The Miocene <Emphasis Type="Italic">Keramidomys</Emphasis> (Rodentia,Eomyidae) from the Sandelzhausen locality (Germany)

In this note the taxonomic position of the tiny eomyid genus Keramidomys (Hartenberger, 1967) from the Early/Middle Miocene boundary locality of Sandelzhausen in the Bavarian Upper Freshwater Molasse is reexamined. As the chronological dating of the Sandelzhausen fossil site has been modified in the past from formerly the Neogene mammal unit MN6 to now MN5 and thanks to new abundant material this rodent is compared with other European forms. It is shown that the Sandelzhausen eomyid must be called K. thaleri Hugueney & Mein, 1968 on the basis of several morphological dental differences from K. carpathicus Schaub & Zapfe, 1953. This rodent seems to be an immigrant from East Asia into Europe. Even if K. thaleri is known in many European localities, all correlated to MN5, it is always a rare element of European rodent faunas. Differentiation from K. carpathicus is not easy and requires a sufficiently large sample.      

The <Emphasis Type="Italic">Eumyarion</Emphasis> (Mammalia,Rodentia, Muridae) assemblage from Sandelzhausen (Miocene,Southern Germany): a test on homogeneity

A large sample of Eumyarion cheek teeth (N = 569) from the Early/Middle Miocene boundary locality Sandelzhausen (MN5, Southern Germany), type locality E. bifidus Fahlbusch, 1964, is studied. It is concluded that this collection contains two species: E. bifidus and E. weinfurteri Schaub and Zapfe, 1953. The similarity in size and morphology of the cheek teeth of these two species is so great that only the M1 and M2 can be recognised with certainty. Eumyarion bifidus seems to be a descendant of E. orhani de Bruijn et al., 2006 from the Early Miocene (MN3) of Southwestern Anatolia and is therefore considered to be an immigrant into Central Europe.      

The pigs and “Old World peccaries” (Suidae and Palaeochoeridae,Suoidea, Artiodactyla) from the Miocene of Sandelzhausen (southern Germany): phylogeny and an updated classification of the Hyotheriinae and Palaeochoeridae

The fossil remains of two species of Suoidea (Artiodactyla, Mammalia) from the Early/Middle Miocene locality of Sandelzhausen (MN5; Bavaria, Germany) are described. A skull and some isolated teeth and bones reveal hitherto unknown features of Schizoporcus muenzenbergensis, Schizoporcini, Taucanaminae, Palaeochoeridae (Old World peccaries), Suoidea. The phylogeny of the Taucanaminae is discussed and an updated classification of the Palaeochoeridae is presented. The new names Schizoporcus and Schizoporcini replace the junior homonyms Schizochoerus Crusafont and Lavocat (1954) and Schizochoerini Golpe-Posse (1974). Remains of several skulls and mandibles, over 50 associated tooth rows, over 300 isolated teeth, and over 200 bones, constitute one of the largest collections of a Miocene suid known, and are assigned to Hyotherium soemmeringi wylensis, Hyotheriini, Hyotheriinae, Suidae (pigs), Suoidea. Hyotherium is the oldest certain suid genus known and many assumed it to be one of the most primitive. While the postcranial bones of the Suidae and Palaeochoeridae differ in many ways, the bones of Hyotherium are already very similar in morphology to those of living pigs, although they are much more slender, suggesting that the genus was more fleet-footed. Features related to rooting behaviour indicate that Hyotherium was a more efficient rooter than Palaeochoeridae and living Dicotylidae, but not as efficient as living suids. The phylogeny of the Hyotheriinae is discussed. The subfamily is divided into Hyotheriini and Aureliachoerini, new tribe, and an updated classification is presented.     

