A unique Middle Miocene European hominoid and the origins of the great ape and human clade

Abstract

The great ape and human clade (Primates: Hominidae) currently includes orangutans, gorillas, chimpanzees, bonobos, and humans. When, where, and from which taxon hominids evolved are among the most exciting questions yet to be resolved. Within the Afropithecidae, the Kenyapithecinae (Kenyapithecini + Equatorini) have been proposed as the sister taxon of hominids, but thus far the fragmentary and scarce Middle Miocene fossil record has hampered testing this hypothesis. Here we describe a male partial face with mandible of a previously undescribed fossil hominid, Anoiapithecus brevirostris gen. et sp. nov., from the Middle Miocene (11.9 Ma) of Spain, which enables testing this hypothesis. Morphological and geometric morphometrics analyses of this material show a unique facial pattern for hominoids. This taxon combines autapomorphic features—such as a strongly reduced facial prognathism—with kenyapithecine (more specifically, kenyapithecin) and hominid synapomorphies. This combination supports a sister-group relationship between kenyapithecins ( Griphopithecus + Kenyapithecus ) and hominids. The presence of both groups in Eurasia during the Middle Miocene and the retention in kenyapithecins of a primitive hominoid postcranial body plan support a Eurasian origin of the Hominidae. Alternatively, the two extant hominid clades (Homininae and Ponginae) might have independently evolved in Africa and Eurasia from an ancestral, Middle Miocene stock, so that the supposed crown-hominid synapomorphies might be homoplastic.

Gibbons and hominoid ancestry

“…Their characters are as follows: skulls with lightly built crania with relatively prominent brow ridges; variable prognathism from low to high; strong angle between face and skull (klinorhynchy) in Hispanopithecus laietanus; reduced maxillary sinus; broad triangular nose; broad palate; high zygomatic root; primitive teeth in D. fontani, molars with broad basins between cusps elongated molars and premolars in Pierolapithecus; teeth with thick enamel in Anoiapithecus and Pierolapithecus; reduced M3 in the three earlier species but not in H. laietanus and R. hungaricus; orthograde (upright) posture; broad chest region; long clavicle; scapula shifted on to back; stiff lumbar region; mobile elbow joint, stable at full extension; mobile wrist; long slender hand phalanges (short and less curved in some); femur head above greater trochanter; femur neck steeply angled. Not all these characters are known for all species, but where they are known for two or more species the characters are consistent, with the conclusion that upright posture, and/or suspensory locomotion had evolved in some species of dryopithecines, particularly in Hispanopithecus laietanus (Crusafont-Pairo and Hurzeler, 1961;Pilbeam and Simons, 1971;Kretzoi, 1975;Morbeck, 1983;Begun et al, 1990Begun et al, , 2003Moyà-Solà et al, 1993, 2004, 2009a, 2009bKordos, 1991;Begun and Kordos, 1993;Moyà-Solà S. and Köhler, 1993, 1995, 1996, 1997Kordos and Begun 1997;Ungar and Kay 1995;Kordos and Begun, 1997;Kordos and Begun, 1997;Begun, 2002Begun, , 2009Ungar, 2005;Alba et al, 2010;Begun et al, 2012). Some of the characters supposedly indicating suspensory locomotion are absent in gibbons, the most suspensory of the apes, for example the stiff lower back.…”

“…One is the Indian ape Sivapithecus sivalensis, the earliest record for which is about 12 Ma, and which gives a minimum age for the origin of the orangutan lineage (Pilbeam, 1996;Pilbeam et al, 1990). However, the postcranial skeleton of this fossil ape is nothing like that of the orangutan (Rose, 1984(Rose, , 1986(Rose, , 1989, whereas the skeleton and some aspects of the skull of Hispanopithecus laietanus from nine-million-year-old deposits in Spain have many similarities with the orangutan (Moyà-Solà and Köhler, 1996;Moyà-Solà et al, 2004, 2009a, 2009b. There is little likelihood, however, that S. indicus and H. laietanus are closely related, and it is clear that one or the other is converging on the orangutan, but which one?…”

The primate fossil record in the Iberian Peninsula

“…Remarks: The holotype and currently only known individual of this taxon includes a partial face and skeleton with Remarks: A. brevirostris has been described on the basis of a partial face and associated mandible from ACM/C3-Aj (Moyà- Solà et al, 2009b), although unpublished dental remains from a second individual have been recovered from the same locality. As for Pierolapithecus, doubts have been raised regarding the distinct taxonomic status of Anoiapithecus relative to Dryopithecus (Begun, 2009;Begun et al, 2012).…”

Ruminant diets and the Miocene extinction of European great apes

“…Records show more than 10 genera ranging from Spain to southeastern Asia (Begun 2007;Moyà-Solà et al 2009). The pliopithecoids, a catarrhine superfamily with no known descendants, were also taxonomically and ecologically diverse.…”