Smilodon populator et Protocyon troglodytes, deux superprédateurs du Pléistocène supérieur de la Serra da Capivara (Piauí) au Nordeste du Brésil

Among the fossiliferous sites of the Serra da Capivara national park region (South Eastern Piauí), two have yielded interesting remains of the two large Upper Pleistocene Carnivora, Protocyon troglodytes (Lund, 1838) and Smilodon populator Lund, 1842, the Toca da Cima dos Pilão and the Toca das Moendas, both in the municipality of Coronel José Dias. In these two caverns, numerous remains of preys were found, namely, for the Toca da Cima dos Pilão, the two peccaries Dicotyles tajacu and Tayassu pecari, the medium sized ground sloth Catonyx cuvieri and the giant armadillo Pampatherium; for the Toca das Moendas Palaeolama, Equids and Cervids add to that list. The two sites were used as dens by the two Carnivora species. In the Toca das Moendas, a near complete adult skull and a hemimandible of the large Canid P. troglodytes were found. The skull is the third ever known for the species. Its dimensions are very similar to those of a complete skull from the Toca da Boa Vista (Campo Formoso, Bahia, Brazil) described by Cartelle et Langguth (1999), and to those of an incomplete skull from the banks of the Bermejo River (Formosa Province, Argentina), described by Prevosti et al. (2005). It fits perfectly, like the teeth, with the anatomical characteristics of the species P. troglodytes: wide muzzle, short palate, very reduced and forwardly offset protocone of the P4/, etc. The dimensions of the cheek teeth correspond well with those of numerous teeth from Lagoa Santa (Minas Gerais, Brazil) of the Lund Collection preserved in the Zoological Museum of Copenhagen. The same site of Toca das Moendas yielded two left hemimandibles of the Machairodontine S. populator Lund, 1842, an adult and a very young ones. We study them together with other remarkable remains from the Toca da Cima dos Pilão, namely an adult upper canine and an adult hemimandible. The upper canine is one of the longest ever described for S. populator. The P/4 are somewhat longer than those of the Californian Smilodon fatalis (Leidy, 1868), and the M/1 are about of the same average length but somewhat narrower. The segment P/4-M/1 is relatively short. The dimensions of the upper canine and of the lower cheek teeth fit well with those of some teeth from Lagoa Santa (Minas Gerais, Brazil) and from Argentina preserved in the Zoological Museum of Copenhagen. We describe particularly the decidual lower dentition, badly known in that species. The rather weak milk canine has a piriform outline. The D/3 is constituted by a strong protoconid flanked with two small cuspids, an anterior and a posterior ones. The D/4 (deciduous carnassial) shows a strong paraconid followed by a higher protoconid and a small posterior cuspid. These milk teeth, without any abrasion mark, suggest that our young specimen was less than three month old.     

U-series dating and taphonomy of Quaternary vertebrates from Brazilian caves

The geochronology and taphonomy of internationally important fossil bearing cave deposits were studied, both in the semi-arid Northern Bahia area and the subtropical southeastern Lagoa Santa area of Brazil. Taphonomic analysis suggests that the processes responsible for bone accumulation in the Brazilian caves vary between sites, and taphonomic bias can therefore be significant in causing differences in faunal composition. In the Toca da Boa Vista caves the presence of single articulated skeletons, and the entrance-related distribution indicate that random penetration of animals is the main mechanism of fossil accumulation, a process that biases the assemblage to smaller species, and takes place over extended time periods. In nearby Toca dos Ossos cave transport by runoff in the cave river is predominant, and biases the fauna remains to larger more robust bones and species. Deposition probably also occurred only at times of enhanced runoff giving a more contemporaneous assemblage. Similar processes were responsible for emplacement of the copious fossil remains in the more humid Lagoa Santa area, where terrigenous fossil deposits are found intercalated by massive speleothem calcite layers. In this area runoff under a drier climate probably accounts for the sediment emplacement inside caves. In both areas the mode of emplacement implies bias in the fossil record, resulting in fossil assemblages that do not mirror surface faunas, limiting palaeoenvironmental reconstruction.

