Stable isotope ecology in the Omo-Turkana Basin

Stable isotopes provide an independent assessment of paleoenvironments in the Omo-Turkana Basin. Stable isotopes track the flow of oxygen and carbon through ecosystems and accordingly are not directly related to changes in mammalian faunal composition or sedimentology. Therefore, isotope studies give insight into the paleoenvironmental conditions in which human evolutionary trends have been recorded. The development of stable isotopes as indicators of continental environmental conditions has proceeded in parallel with questions about the conditions of human environment. What was the vegetation? How hot was it? How dry? What were the diets of animals living among early humans? And most persistently, how important were "savannas" to early hominids? In this review, we take the opportunity to provide extensive background on the use of isotopes in anthropological sites. The application of stable isotope ecology to anthropological sites in the Turkana Basin has a long history, but in many ways the Omo-Turkana Basin has been a proving ground for the development of new proxy methods for understanding tropical terrestrial environments in the Neogene and Quaternary. For that reason, we also describe some of the fundamental aspects of isotope ecology that developed outside the field of paleoanthropology.     

The Omo-Turkana Basin fossil hominins and their contribution to our understanding of human evolution in Africa

The Omo-Turkana Basin, including the hominin fossil sites around Lake Turkana and the sites along the lower reaches of the Omo River, has made and continues to make an important contribution to improving our murky understanding of human evolution. This review highlights the various ways the Omo-Turkana Basin fossil record has contributed to, and continues to challenge, interpretations of human evolution. Despite many diagrams that look suspiciously like comprehensive hypotheses about human evolutionary history, any sensible paleoanthropologist knows that the early hominin fossil record is too meager to do anything other than offer very provisional statements about hominin taxonomy and phylogeny. If history tells us anything, it is that we still have much to learn about the hominin clade. Thus, we summarize the current state of knowledge of the hominin species represented at the Omo-Turkana Basin sites. We then focus on three specific topics for which the fossil evidence is especially relevant: the origin and nature of Paranthropus; the origin and nature of early Homo; and the ongoing debate about whether the pattern of human evolution is more consistent with speciation by cladogenesis, with greater taxonomic diversity or with speciation by anagenetic transformation, resulting in less taxonomic diversity and a more linear interpretation of human evolutionary history.     

Fossil evidence of interactions between plants and plant-eating mammals.

We document changes in mammalian dietary and foraging locomotor adaptation, and appearances and developments of angiosperm fruiting strategies and vegetation types since the late Cretaceous in the Euramerican region, and to some extent in low latitude Africa. These changes suggest: (i): an expansion in the exploitation of dry fruits and seeds by mammals on the ground as well as in the trees after the terminal Cretaceous dinosaur extinction; (ii) a relation between large nuts and rodents, which appear in the late Palaeocene and radiate in the late Eocene; (iii) a relation between primates and fleshy fruits established in the early-Middle Eocene when tropical forests reached their maximum latitudinal extent; (iv) a hiatus of several million years in the vertebrate exploitation of leaves after dinosaur extinction and before the first few mammalian herbivores in the Middle Palaeocene, followed by an expansion in the late Eocene when climates cooled and more open vegetation became established.     

Late Quaternary paleoenvironments in the southwestern Kalahari

Landforms of the southwestern Kalahari in southern Africa include linear dune systems, pans and associated lunette dunes and the valleys of ephemeral rivers. Present day climates in the region are transitional from arid to semi-arid, making the area sensitive to climatic change.

The linear dunes are part of an extensive system of fixed dunes developed in the surface Kalahari sands. The dunes were in existence prior to 32,000 yr B.P., but have been reactivated on a number of occasions since then in conditions of increased wind velocities, more NW winds and reduced rainfall, especially in northern and eastern parts of the region. Periods of dune activity probably occurred at 19,000-17,000, 10,000-6000 and 4000-3000 yr B.P.

