Science 8 February 2013:
Vol. 339 no. 6120 pp. 662-667
The Placental Mammal Ancestor and the Post–K-Pg Radiation of Placentals
Maureen A. O’Leary, Jonathan I. Bloch, John J. Flynn, Timothy J. Gaudin, Andres Giallombardo, Norberto P. Giannini, Suzann L. Goldberg, Brian P. Kraatz, Zhe-Xi Luo, Jin Meng, Xijun Ni, Michael J. Novacek, Fernando A. Perini, Zachary S. Randall, Guillermo W. Rougier, Eric J. Sargis, Mary T. Silcox, Nancy B. Simmons, Michelle Spaulding, Paúl M. Velazco, Marcelo Weksler, John R. Wible11, Andrea L. Cirranello
To discover interordinal relationships of living and fossil placental mammals and the time of origin of placentals relative to the Cretaceous-Paleogene (K-Pg) boundary, we scored 4541 phenomic characters de novo for 86 fossil and living species. Combining these data with molecular sequences, we obtained a phylogenetic tree that, when calibrated with fossils, shows that crown clade Placentalia and placental orders originated after the K-Pg boundary. Many nodes discovered using molecular data are upheld, but phenomic signals overturn molecular signals to show Sundatheria (Dermoptera + Scandentia) as the sister taxon of Primates, a close link between Proboscidea (elephants) and Sirenia (sea cows), and the monophyly of echolocating Chiroptera (bats). Our tree suggests that Placentalia first split into Xenarthra and Epitheria; extinct New World species are the oldest members of Afrotheria.
Zootaxa 3613 (3): 201–228 (11 Feb. 2013)
Taxonomy and redescription of the Fawn Antechinus, Antechinus bellus (Thomas) (Marsupialia: Dasyuridae)
ANDREW M BAKER & STEVE VAN DYCK
We provide a taxonomic redescription of the Fawn Antechinus, Antechinus bellus (Thomas). A. bellus is the only member of its genus to occur in Australia’s Northern Territory, where it can be found in savannah woodlands of the Top End. It is perhaps the most distinctive antechinus, and clearly distinguishable from the other 10 extant species of antechinus found in Australia: externally, A. bellus has pale body fur, white feet and large ears; A. bellus skulls have large auditory bullae and narrow interorbital width, while broadening abruptly at the molar row; mitochondrial and nuclear genes clearly distinguish A. bellus from all congeners, phylogenetically positioning the Fawn Antechinus as sister to Queensland’s A. leo Van Dyck, 1980, with which it shares a curled supratragus of the external ear and a similar tropical latitudinal range.
The phylogenetic distribution of ultraviolet sensitivity in birds
Anders Ödeen and Olle Håstad
BMC Evolutionary Biology 2013, 13:36 doi:10.1186/1471-2148-13-36
Colour vision in birds can be categorized into two classes, the ultraviolet (UVS) and violet sensitive (VS). Their phylogenetic distributions have traditionally been regarded as highly conserved. However, the complicated nature of acquiring spectral sensitivities from cone photoreceptors meant that until recently, only a few species had actually been studied. Whether birds are UVS or VS can nowadays be inferred from a wide range of species via genomic sequencing of the UV/violet SWS1 cone opsin gene.
We present genomic sequencing results of the SWS1 gene from 21 avian orders. Amino acid residues signifying UV sensitivity are found in the two most important spectral tuning sites 86 and 90 of Pteroclidiformes and Coraciiformes, in addition to the major clades, Palaeognathae, Charadriiformes, Trogoniformes, Psittaciformes and Passeriformes, where they where previously known to occur. We confirm that the presumed UVS-conferring amino acid combination F86, C90 and M93 is common to Palaeognathae and unique to this clade, despite available spectrometric evidence showing the ostrich retina to be VS.
By mapping our results together with data from previous studies on a molecular phylogeny we show that avian colour vision shifted between VS and UVS at least 14 times. Single nucleotide substitutions can explain all these shifts. The common ancestor of birds most likely had a VS phenotype. However, the ancestral state of the avian SWS1 opsin’s spectral tuning sites cannot be resolved, since the Palaeognathae are F86, C90 while the Neognathae are ancestrally S86, S90. The phylogenetic distribution of UVS and VS colour vision in birds is so complex that inferences of spectral sensitivities from closely related taxa should be used with caution.
Zootaxa 3613 (6): 573–588 (14 Feb. 2013)
A new species of the Scinax catharinae group (Anura, Hylidae) from Serra da Canastra, southwestern state of Minas Gerais, Brazil
ANA CAROLINA CALIJORNE LOURENÇO, ANDRÉ LUIZ GOMES DE CARVALHO, DÉLIO BAÊTA, TIAGO LEITE PEZZUTI & FELIPE SÁ FORTES LEITE
We describe Scinax pombali sp. n. a new species of treefrog of the Scinax catharinae group from Serra da Canastra, municipality of Capitólio, located in the Cerrado domains of the State of Minas
Gerais, Southeastern Brazil. The new species is characterized by its small size, blotches and color pattern on dorsal surface and hidden regions of flanks and thighs, canthus rostralis lightly concave and well marked, absent nuptial pad, and lack of externally differentiated inguinal gland. Additionally, we describe the tadpole of this new species, which is characterized by the large-sized oral disc and presence of a large number of marginal papillae (two to three rows on its dorsal portion and some rows in unorganized arrangement on its lateroventral portion).