Mass spectrometric U-series analysis of speleothem calcite overlaying fossil remains gives minimum ages for fossil deposition. These ages confirm the previous view that many of the deposits derive from the late glacial, but also show that much older material (some > 350,000 yr) is also present. The habitat requirements of critical fossil species such as bats and monkeys strongly suggest that they derive from much wetter periods when forest cover was present in the currently semi-arid Northern Bahia area. Taphonomy exerts a major control on the diversity and mode of emplacement of cave fossil deposits in eastern Brazil and thus detailed sedimentological and hydrological studies coupled with a sound geochronological approach are essential in quantifying the relative importance of each taphonomic processes before faunal and palaeoecological interpretations can be attempted.     

Les Cervidae (Mammalia, Artiodactyla) du Pléistocène supérieur-Holocène ancien de la région du Parc National Serra da Capivara (Piauí, Brésil)

The Upper Pleistocene/Lower Holocene fossil-bearing sites of the Serra da Capivara National Park Region have yielded three cervid species: Mazama gouazoubira, M. americana and Blastocerus dichotomus, all currently living in South America, the two first in the region. A grand total of more than one hundred remains demonstrates the presence of Mazama gouazoubira in seven sites, mainly the Toca das Moendas, the Toca do Serrote do Artur, the Toca da Cima dos Pilão. This small species shows, since the Upper Pleistocene, a conspicuous tendency to reduce the average dimensions of its teeth and long bones. From the taller M. americana, only a dozen of remains were found in four sites, mainly the Sitio do Meio. In all of these it is sympatric with M. gouazoubira. It differs from this last one by its cheek teeth and its limb bones size and proportions. The oldest site where the species is known is Tarija (Bolivia, Middle Pleistocene) and it does not show any significant changes in size and proportions between recent and fossil samples. Sixteen remains of the large B. dichotomus were found in five sites, mainly the Toca das Moendas and the Toca da Barra do Antonião. The species is a rare fossil, but is frequently figured in the rock art painting of the region, where it is presently unknown.     

Evolutionary Significance of the Entepicondylar Foramen of the Humerus in New World Monkeys (Platyrrhini)

Although consistently absent in extant catarrhine monkeys, the presence and absence of the entepicondylar foramen of the humerus (EEF) vary greatly among living and fossil platyrrhines. Aiming to test the mode of evolution of this character in platyrrhine phylogeny, we performed stochastic character mapping of the presence and absence of the EEF based on museum material and literature research. We also tested for phylogenetic signal of the EEF and its correlation with semi-brachation, vertical clinging, and manipulative foraging in New World monkeys. We found more losses than gains of the EEF in the Haplorhini and Platyrrhini phylogenies. The EEF showed a strong phylogenetic signal congruent with a Brownian model of evolution. All models that assumed a dependence between foraging and locomotion behaviors showed a better fit to the data, but the differences from an independent model were not statistically significant. Thus, we assume that the observed pattern could have originated from genetic drift, except in Leontopithecus where the EEF appears to have been lost due to the narrowing of the distal humerus. Although not functionally relevant, the presence and absence of EEF is taxonomically useful for discriminating between the Aotus and Callicebus species groups, and diagnoses large platyrrhine clades such as marmosets and Atelidae. Thus, it should be considered when inferring systematic relationships among living and extinct platyrrhines.     

Genetic characterization of Zostera asiatica on the Pacific Coast of North America

We gathered sequence information from the nuclear 5.8S rDNA gene and associated internal transcribed spacers, ITS-1 and ITS-2 (5.8S rDNA/ITS), and the chloroplast maturase K (matK) gene, from Zostera samples collected from subtidal habitats in Monterey and Santa Barbara (Isla Vista) bays, California, to test the hypothesis that these plants are conspecific with Z. asiatica Miki of Asia. Sequences from approximately 520 base pairs of the nuclear 5.8S rDNA/ITS obtained from the subtidal Monterey and Isla Vista Zostera samples were identical to homologous sequences obtained from Z. marina collected from intertidal habitats in Japan, Alaska, Oregon and California. Similarly, sequences from the matK gene from the subtidal Zostera samples were identical to matK sequences obtained from Z. marina collected from intertidal habitats in Japan, Alaska, Oregon and California, but differed from Z. asiatica sequences accessioned into GenBank. This suggests the subtidal plants are conspecific with Z. marina, not Z. asiatica. However, we found that herbarium samples accessioned into the Kyoto University Herbarium, determined to be Z. asiatica, yielded 5.8S rDNA/ITS sequences consistent with either Z. japonica, in two cases, or Z. marina, in one case. Similar results were observed for the chloroplast matK gene; we found haplotypes that were inconsistent with published matK sequences from Z. asiatica collected from Japan. These results underscore the need for closer examination of the relationship between Z. marina along the Pacific Coast of North America, and Z. asiatica of Asia, for the retention and verification of specimens examined in scientific studies, and for assessment of the usefulness of morphological characters in the determination of taxonomic relationships within Zosteraceae.     

