Mesanerpeton

Mesanerpeton is an extinct genus of four-limbed stem-tetrapod from the Mississippian (Tournaisian) of Scotland. It contains a single species, Mesanerpeton woodi, who based on a disarticulated specimen including a clavicle, vertebrae, and forelimb bones from the Ballagan Formation. The vertebrae are poorly-ossified and similar to Crassigyrinus, but the forelimb was robust. The shape and level of torsion present in the humerus are intermediate between Devonian stem-tetrapods and later Carboniferous tetrapods. This transitional condition, and the associated rerouting of the brachial artery and median nerve, may indicate that Mesanerpeton had a higher stride length and more efficient locomotion on land compared to its predecessors.