Lagomorphs from the Miocene of Sandelzhausen (southern Germany)

Three genera of lagomorphs, Prolagus, Lagopsis, and “Amphilagus,” were identified during a revision of the lagomorph material from Sandelzhausen (MN5, Early/Middle Miocene boundary, southern Germany). Evidence of two morphological and dimensional classes were observed at some tooth positions in Prolagus (some p3 show an unmistakable P. oeningensis morphology, others closely resemble P. crusafonti), but not at other tooth positions (e.g., M1–2). Insufficient data from Sandelzhausen precludes identification of two different species of Prolagus from this locality, and to define the characteristics of the possible P. crusafonti-like species. Thus, all Prolagus specimens have been classified as P. aff. oeningensis. The genus Lagopsis is represented by L. cf. penai, whose presence is compatible with a MN5 age. The relative abundance of Lagopsis to Prolagus may indicate relatively cool and wet palaeoclimatic conditions. The largest primitive lagomorph species from continental Europe is present at Sandelzhausen. Morphological and dimensional comparisons with other European primitive lagomorphs exclude any affinity with the genera Eurolagus and Titanomys and with the species included in “Amphilagus ulmensis”. Some common features with “Amphilagus antiquus” were observed, although they are not sufficient for the attribution to this taxon. Until there is a general revision of European primitive lagomorphs, the Sandelzhausen giant lagomorph is classified as “Amphilagus” sp. Its origins, whether from evolution within Europe or migration from Asia, remain unknown.      

The diet of <Emphasis Type="Italic">Metaschizotherium bavaricum</Emphasis> (Chalicotheriidae,Mammalia) from the MN 5 of Sandelzhausen (Germany) implied by the mesowear method

The genus Metaschizotherium is a Miocene member of the Schizotheriinae (Chalicotheriidae, Perissodactyla) and appears in the MN 5 of Southern Germany with the species M. bavaricum. The Chalicotheriidae have mostly been reconstructed as browsers. In this study, the mesowear method is applied to 11 upper premolars and molars of M. bavaricum from the Upper Freshwater Molasse locality of Sandelzhausen (MN 5). With this method the amount of abrasive and attritive dental wear is investigated and thus it provides a time-averaged signature of food abrasiveness of ungulates. Principal components analysis is performed on mesowear variables of M. bavaricum. This species is found to classify closest to extant mixed feeding ruminants. This indicates that the diet of M. bavaricum essentially included nonabrasive browse but also a certain amount of abrasive plant material. The composition of the diet of extant reference species indicates that this abrasiveness was most likely imposed by bark and whole branches. In the palaeoecological context of Sandelzhausen M. bavaricum occupied the dietary niche of a mixed feeder or an abrasion-dominated browser. A high degree of similarity is recognised between the mesowear patterns of M. bavaricum from Sandelzhausen and M. fraasi from the MN 6 of the Franconian Alb. This is interpreted as reflecting a similar dietary niche of the two species.      

Ectothermic vertebrates (Actinopterygii,Allocaudata, Urodela,Anura, Crocodylia,Squamata) from the Miocene of Sandelzhausen (Germany,Bavaria) and their implications for environment reconstruction and palaeoclimate

The Early to Middle Miocene fossil locality Sandelzhausen has yielded 48 species of ectothermic vertebrates and thus represents one of the most diverse ectotherm faunas of Miocene age. Thirty-five taxa of fishes, amphibians and reptiles, including three new species: Pelobates fahlbuschi nov. sp. (Pelobatidae, the most abundant vertebrate), Tropidophorus bavaricus nov. sp. (Lygosominae) and Bavaricordylus molassicus nov. sp. (Cordylidae), are described. Three additional species are new, but are not named yet: Ranidae indet. nov. gen. et sp., Anguidae gen. indet. sp. nov. and Palaeoblanus sp. nov. (Amphisbaenidae). In order to reconstruct the palaeoenvironment and past hydrologic conditions, a new methodology (the tooth replacement method, TRM) is introduced, which allows for the detection of autochthonous components within freshwater fish taphocoenose. TRM is tested on 45 localities from the Upper Freshwater Molasse and gives reasonable results in agreement with other analytical approaches. It is therefore viewed as a reliable method to distinguish perennial from seasonal water conditions at the Sandelzhausen locality. Using the TRM it was demonstrated that the palaeohydrology of Sandelzhausen is characterized by a change from temporary water to permanent water conditions. During the period of temporary water conditions (units B to D1, lower part) the ecosystem was driven by seasonal inundations, and the remaining riparian pools have yielded no autochthonous fish population, but acted as spawning places for amphibians (amphibian pool). A mostly open habitat in the close vicinity, with sandy and non-groundwater-affected soils during the dry season, is suggested based on the absolute dominance of the spadefoot Pelobates fahlbuschi nov. sp. This ecosystem changed up-section (late part of unit D1 and during D2 and E) due to the establishment of permanent water conditions of riparian pond type, preserving an autochthonous Palaeocarassius/Channa fish population (fish pond). The reconstructed precipitation values suggest that the observed change in hydrologic conditions was probably driven by climate. The lower part of the section gives semi-arid/sub-humid values, with 571 mm mean annual precipitation (MAP), whereas the upper part yields sub-humid/humid values of 847 mm MAP. The increase in precipitation by about 280 mm was perhaps caused by a less seasonal precipitation regime with concomitant higher regional groundwater tables during units D2 and E. Based on the occurrence of several thermophilous reptile species, and in agreement with palaeobotanical and oxygen isotope data, the climate of Sandelzhausen is interpreted as subtropical with mean annual temperatures from 18°C to 20.8°C, mean cold month temperatures from 12.6°C to 13.3°C and mean warm month temperatures from 25.1°C to 28.1°C.     

