Hyperspecialization in Some South American Endemic Ungulates Revealed by Long Bone Microstructure

Adaptation to aquatic or semi-aquatic habits has been demonstrated in several distantly related mammalian clades worldwide during the Cenozoic, but curiously none has been conclusively evidenced inland for South America although a few South American native ungulates (SANU) have been proposed as possible subaquatic taxa. These taxa mostly correspond to large-sized herbivorous forms among astrapotheres, pyrotheres, and some toxodontid notoungulates, found at the end of the Paleogene and/or beginning of the Neogene. As no clear argument was provided for these ecological hypotheses, an analysis of the microanatomical features of long bones of some of these taxa in a comparative context was conducted in order to address the question of the paleoecology of these organisms. Our study highlights a variety of osseous specializations in the stylopod bones of SANU, and notably that Parastrapotherium, Pyrotherium, and Nesodon are affected by bone mass increase. If the microanatomical features of Parastrapotherium and Nesodon evoke what is observed in some terrestrial or semi-aquatic graviportal taxa, the very high compactness of Pyrotherium suggests extreme functional requirements in this taxon such as a graviportal hyperspecialization. This study thus evidences the occurrence of several convergent adaptations to graviportality and/or subaquatic habits within SANU and contributes to an important step towards a better integration of South American endemic mammals in large-scaled paleoecological studies.     

湖南省第四纪哺乳动物化石新材料

<正> 1984年10月,由中国科学院古脊椎动物与古人类研究所、湖南省博物馆和道县文化局组成联合工作组~1),对湖南省道县乐福堂乡塘贝村附近的一洞穴(下简称塘贝村洞)的更新世堆积进行了发掘,采获了一些第四纪哺乳动物化石.塘贝村洞的洞口高出地面约8米,在洞口的地面上,有扰乱的松散沙土,在洞内比洞口高3米处,可见含化石的堆积物,其范围不大,约有10平方米.另外,在洞壁较高处残留一层胶结得十分坚硬的黄色粗砂.现存的这层堆积,在洞内各部分变化很大,平均厚约1米,中含零星化石.从这层堆积的产状和岩性来看,它的时代要比前面提到的、位置较     

God-Apes and Fossil Men: Paleoanthropology in South Asia

God-Apes and Fossil Men: Paleoanthropology in South Asia. Kenneth A. R. Kennedy. Ann Arbor: University of Michigan Press, 2000.480 pp.     

Fusariosis in a Captive South American Sea Lion (Otaria flavescens): A Case Report

Mycopathologia - Superficial mycoses are commonly reported in captive pinnipeds, usually maintained in wet and warm environments, favorable to fungal growth. Most superficial mycoses in pinnipeds...     

"Canis" ferox Revisited: Diet Ecomorphology of Some Long Gone (Late Miocene and Pliocene) Fossil Dogs

Journal of Mammalian Evolution - The late Miocene was a period of great radiation for the subfamily Caninae in North America. During this time, the early taxa of the two tribes of this subfamily,...     

Ecomorphology of solitary chemosensory cell systems in fish: a review

Synopsis Solitary chemosensory cells (SCCs) are present in the skin of a wide spectrum of lower vertebrates, such as lampreys, elasmobranchs, teleost fishes and some amphibians (Kotrschal 1991, Whitear 1992). However, due to the difficulties studying them, virtually all our present knowledge on SCCs stems from the anterior dorsal fin of two species of rocklings (Gadidae). This fin is a peculiar chemosensory organ, carrying approximately 5 million SCCs (Kotrschal et al. 1984, Kotrschal & Whitear 1988). The evidence derived from this model on the structure of SCCs, on their innervation and brain representation, on the flow dynamics at the receptors, on their electrophysiological responses and behavioral relevance indicates that this fin is actively sampling for substances leaked from other fish, such as body mucus and bile components. Possibly, the rockling anterior dorsal fin aids in predators avoidance. To generate hypotheses on the functions and biological roles of the generalized., scattered SCC systems present in most fishes, their structural parameters are put in perspective to taste bud structure and function and to the rockling results. Ecomorphological reasoning serves to establish testable hypotheses: in essence, SCC systems spread over the body surface may be designed as general water samplers, but not for the exact localization of a stimulus source. If the function of the latter is equally dependent on water flow, as the rockling fin organ, fish would have to rely either on the ambient water flow, or speed up their own swimming to optimize SCC input. If SCCs are indeed evolved in the context of predator avoidance, a comparison between life history intervals and between species should reveal, that the system varies in accordance with predation pressure. It is concluded, that in fish, SCCs are certainly an important source of environmental information. If we do not understand functions and biological roles of SCCs, it will not be possible to explain fish behavior and ecology. Evidently, further investigations are urgently needed.     

