Inferring palaeoecology in extinct tremarctine bears (Carnivora,Ursidae) using geometric morphometrics

Figueirido, B. & Soibelzon, L.H. 2009: Inferring palaeoecology in extinct tremarctine bears (Carnivora, Ursidae) using geometric morphometrics. Lethaia, Vol. 43, pp. 209–222. In this study we explore the ecomorphological patterns of extinct tremarctine bears in South America during the Great American Biotic Interchange (GABI). These patterns are used to derive palaeoautoecological inferences in extinct tremarctines and their palaeosinecological relationships within Plio‐Pleistocene ecosystems. We used geometric morphometrics of landmark data to recover the shape of the craniomandibular skeleton of bears. The results reveal different ecomorphological specializations in extinct tremarctines during the Plio‐Pleistocene of South America. Indeed, these bears could have increased the percentage of plant matter in their diets according with the increased diversity of large carnivores in South America after the GABI. Omnivorous bears retain the ability to behave as carnivores or herbivores depending on resource availability. This fact strongly supports that bears are one of the most ecologically and morphologically adaptable members of the large carnivore guild. Moreover, their skull morphology could reflect ecological adaptations under different selection pressures with the required evolutionary time. □Evolution, GABI, geometric morphometrics, palaeoecology, Tremarctinae.     

Brief communication: Plio‐Pleistocene eagle predation on fossil cercopithecids from the Humpata Plateau,southern Angola

Recent studies suggest a large raptor such as the crowned eagle (Stephanaoetus coronatus) was responsible for collecting at least a portion of the primate fauna from the South African fossil site of Taung, including its lone hominin specimen. This taphonomic signature at Taung is currently regarded as a unique and, most likely, isolated case in primate and human evolution. However, the activities of large, carnivorous birds should also be detectable at other primate fossil localities in Africa if raptors have been a strong selective force throughout primate evolution. Over the last 60 years, a collection of extinct cercopithecids has been assembled from several cave breccias on the Humpata Plateau in southern Angola. The material, dated near the Plio‐Pleistocene boundary, includes an assortment of craniodental and postcranial remains variably assigned to Papio (Dinopithecus) cf. quadratirostris, Parapapio, Cercopithecoides, and Theropithecus. We compare the Angolan and Taung material to remains of extant primates killed by crowned eagles in the Ivory Coast's Tai National Park. Our analysis indicates that the size distribution and composition of fauna from the localities is quite similar and that there are striking consistencies in damage to the crania from each site. The absence of large bodied (>20 kg) primates and other mammalian taxa at the Taung hominin locality and Tai, and their rarity in Angola, combined with the strong likelihood that raptor nests were positioned near fissure openings at both fossil localities, provides additional support for eagle involvement. On the basis of this evidence, we conclude that at least some of the Angolan cercopithecids were most likely raptor prey and hypothesize that raptor predation has been a strong and perhaps underappreciated selective force during the course of primate evolution. Am J Phys Anthropol 2009. © 2009 Wiley‐Liss, Inc.     

Tragelaphus nakuae: evolutionary change,biochronology, and turnover in the African Plio‐Pleistocene

Fossil Bovidae constitute one of the most significant proxy records for evolutionary and palaeoecological change in Africa. Tragelaphus nakuae is a regularly encountered antelope in the East African Plio‐Pleistocene, and is a common component of hominin faunas. As previously understood, this species ranged for almost 2 million years, encompassed a large range of morphological variation, exhibited relative stasis in the face of environmental perturbations, and left no known living descendants. I here review and revise the fossil record of this tragelaphin bovid, finding that specimens older than ～2.8 Mya and previously attributed to T. nakuae or a close form are in fact referable to a distinct, but ancestral, species. This new interpretation adds these fossil tragelaphins to the body of evidence supporting major faunal turnover occurring around 2.8 Mya in concert with global climatic change. I also document morphological changes that occur through the duration of T. nakuae, particularly after 2.3 Mya. These taxonomic revisions allow for refined biochronological estimates for several East African Plio‐Pleistocene sites and specimen assemblages of uncertain age. A phylogenetic analysis suggests that the T. nakuae lineage is related to the extant bongo (Tragelaphus eurycerus), relating this living but enigmatic forest antelope to the fossil record. One resulting palaeoecological hypothesis is that the bongo's modern fragmented range represents the relicts of a much more widely distributed late Pliocene African forest belt. This study highlights the importance of specimen‐based approaches for elucidating the pattern and timing of major evolutionary events. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 162 , 699–711.     

