Bony evidence of a social way of life: Researchers found the remains of an adult smilodon saber-toothed cat to show signs of congenital hip dysplasia. As they explain, due to this deformity, the animal could only hop around and was therefore unable to hunt. That it survived into adulthood thus proves: saber-toothed cats lived in social communities in which needy group members were provided with food, say the scientists.
The literally outstanding fangs are their trademark: the saber-toothed cats are stars of the Ice Age megafauna and became known, among other things, through the animated film Ice Age. The depicted “Diego” is a Smilodon fatalis. This American species from the group of saber-toothed cats is best known from finds from the asphalt pits of Rancho La Brea in Los Angeles. The remains of numerous individuals were discovered in it, dating from around 50,000 years ago to the extinction of Smilodon around 11,000 years ago.
Behavioral advice from pathology
In addition to information about the physique of the big cats, which can weigh up to 300 kilograms, the fossils from Rancho La Brea researchers also provided clues about the behavior of Smilodon. Particularly revealing was the collection of bones showing signs of injury and disease. Traces of frequent injuries to the lower back indicate that the burly predators apparently hunted down large Ice Age prey such as bison by throwing themselves on them. It is already assumed that they lived and hunted in the social association, similar to today’s lions. This is indicated by traces of survived injuries, which were presumably only able to heal because weakened animals were cared for by the group. In this context, the current finding is a particularly convincing indication of life in a social association.
The researchers headed by Mairin Balisi from the La Brea Tar Pits and Museum in Los Angeles focused on the remains of a hip joint and the corresponding femur, which has long been part of the pathology collection of the facility. For more than a century, paleontologists thought that the clearly visible damage to the bones was caused by trauma or infection that eventually led to the animal’s death. But Balisi and his colleagues had doubts about this explanation and therefore re-examined the case with modern methods of pathology: They subjected the remains to a computed tomography. The resulting images were then used to create 3D models that also include the interior of the bones.
Congenital disability
After a detailed analysis of the structures, the team came to the diagnosis: The damage to the joint was not due to an injury sustained during the hunt – the animal instead suffered from congenital hip dysplasia. It is a malformation of the hip joint, which is also known from dogs and cats. As the researchers explain, the finding in an adult smilodon is remarkable, because the animal must have been severely disabled from an early age. As a result, this specimen could not hunt, because Smilodon needed strong hind legs in order to run quickly and to throw itself on prey such as bison or camels.
Against this background, the findings now provide a particularly convincing indication of the complex social behavior of saber-tooth cats, say the scientists: Apparently, the predators within the groups looked after each other. “In this case, the animal suffered from a severely impaired developmental disorder and was still able to survive into adulthood. It is therefore obvious that this individual was supported by others, ”Balisi sums up. His group members provided the needy with food or at least he was tolerated at the feast at the crack.
The researchers conclude that the fact that Smilodon might live in social groups similar to lions was by no means obvious due to the distant family relationships. “Because he was only as close to today’s big cats as our house cats,” says Balisi. Apart from the lions, tigers, jaguars and the like are also loners. “It is usually difficult to infer social behavior from fossils. But in the case of Smilodon we are lucky that there are now several indications that these big cats were social, ”says Balisi.
Source: Natural History Museum of Los Angeles County, Article: Scientific Reports, doi: 10.1038 / s41598-021-99853-1