Soricidae (Mammalia) from the Early Pleistocene of Olduvai Gorge, Tanzania

Soricid remains collected from Bed I of Olduvai Gorge are described. The great majority of the specimens are mandibles. A survey of the mandibles of living African species revealed many differences in characters of the lower teeth and jaw that can be used for identification. On the basis of these characters, nine species are distinguished in the Olduvai collection, of which six are well enough preserved to permit a discussion of their relationships to living species. Three new species and one new subspecies are described. All the Olduvai shrews differ in some respects from their nearest living relatives; three species are close to species from Makapansgat, Swartkrans and Sterkfontein, RSA, though there appear to be slight differences. A change in the soricid fauna takes place within Bed I, interpreted as due to increasing aridity.     

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

Background

The fossil record reveals surprising crocodile diversity in the Neogene of Africa, but relationships with their living relatives and the biogeographic origins of the modern African crocodylian fauna are poorly understood. A Plio-Pleistocene crocodile from Olduvai Gorge, Tanzania, represents a new extinct species and shows that high crocodylian diversity in Africa persisted after the Miocene. It had prominent triangular “horns” over the ears and a relatively deep snout, these resemble those of the recently extinct Malagasy crocodile Voay robustus, but the new species lacks features found among osteolaemines and shares derived similarities with living species of Crocodylus.

Methodology/Principal Findings

The holotype consists of a partial skull and skeleton and was collected on the surface between two tuffs dated to approximately 1.84 million years (Ma), in the same interval near the type localities for the hominids Homo habilis and Australopithecus boisei. It was compared with previously-collected material from Olduvai Gorge referable to the same species. Phylogenetic analysis places the new form within or adjacent to crown Crocodylus.

Conclusions/Significance

The new crocodile species was the largest predator encountered by our ancestors at Olduvai Gorge, as indicated by hominid specimens preserving crocodile bite marks from these sites. The new species also reinforces the emerging view of high crocodylian diversity throughout the Neogene, and it represents one of the few extinct species referable to crown genus Crocodylus.     

A new species of cormorant (Aves: Phalacrocoracidae) from the Pleistocene of Olduvai Gorge,Tanzania

Phalacrocorax owrei nov. sp. is a small cormorant from the Lower Pleistocene of Olduvai Gorge. Osteological proportions are established for the four subgenera of Phalacrocorax, and P. owrei is assigned to the subgenus Stictocarbo. The species was the most abundant bird in the Bed I deposits and is also represented by a few specimens in the middle part of Bed II. Its last known appearance coincides with a change in the local environment when the climate became more arid and the Olduvai Lake became more saline and more alkaline. At other localities in Bed II the extinct P. tanzanice occurs, as well as P. africanus and P. corbo, which breed on the African lakes and seacoast today.     

The puzzle from JK2—A femur and a tibial fragment (O.H.34) from Olduvai Gorge,Tanzania

During excavations in Bed III, Olduvai Gorge, Tanzania in 1962, a slender fossil femur and part of a tibial shaft were recovered. Their strange appearance resulted in their neglect for many years. Anatomical examination now confirms that these bones are hominid, probably hominine, yet distorted in form. The distortion does not appear to be the result of pathology but due to damage and abrasion while in the deposits; deposits dated at approximately 1 million years B.P. O.H. 34 is the first hominid to be recovered from Bed III, Olduvai Gorge.     

The O.H. 7 (Olduvai Gorge,Tanzania) hominid partial brain endocast revisited

The O.H.7 brain endocast was reexamined using a stereoplotting apparatus to quantify the amount of distortion. Some 127 measurements for each of the left and right sides were taken and treated statistically by student t-tests, both in paired and grouped fashion. Grouped data indicated no significant left-right differences. Paired data suggested three small regions of distortion, which produced three pairs of left-right differences that were significantly different. Given the very local nature of these minor distortions, it is concluded that the original reconstruction by Tobias was essentially correct. In addition, multiple regression analyses of selected chord-arc dimensions suggest that a volume in excess of 700 ml is most probable.     

