A New Horned Crocodile from the Plio-Pleistocene Hominid Sites at Olduvai Gorge, Tanzania

Light stable isotope ratios (δ13C and δ18O) of tooth enamel have been widely used to determine the diets and water sources of fossil fauna. The carbon isotope ratios indicate whether the plants at the base of the food web used C3 or C4 photosynthetic pathways, while the oxygen isotope ratios indicate the composition of the local rainfall and whether the animals drank water or obtained it from plants. The contrasting diets of two early hominin species – Homo habilis and Paranthropus boisei – of ca 1.8 Ma (million years ago) in Tanzania were determined by means of stable carbon isotope analysis of their tooth enamel in a previous study. The diets of two specimens of P. boisei, from Olduvai and Peninj, proved to be particularly unusual, because 80% of their carbon was derived from C4 plants. It was suggested that their diet consisted primarily of plants, with particular emphasis on papyrus, a C4sedge. The dominance of C4 plants in the diet of P. boisei is a finding supported in another study of 22 specimens from Kenya. The isotopic ecology and diets of fossil fauna that were present at the same time as the two fossil hominin species are described here, in order to provide a fuller understanding of their contrasting diets and of the moisture sources of their water intake. This information was then compared with the isotopic composition of modern fauna from the same region of Tanzania. The carbon isotope ratios for both fossil and modern specimens show that the habitats in which these faunal populations lived were quite similar – grassland or wooded grassland. They had enough bushes and trees to support a few species of browsers, but most of the animals were grazers or mixed feeders. The oxygen isotope ratios of the fossil and modern fauna were, however, very different, suggesting strongly that the source of moisture for the rain in the Olduvai region has changed during the past 1.8 million years.

Modern humans are characterized by specialized hand morphology that is associated with advanced manipulative skills. Thus, there is important debate in paleoanthropology about the possible cause–effect relationship of this modern human-like (MHL) hand anatomy, its associated grips and the invention and use of stone tools by early hominins. Here we describe and analyse Olduvai Hominin (OH) 86, a manual proximal phalanx from the recently discovered >1.84-million-year-old (Ma) Philip Tobias Korongo (PTK) site at Olduvai Gorge (Tanzania). OH 86 represents the earliest MHL hand bone in the fossil record, of a size and shape that differs not only from all australopiths, but also from the phalangeal bones of the penecontemporaneous and geographically proximate OH 7 partial hand skeleton (part of the Homo habilis holotype). The discovery of OH 86 suggests that a hominin with a more MHL postcranium co-existed with Paranthropus boisei and Homo habilis at Olduvai during Bed I times.

The dental developmental status of six East African juvenile fossil hominids

A Homo habilis maxilla and other newly-discovered hominid fossils from Olduvai Gorge, Tanzania

East Africa is one of the most important paleoanthropological localities on Earth. Laetoli and Olduvai Gorge (Tanzania) are among the world’s premier areas for Australopithecus afarensis, Paranthropus boisei, and Homo habilis remains. Laetoli is also unique in its preservation of footprint trails within Tuff 7 left by Australopithecus afarensis. Tuff 7 has been studied to characterize microorganisms living inside these tuffs and to estimate their potential involvement in destructive processes; 35 species of microfungi, as well as sterile white and dark mycelia were identified by cultural method. The results of the metagenomic analysis show that anamorphic ascomycetes are the predominant group in all samples. They occur as hyphae and mycelia inside the tuffs, and are concentrated in pores, microcracks and cavities. The number of micromycetes is moderate (up to 7000 CFU per gram of substrate). Typical cultivated microfungi are from genera Aspergillus and Fusarium. They are known as active destructors of natural and artificial substrates and can colonize building materials. Molecular genetic methods revealed a large group of different bacteria (23 phyla) within the tuff. The microbiota consists mostly of Actinobacteria, Proteobacteria, Bacteroidetes and Cyanobacteria. Their relative distribution shows the preferential occurrence of Bacteroidetes in the upper part of stratigraphic sections (soil), and concentration of Actinobacteria and Proteobacteria within the tuffs. Exposure of the Footprint tuff could lead to the development of photosynthetic microorganisms (Cyanobacteria). We conclude that microbiological activity within the study area appears to be moderate and the Footprint Tuff does not presently require any treatment with biocides. However, the presence of black biofilms on the surface of the Footprint conservation mound concrete shows that biodestruction does occur.

Most research and public interest in human origins focuses on taxa that are likely to be our ancestors. There must have been genetic continuity between modern humans and the common ancestor we share with chimpanzees and bonobos, and we want to know what each link in this chain looked like and how it behaved. However, the clear evidence for taxic diversity in the human (aka hominin) clade means that we also have close relatives who are not our ancestors (1). Two papers in PNAS focus on the behavior and paleoenvironmental context of Paranthropus boisei , a distinctive and long-extinct nonancestral relative that lived alongside our early Homo ancestors in eastern Africa between just less than 3 Ma and just over 1 Ma. Both papers use stable isotopes to track diet during a largely unknown, but likely crucial, period in our evolutionary history. The first fossil evidence of P. boisei , two upper milk teeth, a very large molar, and a tiny canine, was discovered in 1955 at Olduvai Gorge, in Tanzania (2). The mystery of the owner of the unusual teeth was solved in 1959 when Mary Leakey recognized fragments of a fossil hominin cranium eroding from a hillside. The Olduvai Hominid (OH) 5 cranium had a small ( ca. 500 cm3) brain—not much bigger than that of a gorilla and about a third the size of that of a modern human—a flat and broad face, large attachment areas for chewing muscles, small incisors and canines, and exceptionally large premolar and molar tooth crowns. Louis Leakey proposed a new taxon, Zinjanthropus boisei (3) for OH 5, but within a few years the new genus was dropped in favor of Australopithecus , or Paranthropus ; the latter is our preference. More evidence of P. boisei came in 1964 with the discovery … [↵][1]1To whom correspondence may be addressed. Email: bernardawood{at}gmail.com. [1]: #xref-corresp-1-1

