Researchers Uncover Oldest Known Species of Side-Necked Turtle in North America

The discovery of this ancient species may be evidence of a great turtle pilgrimage to North America from a long-lost supercontinent over a hundred million years ago. 

Modern side-necked turtles on display. (By Womump – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=45638150)

(CN) — Experts have announced the discovery of what they believe to be the oldest known side-necked turtle in North America, a breakthrough that may shed some much-needed light on how these turtles first arrived on North American shores during Earth’s formative years.

Side-necked turtles stand as some of the most ancient turtle species known to man and possess a signature claim to fame that separates them from the rest of their shelled brethren. While most turtles withdraw their heads into their shells for protection when sensing danger, side-necked turtles — as their name implies — retreat with their necks drawn in sideways along the margins of their shell when threatened.

In a study published Thursday in the journal Scientific Reports, scientists have introduced to the world the newest member of this ancient family of turtle: the Pleurochayah appalachius.

Aptly named after the Greek word Pleuro and the Caddo word Cha’yah, which roughly translate to side turtle, researchers discovered fossilized remains of the P. appalachius at the Arlington Archosaur Site in Northeast Texas, with researchers dating the fossil to the early-to-mid Cenomanian period some hundred million years ago.

According to researchers, this outstanding age makes the P. appalachius the oldest known side-necked turtle from North America, taking the crown from the Paiutemys tibert species of turtle discovered in Utah several years ago.

While the fossil’s age makes this discovery exciting on its own right, researchers were also captured by the features of the turtle itself. Data from the fossil tells experts that the P. appalachius likely possessed an extraordinarily sturdy outer shell and had thick, strong bones that extended out of the turtle’s shoulder joint.

Researchers believe that these traits made the newly discovered turtle species uniquely capable of surviving the perils of the ocean. The hardened shell gave the turtles the protection they needed from predators while the jutting bones from their shoulder joint gave the turtles the extra powerful swimming stroke needed to quickly navigate underwater. While these characteristics suggest the turtles were well suited for marine life, researchers say they would like to find more remains of the P. appalachius to help test this theory further.

Based on these features and a good look into the evolutionary relationships of other known turtle types, experts suggest that this newly-minted turtle species likely belonged to the Bothremydidae family of side-necked turtles. Long extinct and unrelated the sea turtles of today, the Bothremydidae family are believed to have hailed from the Gondwana supercontinent nearly 150 million years ago.

If these findings hold up, researchers say the discovery of this new turtle may help experts determine when exactly side-necked turtles settled North America in the first place.

Based on the family they are believed to have belonged to and bodies that seem well-equipped to handle the dangers of the ocean, it would appear side-necked turtles first ventured to North America in the earlier Cenomanian age and likely traveled along the Atlantic Ocean or the Caribbean to do so.

While the discovery of more P. appalachius fossils and further research efforts will help determine if this idea holds water, researchers are optimistic that their discovery could help fill in some crucial gaps in our understanding of these shelled-reptiles and their early evolution on Earth.  

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