Reconstruction and re-evaluation of the skull ofHomo antiquus (hominoidea: Homininae) from Hadar

The skull ofHomo antiquus Ferguson, 1984, represented by cranial remains of a fossilized skeleton, A.L. 288-1, from the Plio/Pleistocene of Hadar in Ethiopia, is reconstructed and the procedure described. Re-evaluation of the skull shows that it is apparently the smallest, normal, unequivocal hominid skull known; and that its cranial morphology is not Australopithecine, but Hominine.     

Morphometric variation in the papionin muzzle and the biochronology of the South African Plio‐Pleistocene karst cave deposits

Papionin monkeys are widespread, relatively common members of Plio‐Pleistocene faunal assemblages across Africa. For these reasons, papionin taxa have been used as biochronological indicators by which to infer the ages of the South African karst cave deposits. A recent morphometric study of South African fossil papionin muzzle shape concluded that its variation attests to a substantial and greater time depth for these sites than is generally estimated. This inference is significant, because accurate dating of the South African cave sites is critical to our knowledge of hominin evolution and mammalian biogeographic history. We here report the results of a comparative analysis of extant papionin monkeys by which variability of the South African fossil papionins may be assessed. The muzzles of 106 specimens representing six extant papionin genera were digitized and interlandmark distances were calculated. Results demonstrate that the overall amount of morphological variation present within the fossil assemblage fits comfortably within the range exhibited by the extant sample. We also performed a statistical experiment to assess the limitations imposed by small sample sizes, such as typically encountered in the fossil record. Results suggest that 15 specimens are sufficient to accurately represent the population mean for a given phenotype, but small sample sizes are insufficient to permit the accurate estimation of the population standard deviation, variance, and range. The suggestion that the muzzle morphology of fossil papionins attests to a considerable and previously unrecognized temporal depth of the South African karst cave sites is unwarranted. Am J Phys Anthropol 2010. © 2009 Wiley‐Liss, Inc.     

Fossil papio cranium from !Ncumtsa (Koanaka) Hills, western Ngamiland, Botswana

Three fossils, a cranium of Papio, a cercopithecid frontal bone, and a mandible of juvenile Papio, have been recovered from cave deposits in the !Ncumtsa (Koanaka) Hills of western Ngamiland, Botswana. These specimens are significant because well‐preserved crania of Papio are extremely rare in the fossil record outside of South Africa and because this is the first report of fossil primate cranial remains from Botswana. Thermoluminescence dating of surrounding cave matrix indicates an age of ≥317 ± 114 ka, within the Middle Pleistocene, although it may be older. Based on univariate and multivariate analyses, the adult !Ncumtsa specimen falls within the range of variation seen in extant forms of Papio, yet is distinct from any living species/subspecies and represents a new taxon, named here as a new subspecies of Papio hamadryas—Papio hamadryas botswanae. Am J Phys Anthropol, 2012. © 2012 Wiley Periodicals, Inc.     

Brief Communication: Beyond the South African cave paradigm—Australopithecus africanus from Plio–Pleistocene paleosol deposits at Taung