The development of pans in the region has been strongly influenced by changes in groundwater conditions. Deflation from pans and formation of lunettes occurred in periods when groundwater levels were higher and fluctuated seasonally more than they do today. Such periods probably occurred 25,000–20,000 yr B.P., around 10,000 yr B.P. and just prior to 1000 yr B.P. Still higher groundwater discharges, promoted by increased regional rainfall, resulted in the formation of spring tufas and seasonal or permanent lakes in the pans, which were also fed by surface runoff, during the intervals between 33,000–28,000; 23,000–21,000; 17,000–15,000 and 12,000–11,000 yr B.P.

The headwaters of the major ephemeral streams lie outside the region, but within the same climatic zone. Increased flow in the Molopo River occurred prior to 19,000, and between 15,000 and 13,000 yr B.P.     

Ancient introductions of mammals in the Mediterranean Basin and their implications for conservation

• 1 The importance of taxonomy to the determination of conservation priorities and actions is widely accepted. It should be not surprising therefore that the taxonomic treatment of mammal species that have been subject to human actions in antiquity may well influence the contemporary assessment of conservation priorities at various levels.
• 2 As a result of early extinctions caused by humans and protohistoric and historic introductions, we suggest that the Mediterranean Basin and its islands are particularly prone to misdirection of efforts towards biodiversity conservation.
• 3 The two main risks associated with the failure to use an evolutionary and palaeoecological approach to conservation efforts are (i) an underestimation of the conservation importance of distinctive continental taxa vs. the apparent endemicity of island taxa; and (ii) a serious risk for native and endemic island species when anthropochorous mammals, especially ungulates, misguidedly become the focus of conservation actions, particularly inside protected areas.
• 4 Urgent measures, including refinement of mammal taxonomy, the exclusion of known anthropochorous taxa from conservation lists and implementation of protective legislation, are necessary to maintain the uniqueness and richness of the Mediterranean biodiversity hotspot.

     

Soils,time, and primate paleoenvironments

Soils are the skin of the earth. From both poles to the equator, wherever rocks or sediment are exposed at the surface, soils are forming through the physical and chemical action of climate and living organisms. The physical attributes (color, texture, thickness) and chemical makeup of soils vary considerably, depending on the composition of the parent material and other variables: temperature, rainfall and soil moisture, vegetation, soil fauna, and the length of time that soil–forming processes have been at work. United States soil scientists¹ have classified modern soils into ten major groups and numerous subgroups, each reflecting the composition and architecture of the soils and, to some extent, the processes that led to their formation. The physical and chemical processes of soil formation have been active throughout geologic time; the organic processes have been active at least since the Ordovician.² Consequently, nearly all sedimentary rocks that were deposited in nonmarine settings and exposed to the elements contain a record of ancient, buried soils or paleosols. A sequence of these rocks, such as most ancient fluvial (stream) deposits, provides a record of soil paleoenvironments through time. Paleosols are also repositories of the fossils of organisms (body fossils) and the traces of those organisms burrowing, food–seeking, and dwelling activities (ichnofossils). Indeed, most fossil primates are found in paleosols. Careful study of ancient soils gives new, valuable insights into the correct temporal reconstruction of the primate fossil record and the nature of primate paleoenvironments.     

泥河湾盆地马圈沟遗址化石哺乳动物及年代讨论

本文简述了马圈沟旧石器遗址产出的哺乳动物化石:出自马圈沟遗址Ⅲ的20个种,马圈沟遗址Ⅰ的4个种,半山遗址的7个种;分析了以Allophaiomys deucalion,Cromeromys gansunicus,Borsodia chinensis等小哺乳动物组合为代表的马圈沟遗址Ⅲ的生物地层时代为早更新世早期,绝对年龄应大于1.80Ma;讨论了该遗址生物地层时代与磁性地层年代的关系.     

