The trematosaurs were a diverse and important group that included many medium-sized to large forms that were semi-aquatic to fully aquatic. The group included long-snouted forms such as the trematosauroids and short, broad-headed forms such as the metoposaurs.
Trematosaurs formed an extensive and crucial category that featured numerous mid-to-large-size animals that could be either partially or entirely aquatic. This group comprised long-nosed types akin to the trematosauroids and shorter, broader-headed varieties like the metoposaurs.