<Emphasis Type="Italic">Democricetodon</Emphasis> and <Emphasis Type="Italic">Megacricetodon</Emphasis> (Mammalia,Cricetidae) from the Miocene of Sandelzhausen,Southern Germany

The cricetid species Democricetodon gracilis (Fahlbusch, 1964), Democricetodon mutilus (Fahlbusch, 1964), Megacricetodon bavaricus (Fahlbusch, 1964), and Megacricetodon minor (Lartet, 1851) from Sandelzhausen (Early/Middle Miocene boundary, MN5, Southern Germany) are represented by more than 2,000 molars providing substantial data on the variability in sizes and on variation in morphologies. Temporal and spatial distributions of these species indicate that they are probably immigrants in SE Germany, originating from south-eastern or more southern areas. Except for M. minor, whose origin is not clear and could be regarded as an immigrant from more eastern areas. Using the length of the mesoloph in the second upper molars as an indicator of habitat, D. gracilis and M. minor had a preference for a humid habitat, D. mutilus and M. bavaricus a preference for drier habitats.      

A Quaternary very young juvenile Tapirus Brisson, 1762 (Mammalia,Perissodactyla) from a cave deposit in northern Brazil: taxonomy and taphonomy

During fieldworks carried out from 2009 to 2013 in Aurora do Tocantins (northern Brazil), three isolated deciduous teeth of Tapirus were recovered. Those fossils come from a sedimentary deposit of presumed Late Pleistocene–early Holocene age in a karstic cave. This contribution aims to present a new locality of fossil Tapirus from northern Brazil, describe for the first time deciduous fossil teeth for South American Tapirus and evaluate the taphonomic aspects of those fossils. The specimens probably belong to the same individual due to there are no repeated teeth and they have the same wear pattern. Furthermore, the crowns of those teeth show no evidence of abrasion produced by transport. However, some abrasion is observed on the borders of the pulp chamber of teeth. These polishing are probably resulting of a very short transport (parautochthonous). These specimens are the only record of Tapiridae in Gruta do Urso cave; due to correspond to isolated and deciduous teeth, its identification to species level was not possible. There is not yet clear evidence that may indicate the kind of death of the individual studied here.     

<Emphasis Type="Italic">Anchitherium aurelianense</Emphasis> (Equidae,Mammalia): a brachydont “dirty browser” in the community of herbivorous large mammals from Sandelzhausen (Miocene,Germany)

