Megachirella wachtleri: World’s Oldest Squamate Fossil Found
Paleontologists have unearthed the world’s oldest squamate fossil — 240-million-year-old specimen of a species called Megachirella wachtleri — from a site in the Dolomite Mountains, Italy.
Megachirella wachtleri is the most ancient ancestor of all modern squamates (lizards, snakes and amphisbaenians).
The specimen — a well-preserved partial skeleton — is at least 75 million years older than the previously known oldest squamate fossils, partially filling the fossil gap in the origin of lizards.
The fossil was originally found in the early 2000s in the Dolomites.
Paleontologists thought it was linked to — but not an ancestor of — modern lizards and snakes.
Further analysis by University of Alberta researcher Tiago Simões and his colleagues determined the specimen was actually the oldest relative ever found of all living lizards and snakes.
“This discovery provides valuable information for understanding the evolution of both living and extinct squamates,” Simões said.
To better understand both the anatomy of Megachirella wachtleri and the earliest evolution of squamates, the team assembled the largest reptile dataset ever created, using fossils and living specimens from more than 130 lizards and snakes from around the world.
The data included CT scans, photographs and molecular analysis collected by the study authors, rather than relying on existing literature.
They combined the new data with CT scans, revealing that Megachirella wachtleri was actually the oldest known squamate.
“Fossils are our only accurate window into the ancient past,” said co-author Professor Michael Caldwell, also from the University of Alberta.
“Our new understanding of Megachirella wachtleri is one point in ancient time, but it tells us things about the evolution of lizards that we simply cannot learn from any of the species of lizards and snakes alive today.”
The research appears in the journal Nature.
Tiago R. Simões et al. 2018. The origin of squamates revealed by a Middle Triassic lizard from the Italian Alps. Nature 557: 706-709; doi: 10.1038/s41586-018-0093-3