In new research, paleontologists reveal new insights into the origin and early history of snakes. For one thing, they kept late hours; for another, they also kept their hind legs.
“We generated the first comprehensive reconstruction of what the ancestral snake was like,” says Allison Hsiang, lead author of the study in BMC Evolutionary Biology. Hsiang is a postdoctoral researcher in Yale University’s geology and geophysics department.
“We infer that the most recent common ancestor of all snakes was a nocturnal, stealth-hunting predator targeting relatively large prey, and most likely would have lived in forested ecosystems in the Southern Hemisphere,” Hsiang says.
Snakes have always captured the imagination of humans. Their long and sinuous body, fearsome reputation, and great diversity—with more than 3,400 living species—make them one of the most recognizable groups of living vertebrate animals.
Yet little has been known about how, where, and when modern snakes emerged.
The team analyzed snake genomes, modern snake anatomy, and new information from the fossil record to find answers. In doing so, the researchers generated a family tree for both living and extinct snakes, illuminating major evolutionary patterns that have played out across snake evolutionary history.
“Our analyses suggest that the most recent common ancestor of all living snakes would have already lost its forelimbs, but would still have had tiny hind limbs, with complete ankles and toes. It would have first evolved on land, instead of in the sea,” says coauthor Daniel Field, a Yale PhD candidate. “Both of those insights resolve longstanding debates on the origin of snakes.”
The researchers say ancestral snakes were non-constricting, wide-ranging foragers that seized their prey with needle-like hooked teeth and swallowed them whole. They originated about 128.5 million years ago, during the middle Early Cretaceous period.
“Primate brains, including those of humans, are hard-wired to attend to serpents, and with good reason,” says Jacques Gauthier, senior author of the study, a Yale professor of geology and geophysics, and curator of fossil vertebrates at the Yale Peabody Museum of Natural History.
“Our natural and adaptive attention to snakes makes the question of their evolutionary origin especially intriguing.”
Support for the research came from the Yale Peabody Museum of Natural History, the Smithsonian Institution, and the Canadian Natural Sciences and Engineering Research Council.
Source: Yale University
