122 research outputs found
The GPS craze: six questions to address before deciding to deploy GPS technology on wildlife
GPS and satellite technology for studies on wildlife have improved substantially over the past decade. It is now possible to collect fine-scale location data from migratory animals, animals that have previously been too small to deploy GPS devices on, and other difficult-to-study species. Often researchers and managers have formatted well-defined ecological or conservation questions prior to deploying GPS on animals, whereas other times it is arguably done simply because the technology is now available to do so. We review and discuss six important interrelated questions that should be addressed when planning a study requiring location data. Answers will clarify whether GPS technology is required and whether its use would increase efficiency of data collection and learning from location data. Specifically, what are required: (1) ecological question(s); (2) frequency and duration of data collection; (3) sample size; (4) hardware (VHF or GPS or satellite) and accessories; (5) environmental data; and (6) data-management and analysis procedures? This approach increases the chance that the appropriate technology will be deployed, budgets will be realistic, and data will be sufficient (but not excessive) to answer the ecological questions of interest. The expected results are important advances in ecological science and evidence-based management decisions
Palaeontology and geological context of a Middle Pleistocene faunal assemblage from the Gladysvale Cave, South Africa
Palaeontological and geological research at the Gladysvale Cave during the last decade has concentrated on de-roofed deposits located outside the Main Chamber. This area has been termed the Gladysvale External Deposit (GVED) and consists of fossil-rich calcified and decalcified sediments. Here we report on the recent analysis of both the faunal material and the geological context of this deposit. The faunal assemblage, excavated from the decalcified sediments contains 29 mammal species including taxa rare or absent in the Witwatersrand Plio-Pleistocene fossil record (e.g. Pelorovis and Kobus leche). Carnivores and porcupines are identified as accumulating agents of the bones. No new hominin findings can be reported from this deposit, and no cultural remains have been recovered. Geologically the calcified and decalcified breccias represent part of a large talus cone that is relatively unexposed. Uniquely for a cave fill in the Witwatersrand hominin-bearing sites, the sediments are horizontally stratified and form a number of flowstone bound sequences. The dating of the in situ cemented sediments is based on electron spin resonance (ESR) and palaeomagnetism. Recent results indicate that the deposits are of Middle-Pleistocene age.Palaeo-Anthropology Scientific Trust; French Embassy in South Africa; Co-operation and Cultural Service; National Geographic Society; John Nash and family; DACEL; University of the Witwatersrand Research Office and School of Geosciences; World Heritage Site Committee; SAHRA; Swiss National Science Foundation; NSF Grants ILl 9151111 and SBR 989628
Elemental signatures of Australopithecus africanus teeth reveal seasonal dietary stress
Reconstructing the detailed dietary behaviour of extinct hominins is challenging1\u2014particularly for a species such as Australopithecus africanus, which has a highly variable dental morphology that suggests a broad diet2,3. The dietary responses of extinct hominins to seasonal fluctuations in food availability are poorly understood, and nursing behaviours even less so; most of the direct information currently available has been obtained from high-resolution trace-element geochemical analysis of Homo sapiens (both modern and fossil), Homo neanderthalensis4 and living apes5. Here we apply high-resolution trace-element analysis to two A. africanus specimens from Sterkfontein Member 4 (South Africa), dated to 2.6\u20132.1 million years ago. Elemental signals indicate that A. africanus infants predominantly consumed breast milk for the first year after birth. A cyclical elemental pattern observed following the nursing sequence\u2014comparable to the seasonal dietary signal that is seen in contemporary wild primates and other mammals\u2014indicates irregular food availability. These results are supported by isotopic evidence for a geographical range that was dominated by nutritionally depauperate areas. Cyclical accumulation of lithium in A. africanus teeth also corroborates the idea that their range was characterized by fluctuating resources, and that they possessed physiological adaptations to this instability. This study provides insights into the dietary cycles and ecological behaviours of A. africanus in response to food availability, including the potential cyclical resurgence of milk intake during times of nutritional challenge (as observed in modern wild orangutans5). The geochemical findings for these teeth reinforce the unique place of A. africanus in the fossil record, and indicate dietary stress in specimens that date to shortly before the extinction of Australopithecus in South Africa about two million years ago