The anatomy of Dolichocebus gaimanensis, a stem platyrrhine monkey from Argentina

Dolichocebus is known from the type skull encased in a concretion, numerous isolated teeth, parts of two mandibles, and a talus. The specimens come from the Trelew Member (early Miocene, Colhuehuapian South American Land Mammal Age) of the Sarmiento Formation near the village of Gaiman, Chubut Province, Argentina, dated to about 20Ma. We describe all Dolichocebus fossil material using conventional surface anatomy and micro-CT data from the cranium. The new material and newly imaged internal anatomy of the skull demonstrate that anatomical characters hitherto supposed to support a phyletic link between Dolichocebus and either callitrichines (marmosets, tamarins, and Callimico) or Saimiri (squirrel monkeys) are either indeterminate or absent. To more fully explore the phyletic position of Dolichocebus, we undertook a comprehensive phylogenetic analysis. We examined 268 characters of the cranium and dentition of 16 living platyrrhine genera, some late Oligocene and early Miocene platyrrhines, Tarsius, some Eocene and Oligocene stem anthropoids, and several extant catarrhines. These analyses consistently indicate that Dolichocebus is a stem platyrrhine, as are late Oligocene Branisella and early Miocene Tremacebus, Soriacebus, and Carlocebus. Platyrrhine evolution often is conceived of as a single ancient adaptive radiation. Review of all available phyolgenetic data suggests a more layered evolutionary pattern, with several independent extinct clades filling modern platyrrhine niche space, and modern platyrrhine families and subfamilies appearing over a nine-million-year interval in the Miocene. The outcome of these analyses highlights the pervasiveness of homoplasy in dental and cranial characters. Homoplasy is a real evolutionary phenomenon that is present at all levels of biological analysis, from amino-acid sequences to aspects of adult bony morphology, behavior, and adaptation.     

Additional postcranial remains of omomyid primates from the Uinta Formation, Utah and implications for the locomotor behavior of large-bodied omomyids

Most omomyids are relatively small bodied (e.g. <500 g), but beginning in the middle Eocene, some omomyids began to grow larger. The largest omomyids occur in the late middle Eocene during the Uintan NALMA, reaching an estimated body mass over 1 kg. The hind limb skeleton of small omomyids is relatively well known, and is generally thought to show active arboreal quadrupedal and leaping adaptations. New postcranial specimens of previously unknown elements from the larger Uintan omomyids, Ourayia (two species), Chipetaia lamporea, and Mytonius hopsoni have recently been recovered from the Uinta Formation, Utah, and from the Mission Valley Formation, California, and they provide additional information concerning their locomotor behavior.The new specimens include several distal tibiae, partial calcanei, a complete talus and a proximal first metatarsal of Chipetaia; distal femora, distal tibiae, cuboids, and partial calcanei of Ourayia uintensis; a complete calcaneus of Ourayia sp.; and a partial calcaneus and talus of Mytonius. Metric analysis of these elements, together with qualitative observations of non-metric traits, indicate that Ourayia and Chipetaia show equal or greater development of traits associated with leaping behavior (including elongation of the calcaneus, navicular and cuboid) than do smaller omomyids from North America. The elements of Mytonius, although fragmentary, lack some leaping features that are well-developed in Ourayia and Chipetaia, suggesting that Mytonius may have relied more on arboreal quadrupedal locomotion than on leaping.     

