Paraplacodus broilli (Peyer 1931) Middle Triassic ~ 240 mya, 1.5 meters long, was derived from a sister Palatodonta phylogenetically preceded Placodus and Placochelys. It is known from a complete, but disarticulated skeleton.
Distinct from Palatodonta, the skull of Paraplacodus included three large and procumbent premaxillary teeth. The naris was elevated above the ventral margin of the the orbit. The maxillary teeth were blunt. Distinct from Claudiosaurus the quadratojugal was strongly arched and somewhat elevated, reducing the lateral temporal fenestra to a slit. The mandible included two procumbent anterior tusks and a very high coronoid process, which helped increased the crushing force of the bite. The nasals were separated as the premaxilla contacted the frontals. The ectopterygoid was greatly expanded and the palatine greatly reduced as the palatal teeth expanded, flattened and were reduced in number to just four per side.
Distinct from Claudiosaurus, each vertebra included long transverse processes, creating a wide, box-like torso. The neural spines were taller. Fewer cervicals were present. The dorsal ribs included costal plates. The chevrons were reduced to absent.
The scapula and coracoid were smaller and not fused. The interclavicle was ventral to the clavicles. The forelimbs were short and robust. The carpus was poorly ossified. The hand was smaller.
The ilium was smaller without a posterior process but connected to three sacral vertebrae. The pubis and ischium formed a broad but shallow ventral basin. The hind limbs were shorter. The foot was smaller with shorter digits.
The family tree of the Enaliosauria is here. The complete reptile family tree is here. |