The Anchitheriinae are an extinct subfamily of Equidae that first appeared in North America near the base of the Miocene. Anchitheriinae are found in subtropical to warm temperate habitats and were long considered to be adapted to eating browse. In Europe the genus Anchitherium first occurred in the MN3 mammal zone and became extinct in MN9. The assemblage from Sandelzhausen (Early/Middle Miocene, boundary MN5) is one of the best dental samples known of Old World Anchitherium. The mesowear method was applied to reconstruct the dietary regime of A. aurelianense from Sandelzhausen. Hierarchical cluster statistics and principal component analysis was performed on mesowear variables. Thirty-five upper cheek teeth of A. aurelianense were analysed, and mesowear signatures compared with those of five ruminant species from Sandelzhausen. The extant analogue species indicate that A. aurelianense at Sandelzhausen had a diet similar in abrasiveness to that of extant mixed feeders and that the Sandelzhausen ruminants all occupied a browsing niche with little or no abrasives in their diet. Knowing now that brachydont anchitheres were able to cope with rather abrasive diets, it is assumed that hypsodont North American equids of the Cormohipparion clade, arriving in Europe successively with the extinction of anchitheres shortly after the “hipparion datum” in the MN9, introduced a new component of competition in their dietary niche. The extinction of the Anchitheriidae can now be better understood as response to this competition.      

Continental molluscs of the fossil site Sandelzhausen (Miocene; Upper Freshwater Molasse from Bavaria) and their value for palaeoecological assessment

The continental mollusc fauna of Sandelzhausen (Southern Germany, Early/Middle Miocene, MN5) is presented and shown to consist of 66 snail and 3 bivalve taxa. Previous ecological interpretations were partly based on poorly preserved material and are shown to be erroneous. Within a series of quantitative samples, ecologically four mollusc communities can be distinguished (two each for terrestrial and freshwater molluscs), highly indicative of ecological conditions and changes in the landscape surrounding the fossil site as well as the locality itself. Open scrub-lands with temporary waters, as indicated by forms such as Granaria and the dominance of lymnaeids, are steadily replaced with damp forests with abundant litter and rotting wood surrounding a perennial lake with small tributaries. These more favorable conditions are indicated by an overall increase of mollusc diversity, rising abundance of planorbids, and presence of restricted forms such as Drepanotrema (intolerant to droughts) as well as certain forest dwellers such as Gastrocopta and hygromiids. Molluscs are highly sensitive to environmental changes, which is reflected in the fossil record of Sandelzhausen.      

Feeding preferences of <Emphasis Type="Italic">Gomphotherium subtapiroideum</Emphasis> (Proboscidea,Mammalia) from the Miocene of Sandelzhausen (Northern Alpine Foreland Basin,southern Germany) through life and geological time: evidence from dental microwear analysis

The objective of this study is to estimate changes in feeding preferences of the proboscidean species Gomphotherium subtapiroideum (Schlesinger 1917) by means of dental microwear analyses. The dietary changes are first evaluated through the ontogeny of this species, between juveniles and adults, and are then studied through geological time, from early Middle Miocene (MN5) to middle Late Miocene (MN8–9) localities of the German Molasse Basin. The microwear patterns of juvenile and adult individuals of G. subtapiroideum from Sandelzhausen (MN5) differ merely by the variable “length of scratches”, emphasizing longer jaw movements during mastication in adults. The microwear signatures of G. subtapiroideum do not vary significantly between the two geological time periods studied, but reflect mixed feeding preferences in both cases. These results imply that, despite an important environmental change at that time (drying and opening), the ecology of G. subtapiroideum and, especially, its feeding habits were not affected. Its dental microwear pattern is then compared with those of other species of Proboscidea from the Middle-Late Miocene of Germany, namely Deinotherium giganteum and Gomphotherium steinheimense.     

The influence of Eurasian beaver Castor fiber activity on fish assemblages in small steppe rivers in Russia

In recent decades, the Eurasian beaver (Castor fiber) has once again become the keystone species in small river ecosystems in Russia. In many places, beaver activity has resulted in a significant change in lotic habitats, affecting the diversity, density, and biomass of aquatic organisms, including fish. While many studies have considered the ecosystem impacts of beavers, relatively few have focused on understanding the influence of beaver activity on steppe rivers. We conducted the first quantitative study of beaver impacts on fish assemblages in beaver-influenced and beaver-free sites on two small steppe rivers in the Don River basin in Russia. The presence of beavers altered the habitats in small steppe rivers and affected the diversity, density, and biomass of fish. A comparison of the number of species, density, and biomass of fish in six types of river habitats showed that these parameters were lower in beaver ponds than at riverine sites without beaver activity. Three fish species primarily preferred a single habitat type. Barbatula barbatula was found in riffles, Misgurnus fossilis in old beaver ponds, and Eudontomyzon mariae in abandoned beaver ponds. Beavers impacted fish distribution and density by changing dissolved oxygen, pH, and water current velocity. Overall, our results showed that the presence of beavers led to a temporary homogenization of fish habitats at a local scale in the valleys of small steppe rivers because beavers occupied these rivers only for a short period. However, habitat heterogeneity may increase if the beaver population stays stable or expands in the future.