The O.H.7 (Olduvai Gorge, Tanzania) parietal fragments and their reconstruction: a reply to Wolpoff

Given Wolpoff's (1981) dimensions for lambda-bregma and biparietal breadth, it was possible to reconstruct a new version of the O.H.7 hominid parietals. The constraints of the anatomical features of the original parietal fragments plus Wolpoff's constraints from his own reconstruction, permit testing his claims as a hypothesis. By comparing the resulting distortion of Wolpoff's proposed reconstruction with that of the original reconstruction by Tobias, it is clear that the latter's is far superior to the former's, and that the cranial capacity of O.H.7 of roughly 700 ml is most probable.     

Cranial remains of Homo erectus from Beds II and IV,Olduvai Gorge,Tanzania

Cranial remains of hominids 9 and 12 from Olduvai Gorge are described in detail. O.H. 9 consists of a heavily built braincase, partly damaged and lacking the face, while O.H. 12 is less complete. The Bed II specimen is about 1.2 million years in age and shows anatomical similarities to the cranium designated ER-3733 from Koobi Fora, east of Lake Turkana. Together these African fossils provide valuable information about Homo erectus in the later Lower Pleistocene. Comparisons of O.H. 9 with several of the Choukoutien crania are also carried out. These Chinese and other Asian remains of Homo erectus cannot be placed in a secure chronological framework, but all of the material should be studied systematically in order to assess relatedness among what must be several different populations.     

First Partial Skeleton of a 1.34-Million-Year-Old Paranthropus boisei from Bed II,Olduvai Gorge,Tanzania

Recent excavations in Level 4 at BK (Bed II, Olduvai Gorge, Tanzania) have yielded nine hominin teeth, a distal humerus fragment, a proximal radius with much of its shaft, a femur shaft, and a tibia shaft fragment (cataloged collectively as OH 80). Those elements identified more specifically than to simply Hominidae gen. et sp. indet are attributed to Paranthropus boisei. Before this study, incontrovertible P. boisei partial skeletons, for which postcranial remains occurred in association with taxonomically diagnostic craniodental remains, were unknown. Thus, OH 80 stands as the first unambiguous, dentally associated Paranthropus partial skeleton from East Africa. The morphology and size of its constituent parts suggest that the fossils derived from an extremely robust individual who, at 1.338±0.024 Ma (1 sigma), represents one of the most recent occurrences of Paranthropus before its extinction in East Africa.     

Unraveling hominin behavior at another anthropogenic site from Olduvai Gorge (Tanzania): new archaeological and taphonomic research at BK, Upper Bed II

New archaeological excavations and research at BK, Upper Bed II (Olduvai Gorge, Tanzania) have yielded a rich and unbiased collection of fossil bones. These new excavations show that BK is a stratified deposit formed in a riverine setting close to an alluvial plain. The present taphonomic study reveals the second-largest collection of hominin-modified bones from Olduvai, with abundant cut marks found on most of the anatomical areas preserved. Meat and marrow exploitation is reconstructed using the taphonomic signatures left on the bones by hominins. Highly cut-marked long limb shafts, especially those of upper limb bones, suggest that hominins at BK were actively engaged in acquiring small and middle-sized animals using strategies other than passive scavenging. The exploitation of large-sized game (Pelorovis) by Lower Pleistocene hominins, as suggested by previous researchers, is supported by the present study.     

Environments and hominin activities across the FLK Peninsula during Zinjanthropus times (1.84 Ma), Olduvai Gorge, Tanzania