The subfossil monkey femur and subfossil monkey tibia of the Antilles: A review

The proximal portion of a subfossil monkey femur found in a Jamaican cave shares all the femoral characters of a mature male Cebus apella.The fragment alone, however, does not prove conspecificity. The Jamaican femur is also of a size that could belong to the extinct Xenothrix mcgregoriof the same island. In contrast, the distal portion of a monkey tibia recovered from a kitchen midden in the Dominican Republic cannot be identified with that of any known living platyrrhine or catarrhine monkey. Geological age, geographic locality, and size of fragment point to probable alignment of the tibia with the recently extinct cebid Saimiri bernensis.Although no conclusive identifications are made, the distinctive characters of the two limb bones are described on the basis of comparisons with femurs and tibias representing all genera of living platyrrhines, most genera of catarrhine monkeys, and some strepsirhines.     

Morphometric analysis of platyrrhine femora with taxonomic implications and notes on two fossil forms

Postcranial elements have been relatively neglected in primate evolutionary studies, especially for platyrrhine primates. We have analyzed 38 variables of the femur in 92 specimens of fossil and extant platyrrhines to determine patterns of shape affinity for comparison with other, more traditional information. Callitrichids¹ and advanced cebids were separated along a morphological continuum bridged by the more generalized cebids (Cebus, Callicebus, Saimiri, Aotus). Callitrichids were very closely interrelated and included Callimico as an integral member. Pithecines (Pithecia, Chiropotes and Cacajao) and atelines (Ateles, Brachyteles, Lagothrix plus Alouatta) form two clusters with considerably greater intra-group variability, inferentially related to the great adaptive radiation and changes undergone by these groups. Two fossil specimens, Homunculus and Cebupithecia, are significantly divergent from all extant ceboids but are nearest callitrichids, lying at the extreme callitrichid pole as that grade is contrasted with cebids.     

Side steps: the erratic pattern of hominin postcranial change through time

The hominin fossil record reveals brain-size expansion, canine reduction, premolar metaconid development, and numerous other craniodental features that become more human-like through time. In general, the postcranial skeleton also gets more human-like through time, but in some respects it does not. This is particularly apparent in the overall morphology of one of the most frequently preserved elements, the distal humerus. Some of the earliest hominins display quite human-like morphologies, whereas later specimens are quite unusual among extant species of Hominoidea: when described metrically and subjected to multivariate discriminant analyses in the context of large samples of extant hominoid humeri, the shapes of the earliest hominin fossils are more human-like than many of the later specimens. The Mahalanobis distances between many of the 1.5-2Ma hominin humeri and Homo sapiens are remarkably large. Many of the less well-represented postcranial specimens do not follow a linear path through time of increasing hominization either. This is particularly noticeable in the fore-to-hind limb joint-size proportions, ulnar morphology, and pelvic architecture. The hominin postcranial fossil record reveals many side-steps: there appears to be no simple march toward our human bodies, but a pattern better explained as adaptations to proximate conditions and constrained by ontogeny and history.     

Comparative analysis of volatiles from Drimys brasiliensis Miers and D. angustifolia Miers (Winteraceae) from Southern Brazil

The essential oils obtained from Southern Brazilian native Drimys brasiliensis Miers and Drimys angustifolia Miers were analyzed by GC and GC/MS. The oils from leaves of both species showed predominance of monoterpenoids, while the oils from stem barks were characterized by sesquiterpenoids. Bicyclogermacrene (20.0% in leaves and 25.4% in stem bark) and drimenol (1.4% in leaves and 26.2% in stem bark) were the most abundant in D. angustifolia, and cyclocolorenone (from 16.0% to 32.3% in fresh and dried leaves and almost 50% in stem bark) in D. brasiliensis. The oil from fruits of D. brasiliensis was also analyzed and presented 31.0% of cyclocolorenone. The predominance of this unusual aromadendrane-type sesquiterpene in D. brasiliensis essential oils could be used as a chemosystematic marker.     

