Testudines are the reptilian clade of turtles, first appearing in the Late Triassic and retaining a remarkably conservative body plan. Their defining feature is the rigid shell, formed by the fusion of ribs, vertebrae, and dermal bones into a dorsal carapace and ventral plastron that fully encase the body.
The shoulder and pelvic girdles lie within the ribcage, an unusual reversal among vertebrates, and the skull shows secondary closure of the temporal openings, setting turtles apart from other sauropsids. Their toothless jaws bear keratinous beaks adapted to varied diets, while limb and shell forms reflect aquatic, semi-aquatic, and terrestrial lifestyles.
Despite little overall change across more than 200 million years, turtles have achieved wide ecological success, their fossil record tracing a lineage of enduring design that has withstood nearly every major extinction event.
Ελληνικά
English
Ἑλληνική ἀρχαία
Κυπριακά
