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NEW LATE MIOCENE DRYOPITHECINE SKELETON FROM SPAIN

See Physical Anthropology: The Core, Chapter 9, pages 229-231;

Physical Anthropology, 6^th edition, Chapter 15, page 394.

Descriptions of many new fossils were published in 1995. These included the material that led to the creation of two new species and one new genus: Ardipithecus ramidus and Australopithecus anamensis. In the first month of 1996 we read about an important discovery in Spain of a significant number of postcranial bones of Dryopithecus.

The find is the only known anthropoid skeleton, other than Oreopithecus, that has been found that dates between the 18-million-year-old Proconsul and the 3.1-million-year-old "Lucy". The new material is significant because it provides information about the evolution of skeletal adaptations for orthograde postures that are found in the modern apes and humans.

The partial skeleton, which belongs to the species Dryopithecus laietanus, was discovered between 1992 and 1994 at the site of Can Llobateres, Spain, The remains are those of an adult male whose body was dismembered by carnivores. The postcranial bones appear to be associated with a partial cranium discovered earlier. The material has been dated by paleomagnetism to 9.5 million B.P.

The skeletal anatomy of living anthropoids can be divided into two basic structures that are related to posture and locomotion. Features of the skeleton associated with pronograde postures, seen in the monkeys, include a long vertebral column, a narrow rib cage, scapulas located to the side, and intermembral indices close to or somewhat below 100. In contrast, the living hominoid skeleton exhibits a shorter and less flexible vertebral column, a broader rib cage, scapulas located more to the back, and intermembral indices over 100.

With the exception of Oreopithecus, Middle to Late Miocene apes were thought to be generalized quadrupeds characterized by pronograde posture. Analysis of the new skeleton shows a contrasting pattern associated with orthograde posture. Details of the skeleton suggest less flexibility in the spine, a broad rib cage, and long clavicles. Details of the arms suggest that they were powerful and capable of a wide range of movement. The leg also shows great hip mobility. These features are associated with climbing and suspensory behavior. The relative sizes of the arms and legs also lead to the same locomotor reconstruction.

With the discovery of this new evidence, paleoanthropologists continue the debate over the divergence of the line leading to the orangutan and that leading to the African apes and hominids. The discoverers of the new material present the argument that the new find is related to the Sivapithecus-orangutan lineage. This interpretation is challenged by others and the real picture is far from clear.

References: S. Moyá-Solá and M. Kühler, "A Dryopithecus Skeleton and the Origins of Great-Ape Locomotion," Nature, 379 (11 January 1996), 156-159; P. Andrews and D. Pilbeam, "The Nature of the Evidence," Nature, 379 (11 January 1996), 123-124.