About 56 million years ago, many species of primitive primates suddenly went extinct in North America. Why this happened has long puzzled scientists, but now they may have ruled out one of the theories of extinction to narrow down the causes.
Researchers have long wondered what happened to the first primates. Known as stem primates, these mammals resembled rodents to some degree but had some primate characteristics, such as long, grasping fingers. In the past, many researchers have suggested that they died off because rodents outcompeted them for their preferred foods. This is largely because these stem primates and rodents were somewhat similar in appearance and may have filled similar niches in the ecosystem.
"Many of these stem primate groups seem to have gone extinct at the same time, but some survived much longer," said Kristen Prufrock, part of the team of paleontologists that examined the primates and rodents. "Ultimately, we want to know what traits made those survivors special and what that tells us about the biology, physiology and adaptations of modern primates."
In order to get to the bottom of exactly what happened, researchers took CT scans of 13 rodent and 181 stem primate jaws held in multiple museums. The shapes of the molars of these animals revealed that most of the primates actually ate different foods than the rodents. This means that competition wouldn't have been a factor when it came to gathering food sources - so what happened?
"We found that one genus of stem primates, Chiromyoides, lived at about the same time and had adapted to eat the same foods as primitive rodents, but the others either were adapted to eating different foods or lived at different times," Prufrock said. "So competition from rodents was unlikely to have been the main reason for the decline of most of the stem primates. Something else must have been the driving force."
Currently, the researchers are still studying the reason why these primates died off. However, the findings show that food source competition may not be the answer. Instead, the scientists will have to delve further in order to find out the true cause of the extinction of these first primates.
