It articulates with the cup-shaped depression on the head of the radius, and is limited to the front and lower part of the bone.

In non-human tetrapods, the name capitellum is generally used, with "capitulum" limited to the anteroventral articular facet of the rib (in archosauromorphs).

Lepidosaurs show a distinct capitellum and trochlea on the centre of the ventral (anterior in upright taxa) surface of the humerus at the distal end.

In non-avian archosaurs, including crocodiles, the capitellum and the trochlea are no longer bordered by distinct etc.- and entepicondyles respectively, and the distal humerus consists two gently expanded condyles, one lateral and one medial, separated by a shallow groove and a supinator process.

In birds, where forelimb anatomy has an adaptation for flight, its functional if not[1] ontogenetic equivalent is the dorsal condyle of the humerus.