We establish through 13 excavations the landscape context and nature of hominin activities across the Zinjanthropus land surface from which the Leakeys recovered the FLK 22 and FLK NN 1 paleoanthropological assemblages. The land surface was created by fluvial incision of the eastern margin of paleo-Lake Olduvai following a major lake withdrawal. Erosion was uneven, leaving a peninsula bounded by a river channel, the FLK Fault, and a freshwater wetland. This FLK Peninsula supported groves of trees that attracted hominins and carnivores, and that preserved the dense concentrations of carcass remains and stone tools they left behind, including those at FLK 22. Some carcasses appear to have been acquired at the ecotone of the Peninsula and Wetland, where another dense artifact and bone assemblage accumulated. A lesser topographic high at the edge of a Typha marsh in the Wetland was the site of FLK NN 1 and a scatter of large stone tools used possibly for rootstock processing.Our landscape reconstruction delimits the vegetation mosaic indicated by previous work and provides a topographical explanation for the existence of FLK 22 and FLK NN 1. Both are unexpected if the FLK area was the flat, featureless lake margin terrain typical of lake basins similar to paleo-Olduvai. The results show that the Leakeys’ sites were not isolated occupation floors but rather parts of a land surface utilized intensively by hominins. Although commonly considered to have been home bases, their likely high predation risk, evidenced by large carnivore feeding traces and the remains of four hominin individuals, suggests visits to them were brief and limited to feeding. Finally, stratigraphic observations confirm that FLK NN 3 accumulated on an older land surface, refuting the hypothesis that the OH 8 foot found there is the same individual as the OH 35 leg from FLK 22.     

Differential Predation by Age and Sex Classes in Blue Wildebeest in Serengeti: Study of a Modern Carnivore Den in Olduvai Gorge (Tanzania)

Age and sex selection of prey is an aspect of predator ecology which has been extensively studied in both temperate and African ecosystems. This dimension, along with fecundity, survival rates of prey and mortality factors other than predation are important in laying down the population dynamics of prey and have important implications in the management of species. A carnivore den located in the short-grassland ecological unit of the Serengeti was studied. Sex- and age- class (using five age categories) of the wildebeest remains recovered were analyzed through horn morphology, biometrics of the bones and tooth wear patterns. We compared our results with previous studies from lion and hyaena kills through multivariate analyses. Seasonality of the accumulation was analyzed through tooth histology. PCA and CVA results show that age class selection by predators depends on season, habitat-type, and growth rate of the wildebeest population. Female-biased predation was found to contradict classical hypotheses based on territorial male behaviour. The lion and spotted hyaena showed strong selection on age classes, contrary to previous studies. Migratory wildebeest sex ratio is regulated through differential predation by seasons and female deaths in the wet season are a trade-off for population stability. These data are crucial for an effective management of the species and the new method created may be useful for different carnivore species and their prey.     

Carbonate horizons, paleosols, and lake flooding cycles: Beds I and II of Olduvai Gorge, Tanzania

This study documents the petrology and stable isotope geochemistry of carbonates from six horizons from Beds I and II of Olduvai Gorge, Tanzania. The studied succession, immediately below and above Tuff IF, consists of interbedded waxy and earthy claystones with discrete carbonate horizons and thin sandstones. The succession was deposited in response to repeated flooding and withdrawal of a saline-alkaline lake. The carbonates and their overlying disconformities are important because they help define the surfaces on which hominin activity took place and allow very high-resolution correlation of geographically separated levels of hominin exploitation.The range of different carbonates includes unambiguous land-surface and pedogenic features including calcified rootmat horizons, rhizocretions, and micritic nodules, together with less determinate sparry calcite nodules. Stellate nodules are interpreted as pseudomorphs after sulfate-roses. The carbonate nodules are synsedimentary features, truncated by fluvial and other erosional surfaces. The isotopic composition of the carbonates is variable with δ¹⁸O ranging from −7.0‰ to −4.3‰, and δ¹³C from −8.5‰ to −1.6‰. A covariant increase in δ¹³C and δ¹⁸O repeats in each carbonate horizon and in individual nodules (inner to outer layers): it reflects the evolution of synsedimentary groundwaters. At times of low lake level, the carbonates started to precipitate from meteoric waters with low isotopic values and continued to form as lake levels rose and the waters became increasingly saline. Some of the samples have a last-stage cement of strontium rich dolomite, which supports late-stage flooding by the saline-alkaline lake. Previous studies of carbonate horizons from Olduvai have interpreted carbon isotope values in terms of changes in C₃ and C₄ plants that colonized the land surface. This study demonstrates that in some instances the isotope values from carbonates deposited in these lake marginal settings reflect changes in hydrology rather than vegetation.     

