Papers by Yohannes Haile-Selassie
Ardipithecus kadabbaLate Miocene Evidence from the Middle Awash, Ethiopia, 2009
Ardipithecus kadabbaLate Miocene Evidence from the Middle Awash, Ethiopia, 2009
Recent fieldwork at Woranso-Mille, Ethiopia led to the recovery of an abundant, diverse mammalian... more Recent fieldwork at Woranso-Mille, Ethiopia led to the recovery of an abundant, diverse mammalian fauna that includes remains of the early hominid Australopithecus afarensis. Proboscideans are among the taxa well sampled at the site, primarily by gnathodental specimens, dated to the mid-Pliocene interval of 3.8-3.6 Ma. These fossils document traces of the last anancine gomphotheres (Anancus ultimus) in eastern Africa and several elephant taxa. Comparative study of the elephant fossils indicates the presence of cf. Mammuthus sp. "Hadar-type," cf. Elephas ekorensis, E. recki brumpti, and cf. Loxodonta adaurora adaurora. Proboscidean evolution in the mid-Pliocene is interesting because during this time archaic elephants were completely replaced by basal members of crown elephant lineages, taxonomic diversity was high (multiple elephant species, anancine gomphotheres, stegodonts, and deinotheres), and elephants were undergoing substantial reorganization of the craniodental masticatory apparatus, presumably in response to the spread of more open habitats and greater competition for grazing resources. The Woranso-Mille sample is important because this interval is only represented elsewhere in eastern Africa by a small number of sites, and because adaptive diversification among early crown elephants requires greater clarification. Morphometric contrasts among the fossil dentition from Woranso-Mille presage the differential success of elephant lineages in eastern Africa during the Pleistocene, providing hints about the beginnings of competitive displacement. Differences between E. recki brumpti from Woranso-Mille and the slightly younger Sidi Hakoma Member of the Hadar Formation reveal the beginnings of continuous, directional morphometric change that characterized the lineage. Reconsideration of E. recki subspecies indicates that they are arbitrary lineage divisions tied to geochronological boundaries (with utility for biochronological correlation at well sampled sites) rather than real phylogenetic entities, but does not reject monophyly or anagenetic evolution of the lineage.
ABSTRACT Kolpochoerus (Mammalia: Suidae) is a suine genus represented by a number of species from... more ABSTRACT Kolpochoerus (Mammalia: Suidae) is a suine genus represented by a number of species from Plio-Pleistocene sites in Africa. While the general trends in Kolpochoerus evolution are broadly known, gaps in the fossil record preclude an understanding of the details of its evolutionary tempo and mode. Here, we describe a new species, Kolpochoerus millensis, based on new fossil material from the Woranso-Mille and Gona sites in the Central Afar region of Ethiopia and dated to 3.5–3.8 million years ago (Ma). Third molars of K. millensis are metrically and morphologically intermediate between the early Pliocene K. deheinzelini and earliest late Pliocene K. afarensis. It appears that K. deheinzelini, K. millensis, and K. afarensis are temporally disjunct and phenetically distinguishable parts of a single evolving lineage. The recognition of these chronospecies provides additional evidence for anagenetic evolution. It demonstrates clearly the presence of transitional forms in the fossil record. The extensive and well-dated Kolpochoerus fossil record serves as one of the best documented examples of the occurrence of phyletic evolution. Moreover, K. millensis is one of the best biochronological markers in eastern Africa for the time between 3.5 and 3.8 Ma.
... Photos may offer clues over Ethiopian fossil site. Yohannes Haile-Selassie 1. ... Register no... more ... Photos may offer clues over Ethiopian fossil site. Yohannes Haile-Selassie 1. ... Register now. I want to subscribe to Nature. Price: US$199. This includes a free subscription to Nature News together with Nature Journal. Subscribe now. I want to rent this article. ...
... The family Canidae is represented by one species of Eucyon, possibly a second species in the ... more ... The family Canidae is represented by one species of Eucyon, possibly a second species in the latest Miocene of eastern Africa or conspecific with Eucyon intrepidus from the Lukeino Formation of Kenya [19]. 2. Systematics. 2.1. Genus Torolutra Petter, Pickford, and Howell 1991. ...
The earliest evidence of Australopithecus goes back to ca 4.2 Ma with the first recorded appearan... more The earliest evidence of Australopithecus goes back to ca 4.2 Ma with the first recorded appearance of Australopithecus 'anamensis' at Kanapoi, Kenya. Australopithecus afarensis is well documented between 3.6 and 3.0 Ma mainly from deposits at Laetoli (Tanzania) and Hadar (Ethiopia). The phylogenetic relationship of these two 'species' is hypothesized as ancestor-descendant. However, the lack of fossil evidence from the time between 3.6 and 3.9 Ma has been one of its weakest points. Recent fieldwork in the Woranso-Mille study area in the Afar region of Ethiopia has yielded fossil hominids dated between 3.6 and 3.8 Ma. These new fossils play a significant role in testing the proposed relationship between Au. anamensis and Au. afarensis. The Woranso-Mille hominids (3.6-3.8 Ma) show a mosaic of primitive, predominantly Au. anamensis-like, and some derived (Au. afarensis-like) dentognathic features. Furthermore, they show that, as currently known, there are no discrete and functionally significant anatomical differences between Au. anamensis and Au. afarensis. Based on the currently available evidence, it appears that there is no compelling evidence to falsify the hypothesis of 'chronospecies pair' or ancestor-descendant relationship between Au. anamensis and Au. afarensis. Most importantly, however, the temporally and morphologically intermediate Woranso-Mille hominids indicate that the species names Au. afarensis and Au. anamensis do not refer to two real species, but rather to earlier and later representatives of a single phyletically evolving lineage. However, if retaining these two names is necessary for communication purposes, the Woranso-Mille hominids are best referred to as Au. anamensis based on new dentognathic evidence.
The Lemudong'o Formation in the Narok District of Kenya comprises a 135-m-thick series of predomi... more The Lemudong'o Formation in the Narok District of Kenya comprises a 135-m-thick series of predominantly lacustrine and lake basin margin sedimentary rocks with interstratified primary and reworked tuffs. The formation, deposited ,6 Ma, records deposition within the second of three sequential lake basins created by tectonic and volcanic activity on the western margin of the southern Rift Valley of Kenya. These sedimentary paleobasins are exposed in the vicinity of the confluence of three rivers cutting steep cliffs into rugged, vegetated terrain. Over 1200 fossils of terrestrial vertebrates have been recovered from the site of Lemudong'o Locality 1 (LEM 1), which was formed at the edge of a shallow lake fed by slow-moving streams. Much like smaller Rift Valley lake basins in Kenya today, the Lemudong'o lake margin probably supported a mosaic of habitats ranging from closed riparian woodland to grassland and swamps.
... José Miguel CARRETERO 1,3*, Yohannes HAILESELASSIE 2, Laura RODRIGUEZ 1, JuanLuis ARSUAGA 3,... more ... José Miguel CARRETERO 1,3*, Yohannes HAILESELASSIE 2, Laura RODRIGUEZ 1, JuanLuis ARSUAGA 3,4 ... Arsuaga et al., 1997b, c ... Mosbach, or Arago (MIS 1216) which approximately date to between 450 and 600 ka based on faunal and radiometric criteria (García et al ...
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Papers by Yohannes Haile-Selassie