The upper limb of Paranthropus boisei from Ileret, Kenya

Who ate OH80 (Olduvai Gorge, Tanzania)? A geometric-morphometric analysis of surface bone modifications of a Paranthropus boisei skeleton

Paleoecological evidence for environmental specialization in Paranthropus boisei compared to early Homo.

Australopithecus boisei was first described from a cranium recovered in 1959 from Olduvai Gorge, Tanzania. This and subsequent finds, mostly from Kenya's Turkana basin, resulted in its characterization as a specialized Australopithecus species with a hyper-robust masticatory apparatus. A distinct A. boisei facial morphology has been emphasized to differentiate robust Australopithecus lineages from East and South Africa. A preference for closed and/or wet habitats has been hypothesized. Here we report some new A. boisei specimens, including the taxon's first cranium and associated mandible, from Konso, Ethiopia. These fossils extend the known geographical range of A. boisei. They provide clear evidence for the coexistence of A. boisei and Homo erectus within a predominantly dry grassland environment. The A. boisei specimens from Konso demonstrate considerable morphological variation within the species. The unexpected combination of cranial and facial features of this skull cautions against the excessive taxonomic splitting of early hominids based on morphological detail documented in small and/or geographically restricted samples.

The human lineage

Humans and human ancestors have exploited wetland resources for at least two million years. The most significant predators in these landscapes are crocodiles, which leads to two potential taphonomic problems: 1) human-accumulated bones may become intermingled with crocodile-modified bones; and 2) hominins themselves may have been victims of crocodiles. Davidson and Solomon (1990) significantly contributed to this literature through theirsuggestion that a crocodile attack led to the tooth marks on the type specimen of Homo habilis (OH 7) found in Olduvai Gorge, Tanzania. The Australasian tropics were also home to a variety of crocodilian species, crocodile damage to hominin bones being inferred in Trinil and Sangiran, Java. Furthermore, two Pleistocene Australian archaeological sites have stone artefacts in association with crocodile-damaged bone. A referential taphonomic framework is needed to understand the degree and nature of crocodile-hominin interactions on paleolandscapes of Sunda, the ancient Pleistocene landmass incorporating the islands of SE Asia, and Sahul, the Pleistocene landmass of ancient Australia incorporating Papua New Guinea, Australia and Tasmania. This paper provides initial results from crocodile feeding experiments aimed at characterising feeding damage inflicted on bones by the largest extant Australasian crocodile, Crocodylus porosus. Due to close similarity among Crocodylus species in dental and cranial morphology there are some general patterns in the way they modify bones. However, some differences arise when the taphonomic signatures are compared to those of the Nile crocodile (Crocodylus niloticus). We suggest that these differences are attributable to evolved differences in the feeding ecologies of the two species.

The palaeoanthropological sites of Oldupai Gorge (previously known as Olduvai) and Laetoli are located on the Eastern Serengeti Plains, at the foot of the Ngorongoro Highlands, northern Tanzania. Hominin fossils and Oldowan stone tools have been unearthed from Plio-Pleistocene sequences of lacustrine sediments and volcanic ashes exposed in a shallow ravine carved by the ephemeral Oldupai River. The sediments and ashes accumulated in a small basin which formed due to warping of the regional plateau. Warping was triggered by the southward propagation of the East African Rift System (EARS). The presence of repetitive layers of water-lain volcanic ashes, or tuffs, derived from the Ngorongoro Volcanism, is particularly significant as they yield precise radiometric dates. Bed I of the Oldupai Group, where the first discoveries of Zinjanthropus boisei (OH-5) and Homo habilis (OH-7) were made by Mary Leakey, in 1959 and 1960, has an age of 2.015–1.803 Ma. The age of these two, partially intact hominin skulls has been determinded as 1.848 Ma (OH-5) and 1.848–1.832 (OH-7). Oldupai Gorge has also yielded fossils of Homo erectus (1.2–0.70 Ma) and the coexistence of different species of hominin is a unique feature of the locality. Reactivation of faulting associated with the Gregory Rift at approximately 1.15 Ma caused some of the older deposits to be reworked and buried beneath younger sediments and ashes. The youngest component of the Oldupai Group comprises wind-blown volcanic ashes from volcanoes located in the Gregory Rift Valley near Lake Natron. The Laetoli site has yielded hominin fossils and footprints from an area, where the Pliocene-age Laetoli Group is exposed in shallow gullies and areas of badland erosion. The most significant find is the 27-m-long trail made by Australopithecus afarensis (dated at 3.6 Ma), discovered by Paul Adell in 1978. The footprints are preserved in volcanic ash derived from the Sadiman Volcano.

Preliminary small mammal taphonomy of FLK NW level 20 (Olduvai Gorge, Tanzania)

Potassium-Argon Dating at Olduvai Gorge