A team of researchers discovered a new species of an ancient turtle in Texas that gives new evolutionary insights into how reptiles have migrated to the North American continent.
Study lead author Brent Adrian, a senior research specialist in anatomy at the Midwestern University College of Graduate Studies, and colleagues have named the species Pleurochayah appalachius.
According to EurekAlert!, the name came from the Greek word Pleuro that means side, and the Caddo word Cha'yah which means turtle, while "appalachius" is derived from the North American region where it was found.
P. appalachius is said to be the oldest known North American species of side-necked turtle, a species that withdraw their necks sideways into their shells when under threat. The study suggests that the turtle may have migrated to North America around 94 to 100 million years ago during Cenomanian Age.
Oldest Known Side-Necked Turle in North America
The study, "An early bothremydid from the Arlington Archosaur Site of Texas" published in the journal Scientific Reports, reported that P. appalachius is a bothremydid turtle adapted for coastal life.
Researchers found its fossilized remains at the Arlington Archosaur Site of the Woodbine Group in Texas. The team believes that it is even older than Paiutemys tibert, a side-necked turtle species from Utah during the late Cenomanian era and was previously known as the oldest known side-necked turtle in North America.
Moreover, further analysis showed that they belong to the extinct lineage of pleurodiran or side-necked turtles that are called Bothremydidae. According to Phys.org, they are a diverse and geographically widespread clade that lives on a wide range of ecological niches that originated in Gondwana and migrated to the northern continents during the Early Cretaceous era.
The discovery of the oldest known side-necked turtle represents one of the earliest examples of intercontinental dispersals by the species.
Anatomy of the Oldest Side-Necked Turtle in North America
The team reported several features they saw on P. appalachius that may have suggested that they are adapted to marine life, EurekAlert! reported. These combinations of morphological adaptations to a highly aquatic lifestyle may have helped them in their migration to North America.
They have robust bony protrusions at the end of their humerus that also forms part of their shoulders, which may have enabled them to be a good swimmer.
Also, they noticed a thick outer surface of its shell bones that may have strengthened the shell and act as a protection for the side-necked turtle in marine environments.
Furthermore, the turtle's cranium is a combination of primitive and derived traits that the bothremydid species also had. Phylogenetic analysis showed that P. appalachius shares characteristics that most Cearachelyini and Kurmademydini basal bothremydid clades possess. It also places the oldest side-necked turtle as a basal member of the bothremydid clade.
"This discovery provides the earliest evidence of side-necked turtles in North America and expands our understanding of the first migrations of the extinct bothremydids. It further establishes the Arlington Archosaur Site as an important fossil unit that is revealing the foundations of an endemic Appalachian fauna," Adrian said, according to Phys.org.
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