A trematosauroid temnospondyl from the Middle Triassic of Jordan

Abstract. A well-preserved mandible from the Lower Anisian Mukheiris Formation from near the Dead Sea (Jordan) proves the presence of tetrapods in the region. It is identified as a stereospondyl lower jaw sharing synapomorphies with the Trematosauroidea. It has the following combination of features: (1) Meckelian fenestra almost one-third the length of the ramus, (2) postglenoid area posterodorsally rising and robust, as long as glenoid facet, (3) preglenoid process substantially higher than medial margin of adductor chamber, (4) all teeth anteriorly and posteriorly carinate, and (5) symphysis without additional tooth rows, with a pair of unequal fangs as part of the dentary arcade, which contains unusually large teeth. The Jordan specimen shares most character-states with South African Microposaurus (size of teeth, bicarinate structure) and the Russian Inflectosaurus (preglenoid process, PGA). Phylogenetic analysis finds it to nest with Microposaurus, whereas Inflectosaurus forms an unresolved polytomy with other trematosauroids.

doi:10.1002/mmng.201100002