Fossil leaves from Lukeino,a 6-million-year-old Formation in the Baringo Basin,Kenya

Thirty-eight dicotyledonous leaf morphotypes and some monocot leaf fragments are described from the Kapcharar, Kabogongoi, Koibo Chepkweny and Inoswa Kamelon localities in the upper third of the Lukeino Formation, Tugen Hills, Baringo Basin (Kenya). The leaves are preserved in fine-grained paper shales and range in length from 9 to 160 mm. Some of the leaves show affinities with extant species in the Burseraceae, Ebenaceae, Euphorbiaceae, Fabaceae, Loganiaceae, Malvaceae and Sapotaceae families that are common in the local flora today. There are compound and simple leaves, mostly entire-margined and with only 10% non-entire margins. A CLAMP analysis of the Kapcharar leaves indicates that the local climate was seasonal, summer wet with 1723 mm mean annual rainfall and with a mean annual temperature of 19.8 °C. The vegetation was a deciduous forest or woodland with open areas nearby. A monocot leaf and two fragments of fern pinnae are also described; they imply locally wetter environments. The flora described here is directly associated with the early hominid Orrorin tugenensis.     

Fossil woods from Janggi Group (Early Miocene) in Pohang Basin,Korea

Sixty-four silicified fossil woods were collected from the Early Miocene Upper Coal-bearing Formation of Janggi Group in Pohang City, the Korean Peninsula. Out of them 23 specimens were identified as gymnosperms and 27 specimens as dicotyledons. The taxa identified include Picea palaeomaximowiczii Watari, Taxodioxylon cunninghamioides (Watari) Watari, T. sequoianum (Merckl.) Gothan, Fagus hondoensis (Watari) Watari, Cercidiphyllum sp., Camellia japonoxyla Suzuki et Terada, Distylium chiharu-hirayae Suzuki et Terada, Aesculus sp., Wataria miocenica (Watari) Terada et Suzuki and W. parvipora Terada et Suzuki. All of these species are reported for the first time from the Tertiary basins of Korea. Compared with those of the Miocene Formations in Japan, most taxa we found are common between the paleo-floras in Korea and Japan during the Early to Middle Miocene.     

Insular biogeography of the montane butterfly faunas in the Great Basin: comparison with birds and mammals

Summary Butterfly species lists were assembled for 18 Great Basin mountain ranges for which distributional data on mammals and birds have been analysed previously by other workers. The ranges represent remnant islands of the boreal habitat that once was continuous across the Great Basin but is now restricted to higher elevations as a result of climatic change at the close of the Pleistocene. The effects of biogeographic factors (area, distance, elevation) and habitat diversity on butterfly species number were examined. The Great Basin boreal butterfly faunas were found to be depauperate overall relative that of the principal mainland source, the Rocky Mountains, and were found to have fewer species than predicted by the mainland species-area data. However, only a weak area effect, and no distance effect, was detected by bivariate and multivariate analysis. Furthermore, the habitat diversity score found to explain virtually all the variation in bird species number in the same ranges in previous studies is only marginally significantly correlated with butterflies. When the butterflies are subdivided according to their vagility, the relative differences in the species-area correlation and slope (z-value) between the vagility categories were consistent with those found previously for mammals and birds, and, as predicted by theory, less vagile taxa exhibit higher species-area correlations and z-values. Overall, differences in the insular biogeography of buttterflies and vertebrates seem to reflect fundamental ecological differences between the taxa.     