Divergence Times and the Evolutionary Radiation of New World Monkeys (Platyrrhini,Primates): An Analysis of Fossil and Molecular Data

The estimation of phylogenetic relationships and divergence times among a group of organisms is a fundamental first step toward understanding its biological diversification. The time of the most recent or last common ancestor (LCA) of extant platyrrhines is one of the most controversial among scholars of primate evolution. Here we use two molecular based approaches to date the initial divergence of the platyrrhine clade, Bayesian estimations under a relaxed-clock model and substitution rate plus generation time and body size, employing the fossil record and genome datasets. We also explore the robustness of our estimations with respect to changes in topology, fossil constraints and substitution rate, and discuss the implications of our findings for understanding the platyrrhine radiation. Our results suggest that fossil constraints, topology and substitution rate have an important influence on our divergence time estimates. Bayesian estimates using conservative but realistic fossil constraints suggest that the LCA of extant platyrrhines existed at ca. 29 Ma, with the 95% confidence limit for the node ranging from 27–31 Ma. The LCA of extant platyrrhine monkeys based on substitution rate corrected by generation time and body size was established between 21–29 Ma. The estimates based on the two approaches used in this study recalibrate the ages of the major platyrrhine clades and corroborate the hypothesis that they constitute very old lineages. These results can help reconcile several controversial points concerning the affinities of key early Miocene fossils that have arisen among paleontologists and molecular systematists. However, they cannot resolve the controversy of whether these fossil species truly belong to the extant lineages or to a stem platyrrhine clade. That question can only be resolved by morphology. Finally, we show that the use of different approaches and well supported fossil information gives a more robust divergence time estimate of a clade.     

Fossil frogs (Anura) from Shanwang (Middle Miocene; Shandong Province, China)

The early middle Miocene biota from the Shanwang locality in eastern China is one of the most diverse and well preserved in the world. This overall richness contrasts with its low diversity of anuran amphibians. The most abundant anurans are representatives of the family Ranidae, which remains the dominant group in the extant anuran fauna of China. Besides Rana basaltica Young, some other ranids can be recognised at the locality, and are clearly distinguishable from R. basaltica based on their larger size and different proportions. Ranids are also represented by a developmental series of tadpoles, ranging from approximately Nieuwkoop-Faber (NF) stage 43 to a metamorphosing tadpole of NF stage 57. This is the first known developmental series of fossil non-pipoid Anura outside the Pelobatidae. In addition to the ranids, Bufo shandongensis nov. sp. (replacement name for B. linquensis), represented by one of the earliest known articulated bufonid skeletons, is described and illustrated. Another large toad, Macropelobates linquensis (Yang) nov. comb., is re-described; it can be assigned to the Pelobatoidea, with a possible relationship to the Scaphiopodidae, and can be considered, based on the presence of a large spade, a tibiofibula shorter than the femur, and a short astragalus and calcaneus, to be the earliest known anuran burrower.     

Early Miocene catarrhine dietary behaviour: the influence of the Red Queen Effect on incisor shape and curvature

The early Miocene catarrhine fossil record of East Africa represents a diverse and extensive adaptive radiation. It is well accepted that these taxa encompass a dietary range similar to extant hominoids, in addition to some potentially novel dietary behaviour. There have been numerous attempts to infer diet for these taxa from patterns of dental allometry and incisor and molar microwear, however, morphometric analyses until now have been restricted to the post-canine dentition. It has already been demonstrated that given the key functional role of the incisors in pre-processing food items prior to mastication, there is a positive correlation between diet and incisal curvature (Deane, A.S., Kremer, E.P., Begun, D.R., 2005. A new approach to quantifying anatomical curvatures using High Resolution Polynomial Curve Fitting (HR-PCF). Am. J. Phys. Anthropol. 128(3), 630-638.; Deane, A.S., 2007. Inferring dietary behaviour for Miocene hominoids: A high-resolution morphometric approach to incisal crown curvature. Ph.D. Dissertation. The University of Toronto.). This study seeks to re-examine existing dietary hypotheses for large-bodied early Miocene fossil catarrhines by contrasting the incisal curvature for these taxa with comparative models derived from prior studies of the correlation between extant hominoid incisor curvature and feeding behaviour. Incisor curvature was quantified for 78 fossil incisors representing seven genera, and the results confirm that early Miocene fossil catarrhines represent a dietary continuum ranging from more folivorous (i.e., Rangwapithecus) to more frugivorous (i.e., Proconsul) diets, as well as novel dietary behaviours that are potentially similar to extant ceboids (i.e., Afropithecus). Additionally, early Miocene fossil catarrhine incisors are less curved than extant hominoid incisors, indicating a general pattern of increasing mesio-distal and labial curvature through time. This pattern of morphological shifting is consistent with the Red Queen Effect (Van Valen, L., 1973. A new evolutionary law. Evol. Theory 1, 1-30), which predicts that taxa that are removed from one another by geological time, although potentially having similar diets, may exhibit differing degrees of a similar dietary adaptation (i.e., differing degrees of incisal curvature).     

