Search

Many important Pliocene hominin specimens have been recovered from Woranso-Mille, a paleontological research area in the Afar region of Ethiopia, including the complete cranium of Australopithecus anamensis , a partial skeleton of Australopithecus afarensis , mandibular and maxillary elements representing a new species, Australopithecus deyiremeda , and a partial foot of an as-yet-unnamed species. Woranso-Mille is the only site, so far, to have reported the co-existence of more than one early hominin species between 3.8 and 3.3 Ma and the temporal overlap between A. anamensis and A. afarensis. Thus, the site has important implications for our understanding of the paleoecology and taxonomic diversity of early hominins and their ecological niche. This paper explores the paleohabitats of Woranso-Mille through its faunal community ecological structure and taxonomic composition using correspondence analysis and Forbes modified similarity index. The results suggest that Pliocene Woranso-Mille was a mosaic of different habitat types, with riparian woodland and floodplain grassland along rivers draining into a lake, along with less mesic habitats such as woodland, grassland, and shrubland. The apparent high level of vegetation heterogeneity may have promoted dietary specializations and niche differentiation among the different Australopithecus species at Woranso-Mille and allowed for their co-existence at the site. [ABSTRACT FROM AUTHOR]

Abstract: Hominins are a very rare component of the large-mammal fauna at Laetoli. Although no equivalent data are available for Hadar, the much higher count and relative abundance of hominins suggests that they may have been more common at the latter site. The apparent relative rarity of hominins at Laetoli may have significant implications for understanding the ecology of Australopithecus afarensis. However, it is essential to first assess the extent to which taphonomic variables might have been a contributing factor. Using data from fossil ruminants, we show that the survivability of skeletal elements at Laetoli relates to the extent to which they can resist carnivore scavenging and their likelihood of being entirely buried by volcanic ashes and tuffaceous sediments. The rarity of hominins at Laetoli is probably due in part to the influence of these two taphonomic factors. However, these factors cannot account entirely for the difference in hominin relative abundance between these two sites, and ecological differences were probably a contributing factor. The highest population densities of chimpanzees today occur in forest and closed woodland, with reduced densities in open woodland. If similar levels of population-density variation characterized A. afarensis, the differences between Hadar and Laetoli may relate to the quality/optimality of the habitats. Hadar was, in general, much more densely wooded and mesic than Laetoli, with permanent and substantial bodies of water. In contrast, Laetoli was predominantly a woodland-shrubland-grassland mosaic supported only by ephemeral streams and ponds. The apparent greater relative abundance of hominins at Hadar compared with Laetoli suggests that, like chimpanzees, A. afarensis may have been more successful in more densely wooded habitats. Compared with Hadar, Laetoli probably represented a less optimal habitat for the foraging and dietary behavior of A. afarensis, and this is reflected in their inferred lower abundance, density, and biomass. [Copyright &y& Elsevier]

A dentate mandible and proximal femur of Mesopithecus pentelicus Wagner, 1839 are described from the Shuitangba lignite mine in Zhaotong Prefecture, northeastern Yunnan Province, China. The remains were retrieved from sediments just below those that yielded a juvenile Lufengpithecus cranium and are dated at about ∼6.4 Ma. The mandible and proximal femur were found in close proximity and are probably of the same individual. The lower teeth are metrically and morphologically closely comparable with those of confirmed M. pentelicus from Europe, and on this basis, the specimen is assigned to this species. The anatomy of the proximal femur indicates that the Shuitangba Mesopithecus was a semiterrestrial quadruped that engaged in a range of mostly arboreal activities, including walking, climbing, and occasional leaping, with an abducted hip joint. The Shuitangba Mesopithecus is dentally typical for the genus but may have been more arboreal than previously described for M. pentelicus. M. pentelicus is well known from late Miocene (MN 11–12) sites in Europe and southwest Asia. Its estimated average rate of dispersal eastward was relatively slow, although it could have been episodically more rapid. The presence of a colobine, only slightly lower in the same section at Shuitangba that produced Lufengpithecus , is one of the only two well-documented instances of the near or actual co-occurrence of a monkey and ape in the Miocene of Eurasia. At Shuitangba, M. pentelicus occupied a freshwater-margin habitat with beavers, giant otters, swamp rabbits, and many aquatic birds. The presence of M. pentelicus in southwest China near the end of the Miocene further attests to the ecological versatility of a species long recognized as widespread and adaptable. The modern colobines of Asia, some or all of which are probable descendants of Mesopithecus , have gone on to inhabit some of the most highly seasonal and extreme habitats occupied by nonhuman primates. [ABSTRACT FROM AUTHOR]