Following the discovery of the “Taung Child” (Australopithecus africanus) in 1924 in the Buxton‐Norlim Limeworks near Taung, the fossil‐bearing deposits associated with the Dart and Hrdli?ka pinnacles have been interpreted as the mined remnants of cave sediments that formed within the Plio–Pleistocene Thabaseek Tufa: either as a younger cave‐fill or as contemporaneous carapace caves. When combined with the Plio–Pleistocene dolomitic cave deposits from the “Cradle of Humankind,” a rather restricted view emerges that South African early hominins derived from cave deposits, whereas those of east and central Africa are derived from fluvio‐lacustrine and paleosol deposits. We undertook a sedimentological and paleomagnetic analysis of the pink‐colored deposit (PCS) from which the “Taung Child” is purported to have derived and demonstrate that it is a calcrete, a carbonate‐rich pedogenic sediment, which formed on the paleo‐land surface. The deposit extends 100 s of meters laterally beyond the Dart and Hrdli?ka Pinnacles where it is interbedded with the Thabaseek Tufa, indicating multiple episodes of calcrete development and tufa growth. The presence of in situ rhizoconcretions and insect trace fossils (Celliforma sp. and Coprinisphaera sp.) and the distinctive carbonate microfabric confirm that the pink deposit is a pedogenic calcrete, not a calcified cave sediment. Paleomagnetic and stratigraphic evidence indicates that a second, reversed polarity, fossil‐bearing deposit (YRSS) is a younger fissure‐fill formed within a solutional cavity of the normal polarity tufa and pink calcrete (PCS). These observations have implications for the dating, environment, and taphonomy of the site, and increase the likelihood of future fossil discoveries within the Buxton‐Norlim Limeworks. Am J Phys Anthropol 151:316–324, 2013. © 2013 Wiley Periodicals, Inc.     

Earliest colobine skeletons from Nakali,Kenya

Old World monkeys represent one of the most successful adaptive radiations of modern primates, but a sparse fossil record has limited our knowledge about the early evolution of this clade. We report the discovery of two partial skeletons of an early colobine monkey (Microcolobus) from the Nakali Formation (9.8–9.9 Ma) in Kenya that share postcranial synapomorphies with extant colobines in relation to arboreality such as mediolaterally wide distal humeral joint, globular humeral capitulum, distinctly angled zona conoidea, reduced medial trochlear keel, long medial epicondyle with weak retroflexion, narrow and tall olecranon, posteriorly dislocated fovea on the radial head, low projection of the femoral greater trochanter, wide talar head with a greater rotation, and proximodistally short cuboid and ectocuneiform. Microcolobus in Nakali clearly differs from the stem cercopithecoid Victoriapithecus regarding these features, as Victoriapithecus is postcranially similar to extant small‐sized terrestrial cercopithecines. However, degeneration of the thumb, a hallmark of modern colobines, is not observed, suggesting that this was a late event in colobine evolution. This discovery contradicts the prevailing hypothesis that the forest invasion by cercopithecids first occurred in the Plio‐Pleistocene, and shows that this event occurred by the late Miocene at a time when ape diversity declined. Am J Phys Anthropol 143:365‐382, 2010. © 2010 Wiley‐Liss, Inc.     

A tale of the nearly tail‐less: the effects of Plio‐Pleistocene climate change on the diversification of the African avian genus Sylvietta

Sylvietta is a broadly distributed group of African species inhabiting a wide range of habitats and presents an interesting opportunity to investigate the historic mechanisms that have impacted the biogeography of African avian species. We collected sequence data from 50 individuals and used model‐based phylogenetic methods, molecular divergence estimates and ancestral area estimates to construct a time‐calibrated phylogeny and estimation of biogeographic history. We estimate a southern African origin for Sylvietta, with an initial divergence splitting the genus into two clades. The first consists of arid‐adapted species, with a southern African origin and subsequent diversification north into Ethiopia–Somalia. The second clade is estimated as having a Congolian forest origin with an eastward pattern of colonization and diversification as a result of Plio‐Pleistocene forest dynamics. Additionally, two members of the genus Sylvietta display interesting patterns of intraspecific diversification. Sylvietta rufescens is an arid‐adapted species inhabiting southern Africa, and we recover two subclades with a divergence dating to the Pleistocene, a unique pattern for avian species which may be explained via isolation in arid habitat fragments in the early Pleistocene. Second, Sylvietta virens, a species endemic to Afro‐tropical forests, is recovered with geographically structured genetic diversification across its broad range, an interesting result given that recent investigations of several avian forest species have found similar and substantial geographically structured genetic diversity relating to Plio‐Pleistocene forest fragmentation. Overall, Plio‐Pleistocene habitat cycling played a significant role in driving diversification in Sylvietta, and this investigation highlights the substantial impact of climate‐driven habitat dynamics on the history of sub‐Saharan species.     

