In:
Science, American Association for the Advancement of Science (AAAS), Vol. 334, No. 6063 ( 2011-12-23), p. 1699-1703
Abstract:
Several groups of tetrapods have expanded sesamoid (small, tendon-anchoring) bones into digit-like structures (“predigits”), such as pandas’ “thumbs.” Elephants similarly have expanded structures in the fat pads of their fore- and hindfeet, but for three centuries these have been overlooked as mere cartilaginous curiosities. We show that these are indeed massive sesamoids that employ a patchy mode of ossification of a massive cartilaginous precursor and that the predigits act functionally like digits. Further, we reveal clear osteological correlates of predigit joint articulation with the carpals/tarsals that are visible in fossils. Our survey shows that basal proboscideans were relatively “flat-footed” (plantigrade), whereas early elephantiforms evolved the more derived “tip-toed” (subunguligrade) morphology, including the predigits and fat pad, of extant elephants. Thus, elephants co-opted sesamoid bones into a role as false digits and used them for support as they changed their foot posture.
Type of Medium:
Online Resource
ISSN:
0036-8075
,
1095-9203
DOI:
10.1126/science.1211437
Language:
English
Publisher:
American Association for the Advancement of Science (AAAS)
Publication Date:
2011
detail.hit.zdb_id:
128410-1
detail.hit.zdb_id:
2066996-3
detail.hit.zdb_id:
2060783-0
SSG:
11
