http://upload.wikimedia.org/wikipedia/commons/5/58/Carpus.svg

Segment of the forearm corresponding to the carpus. It consists of several elements that articulate with the radius and ulna at one end and the metacarpals at the other end.[AAO]

we assume MA:carpus belongs here, as there is a distinct class MA:wrist, with the carpal bone being part of the former. XAO:carpus is part of the forelimb skeleton. FMA set-of class lacks definition but we assume this to be equivalent.

fore mesopodium

set of carpal bones

carpus

ossa carpi

uberon

The three main outgroup taxa of tetrapods, panderichthyids, osteolepiforms, and rhizodontids, have endoskeletal elements corresponding to the stylo- and zeugopodial elements in a tetrapod limb. In addition, there are elements that share the position and possibly the developmental derivation of the ulnare and the intermedium. From these observations, most authors have concluded that the stylo- and zeugopodial elements as well as the proximal mesopodial elements have counterparts in the fins of tetrapod ancestors, but there are no indications of wrist or ankle joints.[well established][VHOG]

UBERON:0009880

Not always associated with digits, in sarcopterygians the ulnare is present without true digits being formed, though their homologous radial elements are present[PHENOSCAPE:ad].

The structure of the carpus varies widely between different groups of tetrapods, even among those that retain the full set of five digits. In primitive fossil amphibians, such as Eryops, the carpus consists of three rows of bones; a proximal row of three carpals, a second row of four bones, and a distal row of five bones. The proximal carpals are referred to as the radiale, intermediale, and ulnare, after their proximal articulations, and are homologous with the scaphoid, lunate, and triquetal bones respectively. The remaining bones are simply numbered, as the first to fourth centralia (singular: centrale), and the first to fifth distal carpals. Primitively, each of the distal bones appears to have articulated with a single metacarpal. However, the vast majority of later vertebrates, including modern amphibians, have undergone varying degrees of loss and fusion of these primitive bones, resulting in a smaller number of carpals. Almost all mammals and reptiles, for example, have lost the fifth distal carpal, and have only a single centrale - and even this is missing in humans. The pisiform bone is somewhat unusual, in that it first appears in primitive reptiles, and is never found in amphibians. Because many tetrapods have less than five digits on the forelimb, even greater degrees of fusion are common, and a huge array of different possible combinations are found. The wing of a modern bird, for example, has only two remaining carpals; the radiale (the scaphoid of mammals) and a bone formed from the fusion of four of the distal carpals. In some macropods, the scaphoid and lunar bones are fused into the scaphollunar bone