The Chacoan peccary,Catagonus wagneri (Mammalia,Tayassuidae), in the late Pleistocene (northern Uruguay,South America): paleoecological and paleobiogeographic considerations

Catagonus wagneri has the most restricted geographical distribution among extant Tayassuidae and inhabited semi-arid thorny forests of dry Chaco in Paraguay, Bolivia and Argentina. Until now, C. wagneri has only been recorded in archaeological, pre-Hispanic deposits from the Santiago del Estero Province, Argentina. A new partially complete skull from the Sopas Formation (Late Pleistocene; Uruguay) is identified as C. wagneri. This is the only fossil record of the species which extends its biochron until the late Pleistocene, and the first one substantially far from its current range; the first fossil record of the species in Uruguay; the most complete fossil material of the species; and it provides relevant ecological and climatic information. According to the ecological and climatic available information of C. wagneri, the presence of this mammal in the late Pleistocene of northern Uruguay indicates a warm climate and arid to semi-arid environments. Even though not associated with the fossil remains of C. wagneri, some mammals included in the sedimentary levels of the Sopas Formation also suggest arid to semi-arid environments. Climatic changes, in particular in the late Pleistocene and Holocene, could be invoked to explain modifications of its geographic range.http://zoobank.org/ECF04BCF-8246-4F11-AAB8-5FAA9F437BDA     

Trachypithecus auratus sangiranensis,A New Fossil Monkey from Sangiran,Central Java,Indonesia

We describe a new extinct subspecies of the Javan lutung—Trachypithecus auratus sangiranensis—based on an isolated, tooth-bearing upper jaw. The specimen was in volcanic breccia situated between the Lower Pucangan and the Upper Kalibeng Formations 500 m south of the village of Sangiran, near Surakarta, central Java, Indonesia. The new fossil monkey bears morphological similarities to the two living species of leaf monkey from Java, Presbytis comata comata and Trachypithecus auratus auratus, and to the Middle Pleistocene form, Trachypithecus cristatus [=auratus] robustus, from Tegoean, central Java. It is significantly larger than any of these forms, and differs from them in details of dental anatomy. Because the greatest number of similarities are between the new fossil and Trachypithecus auratus subspecies, we designated the specimen as T. a. sangiranensis. The geochronological age of the breccia from which the fossil came, is 1.9± 0.05 Ma (million years), making T. a. sangiranensis one of the oldest fossil monkeys from eastern Asia.     

The evolution of sexual and parthenogenetic Warramaba: a window onto Plio–Pleistocene diversification processes in an arid biome

Environmental changes over the Plio‐Pleistocene have been key drivers of speciation patterns and genetic diversification in high‐latitude and mesic environments, yet comparatively little is known about the evolutionary history of species in arid environments. We applied phylogenetic and phylogeographic analyses to understand the evolutionary history of Warramaba grasshoppers from the Australian arid zone, a group including sexual and parthenogenetic lineages. Sequence data (mitochondrial COI) showed that the four major sexual lineages within Warramaba most likely diverged in the Pliocene, around 2–7 million years ago. All sexual lineages exhibited considerable phylogenetic structure. Detailed analyses of the hybrid parthenogenetic species W. virgo and its sexual progenitors showed a pattern of high phylogenetic diversity and phylogeographic structure in northern lineages, and low diversity and evidence for recent expansion in southern lineages. Northern sexual lineages persisted in localized refugia over the Pleistocene, with sustained barriers promoting divergence over this period. Southern parts of the present range became periodically unsuitable during the Pleistocene, and it is into this region that parthenogenetic lineages have expanded. Our results strongly parallel those for sexual and parthenogenetic lineages of the gecko Heteronotia from the same region, indicating a highly general effect of Plio‐Pleistocene environmental change on diversification processes in arid Australia.     