First skull of Antillothrix bernensis,an extinct relict monkey from the Dominican Republic

The nearly pristine remains of Antillothrix bernensis, a capuchin-sized (Cebus) extinct platyrrhine from the Dominican Republic, have been found submerged in an underwater cave. This represents the first specimen of an extinct Caribbean primate with diagnostic craniodental and skeletal parts in association, only the second example of a skull from the region, and one of the most complete specimens of a fossil platyrrhine cranium yet discovered. Cranially, it closely resembles living cebines but is more conservative. Dentally, it is less bunodont and more primitive than Cebus, with crowns resembling Saimiri (squirrel monkeys) and one of the oldest definitive cebines, the late Early Miocene Killikaike blakei from Argentina. The tricuspid second molar also resembles the enigmatic marmosets and tamarins, whose origins continue to present a major gap in knowledge of primate evolution. While the femur is oddly short and stout, the ulna, though more robust, compares well with Cebus. As a member of the cebid clade, Antillothrix demonstrates that insular Caribbean monkeys are not monophyletically related and may not be the product of a single colonizing event. Antillothrix bernensis is an intriguing mosaic whose primitive characters are consistent with an early origin, possibly antedating the assembly of the modern primate fauna in greater Amazonia during the La Venta horizon. While most Greater Antillean primate specimens are quite young geologically, this vanished radiation, known from Cuba (Paralouatta) and Jamaica (Xenothrix) as well as Hispaniola, appears to be composed of long-lived lineages like several other mainland clades.     

Effect of intestinal erythrocyte agglutination on the feeding performance of Triatoma brasiliensis (Hemiptera: Reduviidae)

Triatoma brasiliensis is an important vector of Trypanosoma cruzi in Brazil. The feeding efficiency on its hosts depends on several parameters including the maintenance of the ingested blood at low viscosity, which could be modulated by the anterior midgut (crop) anticoagulant and haemagglutinant activities. In the present study, we characterized T. brasiliensis crop haemagglutination activity and evaluated its importance in the feeding process. Soluble crop contents (SCC) of T. brasiliensis were able to agglutinate rat, mouse and rabbit eryhtrocytes, but had no activity on cattle and Thrichomys apereoides, a rodent species commonly associated with T. brasiliensis in the wild. The haemagglutination was characterized by the immediate formation of several clusters of erythrocytes connected by flexible elastic-like fibers. The feeding efficiency of T. brasiliensis on rat (agglutinated by SCC) was almost double that from T. apereoides (not agglutinated by SCC). The influence of haemagglutination on feeding was confirmed by artificially feeding bugs on a diet composed of cattle or rat erythrocytes. The bugs fed on cattle erythrocytes had lower ingestion rates in comparison to those fed on rats. The results indicate that, in addition to other parameters, haemagglutination brought about by SCC has an important role in the feeding efficiency of T. brasiliensis.     

A description of the Omo I postcranial skeleton, including newly discovered fossils

