[PaleoAnthropology • 2015]

[PaleoAnthropology • 2015]  

Pliobates cataloniae • Miocene Small-bodied Ape from Eurasia sheds light on Hominoid Evolution

A team of researchers from the George Washington University and the Institut Català de Paleontologia Miquel Crusafont identified a new genus and species of small ape that existed before the evolutionary split of humans/great apes (hominids) and gibbons (the 'lesser apes' or hylobatids).

Illustration: Marta Palmero / Institut Català de Paleontologia Miquel Crusafont 

ABSTRACT

Miocene small-bodied anthropoid primates from Africa and Eurasia are generally considered to precede the divergence between the two groups of extant catarrhines—hominoids (apes and humans) and Old World monkeys—and are thus viewed as more primitive than the stem ape Proconsul. Here we describe Pliobates cataloniae gen. et sp. nov., a small-bodied (4 to 5 kilograms) primate from the Iberian Miocene (11.6 million years ago) that displays a mosaic of primitive characteristics coupled with multiple cranial and postcranial shared derived features of extant hominoids. Our cladistic analyses show that Pliobates is a stem hominoid that is more derived than previously described small catarrhines and Proconsul. This forces us to reevaluate the role played by small-bodied catarrhines in ape evolution and provides key insight into the last common ancestor of hylobatids (gibbons) and hominids (great apes and humans).

 STRUCTURED ABSTRACT

INTRODUCTION

Reconstructing the ancestral morphotype from which extant hominoids (apes and humans) evolved is complicated by the mosaic nature of ape evolution, the confounding effects of independently evolved features (homoplasy), and the virtual lack of hylobatids (gibbons and siamangs) in the Miocene fossil record. For several decades, small-bodied anthropoid primates from Africa and Eurasia have not played an important role in this debate, because they generally lack the shared derived features of extant catarrhines (hominoids and Old World monkeys) and are thus considered to precede their divergence. Even some small-bodied catarrhines from Africa (dendropithecids), considered to be stem hominoids by some authors, are viewed as more primitive than the larger-bodied stem ape Proconsul. This has led to the assumption that hylobatids are a dwarfed lineage that evolved from a larger-bodied and more great ape–like common ancestor with hominids (great apes and humans).

RATIONALE

Here we describe a new genus of small-bodied (4 to 5 kg) ape from the Miocene (11.6 Ma), discovered in the Abocador de Can Mata stratigraphic series (Vallès-Penedès Basin, northeast Iberian Peninsula), that challenges current views on the last common ancestor of extant hominoids. This genus is based on a partial skeleton that enables a reliable reconstruction of cranial morphology and a detailed assessment of elbow and wrist anatomy. It exhibits a mosaic of primitive (stem catarrhine–like) and derived (extant hominoid–like) features that forces us to reevaluate the role played by small-bodied catarrhines in ape evolution.

Order: Primates

Suborder: Haplorhini

Superfamily: Hominoidea

Family: Pliobatidae Alba et al. 2015

Genus: Pliobates Alba et al. 2015

Species: Pliobates cataloniae Alba et al. 2015

Reconstruction of the skull (front and side view) and representation of life appearance of Pliobates cataloniae are shown.

Credit: Marta Palmero / Institut Català de Paleontologia Miquel Crusafont 

Long bones from the left arm of Pliobates cataloniae. Humerus (A), radius (B) and ulna (C).

photos: Institut Català de Paleontologia Miquel Crusafont (ICP) 

RESULTS

The new genus retains some features that are suggestive of generalized above-branch quadrupedalism, but it possesses more extensive hominoid-like postcranial features (mostly related to enhanced forearm rotation and ulnar deviation capabilities) than those convergently displayed by atelids. Its overall body plan is more compatible with an emphasis on cautious and eclectic climbing, combined with some degree of below-branch forelimb-dominated suspension (although less acrobatic than in extant gibbons). Its relative brain size implies a monkey-like degree of encephalization (similar to that of hylobatids but below that of great apes), and dental microwear indicates a frugivorous diet. From a phylogenetic viewpoint, the new genus combines craniodental and postcranial primitive features (similar to those of dendropithecids) with multiple derived cranial and postcranial features shared with extant hominoids. Some cranial similarities with gibbons would support a closer phylogenetic link between the new genus and hylobatids. However, this possibility is not supported by the total evidence. A cladistic analysis based on more than 300 craniodental and postcranial features reveals that the new genus is a stem hominoid (preceding the divergence between hylobatids and hominids), although more derived than previously known small catarrhines and Proconsul.

CONCLUSION

As the first known Miocene small-bodied catarrhine to share abundant derived features with extant hominoids, the new genus indicates a greater morphological diversity than previously recognized among this heterogeneous group, and it provides key insight into the last common ancestor of hylobatids and hominids. Our cladistic results, coupled with the chronology and location of the new genus, suggest that it represents a late-surviving offshoot of a small African stem hominoid that is more closely related to crown hominoids than Proconsul is. These results suggest that, at least in size and cranial morphology, the last common ancestor of extant hominoids might have been more gibbon-like (less great ape–like) than generally assumed.

Representation of the environment and some of the species that inhabited the area of Els Hostalets de Pierola about 12 million years ago.

Illustration: Oscar Sanisidro / Institut Català de Paleontologia Miquel Crusafont (ICP) 

D. M. Alba, S. Almecija, D. DeMiguel, J. Fortuny, M. P. de los Rios, M. Pina, J. M. Robles, S. Moya-Sola. 2015. Miocene Small-bodied Ape from Eurasia sheds light on Hominoid Evolution. Science. 350 (6260): aab2625. DOI: 10.1126/science.aab2625

 Meet your gibbon cousin

Apes are divided into two groups: larger-bodied apes, or hominoids, such as humans, chimps, and gorillas; and smaller-bodied hylobatids, such as gibbons. These two lineages are thought to have diverged rather cleanly, sharing few similarities after the emergence of crown hominoids. Alba et al. describe a new ape from the Miocene era that contains characteristics from both hominoids and small-bodied apes (see the Perspective by Benefit and McCrossin). Thus, early small-bodied apes may have contributed more to the evolution of the hominoid lineage than previously assumed.

New Fossil Suggests We Had A Gibbon-Like Early Ancestor | IFLScience http://www.iflscience.com/plants-and-animals/new-fossil-suggests-we-had-gibbon-early-ancestor

A new primate species at the root of the tree of extant hominoids http://phy.so/365332715 via  @physorg_com