North American Glyptodontines (Xenarthra, Mammalia) in the Upper Pleistocene of northern South America

The Glyptodontidae is one of the most conspicuous groups in the Pleistocene megafauna of the Americas. The Glyptodontinae were involved in the Great American Biotic Interchange (GABI) and their earliest records in North America are about 3.9 Ma, suggesting an earlier formation of the Panamanian landbridge. Taxonomically it is possible to recognize two Pleistocene genera of Glyptodontinae:Glyptodon (ca. 1.8 – 0.008 Ma), restricted to South America, andGlyptotherium (ca. 2.6 – 0.009 Ma), including records in both North and Central America. Here we present the first report of the genusGlyptotherium in South America, from the Late Pleistocene of several fossil localities in Falcón State, northwestern Venezuela. A comparative analysis of the material, represented by cranial and postcranial parts, including the dorsal carapace and caudal rings, suggests a close affinity withGlyptotherium cylindricum (Late Pleistocene of Central Mexico). This occurrence in the latest Pleistocene of the northernmost region of South America Supports the bidirectional faunal migration during the GABI and the repeated re-immigration from North America of South American clades, as has been reported in other members of the Cingulata (e.g., Pampatheriidae).      

South African fossil Cercopithecoidea: A re-assessment including a description of new material from Makapansgat,Sterkfontein and Taung

The fossil cercopithecoid material from South Africa has been reviewed according to sites and species. The 722 specimens considered comprise 6 genera including 16 taxa and come from 16 sites. Aspects of taxonomic controversy and interest are discussed. In particular, the Parapapio material from Makapansgat has been re-evaluated and the taxonomy of the genus Simopithecus is reconsidered. A number of proposals are put forward. Four new specimens from Makapansgat and one from Sterkfontein are described; a previously partially described specimen from Taung is re-described in detail.     

Pleistocene human remains and conservation treatments: the case of a mandible from Atapuerca (Spain)

Research on human evolution depends in many cases on the study of fossil remains that have been treated by conservators. Conservation is a discipline with its own principles and methods. Its goal is not only long-term preservation, but also information recovery and the facilitation of research. Therefore, specialists in conservation propose and carry out the interventions, while research requirements must act as a guide in many steps of the process. In this article, we present an example of a strict conservation methodology applied to a human mandible from the Pleistocene site of Gran Dolina (Sierra de Atapuerca, Spain). An extensive diagnostic examination before the intervention included a computer tomography (CT) scan and stereoscopic light microscopy. This paper describes both the intervention and the mechanical preparation in detail. Finally, the intervention is discussed, as well as general conservation techniques. The compiled details show how this interdisciplinary work allowed retention of both the integrity of the specimen and its information. In conclusion, the development of a suitable method of conservation requires collaboration among all the specialists involved in the study of fossil remains.     

Mummified fossil of Keteleeria from the Late Pleistocene of Maoming Basin,South China,and its phytogeographical and paleoecological implications

Keteleeria is a small genus of Pinaceae now mainly restricted to eastern Asia. Although this genus has been documented with a wide distribution in the geologic record of Europe, North America, and Asia, its history in low‐latitude areas (including South China) has remained obscure. In this paper, a fossil wood of Keteleeria sp. is described from the Late Pleistocene (29–27 ka BP) of the Maoming Basin, South China. This wood is the most ancient megafossil evidence of Keteleeria within the modern distribution area of this genus. The fossil records of Keteleeria suggests that this thermophyllous genus migrated into South China by the Middle Pleistocene escaping from glacial cooling and became widespread over this region in the Late Pleistocene beginning from the interglacial stage preceding the Last Glacial Maximum. The analysis of growth rings in the fossil wood and its comparison with those of modern Keteleeria davidiana (Bertrand) Beissner indicates that in the Late Pleistocene of Maoming Basin (29–27 ka BP) there was a humid climate with less pronounced seasonality of precipitation than that seen in the subtropical monsoonal climate of modern northeastern Vietnam. Apparently, the Maoming Basin was influenced by interglacial regime with summer–monsoon circulation. The previously proposed method to distinguish between evergreen and deciduous conifers based on growth ring anatomy, is not reliable because of the wide variance and ambiguity in its results.     

