Fossil of Earliest Known ‘Jesus Lizard,’ A Reptile That Walked on Water, Discovered in Wyoming

It had three-pointed teeth, prominent cheekbones, and a long ridge protruding over its eyes that likely bestowed what experts have described as “an angry look.”

But probably the most distinguishing trait of a 48-million-year-old lizard whose fossilized remains were recently found in Wyoming was that it could walk on water.

The specimen, found in the Bridger Formation of southwestern Wyoming, is thought to be the earliest known example of a corytophanid, otherwise known as a casquehead or helmeted lizard, the family of reptiles that includes the so-called Jesus lizards, known for their ability to run across the surface of standing water.

In addition to being likely the oldest known of its kind, the animal also appears to be a previously unknown species, one that thrived much farther north than its modern, tropical descendants do.

“Although modern corytophanids are restricted to Central and South America,” wrote Dr. Jack Conrad, reporting the find in the journal PLOS One, “I posit that the group had a Eurmerican/Laurasian origin and became restricted to lower latitudes after post-Eocene global cooling.”

During the Eocene epoch, which began after the extinction of the dinosaurs, the world’s land masses were somewhat similar to what we know today, but the climate was radically different.

Earth was nearly ice-free, rainfall was heavy, and the average global temperature was about 9 degrees C (16 degrees F) hotter than today’s.

“Fossil members of various animal, plant, fungal, and other clades currently confined to the tropics or subtropical areas are often found in the mid-to-high latitudes during warm periods,” noted Conrad, a research associate at the American Museum of Natural History. [Learn how Eocene heat changed ancient mammals: “Prehistoric Global Warming Caused Dwarfism in American Mammals, Fossils Show“]

As such, it may come as little surprise that a tropical reptile would be found in what’s now an arid corner of Wyoming. [See more evidence of ancient tropical life in Wyoming: “Extinct Tropical Bird Discovered in Wyoming“]

What’s more surprising is the discovery of any corytophanid fossil, given their scarcity in the geological record.

The fossil includes a complete skull, lower jaws and top two vertebrae, Conrad reported.

The fossil includes the skull, lower jaws, and top two vertebrae of a 48-million-year-old lizard called a corytophanid. (Conrad et al., PLOS One)
[See another nearby fossil find: “Tiny, Toothy Mammal Discovered in Wyoming Fossil Named for Lady Gaga“]

And together, they show the specimen to be a type of corytophanid known as a basilisk, a lizard that uses its large back feet, laced with retractable scales, to support the lizard’s weight as it flees predators across open water.

As the earliest known Jesus lizard, Conrad gave the new specimen the name Babibasiliscus, using the Shoshone prefix for “older male cousin” to describe its relationship to modern basilisks.

In addition to elucidating the history of these unusual animals, the discovery of tropical Babibasiliscus in Wyoming is a reminder of how different the world used to be, even if its life sometimes remains familiar.

“Given our current period of global climate fluctuation, looking to the fossil record offers an important opportunity to observe what is possible,” Conrad said in a press statement, “and may give us an idea of what to expect from our dynamic Earth.”

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