     

Siliceous scales of filose-amoebae (Pompholyxophryidae,Rotosphaerida) from deep Southern Ocean sediments,including first records for the Southern Hemisphere

The world of protists remains largely unexplored. A thorough electron-microscopic investigation of a few microlitres of deep-sea sediment from 2,964 m water depth near the South Sandwich Islands (Southern Ocean) revealed siliceous scales of filose-amoeba protist species, two of which have not been reported previously from Antarctica or from elsewhere in the Southern Hemisphere. However, all the species are known from other oceans and, in one case, from freshwater habitats. The Antarctic protistan scales belong to four species of filose amoebae: Pinaciophora fluviatilis Greef 1869, Pinaciophora denticulata Thomsen 1978, Pinaciophora multicosta Thomsen 1978 and Rabdiaster reticulata (Thomsen 1979) Mikrjukov 1999 nov. comb. Our study shows that (1) none of the species has been recorded from the Australasian biogeograpical region, (2) Pinaciophora multicosta and Rabdiaster reticulata are new records for the Southern Ocean and for the Southern Hemisphere as a whole, (3) prior to this investigation, Pinaciophora multicosta had been reported once only, from the Baltic Sea (Europe). These results highlight the problem of undersampling in the study of the global distribution of protists.     

Beavers (Castor canadensis) influence habitat for juvenile salmon in a large Alaskan river floodplain

Our aim was to determine how beavers affect habitats and food resources for juvenile salmon in the Kwethluk River in western Alaska.

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Potential Bark and Fruit Browsing as Revealed by Stereomicrowear Analysis of the Peculiar Clawed Herbivores Known as Chalicotheres (Perissodactyla,Chalicotherioidea)

This low magnification stereomicrowear study samples a broad range of chalicotheres (Perissodactyla, Chalicotherioidea), including basal chalicotheres and the two chalicotheriid subfamilies Schizotheriinae and Chalicotheriinae, primarily including species from North America and Europe, but also some from Asia. The schizotheriines Moropus, Tylocephalonyx, and Metaschizotherium and the chalicotheriines Anisodon and Chalicotherium are best represented. Paleodiets are interpreted via discriminant analysis, using comparison of microwear variables from fossil chalicothere teeth with those from a database of extant ungulates with known diets. The results suggest that all of the chalicotheres in the study were browsers, with no evidence of significant grass consumption. Basal chalicotheres, like basal equids, seem to have been standard fruit-dominated browsers. Stereomicrowear agrees with mesowear results by Schulz et al. (2007) and Schulz and Fahlke (2009) for Metaschizotherium bavaricum, Metaschizotherium fraasi, Anisodon grande, and Chalicotherium goldfussi in showing a highly abrasive aspect to the diet. In these species, hard food objects such as fibrous fruits, seeds, pits, and nuts may have abraded the teeth (based on high pit counts, the presence of large puncture pits, and many individuals with coarse to hypercoarse scratches). Anisodon grande and C. goldfussi, despite their relatively short, brachydont teeth, show the highest degree of abrasion within the studied sample. Moropus and Tylocephalonyx from North America show somewhat different but also abrasive microwear; in these taxa the resistant foods may have been twigs and bark (large pits common, but gouging more prevalent than puncture pits). A preliminary comparison of stereomicrowear on DP4, the deciduous upper fourth premolar, with that on molars suggests that juveniles consumed similar foods as adults but without the most abrasive elements. Some important methodological differences regarding the scoring of microwear features by different low-magnification microwear methodologies are discussed.     

