title: The distal tibia of Hispanopithecus laietanus: more evidence for mosaic evolution in Miocene apes.
abstract: IPS18800 is a partial skeleton attributed to the fossil great ape Hispanopithecus laietanus, and dated to 9.6 Ma (millions of years ago). Previous studies on the postcranial anatomy of this taxon have shown that it displayed a derived, extant great ape-like orthograde body plan with suspensory adaptations, uniquely coupled with adaptations for above-branch pronograde locomotion. Here, for the first time, we describe and analyze in detail the distal tibia of the IPS18800 skeleton of Hispanopithecus with the aid of three-dimensional geometric morphometrics based on 53 landmarks and semilandmarks collected on a broad sample of extant catarrhines and fossil hominoids. Results of principal components and canonical variate analyses reveal that the distal tibia of Hispanopithecus occupies a unique position in the morphospace, similar in some respects to pronograde monkeys, and in other respects to extant apes. The IPS18800 distal tibia combines adaptations for above branch quadrupedalism, such as a keeled trochlear surface and strong intercollicular groove, with adaptations for vertical climbing, such as an anteroposteriorly flattened shaft, enlarged fibular facet and a tibial stop. These results on the distal tibia agree with those from other anatomical regions, indicating that this taxon displayed a locomotor repertoire unlike any extant ape, combining vertical climbing and clambering with above-branch quadrupedalism.
authors.affiliation: Department of Biomedical Sciences, Grand Valley State University, Padnos Hall, Allendale, MI 49401, USA. tallmame@gvsu.edu
authors.forename: Melissa
authors.initials: M
authors.lastname: Tallman
authors.forename: Sergio
authors.initials: S
authors.lastname: Almécija
authors.forename: Samantha L
authors.initials: SL
authors.lastname: Reber
authors.forename: David M
authors.initials: DM
authors.lastname: Alba
authors.forename: Salvador
authors.initials: S
authors.lastname: Moyà-Solà
mesh_terms: D000818:Animals; D005075:Biological Evolution; D005580:Fossils; D015186:Hominidae / Q000033:anatomy & histology* / Q000235:genetics; D008124:Locomotion; D025341:Principal Component Analysis; D013030:Spain; D013977:Tibia / Q000033:anatomy & histology*