Cyamodontoids

Cyamodontoids are an extinct group of placodont marine reptiles that lived during the Triassic period. They are distinguished by their broad, flattened, and often toothless jaws, which were covered in bony plates. This unique dental adaptation is believed to have been used for crushing hard-shelled prey, such as mollusks and crustaceans. The name "cyamodontoid" itself is derived from Greek words meaning "bean tooth," referring to the tooth-like plates found in some members of the group.

Fossils of cyamodontoids have been found primarily in Europe and Asia. These reptiles varied in size, with some reaching lengths of up to two meters. Their bodies were typically robust, with a broad torso and paddle-like limbs, suggesting they were adapted for a bottom-dwelling lifestyle in shallow marine environments. Unlike other placodonts, which often possessed gastroliths (stomach stones) for grinding food, cyamodontoids likely relied entirely on their specialized jaw plates for processing their diet.

The evolutionary history of cyamodontoids is closely tied to the broader placodont lineage, which emerged in the Early Triassic. Cyamodontoids represent a specialized offshoot within this group, characterized by their extreme tooth reduction and the development of large, crushing plates. Their extinction at the end of the Triassic coincided with a major global extinction event, though the specific reasons for their demise remain a subject of ongoing research.