaurus skull show that its nervous system was optimized for a rather fast movement – which is in contrast to what was previously assumed,” says the paleontologist .
Source: University of the Witwatersrand, specialist article: Acta Palaeontologica Polonica, doi: 10.4202 / app.00800.2020