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R E Leakey

Publications and source records attributed to R E Leakey.

At least 19 recordsLinked to original sources
PubMed1993

New Australopithecus boisei calvaria from East Lake Turkana, Kenya.

The calvaria of an adult Australopithecus boisei from Area 104, Koobi Fora, Lake Turkana, is described. The specimen, KNM-ER 23000, comes from sediments dated to about 1.9 Ma. It consists of the frontal, both parietals, both temporals, most of the occipital as well as two small pieces of sphenoid, and a mandibular tooth root. The specimen is presumed to be an adult male, based on its size and the great development of features associated with the masticatory apparatus. KNM-ER 23000 is close in general size and shape to KNM-ER 406, KNM-ER 13750, and Olduvai Hominid 5 and it has a mixture of features seen in these three roughly contemporaneous crania. The frontal, especially the tori, resembles that of OH 5; the parietals are most like those of KNM-ER 13750; the occipital is like those of the two other Turkana specimens, and the temporals have a mixture of features from all of these, This specimen adds to our knowledge of variability in A. boisei.

Adult↗
PubMed1993

Hominid radius from the middle Pliocene of Lake Turkana, Kenya.

A nearly complete left radius, KNM-ER 20419, was recovered from middle Pliocene sediments east of Lake Turkana, Kenya in 1988. Ape-like characteristics of the fossil include an eccentrically positioned articular fovea, relatively long radial neck, wide distal metaphysis, and large brachioradialis crest. The robustness of the radial neck in proportion to the radial head, and the semilunar shape of the distal diaphysis, however, clearly distinguish KNM-ER 20419 as hominid. The distal articular surface possesses a larger area for radius-lunate articulation than for radius and scaphoid, a radiocarpal arrangement that is associated with increased wrist adduction among quadrumanous climbers. Since this morphology is also found in hylobatids, Pongo, and other early australopithecines, it is argued to be plesiomorphic for hominoids. This further supports the argument that vertical climbing was an important locomotor behavior among both early hominoids and our more immediate prebipedal ancestors.

Animals↗
PubMed1991

Similarities in Aegyptopithecus and Afropithecus facial morphology.

Recently discovered cranial fossils from the Oligocene deposits of the Fayum depression in Egypt provide many details of the facial morphology of Aegyptopithecus zeuxis. Similar features are found in the Miocene hominoid Afropithecus turkanensis. Their presence is the first good evidence of a strong phenetic link between the Oligocene and Miocene hominoids of Africa. A comparison of trait lists emphasizes the similarities of the two fossil species, and leads us to conclude that the two fossil genera share many primitive facial features. In addition, we studied facial morphology using finite-element scaling analysis and found that the two genera show similarities in morphological integration, or the way in which biological landmarks relate to one another in three dimensions to define the form of the organism. Size differences between the two genera are much greater than the relatively minor shape differences. Analysis of variability in landmark location among the four Aegyptopithecus specimens indicates that variability within the sample is not different from that found within two samples of modern macaques. We propose that the shape differences found among the four Aegyptopithecus specimens simply reflect individual variation in facial characteristics, and that the similarities in facial morphology between Aegyptopithecus and Afropithecus probably represent a complex of primitive facial features retained over millions of years.

Animals↗
PubMed1988

New Australopithecus boisei specimens from east and west Lake Turkana, Kenya.

New specimens of Plio-Pleistocene Australopithecus boisei are described from east and west Lake Turkana in Northern Kenya. These include a cranium and partial mandible from deposits close to 2.5 Myr and two partial crania and two mandibles from later horizons. The earlier fossils enable us to decipher, for the first time, some of the in situ evolution of this species within the Turkana Basin. The following are among the important changes in the cranium through time: 1) increase in size and change in shape of the braincase, 2) changes in the meningeal vessel pattern and possibly in the venous drainage pattern, 3) increased flexion of the cranial base and decreased prognathism, and 4) changes in the temporal bone to bring about a more vertical posterior face of the petrous pyramid and the development of a strong articular eminence.

Animals↗
PubMed1988

Morphology of Turkanapithecus kalakolensis from Kenya.

The type specimen of Turkanapithecus kalakolensis recently recovered from northern Kenya preserves a partial cranium and mandible. This specimen, together with postcranial elements that are probably associated with it, and two additional specimens are described. The collection is compared with other Miocene hominoids.

Animals↗
PubMed1988

Morphology of Afropithecus turkanensis from Kenya.

Forty-six specimens of a large Miocene hominoid, Afropithecus turkanensis, recently recovered from northern Kenya preserve many morphological details that are described. The specimens include cranial, mandibular, and postcranial parts. They are compared briefly with other Miocene hominoids. It is suggested that Afropithecus may have affinities with Heliopithecus, Kenyapithecus, and the large hominoid from Moroto and Napak, although it is noted that the comparative material is limited in the number of common anatomical parts preserved.

Animals↗
PubMed1987

East African cheetahs: evidence for two population bottlenecks?

A combined population genetic and reproductive analysis was undertaken to compare free-ranging cheetahs from east Africa (Acinonyx jubatus raineyi) with the genetically impoverished and reproductively impaired south African subspecies (Acinonyx jubatus jubatus). Like that of their south African counterparts, the quality of semen specimens from east African cheetahs was poor, with a low concentration of spermatozoa (25.3 X 10(6) per ejaculate) and a high incidence of morphological abnormalities (79%). From an electrophoretic survey of the products of 49 genetic loci in A. jubatus raineyi, two allozyme polymorphisms were detected; one of these, for a nonspecific esterase, shows an allele that is rare (less than 1% incidence) in south African specimens. Estimates of polymorphism (2-4%) and average heterozygosity (0.0004-0.014) affirm the cheetah as the least genetically variable felid species. The genetic distance between south and east African cheetahs was low (0.004), suggesting that the development of genetic uniformity preceded the recent geographic isolation of the subspecies. We propose that at least two population bottlenecks followed by inbreeding produced the modern cheetah species. The first and most extreme was ancient, possibly late Pleistocene (circa 10,000 years ago); the second was more recent (within the last century) and led to the south African populations.

Africa, Eastern↗
PubMed1976

New hominids from East Turkana, Kenya.

Thirty-five new fossil hominid specimens are described. They were recovered from the Plio-Pleistocene sediments to the east of Lake Turkana (formerly Lake Rudolf). They include cranial and mandibular parts, teeth, and postcranial bones of upper and lower limbs. Parts of a single skeleton are also described. All of the specimens are described in anatomical detail and selected measurements are given. Some of the specimens are illustrated. It is proposed that they should be attributed to the family Hominidae, with genus and species undetermined until detailed comparative studies have been undertaken.

Animals↗
PubMed1975

New hominids from East Rudolf, Kenya, I.

Important new hominid fossils from the Plio-Pleistocene sediments of Lake Rudolf, Kenya, are described. They include: a partial, adult cranium with most of the calvaria and some of the facial skeleton preserved; a complete right femur; and bones of a single left lower limb--femur and upper and lower parts of the tibia and a small portion of fibula. Detailed comparative descriptions will be published later.

Animals↗