Carnivorous dinosaurs may have evolved to use giant carcasses for their own purposes, according to a study published Nov. 1, 2023, in the open-access journal PLOS ONE by Cameron Pal and Luis Ruedas of Portland State University in Oregon and their colleagues.

Carnivorous dinosaurs lived in ecosystems rich in both live and dead prey. The authors suggest that the giant carcasses, which resemble those of sauropod dinosaurs, may have been the main food source for large predators.

To test this hypothesis, the researchers created an agent-based model of a simplified virtual simulation of a dinosaur ecosystem. This model was based on the ancient fauna of the Jurassic Morrison Formation, which included large carnivores such as Allosaurus, as well as large sauropods, their carcasses, and the eternal hunter stegosaurs.

In the model, carnivores (intended to mimic allosaurs) were given traits that would improve their ability to hunt or scavenge while obtaining energy from meat sources (imitating live prey or sauropod carcasses).

The model measured the evolutionary fitness of these simulated predators and found that scavenging was more profitable than hunting when large sources of sauropod carcasses were available; This suggested that predators in such ecosystems may have evolved special features to help them detect and use carcasses.

The authors emphasize that this model is a simplified abstraction of a complex system and that results may change if more variables are included, such as additional dinosaur species or life history traits of the modeled dinosaurs. They note that such models could improve our understanding of how carrion availability may influence the evolution of predators.

The authors add: “Our evolutionary model suggests that large theropods such as Allosaurus may have evolved to feed on sauropod carrion as a primary resource. Even when prey was available to them, selection pressures favored scavengers, while predators suffered from lower fitness.”

“So we think that allosaurs probably waited until a group of sauropods died during the dry season, fed on their carcasses, stored fat in their tails, and then waited until the next season to repeat the process. It also makes sense because a single sauropod carcass can kill around 25 allosaurs for weeks, even weeks.” It had enough calories to feed for months, and sauropods were generally the most numerous dinosaurs around.