Fossil Records in the Lythraceae

The Lythraceae (Myrtales) are a family of 28 genera and ca. 600 species constituting with the Combretaceae and sister family Onagraceae a major lineage of the Myrtales and including the former Sonneratiaceae, Duabangaceae, Punicaceae, and Trapaceae. The fossil record of the family is extensive and significant new discoveries have been added to the record in recent years. This review provides a vetted summary of fossils attributed to the Lythraceae, their geographic distributions, and their stratigraphic ranges. It anticipates the use of the information to generate robustly dated molecular phylogenies to accurately reconstruct the evolutionary and biogeographic history of the family. Fossils of 44 genera or form genera have been attributed to the Lythraceae; 24 are accepted here as lythracean. Fourteen of the 28 modern genera have fossil representatives: Adenaria, Crenea, Cuphea, Decodon, Duabanga, Lafoensia, Lagerstroemia, Lawsonia, Lythrum, Pemphis, Punica, Sonneratia, Trapa, and Woodfordia. Ten extinct genera are recognized. The most common kinds of fossil remains are seeds and pollen. The only fossil flower confidently accepted in the family is the extinct genus Sahnianthus from the Early Paleocene of India. The oldest confirmed evidence of the Lythraceae is pollen of Lythrum/Peplis from the Late Cretaceous (early Campanian, 82?81 Ma) of Wyoming. Seeds of Decodon from the late Campanian (73.5 Ma) of northern Mexico are next oldest. Sonneratia, Lagerstroemia, and extinct Sahnianthus first appear in the Paleocene of the Indian subcontinent; extinct Hemitrapa fruits first occur in the Paleocene of northwestern North America. Diversification of the Lythraceae occurred primarily during two major periods of global temperature change, during the Paleocene-Eocene Thermal Maximum and from the middle Miocene forward when temperatures decreased markedly and seasonality and dry-adapted vegetation types became more prominent. Fossils of the Lythraceae from South America and Africa are limited in number. The few dates available for South American genera are comparatively young and diversification of the largest genus, Cuphea (ca. 240 species), was mainly a Quaternary event. A phylogeny of the family is briefly explored and examples of specialized characters occurring in the oldest known genera are noted. The fossil record of the Lythraceae is presently too fragmentary to confidently reconstruct the early history of the family. The record indicates, however, that the family was well-diversified and widely dispersed globally over a wide latitudinal range by the end of the Paleocene.     

The paleoenvironments of azhdarchid pterosaurs localities in the Late Cretaceous of Kazakhstan

Five pterosaur localities are currently known from the Late Cretaceous in the northeastern Aral Sea region of Kazakhstan. Of these, one is Turonian-Coniacian in age, the Zhirkindek Formation (Tyulkili), and four are Santonian in age, all from the early Campanian Bostobe Formation (Baibishe, Akkurgan, Buroinak, and Shakh Shakh). All so far collected and identifiable Late Cretaceous pterosaur bones from Kazakhstan likely belong to Azhdarchidae: Azhdarcho sp. (Tyulkili); Aralazhdarcho bostobensis (Shakh Shakh); and Samrukia nessovi (Akkurgan). These latter two taxa, both from the Bostobe Formation might be synonyms. Azhdarcho sp. from the Zhirkindek Formation lived in a tropical-to-subtropical relatively humid climate on the shore of an estuarine basin connected to the Turgai Sea. Known fossils were collected in association with brackish-water bivalves and so the overall paleoenvironment of this pterosaur was likely an estuarine marsh as indicated by the dominance of conifers and low relative counts of ferns and angiosperms. Aralazhdarcho bostobensis, from the Bostobe Formation, lived on a coastal fluvial plain along the Turgai Sea. This paleoenvironment was either floodplain (Akkurgan, Buroinak, and Shakh Shakh) or estuarine (Baibishe). In the Santonian – early Campanian, shallow waters near this coastal plain were sites for the intensive accumulation of phosphates under upwelling conditions caused by strong winds from the ancient Asian landmass. These winds also caused significant aridization of the climate during this time. We speculate that pterosaurs may have been attracted to this area by the abundant resources in the bio-productive estuaries and nearshore upwelling waters.     

Fossil record and dynamics of Late Miocene small mammal faunas of the Vienna Basin and adjacent basins,Austria

The Late Miocene small mammal assemblages of the hinterland of Lake Pannon in Austrian Basins are represented by 99 species-level taxa and 30,400 specimens. The fossil-bearing localities can be grouped into eight intervals spanning about three million years from the Early Vallesian to the Middle Turolian. Each time slice is characterised by the occurrence and/or dominance of certain species. The retreat of Lake Pannon is reflected by a distinct diversification. This pattern may be a regional signal due to increasing habitat availability but may also be taphonomically biased due to a rather poor Earliest Vallesian record. Nevertheless, the overall community structure is quite stable throughout the Vallesian and no indication of a Vallesian Crisis can be detected. Instead, a moderate turnover occurs with the onset of the Turolian, reflected by the increasing abundance of xerophilic taxa.     