Drimolen cranium DNH 155 documents microevolution in an early hominin species
Paranthropus robustus is a small-brained extinct hominin from South Africa characterized by derived, robust craniodental
morphology. The most complete known skull of this species is DNH 7 from Drimolen Main Quarry, which differs from
P. robustus specimens recovered elsewhere in ways attributed to sexual dimorphism. Here, we describe a new fossil specimen
from Drimolen Main Quarry, dated from approximately 2.04–1.95 million years ago, that challenges this view. DNH 155 is a
well-preserved adult male cranium that shares with DNH 7 a suite of primitive and derived features unlike those seen in adult
P. robustus specimens from other chronologically younger deposits. This refutes existing hypotheses linking sexual dimorphism,
ontogeny and social behaviour within this taxon, and clarifies hypotheses concerning hominin phylogeny. We document
small-scale morphological changes in P. robustus associated with ecological change within a short time frame and restricted
geography. This represents the most highly resolved evidence yet of microevolutionary change within an early hominin species
Discovery of Middle Pleistocene fossil and stone tool-bearing deposits at Groot Kloof, Ghaap escarpment, Northern Cape province
We report the discovery of a major fossil-bearing and archaeological complex of karstic deposits at Groot Kloof in the escarpment of the Ghaap Plateau, around 100 km southwest of Taung. The region is known for open fluvial and lacustrine sites sampling Lower and Middle Pleistocene tool types and the long, but discontinuous sequence ofWonderwerk Cave. Research at Groot Kloof has concentrated on two of four localities. One locality has yielded fossils from the Florisian Land Mammal Age and lithics that may sample a late Early Stone Age/early Middle Stone Age type industry. The second locality has been dated using U-Th to 248 <U>+</U> 37 kyr ago for fossil-bearing tufa, and normal magnetic polarity for various tufa and breccia. The occurrence of fossils embedded within tufa rather than infilling a cavity is unusual. Small pockets of Later Stone Age artefact-bearing breccia and rock art also occur. The significance of Groot Kloof is underscored by current debate about the emergence of modern humans in which the appearance of modern behaviour is posited to have occurred inthis and other regions during this part of the Middle Pleistocene
Scientific Drilling of Lake Sediments at Darwin Crater, Tasmania
A 70 meters long continental sediment record was recovered at Darwin Crater in western Tasmania, Australia. The new sedimentary archive includes a pre-lake deposit and the complete lake sediment succession accumulated over several glacial/interglacial climate cycles in the ~816 ka meteorite impact crater. A total of 160 meters of overlapping sediment cores were drilled from three closely-spaced holes. Here we report on the drilling operations at Darwin Crater and present the first results from multi-sensor whole core logging, sediment description and multi proxy pilot analysis of core end samples. The multi-proxy dataset includes spectrophotometry, particle size, natural gamma ray, paleo- and rock-magnetism, loss-on-ignition and pollen analyses. The results provide clear signatures for alternating glacial and interglacial sediment facies. The succession returns a minimum of seven inferred glacial cycles. Initial paleomagnetic analysis indicate reversed magnetic polarity in the deepest sediments drilled at Hole B. If geomagnetic in origin, this result constrains the sediment 2.5 m below commencement of lacustrine deposition to an age between ~816 ka and the Matuyama-Brunhes geomagnetic reversal ~773 ka, which is consistent with the interpretation of seven glacial cycles. High-resolution analysis and detailed multi-disciplinary studies are underway with a primary focus on dating, paleomagnetism, and paleoclimate
New Oldowan locality Sare-Abururu (ca. 1.7 Ma) provides evidence of diverse hominin behaviors on the Homa Peninsula, Kenya