Herbaceous Forage and Selection Patterns by Ungulates across Varying Herbivore Assemblages in a South African Savanna

Herbivores generally have strong structural and compositional effects on vegetation, which in turn determines the plant forage species available. We investigated how selected large mammalian herbivore assemblages use and alter herbaceous vegetation structure and composition in a southern African savanna in and adjacent to the Kruger National Park, South Africa. We compared mixed and mono-specific herbivore assemblages of varying density and investigated similarities in vegetation patterns under wildlife and livestock herbivory. Grass species composition differed significantly, standing biomass and grass height were almost twice as high at sites of low density compared to high density mixed wildlife species. Selection of various grass species by herbivores was positively correlated with greenness, nutrient content and palatability. Nutrient-rich Urochloa mosambicensis Hack. and Panicum maximum Jacq. grasses were preferred forage species, which significantly differed in abundance across sites of varying grazing pressure. Green grasses growing beneath trees were grazed more frequently than dry grasses growing in the open. Our results indicate that grazing herbivores appear to base their grass species preferences on nutrient content cues and that a characteristic grass species abundance and herb layer structure can be matched with mammalian herbivory types.     

The American South in a Global World

The American South in a Global World. James L. Peacock, Harry L. Watson, and Carrie R. Matthews, eds. Chapel Hill: University of North Carolina Press, 2005. 299 pp.     

Structural Path Analysis of Fossil Fuel Based CO2 Emissions: A Case Study for China

Environmentally extended input-output analysis (EEIOA) has long been used to quantify global and regional environmental impacts and to clarify emission transfers. Structural path analysis (SPA), a technique based on EEIOA, is especially useful for measuring significant flows in this environmental-economic system. This paper constructs an imports-adjusted single-region input-output (SRIO) model considering only domestic final use elements, and it uses the SPA technique to highlight crucial routes along the production chain in both final use and sectoral perspectives. The results indicate that future mitigation policies on household consumption should change direct energy use structures in rural areas, cut unreasonable demand for power and chemical products, and focus on urban areas due to their consistently higher magnitudes than rural areas in the structural routes. Impacts originating from government spending should be tackled by managing onsite energy use in 3 major service sectors and promoting cleaner fuels and energy-saving techniques in the transport sector. Policies on investment should concentrate on sectoral interrelationships along the production chain by setting up standards to regulate upstream industries, especially for the services, construction and equipment manufacturing sectors, which have high demand pulling effects. Apart from the similar methods above, mitigating policies in exports should also consider improving embodied technology and quality in manufactured products to achieve sustainable development. Additionally, detailed sectoral results in the coal extraction industry highlight the onsite energy use management in large domestic companies, emphasize energy structure rearrangement, and indicate resources and energy safety issues. Conclusions based on the construction and public administration sectors reveal that future mitigation in secondary and tertiary industries should be combined with upstream emission intensive industries in a systematic viewpoint to achieve sustainable development. Overall, SPA is a useful tool in empirical studies, and it can be used to analyze national environmental impacts and guide future mitigation policies.     

Paleopathology in South American mummies: a review and new findings

This article is a review of research and additional unpublished diseases that have been discovered and documented in naturally mummified remains recovered from South America. A new impetus in paleopathological studies was the work and discovery of a solution for rehydration of mummified tissues by Sir Marc Armand Ruffer in 1913. This solution allows the paleopathologist, after performing the autopsy, to process the tissues in a manner similar to current practices in pathology. In our studies, the most common diseases were infectious in nature, similar to the diseases that are most prominent today in the same regions.     