Paleosols and paleoenvironments of the middle Miocene,Maboko Formation,Kenya

The middle Miocene (15 Ma) Maboko Formation of Maboko Island and Majiwa Bluffs, southwestern Kenya, has yielded abundant fossils of the earliest known cercopithecoid monkey (Victoriapithecus macinnesi), and of a kenyapithecine hominoid (Kenyapithecus africanus), as well as rare proconsuline (Simiolus leakeyorum, cf. Limnopithecus evansi) and oreopithecine apes (Mabokopithecus clarki, M. pickfordi), and galagids (Komba winamensis). Specific habitat preferences can be interpreted from large collections of primate fossils in different kinds of paleosols (pedotypes). Fossiliferous drab-colored paleosols with iron-manganese nodules (Yom pedotype) are like modern soils of seasonally waterlogged depressions (dambo). Their crumb structure and abundant fine root-traces, as well as scattered large calcareous rhizoconcretions indicate former vegetation of seasonally wet, wooded grassland. Other fossiliferous paleosols are evidence of nyika bushland (Ratong), and early-successional riparian woodland (Dhero). No fossils were found in Mogo paleosols interpreted as saline scrub soils. Very shallow calcic horizons (in Yom, Ratong, and Mogo paleosols) and Na-montmorillonite (in Mogo) are evidence of dry paleoclimate (300-500 mm MAP=mean annual precipitation). This is the driest paleoclimate and most open vegetation yet inferred as a habitat for any Kenyan Miocene apes or monkeys. Victoriapithecus was abundant in dambo wooded grassland (Yom) and riparian woodland (Dhero), a distribution like that of modern vervet monkeys. Kenyapithecus ranged through all these paleosols, but was the most common primate in nyika bushland paleosols (Ratong), comparable to baboons and macaques today. Mabokopithecus was virtually restricted to riparian woodland paleosols (Dhero), and Simiolus had a similar, but marginally wider, distribution. Habitat preferences of Mabokopithecus and Simiolus were like those of modern colobus monkeys and mangabeys. A single specimen of Komba was found in dambo wooded grassland paleosol (Yom), a habitat more like that of the living Senegal bushbaby than of rainforest galagids. A shift to non-forest habitats may explain the terrestrial adaptations of Victoriapithecus, basal to the cercopithecid radiation, and of Kenyapithecus, basal to the hominoid radiation. Both taxa are distinct from earlier Miocene arboreal proconsulines, oreopithecines and galagids.     

Fossil woods from the Lower Coal-bearing Formation of the Janggi Group (Early Miocene) in the Pohang Basin,Korea

Fourteen species of fossil wood belonging to eleven genera and seven families were identified from 38 well preserved specimens collected from the Lower Coal-bearing Formation of Janggi Group at Donghae-myeon, Pohang City, Gyeongsangbuk-do Prefecture, Korea. Seven new taxa were found and described; they are Carya koreana Jeong et Kim, Betula janggiensis Jeong et Kim, Carpinus donghaensis Jeong et Kim, Ostrya geumgwangensis Jeong et Kim, Stewartia pseudo-camellioxylon Jeong et Kim, Acer minokamoensis Jeong, Kim et Suzuki and Acer pohangensis Jeong et Kim. The most abundant taxa are Betulaceae, Aceraceae, Ulmaceae, and Wataria. Except Wataria of which the habitat preference has not been confirmed, these taxa are major elements of cool-temperate vegetation and are similar to the Aniai-type flora of Japan. Previous studies of fossil plants from the Geumgwangdong Shale (leaves and seeds), the Upper Coal-bearing Formation (fossil woods) and the Yeonil Group (leaves and seeds) and this study, show that the climate of the Pohang Basin changed from cool-temperate to warm-temperate and subtropical during the Miocene.