Virtual brain endocast of Antifer (Mammalia: Cervidae), an extinct large cervid from South America

A diverse fossil record of Cervidae (Mammalia) has been documented in the South American Pleistocene, when these animals arrived during the Great American Biotic Interchange. Using computed tomography-scanning techniques, it is possible to access the endocranial morphology of extinct species. Here, we studied the brain endocast of the extinct late Pleistocene cervid Antifer ensenadensis from southern Brazil, one of the largest forms that lived on this continent, using comparative morphology, geometric morphometrics, and encephalization quotients. The analyzed endocasts demonstrate that A. ensenadensis had a gyrencephalic brain, showing a prominent longitudinal sinus (=sagittal superior sinus), which is also observed in the large South American cervid Blastocerus dichotomus. The encephalization quotient is within the variation of extant cervids, suggesting maintenance of the pattern of encephalization from at least the late Pleistocene. Geometric morphometric analysis suggested a clear and linear allometric trend between brain endocast size and shape, and highlights A. ensenadensis as an extreme form within the analyzed cervids regarding brain morphology.     

Precision and accuracy of acetabular size measures in fragmentary hominin pelves obtained using sphere‐fitting techniques

Hip joint diameter is highly correlated with body size in primates and so can potentially provide important information about the biology of fossil hominins. However, quantifying hip joint size has been difficult or impossible for many important but fragmentary specimens. New three‐dimensional technologies can be used to digitally fit spheres to the acetabular lunate surface, potentially allowing hip joint diameter estimates for incomplete joint surfaces. Here we evaluate the reliability of sphere‐fitting to incomplete lunate surfaces in silico using three‐dimensional polygonal models of extant anthropoid hipbones. Measurement error in lunate sphere‐fitting was assessed at the individual observer level, as well as between observers. Prediction error was also established for acetabular sphere size estimates for smaller divisions of the lunate surface. Sphere‐fitting techniques were then applied to undistorted regions of lunate surface in Plio‐Pleistocene hominin pelves, with a range of diameters constructed from extant error estimates. The results of this study indicate that digital sphere‐fitting techniques are precise and that the lunate does not need to be completely preserved to accurately infer hip dimensions, although some aspects of joint size and morphology can influence sphere size estimates. Joint diameter is strongly predicted by spheres fit to the cranial and caudal halves of the lunate in all anthropoids. We present new hip joint size estimates for a number of fossil hominins, and outline additional applications for digital sphere‐fitting as a morphometric technique. Am J Phys Anthropol 150:565–578, 2013. © 2013 Wiley Periodicals, Inc.     

Body size structure in north-western Mediterranean Plio-Pleistocene mammalian faunas

Aim We investigated the patterns of body‐size changes of the north‐western Mediterranean Plio‐Pleistocene large mammal faunas (excluding rodents, bats, lagomorphs and insectivores) in order to identify the tempo and mode of the major shifts in body size distribution, and to put them in the context of Plio‐Pleistocene environmental changes and the development of the Mediterranean climate. Location We analysed fossil faunas of Spain, France and Italy. A set of recent regional faunas from several macroclimatic regions was selected to serve as elements for comparison of the size distribution of past faunas, consisting of: Spain, France and Italy together, Florida, California, Central Chile, Indochina, India, Korea‐Manchuria, Malawi, The Cape, North Africa, Turkey and Australia. Methods Mammal species were grouped into five body size categories for carnivores and four categories for noncarnivore species. The number of species in each size category was computed and the resulting matrix of body weight classes × regions and time intervals was used as an input matrix in a Correspondence Analysis. Results Recent and fossil faunas strongly differ in body size structure. The distribution of recent faunas within the CA seems to reflect both ecological and historic factors, intertwined in a complex fashion. No clear relationship has been observed between body size structure and environmental factors. During the late Pliocene to early Pleistocene there were only minor changes in the pattern of size distribution, although plant communities were in a transition process from subtropical forests to Mediterranean woodlands and steppes. The major change in body size structure of the north‐western Mediterranean fauna occurred at the Galerian, around 1 Ma ago. This marked the beginning of the modern fauna, and a general trend towards a larger body size, reduction in the number of medium sized herbivores, and an increase of large herbivores and megaherbivores. Main conclusions The Plio‐Pleistocene faunas lack modern analogues. The body size structure of mammalian regional faunas appears to be strongly dependent on historical factors. The only major shift in body size distribution occurred during the Plio‐Pleistocene, in the late Villafranchian‐Galerian transition, coincident with the onset of the Pleistocene high intensity glacial cycles.