The Homa Peninsula, in southwestern Kenya, continues to yield insights into Oldowan hominin landscape behaviors. The Late Pliocene locality of Nyayanga (∼3–2.6 Ma) preserves some of the oldest Oldowan tools. At the Early Pleistocene locality of Kanjera South (∼2 Ma) toolmakers procured a diversity of raw materials from over 10 km away and strategically reduced them in a grassland-dominated ecosystem. Here, we report findings from Sare-Abururu, a younger (∼1.7 Ma) Oldowan locality approximately 12 km southeast of Kanjera South and 18 km east of Nyayanga. Sare-Abururu has yielded 1754 artifacts in relatively undisturbed low-energy silts and sands. Stable isotopic analysis of pedogenic carbonates suggests that hominin activities were carried out in a grassland-dominated setting with similar vegetation structure as documented at Kanjera South. The composition of a nearby paleo-conglomerate indicates that high-quality stone raw materials were locally abundant. Toolmakers at Sare-Abururu produced angular fragments from quartz pebbles, representing a considerable contrast to the strategies used to reduce high quality raw materials at Kanjera South. Although lithic reduction at Sare-Abururu was technologically simple, toolmakers proficiently produced cutting edges, made few mistakes and exhibited a mastery of platform management, demonstrating that expedient technical strategies do not necessarily indicate a lack of skill or suitable raw materials. Lithic procurement and reduction patterns on the Homa Peninsula appear to reflect variation in local resource contexts rather than large-scale evolutionary changes in mobility, energy budget, or toolmaker cognition
Frontal sinuses and human evolution
The frontal sinuses are cavities inside the frontal bone located at the junction between the face and the cranial vault and close to the brain. Despite a long history of study, understanding of their origin and variation through evolution is limited. This work compares most hominin species? holotypes and other key individuals with extant hominids. It provides a unique and valuable perspective of the variation in sinuses position, shape, and dimensions based on a simple and reproducible methodology. We also observed a covariation between the size and shape of the sinuses and the underlying frontal lobes in hominin species from at least the appearance of Homo erectus. Our results additionally undermine hypotheses stating that hominin frontal sinuses were directly affected by biomechanical constraints resulting from either chewing or adaptation to climate. Last, we demonstrate their substantial potential for discussions of the evolutionary relationships between hominin species. Variation in frontal sinus shape and dimensions has high potential for phylogenetic discussion when studying human evolution
Human Remains from the Pleistocene-Holocene Transition of Southwest China Suggest a Complex Evolutionary History for East Asians
BACKGROUND: Later Pleistocene human evolution in East Asia remains poorly understood owing to a scarcity of well described, reliably classified and accurately dated fossils. Southwest China has been identified from genetic research as a hotspot of human diversity, containing ancient mtDNA and Y-DNA lineages, and has yielded a number of human remains thought to derive from Pleistocene deposits. We have prepared, reconstructed, described and dated a new partial skull from a consolidated sediment block collected in 1979 from the site of Longlin Cave (Guangxi Province). We also undertook new excavations at Maludong (Yunnan Province) to clarify the stratigraphy and dating of a large sample of mostly undescribed human remains from the site. METHODOLOGY/PRINCIPAL FINDINGS: We undertook a detailed comparison of cranial, including a virtual endocast for the Maludong calotte, mandibular and dental remains from these two localities. Both samples probably derive from the same population, exhibiting an unusual mixture of modern human traits, characters probably plesiomorphic for later Homo, and some unusual features. We dated charcoal with AMS radiocarbon dating and speleothem with the Uranium-series technique and the results show both samples to be from the Pleistocene-Holocene transition: ∼14.3-11.5 ka. CONCLUSIONS/SIGNIFICANCE: Our analysis suggests two plausible explanations for the morphology sampled at Longlin Cave and Maludong. First, it may represent a late-surviving archaic population, perhaps paralleling the situation seen in North Africa as indicated by remains from Dar-es-Soltane and Temara, and maybe also in southern China at Zhirendong. Alternatively, East Asia may have been colonised during multiple waves during the Pleistocene, with the Longlin-Maludong morphology possibly reflecting deep population substructure in Africa prior to modern humans dispersing into Eurasia
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