Recent fieldwork in the Kibish Formation has expanded our knowledge of the geological, archaeological, and faunal context of the Omo I skeleton, the earliest known anatomically modern human. In the course of this fieldwork, several additional fragments of the skeleton were recovered: a middle manual phalanx, a distal manual phalanx, a right talus, a large and a small fragment of the left os coxae, a portion of the distal diaphysis of the right femur that conjoins with the distal epiphysis recovered in 1967, and a costal fragment. Some researchers have described the original postcranial fragments of Omo I as anatomically modern but have noted that a variety of aspects of the specimen's morphology depart from the usual anatomy of many recent populations. Reanalysis confirms this conclusion. Some of the unusual features in Omo I--a medially facing radial tuberosity, a laterally flaring facet on the talus for the lateral malleolus, and reduced dorsovolar curvature of the base of metacarpal I--are shared with Neandertals, some early modern humans from Skhul and Qafzeh, and some individuals from the European Gravettian, raising the possibility that Eurasian early modern humans inherited these features from an African predecessor rather than Neandertals. The fragment of the os coxae does not unambiguously diagnose Omo I's sex: the greater sciatic notch is intermediate in form, the acetabulum is large (male?), and a preauricular sulcus is present (female?). The preserved portion of the left humerus suggests that Omo I was quite tall, perhaps 178-182 cm, but the first metatarsal suggests a shorter stature of 162-173 cm. The morphology of the auricular surface of the os coxae suggests a young adult age.     

Presence and histopathological effects of the Parvatrema sp. (Digenea, Gymnophallidae) in the stout razor clam Tagelus plebeius (Bivalvia, Psammobiidae)

The stout razor clam Tagelus plebeius (Bivalvia, Psammobiidae) has a wide geographic distribution range, including the Brazilian coasts from the northeast (Alagoas) to the south (Santa Catarina). In March 2008, an episode of mass T. plebeius mortality (70%) occurred in an intertidal bed at The Pontal da Daniela, State of Santa Catarina, Brazil. We report here high prevalences (to 100%) of the trematode parasite Parvatrema sp. Cable, 1953 (Digenea, Gymnophallidae) infecting T. plebeius at high intensities. We describe the gymnophalid, echinostomatid and unidentified metacercariae parasites infecting the clam and the host reactions elicited by them. The use of special diagnostic techniques such as Ray’s fluid thioglycollate medium (RFTM) and PCR assays to detect Perkinsus sp. pathogens, hemolymph cytology, and histopathological examinations did not show Perkinsus sp. infections, microcell infections, or neoplastic conditions. However, neither infections or pathology caused by trematode parasites; nor any other pathological condition could be uniquely correlated with the mortality event. A coincident flash flood might have contributed to cause the mortality episode. This is the first report of the Parvatrema sp. metacercariae larvae infecting the stout razor clam T. plebeius from Brazil.     

Palaeomagnetic analysis of the Sterkfontein palaeocave deposits: implications for the age of the hominin fossils and stone tool industries

Palaeomagnetic analysis was conducted on speleothems from Members 1-5 at Sterkfontein Cave, South Africa. Palaeomagnetic analysis of siltstone and speleothem from the bulk of Member 4 indicate a reversed magnetic polarity that dates the deposits and its Australopithecus africanus fossils to between 2.58 and ∼2.16 Ma. Further confirmation of this age comes in the form of two short normal polarity events correlated to the Rèunion (∼2.16 Ma) and Huckleberry Ridge (∼2.05 Ma) events in speleothem capping the bulk of Member 4 and coeval with deposition of the final phase of Member 4, including A. africanus fossil Sts 5. At ∼2.16-2.05 Ma, Sts 5 is the youngest representative of A. africanus yet discovered. Palaeomagnetic analysis of the Silberberg Grotto deposits identifies a single short geomagnetic field event in flowstone overlying the StW 573 Australopithecus fossil, which is suggested to represent the Rèunion event at ∼2.16 Ma. This further supports the uranium lead age estimates of 2.3-2.2 Ma for the StW 573 fossil. Based on a reversed polarity for the deposits below the skeleton it cannot be older than 2.58 Ma. If StW 573 is considered to be a second species of Australopithecus then this indicates that two species of Australopithecus are present at Sterkfontein between 2.6 and 2.0 Ma. All of the Member 5 deposits date to less than 1.8 Ma based on a comparison of palaeomagnetic, faunal, and electron spin resonance age estimates. The StW 53 fossil bearing infill (M5A) is intermediate in age between Member 4 and the rest of Member 5 (B-C) at around 1.78-1.49 Ma. The rest of Member 5 (B-C) containing Oldowan and Acheulian stone tools and Homo and Paranthropus fossils was deposited gradually between 1.40 and 1.07 Ma, much younger than previously suggested.