(40)Ar/(39)Ar dating of Bed I, Olduvai Gorge, Tanzania, and the chronology of early Pleistocene climate change

⁴⁰Ar/³⁹Ar dating of tuffs and lavas of the late Pleistocene volcanic and sedimentary sequence of Olduvai Gorge, north-central Tanzania, provides the basis for a revision of Bed I chronostratigraphy. Bed I extends from immediately above the Naabi Ignimbrite at 2.038 ± 0.005 Ma to Tuff IF at 1.803 ± 0.002 Ma. Tuff IB, a prominent widespread marker tuff in the basin and a key to understanding hominin evolutionary chronologies and paleoclimate histories, has an age of 1.848 ± 0.003 Ma. The largest lake expansion event in the closed Olduvai lake basin during Bed I times encompassed the episode of eruption and emplacement of this tuff. This lake event is nearly coincident with the maximum precessional insolation peak of the entire Bed I/Lower Bed II interval, calculated from an astronomical model of the boreal summer orbital insolation time-series. The succeeding precessional peak also apparently coincides with the next youngest expansion of paleo-Lake Olduvai. The extreme wet/dry climate shifts seen in the upper part of Bed I occur during an Earth-orbital eccentricity maximum, similar to episodic lake expansions documented elsewhere in the East African Rift during the Neogene.     

Functional and morphological affinities of the subadult hand (O.H. 7) from Olduvai Gorge.

Study of the O.H. 7 hand was based primarily on morphological comparisons with a large series of hand skeletons of extant hominoid primates. Most of the hand elements are fragmentary or have missing epiphyses and only comparisons based on qualitative morphological observations are possible. The distal phalanges are complete, however, and were analyzed metrically utilizing univariate and multivariate statistical techniques. To compensate for size differences among the Hominoidea a number of size adjustments were employed. None of the adjustments were totally satisfactory from theoretical and practical standpoints and none completely eliminated the influence of size. There is no entirely satisfactory procedure to eliminate size and it is advisable to use several techniques that are not closely related, to compare the results and interpret them with caution. In certain features the wrist and fingers resemble those of African apes; in others they are more like modern human hands; in still others they are unique. The scaphoid and the proximal articular surface of the trapezium retain ape-like features, as do the proximal and middle phalanges. The pollical carpometacarpal joint and the distal phalanges are closer in morphology to those of modern humans. The scaphoid, proximal phalanges and middle phalanges of rays II-V indicate a hand capable of a strong power grip. A number of features of the thumb and the distal phalanges suggest that the O.H. 7 individual was capable of more precise manipulation that extant apes. FLK NN-A, a first distal phalanx, does not closely resemble the first distal phalanx of any of the living Hominoidea. Multivariate distance analysis indicates, however, that it is closest in overall morphology to the pollical distal phalanx of modern humans. In some features not included in the metric analysis, FLK NN-A also resembles the hallucial distal phalanx of modern humans.     

Meat-eating by early hominids at the FLK 22Zinjanthropussite, Olduvai Gorge (Tanzania): an experimental approach using cut-mark data

The meat-eating behavior of Plio-Pleistocene hominids, responsible for the bone accumulations at the earliest archaeological sites, is still a hotly-debated issue in paleoanthropology. In particular, meat-eating and bone marrow consumption are often presented as either complementary or opposing strategies of carcass exploitation. The presence of cut marks on fossil archeofauna is a potential source of information that has not been consistently used as evidence of carcass consumption by hominids. Some authors interpret cut marks as the result of hominids manipulating meat-bearing bones, while others argue that they can also be the result of hominids extracting marginal scraps of carcass flesh that have survived carnivores’ initial consumption. In this study, a referential framework concerning the interpretation of cut marks is presented, based on a set of experiments conducted by the author. It is suggested, according to these experiments and data drawn from the FLK “Zinj” site, that hominids processed meat-bearing bones (on which flesh was abundant) rather than defleshed carcasses from felid kills.     

