Reconstruction of the fossil individual Hispanopithecus laietanus, on the basis of the remains recovered from Can Llobateres. Laura Celià. ICP

The journal PLoS ONE published last week the discovery of fossil remains of the hominid Hispanopithecus laietanus at the paleontological site of Can Feu (Sant Quirze del Vallès, Barcelona), in a paper coauthored by several researchers from the Institut Català de Paleontologia Miquel Crusafont (ICP). This research confirms that this hominid from about 10 million years ago had a different locomotion compared to the remaining known apes, both fossil and extant.

Dental remains of Hispanopithecus recovered from Can Feu. David M. Alba. ICP

The paper published in the journal PLoS ONE, led by the ICP researcher David M.  Alba describes the fifteen remains of an adult female skeleton of Hispanopithecus laietanus, with a body mass between 22 and 25 kg, recovered at the paleontological site of Can Feu, dating from the late Miocene, about 10 million years ago. The body mass estimate agrees well with the sex inferred from the morphology of the fossil remains, and in particular from the size and shape of several teeth. In the case of Jordi, an adult male specimen, a mass of about 39 kg was estimated. This evidence shows that H. laietanus displayed a significant size dimorphism, with males being 50% larger than females. This is also the case in extant non-human hominids, with a moderate dimorphism displayed by chimpanzees and bonobos (about one-third larger) and a higher dimorphism displayed by gorillas and orang-utans (more than twice as heavy).

The locomotion of this taxon was well known thanks to the skeleton of Jordi, and especially to the abundant remains of the hand. These indicate that H. laietanus not only had an orthograde (erect) posture suitable for vertical climging along tree  trunks and adaptations to suspend from the branches like orangutans do today, but also retained adaptations for moving quadrupedally above the branches. This combination of suspension and arboreal quadrupedalism had not been documented in any other hominid, extant or fossil, and had been questioned by some members of the international scientific community.

Ulna of Hispanopithecus recovered from the paleontological site of Can Feu. David M. Alba. ICP

The remains of Can Feu, however, include fragments of the chest, shoulder and forearm that strengthen the hypothesis that H. laietanus locomotor repertoire was different from that of other known apes. Specifically, the first rib and the clavicle remains show a mixture of primitive features, such as those of monkeys, and more derived ones, such as those of modern hominids. Especially important is the morphology of the ulna, very characteristic of extant hominids, and which in Hispanopithecus shows a combination of suspensory adaptations with some features that confirm the retention of arboreal quadrupedal behaviors.

This work therefore confirms that Miocene apes had locomotor repertoires differen from those of extant hominids, so that it is impossible to reconstruct the ancestral locomotor behaviors of the various lineages only on the bases of extant species. The study of the fossil record emerges, once again, as the key for understanding the morphological and behavioral diversity of extant species.

The age of the paleontological site of Can Feu, between 10.0 and 9.7 Ma, has been estimated based on the fossil remains of rodents and other small mammals that were found associated to the skeleton of Hispanopithecus. This results were published earlier this year by the ICP researcher Isaac Casanovas-Vilar and coauthors, in the Journal of Vertebrate Paleontology.

+ info Alba, D.M., Almécija, S., Casanovas-Vilar, I., Méndez, J.M., Moyà-Solà, S.(2012). A partial skeleton of Hispanopithecus laietanus from Can Feu and the mosaic evolution of crown-hominoid positional behaviors. PLoS ONE 7(6): e39617. doi:10.1371/journal.pone.0039617.