Character-taxon matrix from: A new leatherback marine turtle from the lower Oligocene of North America and a phylogenetic nomenclature for Dermochelyidae

The modern leatherback sea turtle Dermochelys coriacea possesses a unique,
flexible mosaic carapace adapted for deep diving. The evolutionary origins
of this structure remain poorly understood because of the fragmentary
nature of the fossil record. Here we describe Ueloca colemanorum n. gen.
n. sp., a novel ridgeless leatherback turtle from the lower Oligocene
Glendon Limestone of Alabama, USA. This specimen (MSC 49490) represents
one of the most complete fossil leatherback carapaces known and provides
new insight into dermochelyid diversity and shell evolution. The carapace
is composed of parallel rows of enlarged ossicles interspersed with
smaller ossicles arranged in distinctive floriform patterns. Histological
analysis reveals a cancellous core with an external cortex but no basal
cortex, a condition also observed in Dermochelys coriacea. Phylogenetic
analysis places Ueloca within a clade of ridgeless leatherbacks
(Uelocini), which diverged from ridge-bearing Dermochelyini in the Eocene.
Our revised phylogeny suggests that Uelocini and Dermochelyini represent
the two main lineages of dermochelyines, both characterized by mosaic
carapaces that undergo parallel morphological trends. These findings
clarify the deep history of leatherback shell evolution and emphasize the
need for additional well-preserved fossils to further refine dermochelyid
systematics.