A newly described fossil snake with legs may have climbed higher into the snake family tree than previously thought.
The 95-million-year-old fossil snake, dubbed Haasiophis terrasanctus, is a relative of another legged fossil snake—Pachyrhachis problematicus—that some scientists think may be the earliest link between snakes and extinct marine lizards, like mosasaurs (SN: 4/19/97, p. 238).
However, the new fossil suggests that the two-limbed snakes are advanced big-mouthed snakes, like pythons and boas, rather than primitive serpentine ancestors, says paleontologist Olivier Rieppel of the Field Museum of Natural History in Chicago.
Rieppel and his colleagues compared the fossils' skulls with skulls from other snakes, living and extinct. T