A new study suggests that an ancient sea turtle recently found and identified in Alabama might be a second ancestor to certain present-day varieties. Scientists believe this species existed in the Late Cretaceous period, approximately 100 to 66 million years ago.
As explained by Science Daily, some species of modern sea turtles were once believed to have descended from one single prehistoric species in the Peritresius family. This species, which also lived in the Late Cretaceous, was given the scientific name Peritresius ornatus, and might have been found only in North American waters during those ancient times.
Considering the limited number of Peritresius discoveries in the Southeastern U.S., a team of researchers from the University of Alabama at Birmingham studied sea turtle fossils from both Alabama and Mississippi, in hopes of identifying their species. The fossils dated back approximately 83 to 66 million years ago, and some of the ones found in Alabama were revealed to belong to a different species from P. Ornatus, though still belonging to the Peritresius family of sea turtles. This species was named Peritresius martini, in honor of its discoverer, George Martin.
According to the researchers’ findings, which were published Wednesday in the journal PLOS One, P. martini had a shell measuring more than 35 inches (90 centimeters) long and 29 inches (75 centimeters) wide, making it much larger than that of P. ornatus. The researchers also noted another interesting detail about P. ornatus, as its shell was found to have one peculiarity not found in any other known species of Cretaceous marine turtles.
As P. ornatus‘ shell had sculptured skin elements that might have been “well-suplied” with blood vessels, the UAB team believes that the ancient turtle might have been capable of thermoregulation, thus allowing it to survive the drastic changes in climate that were taking place during the Late Cretaceous, and outlast other sea turtles that went extinct due to the global cooling at the time.
In a statement, UAB researcher and study lead author Drew Gentry explained that the new sea turtle discovery in Alabama suggests that the Peritresus family was more widely distributed and slightly more diverse than once thought.
“This discovery not only answers several important questions about the distribution and diversity of sea turtles during this period but also provides further evidence that Alabama is one of the best places in the world to study some of the earliest ancestors of modern sea turtles,” said Gentry.