High-Throughput Sequencing of a South American Amerindian

The emergence of next-generation sequencing technologies allowed access to the vast amounts of information that are contained in the human genome. This information has contributed to the understanding of individual and population-based variability and improved the understanding of the evolutionary history of different human groups. However, the genome of a representative of the Amerindian populations had not been previously sequenced. Thus, the genome of an individual from a South American tribe was completely sequenced to further the understanding of the genetic variability of Amerindians. A total of 36.8 giga base pairs (Gbp) were sequenced and aligned with the human genome. These Gbp corresponded to 95.92% of the human genome with an estimated miscall rate of 0.0035 per sequenced bp. The data obtained from the alignment were used for SNP (single-nucleotide) and INDEL (insertion-deletion) calling, which resulted in the identification of 502,017 polymorphisms, of which 32,275 were potentially new high-confidence SNPs and 33,795 new INDELs, specific of South Native American populations. The authenticity of the sample as a member of the South Native American populations was confirmed through the analysis of the uniparental (maternal and paternal) lineages. The autosomal comparison distinguished the investigated sample from others continental populations and revealed a close relation to the Eastern Asian populations and Aboriginal Australian. Although, the findings did not discard the classical model of America settlement; it brought new insides to the understanding of the human population history. The present study indicates a remarkable genetic variability in human populations that must still be identified and contributes to the understanding of the genetic variability of South Native American populations and of the human populations history.     

Tropical Fossil Caviomorph Rodents from the Southwestern Brazilian Amazonia in the Context of the South American Faunas: Systematics,Biochronology, and Paleobiogeography

The fossil-bearing stratigraphic sections of the Solimões Formation (southwestern Brazilian Amazonia) are exposed mainly along the Juruá, Purus, and Acre rivers, and in road cuts. These deposits have provided fossils of the four main lineages of Caviomorpha – Cavioidea, Erethizontoidea, Octodontoidea, and Chinchilloidea, contributing to the understanding on the evolution of tropical Neogene rodents. Herein, our knowledge about fossil rodents from this region is reviewed. New specimens are recorded, including taxa mentioned for this region for the first time, such as basal cavioids, Dolichotinae, Caviodon (Hydrochoeridae), and Drytomomys (Dinomyidae). Unfortunately, the deposits have no absolute ages, and based on palynological data and the biochronology of several taxa (mainly mammals), the encompassed fauna has been constrained to the late Miocene. However, some rodent lineages recorded here seem to be more related to older faunas, from the middle Miocene and Paleogene. Regarding the biogeographic and paleoenvironmental affinities, most of the Neogene rodents from the Acre region show more similarities to those from the Entre Rios, Argentina, and Urumaco, Venezuela, where wet environments were present during Neogene times. An increase in prospecting along southwestern Amazonian rivers looking for rodents (among other vertebrates) associated with methods to better constrain the ages of these faunal assemblages will contribute to a better understanding of the evolution of the tropical rodents as well as the stratigraphy and age of that portion of the basin.     

Fossil Mice and Rats Show Isotopic Evidence of Niche Partitioning and Change in Dental Ecomorphology Related to Dietary Shift in Late Miocene of Pakistan

Stable carbon isotope analysis in tooth enamel is a well-established approach to infer C₃ and C₄ dietary composition in fossil mammals. The bulk of past work has been conducted on large herbivorous mammals. One important finding is that their dietary habits of fossil large mammals track the late Miocene ecological shift from C₃ forest and woodland to C₄ savannah. However, few studies on carbon isotopes of fossil small mammals exist due to limitations imposed by the size of rodent teeth, and the isotopic ecological and dietary behaviors of small mammals to climate change remain unknown. Here we evaluate the impact of ecological change on small mammals by fine-scale comparisons of carbon isotope ratios (δ¹³C) with dental morphology of murine rodents, spanning 13.8 to ∼2.0 Ma, across the C₃ to C₄ vegetation shift in the Miocene Siwalik sequence of Pakistan. We applied in-situ laser ablation GC-IRMS to lower first molars and measured two grazing indices on upper first molars. Murine rodents yield a distinct, but related, record of past ecological conditions from large herbivorous mammals, reflecting available foods in their much smaller home ranges. In general, larger murine species show more positive δ¹³C values and have higher grazing indices than smaller species inhabiting the same area at any given age. Two clades of murine rodents experienced different rates of morphological change. In the faster-evolving clade, the timing and trend of morphological innovations are closely tied to consumption of C₄ diet during the vegetation shift. This study provides quantitative evidence of linkages among diet, niche partitioning, and dental morphology at a more detailed level than previously possible.     

Grazing impacts on phytoplankton in South American water ecosystems: a synthesis

Hydrobiologia - The role of grazing as a controlling factor of phytoplankton has an extensive debate in the literature. In this article, five mechanisms that have been explored as potential...