Isolation and characterisation of anaerobic cellulose-degrading bacteria from East African porcupine (Hystrix cristata)

Two strains of obligately anaerobic cellulolytic bacteria designated as PS7 and PS8 (PS for porcupine species) were isolated from hindgut fluid of a crested porcupine (Hystrix cristata). The rates of cellulose degradation, total volatile fatty acids, and gas production from cellulose by the isolates were determined in comparison with Ruminococcus flavefaciens FD-1. Ruminococcus flavefaciens FD-1 degraded acid swollen cellulose and produced total volatile fatty acid at a faster rate (0.03145 mg/d; 3.8350 μmol/mL) than PS7 (0.03113 mg/d; 2.5278 μmol/mL) and PS8 (0.0125 mg/d; 2.1080 μm/mL). However, PS7 degraded cellulose strips (untreated) faster (1.5 weeks) than R. flavefaciens FD-1 (2 weeks). Furthermore, PS7 produced gas at a higher rate (0.1055 ml/d) than R. flavefaciens FD-1 (0.03145 ml/d) more produced butyric, isovaleric acids and almost twice the amounts of total volatile fatty acids from acid swollen cellulose. Both PS7 and PS8 were Gram variable, rod shaped and motile. On cellobiose medium, PS7 grew at temperature ranges from 25 to 45°C while PS8 did not grow at 25 and 45°C. Both isolates grew at pH levels between 6.2 and 11. Characterisation based on carbohydrate fermentation and morphology indicated that these two isolates were similar. Characterisation by RAPD-PCR suggested that PS7 and PS8 were genotypically similar but distinct. Phylogenetic analysis using the nucleotide sequence (1450 bp) of the 16S rRNA gene suggested that PS7 clustered with Clostridium sub-phylum and exhibited the highest similarity (95%) withClostridium lentocellum . The phylogenetic results suggest that PS7 might represent a new taxon.     

小麦族下Hystrix longearistata和Hystrix duthiei的生物系统学研究

对Hystrix duthiei、H．longearistata和它们的人工种间杂种花粉母细胞减数分裂染色体配对行 为、繁育特征和形态特征进行了比较分析,结果表明：(1)这两个分类单位形态差异较小,H．longearista－ ta的外稃芒较长,叶片较宽,每小穗具2--3个小花;H．duthiei的外稃芒较短,叶片较窄,每小穗具1～2 个小花。(2)它们很容易杂交,杂种F_l染色体配对频率很高,为13～14个二价体。(3)亲本种花粉育 性和结实性正常,杂种F_l花粉育性较低,结实性较差。(4)H．longearistata和H．duthiei亲缘关系很 近,是同一物种。由于地理分布和生境的差异,使它们在形态上开始分异,并出现一定程度的生殖隔离。把H．longearistata处理为Hystrix duthiei的一亚种是合理的。     

Biosystematic studies on Hystrix longearistata from Japan and Hystrix duthiei from China (Poaceae: Triticeae)

Morphological comparison, cytogenetic study and fertility analysis of Hystrix duthiei (2n = 28) from China, Hystrix longearistata (2n= 28) from Japan and their artificial hybrids were carried out. Morphologically H. duthiei was similar to H. longearistata. H. longearistata had longer lemma awn, wider leaf and 2～3 florets per spikelet, while H. duthiei had 1～2 florets per spikelet. These two taxa can be easily crossed. F_l hybrids showed very high degree of bivalent pairing (13～14 bivalents) at the metaphase- I of meiosis. No multivalents were found. The fertility of pollen and seed set of the parents were normal, while the F_l hybrids were of only partial fertility. H. longearistata was closely related to H. duthiei. They should be included in the same species. Because of the differences of their distributions and habitats, some morphological divergency and a little sterility barrier have had appeared between them. It is reasonable to treat Hystrix longearistata as a sub-species of Hystrix duthiei .