Carpal bones, carpal fusions and footprints of Myotragus: clues for locomotion and behavior

• Autores: Pere Bover Arbós, Joan Josep Fornós Astó, Josep Antoni Alcover
• Localización: Proceedings of the International Symposium "Insular Vertebrate Evolution: the Palaeontological Approach": September, 16-19 Mallorca / coord. por Josep Antoni Alcover, Pere Bover Arbós, 2005, ISBN 84-609-6472-8, págs. 59-72
• Idioma: inglés
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• Resumen

  • Some of the anatorrtical features of the Myotragus balearicus limb bones show that this species displayed a "low gear" locomotion. These features are the fusion of the nabiculocuboid complex to the large and small cuneiforms and to the metatarsal bone, limb bones morphology and very stout leg bones with important muscular and ligament insertions. Ali these features have been identified as a way to stabilise the joints due to a great body mass in relation with the body height, in detriment of a cursoriallocomotion. From the excavation of deposits as Cova Estreta (Pollença, Mallorca) and Cova des Moro (Manacor, Mallorca) several bones have been obtained displayíng undescribed features that agree with the above explained proposal. Specifically, it has been obtained a bone produced as the result ofthe fusion ofscaphoid and lunar and a bone result of the fusion ofpisiform and cuneiform. For the present, only have been obtained two specimens of the former case and just one ofthe later. None ofthe bones seem to be pathologic, and they do not show any kind of bone regrowth in the fusion zone.

    Fused scaphoid and lunar, and fused cuneiform and pisiform, seems to limit this movement, and together with anatorrtical characteristics of other joints (mainly in the fore leg), shows that the legs were not placed just under the body, as the almost all the extant bovids. Again, it seems that these fusions (together with the stoutness of the carpal bones) are also related with the stability of the joint.

    Tracks and trackways can be important sources of information on locomotion and behaviour of fossil (and extant) species.

    Although a considerable amount of Myotragus footprints are available, just few trackways can be followed and measured.

    Particularly, the deposits of s'Estret des Temps and Ses Piquetes in Santanyí (Mallorca) have furnished three trackways that have been here studied in detail. The measurement of path length, width between limbs (fore and hind limbs) and feet orientation can give some clues on locomotion and body design of this species. The feet angle (outwards) of M. balearicus is considerably larger than in other ungulate species studied, as Cervus elaphus and Ouis aries. This measurement together with the relative separation of the limbs (related to the path length) show that the limbs of this species were not positioned just under the body during walking (as almost all the extant bovids), as can be inferred from other anatomical characteristics.