A remarkable discovery in western Wyoming has unearthed four nearly complete snake fossils, estimated to be between 34 and 38 million years old. These exceptionally well-preserved specimens—identified as a new species named Hibernophis breithaupti—offer rare insights into the evolution, anatomy, and behavior of ancient snakes. Found in a delicate layer of mudstone, the fossils include skulls, ribs, and over 200 vertebrae still intact, making them among the most complete snake fossils ever discovered. The findings shed light on the evolutionary history of modern boas and even suggest early evidence of social behaviors such as communal hibernation.
34-Million-Year-Old Snakes: A Rare and Remarkable Discovery in the U.S.
In western Wyoming, scientists have uncovered an extraordinary fossil find: four nearly complete snake skeletons dating back 34 to 38 million years. Unlike typical snake fossils, which often consist of scattered vertebrae and rib fragments, these specimens were found nearly fully articulated. Their exceptional preservation allowed researchers to reconstruct the snakes’ entire skeletal structure from head to tail—an achievement rarely possible in paleontology. This groundbreaking discovery is shedding new light on the development and function of snake skeletons in both juvenile and adult forms.
Introducing a New Species: Hibernophis breithaupti
Initially mistaken for previously known genera such as Ogmophis and Calamagras, the fossils were later determined to represent a new species due to notable differences in jaw structure, tooth pattern, and vertebral features. Named Hibernophis breithaupti, these small-bodied snakes were likely burrowers. The presence of individuals at different growth stages provided scientists with a unique opportunity to examine both juvenile and adult forms within a single species.
Clues to Boa Evolution
Through detailed skeletal analysis and genetic comparisons, Hibernophis was found to be closely related to modern boas. The fossils suggest that early boas were relatively small and had already begun to diversify by the Oligocene epoch. The articulated spines enabled researchers to trace bone development through different life stages—a major advance for evolutionary biology and fossil classification.
Evidence of Ancient Social Behavior
Perhaps most intriguing is the way the fossils were found: the four snakes were curled together in what appears to have been a shared underground shelter, or hibernaculum. This arrangement hints at communal hibernation—a behavior rarely seen in modern reptiles. The discovery suggests that social behaviors like group thermoregulation may have existed tens of millions of years ago, similar to what is observed in modern garter snakes today.
Preserved by Nature’s Timing
The exceptional condition of the fossils is thanks to a unique sequence of natural events. A combination of volcanic ash and seasonal flooding quickly sealed the snakes’ hibernation chamber in fine mud, creating an oxygen-poor environment ideal for fossil preservation. These perfect conditions allowed scientists to examine the bones in rare detail and draw groundbreaking conclusions about snake biology and behavior.
Reshaping the Snake Family Tree
The discovery of Hibernophis breithaupti not only enhances our understanding of snake evolution but also challenges long-standing assumptions about their anatomy and social habits. As researchers continue to analyze these fossils, they may ultimately help rewrite major chapters of reptilian evolutionary history.