Redescription of a poorly known acropomatid, <Emphasis Type="Italic">Verilus sordidus</Emphasis> Poey 1860, and comparison with <Emphasis Type="Italic">Neoscombrops atlanticus</Emphasis> Mochizuki and Sano 1984 (Teleostei: Perciformes)

A poorly known acropomatid, Verilus sordidus Poey 1860, is redescribed based on six specimens from the western central Atlantic. We present diagnostic characters to differentiate this species from Neoscombrops atlanticus Mochizuki and Sano 1984, which has been confused with this species, and designate a neotype of V. sordidus. This species is distinguishable from N. atlanticus by the proximal-middle radial of the first anal-fin pterygiophore being slender with no trough or hollow on the anterodorsal portion (vs. hollow in N. atlanticus), several canine teeth posterior to the large canine teeth on either side of the symphysis of the lower jaw (vs. villiform teeth posterior to enlarged canines), and by the modal numbers of pectoral-fin rays, lateral-line scales, and gill rakers on the lower limb of the first arch.     

Factors influencing forage selection by the North American beaver (Castor canadensis)

Across their range, a large number of biotic and abiotic factors are known to influence the choice of browse plant and the foraging behaviour of the North American beaver (Castor canadensis). We used generalized linear mixed-effects models to investigate sets of variables that may influence the foraging choices of beaver: forage species, distance of forage from water, forage density, and site. Communities across the study sites in central British Columbia, Canada, were dominated by Salix sitchensis, Salix lucida, and Alnus spp. Density had no impact on forage selection, while site, distance from water, and species identity all influenced the foraging decisions of beaver. We postulated that these factors may be ordered hierarchically: large-scale factors, such as site, followed by the medium-scale distance from water, and species of plant at the finest scale. Forage items in some sites had a higher probability of being browsed than in others, while in all sites the probability of being browsed decreased with increasing distance from water. Beaver appeared to be foraging as “picky” generalists; of the 9 plant species examined, 3 species of Salix (S. scouleriana, S. drummondiana and S. sitchensis) were selected by beaver, Salix bebbiana was avoided, and 5 species were neither selected for nor against. Browse selection within the genus Salix implied that beaver were able to differentiate among closely related species. Detailed information on forage selection is a crucial first step in designing and interpreting models that predict large-scale distributional patterns of beaver.     

Population-Genetic Structure of Beaver (Castor fiber L., 1758) Communities and Estimation of Effective Reproductive Size N e of an Elementary Population

The absence of panmixia at all hierarchical levels of the European beaver communities down to individual families implies a complex organization of the population-genetic structures of the species, in particular, a large intergroup component of gene diversity in the populations. Testing this assumption by analysis of 39 allozyme loci in the communities of reintroduced beaver from the Vyatka river basin (Kirov oblast) has shown that only the beaver colonies exhibit high intergroup gene diversity (G _st = 0.32) whereas this parameter is much lower when estimated among beaver groups from individual Vyatka River tributaries and among localities of one of the tributaries (0.07 and 0.11, respectively). The data suggesting genetic heterogeneity among individual settles within colonies have been obtained. The factors affecting the structure of the beaver communities of the lower hierarchical ranks are considered: the common origin, founder effect, selection, gene drift, assortative mating, and social and behavior features of the species. The conclusion is drawn that the founder effect could be the primary factor of population differentiation only at the time of their formation. The heterogeneity among colonies and among settles is maintained largely by isolation of colonies from one another. The strong interspecific competition for food resources, which is behaviorally implemented in the species at the level of minimal structural units (individual settles) creates a profound and unique population-genetic subdivision of the species. These results substantiate the suggestion that an elementary population (micropopulation) of European beaver is a colony, i.e., a set of related settles of different types. Based on ecological and genetic parameters, the effective reproductive size N _e of the minimum beaver population was estimated to be equal to three animals. This extremely low value of effective reproductive population size largely explains the high tolerance of European beaver to inbreeding and striking viability of the species, which from the early 19th century has been for more than hundred years on the brink of survival in the condition which would made any other mammalian species vanish from the Earth.