2025/10/06 by Seishiro Tada, Takanobu Tsuihiji, Donald J. Morgan +2 · 1 voice · 2 citations
Environmental Science · Earth and Planetary Sciences · Medicine · #Turtle Biology and Conservation #Paleontology and Evolutionary Biology #Comparative Animal Anatomy Studies
paper · pdf · doi:10.1186/s13358-025-00403-3
Abstract The cephalic vasculature of turtles has been explored extensively for its evolutionary history. However, the rostral portion of the cephalic vasculature has rarely been investigated compared to that of the basicranial region, despite its unique morphology among diapsids and a wide range of variation within crown turtles. Here, a broad range of diapsid taxa were examined to explore the evolution of the rostral vasculature in turtles. We show that the arrangement of the rostral vasculature specific to extant turtles, bifurcation of the maxillary artery, and the caudally shifted foramen praepalatinum transmitting the palatine artery, could at least be traced back to the mesochelydians based on osteological evidence. Although one of the oldest testudinatans Proganochelys quenstedtii had a medially shifted maxillary artery as in crown turtles, its rostral vasculature likely retained the ancestral diapsid condition, consistent with the generally plesiomorphic morphology of the cranium. The crownward evolution of the rostral vascular patterning is likely related to associated rostral morphological changes, such as the keratinous beak, nasolacrimal duct, and medial nasal gland. In addition, variations of the osteological correlates for the maxillary and palatine arteries were found in crown turtles. Trionychians have a unique large opening termed foramen intermaxillaris instead of the paired foramina praepalatina on the floor of the nasal cavity, but they were shown to be homologous based on the shared palato-nasal neurovascular pattern. Chelonioids exhibited the most deviation from the generalized turtle rostral vascular patterning. Those deviations within crown turtles are likely associated with the relevant anatomical changes of the rostrum, such as the secondary palate of cheloniids.