Placodontia
Placodontia is an extinct group of Triassic marine reptiles, mostly shallow-water animals with crushing teeth adapted to eating hard-shelled prey.
Sauropterygia: A major group of extinct marine reptiles that includes placodonts, nothosaurs, and plesiosaurs. Placodontia is commonly classified within this broader marine-reptile lineage.
Dental occlusion: The contact relationship between the teeth of the upper and lower jaws when they meet. Tooth contact helped distribute force as placodonts crushed shells.
Placodus: A genus of Middle Triassic placodont marine reptiles with broad crushing teeth and enlarged front teeth. Placodus is the namesake genus and a classic example of shell-crushing placodont anatomy.
Reptile: A vertebrate in the amniote lineage that includes turtles, lizards, snakes, crocodilians, birds, and extinct relatives. Placodonts were reptiles whose ancestors adapted to marine environments.
Nothosauria: An extinct group of Triassic marine reptiles with elongated bodies and limbs adapted for swimming. Nothosaurs were close relatives but generally had pointed teeth and a different feeding ecology.
Triassic: The geologic period from about 252 to 201 million years ago, between the Permian and Jurassic periods. Placodonts lived during this period, when marine ecosystems were recovering and diversifying.
Tooth plate: A broad, flattened dental structure that bears multiple tightly packed teeth or tooth-like units. Some placodonts had broad crushing surfaces suited to hard prey.
Cyamodus: A genus of Triassic placodonts with broad, often flattened skulls and shell-crushing teeth. Its skull and teeth illustrate a distinct placodont approach to processing hard prey.
Marine reptile evolution: The evolutionary history of reptiles that became adapted to life in marine environments. Placodontia arose during the broader Triassic expansion of reptiles into marine ecosystems.
Plesiosauria: An extinct group of marine reptiles known for paddle-like limbs and, in many forms, long necks. Plesiosaurs represent a later marine-reptile radiation with body plans unlike placodonts.