Are turtles dinosaurs
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Are Turtles Dinosaurs?
Introduction to Reptilian Classification
The classification of reptiles has traditionally hinged on the presence and type of fenestration in the temporal region of the skull. Reptiles are divided into two main groups based on this characteristic: diapsids and anapsids. Diapsids, which include snakes, lizards, crocodiles, and dinosaurs, have two holes in the temporal region of their skulls. Anapsids, on the other hand, have a completely roofed skull with no temporal fenestration, a category that includes turtles (Testudines).
Turtles and Their Phylogenetic Affinities
Recent analyses have challenged the traditional view of turtles as primitive reptiles. By incorporating a broader range of Mesozoic and extant taxa, studies have robustly supported the diapsid affinities of turtles, suggesting that they are more closely related to other diapsid reptiles than previously thought. This finding necessitates a reassessment of the use of turtles in phylogenetic reconstructions and highlights the complexities of classifying groups with unique morphologies.
Turtles in the Mesozoic Era
Fossil evidence from various Mesozoic sites provides insights into the coexistence of turtles and dinosaurs. For instance, a site in southern Poland revealed isolated bones of a Palaeochersis-like turtle alongside bones of coelophysoid dinosaurs and other vertebrates from the Late Triassic period. Similarly, the Late Jurassic sediments of Switzerland have yielded turtle remains in close association with dinosaur footprints, suggesting that these turtles occasionally visited tidal flat environments frequented by dinosaurs.
Turtle and Dinosaur Trackways
Trackways from different geological formations further illustrate the coexistence of turtles and dinosaurs. In the Upper Jurassic Lastres Formation of Spain, turtle tracks have been found alongside dinosaur tracks, indicating that turtles shared these environments with dinosaurs. In the Upper Cretaceous formations near Denver, Colorado, turtle tracks have been discovered in the same layers as dinosaur footprints, providing additional evidence of their cohabitation.
Conclusion
While turtles are not classified as dinosaurs, they share a close evolutionary relationship with other diapsid reptiles, including dinosaurs. Fossil evidence from various Mesozoic sites demonstrates that turtles and dinosaurs coexisted in the same environments, further underscoring their phylogenetic connections. The reclassification of turtles as diapsids rather than anapsids marks a significant shift in our understanding of reptilian evolution and highlights the intricate relationships within this diverse group.
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