Biodiversity decreases disease through predictable changes in host community competence
Pieter T. J. Johnson, Daniel L. Preston, Jason T. Hoverman & Katherine L. D. Richgels
Nature 494, 230–233 (14 February 2013) doi:10.1038/nature11883
Accelerating rates of species extinctions and disease emergence underscore the importance of understanding how changes in biodiversity affect disease outcomes. Over the past decade, a growing number of studies have reported negative correlations between host biodiversity and disease risk, prompting suggestions that biodiversity conservation could promote human and wildlife health. Yet the generality of the diversity–disease linkage remains conjectural, in part because empirical evidence of a relationship between host competence (the ability to maintain and transmit infections) and the order in which communities assemble has proven elusive. Here we integrate high-resolution field data with multi-scale experiments to show that host diversity inhibits transmission of the virulent pathogen Ribeiroia ondatrae and reduces amphibian disease as a result of consistent linkages among species richness, host composition and community competence. Surveys of 345 wetlands indicated that community composition changed nonrandomly with species richness, such that highly competent hosts dominated in species-poor assemblages whereas more resistant species became progressively more common in diverse assemblages. As a result, amphibian species richness strongly moderated pathogen transmission and disease pathology among 24,215 examined hosts, with a 78.4% decline in realized transmission in richer assemblages. Laboratory and mesocosm manipulations revealed an approximately 50% decrease in pathogen transmission and host pathology across a realistic diversity gradient while controlling for host density, helping to establish mechanisms underlying the diversity–disease relationship and their consequences for host fitness. By revealing a consistent link between species richness and community competence, these findings highlight the influence of biodiversity on infection risk and emphasize the benefit of a community-based approach to understanding infectious diseases.
Sangster, G.; King, B. F.; Verbelen, P.; Trainor, C. R. 2013.
A New Owl Species of the Genus Otus (Aves: Strigidae) from Lombok, Indonesia. PLoS ONE. 8 (2): e53712. doi: 10.1371/journal.pone.0053712
The avifauna of Indonesia is one of the richest in the world but the taxonomic status of many species remains poorly documented. The sole species of scops owl known from Lombok has long been assigned to the widespread Moluccan Scops Owl Otus magicus on the basis of superficial similarities in morphology. Field work in 2003 has shown that the territorial song of the scops owls inhabiting the foothills of Gunung Rinjani differs dramatically from that of O. magicus and is more similar to those of Rufescent Scops Owl O. rufescens and Singapore Scops Owl O. cnephaeus. Detailed comparisons of sound recordings and museum specimens with those of other scops owls in Wallacea and the Indo-Malayan region have confirmed the distinctiveness of the Lombok population. We describe Otus jolandae as a new species, the Rinjani Scops Owl. It is locally common at elevations from 25–1350 m. and occurs within Gunung Rinjani National Park. The new species is known from seven specimens collected by Alfred Everett in 1896. Otus jolandae represents the first endemic bird species from Lombok.
Genome differentiation in a species pair of coregonine fishes: an extremely rapid speciation driven by stress-activated retrotransposons mediating extensive ribosomal DNA multiplications
Symonová R, Majtánová Z, Sember A, Staaks GB, Bohlen J, Freyhof J, Rábová M, Ráb P
BMC Evolutionary Biology 2013, 13:42 (14 February 2013)
Sympatric species pairs are particularly common in freshwater fishes associated with postglacial lakes in northern temperate environments. The nature of divergences between co-occurring sympatric species, factors contributing to reproductive isolation and modes of genome evolution is a much debated topic in evolutionary biology addressed by various experimental tools. To the best of our knowledge, nobody approached this field using molecular cytogenetics. We examined chromosomes and genomes of one postglacial species pair, sympatric European winter-spawning Coregonus albula and the local endemic dwarf-sized spring-spawning C. fontanae, both originating in Lake Stechlin. We have employed molecular cytogenetic tools to identify the genomic differences between the two species of the sympatric pair on the sub-chromosomal level of resolution.
Fluorescence in situ hybridization (FISH) experiments consistently revealed a distinct variation in the copy number of loci of the major ribosomal DNA (the 45S unit) between C. albula and C. fontanae genomes. In C. fontanae, up to 40 chromosomes were identified to bear a part of the major ribosomal DNA, while in C. albula only 8–10 chromosomes possessed these genes. To determine mechanisms how such extensive genome alternation might have arisen, a PCR screening for retrotransposons from genomic DNA of both species was performed. The amplified retrotransposon Rex1 was used as a probe for FISH mapping onto chromosomes of both species. These experiments showed a clear co-localization of the ribosomal DNA and the retrotransposon Rex1 in a pericentromeric region of one or two acrocentric chromosomes in both species.
We demonstrated genomic consequences of a rapid ecological speciation on the level undetectable by neither sequence nor karyotype analysis. We provide indirect evidence that ribosomal DNA probably utilized the spreading mechanism of retrotransposons subsequently affecting recombination rates in both genomes, thus, leading to a rapid genome divergence. We attribute these extensive genome re-arrangements associated with speciation event to stress-induced retrotransposons (re)activation. Such causal interplay between genome differentiation, retrotransposons (re)activation and environmental conditions may become a topic to be explored in a broader genomic context in future evolutionary studies.
Contrasting parasite communities among allopatric colour morphs of the Lake Tanganyika cichlid Tropheus
Raeymaekers JA, Hablützel PI, Grégoir AF, Bamps J, Roose AK, Vanhove MP, Van Steenberge M, Pariselle A, Huyse T, Snoeks J, Volckaert FA
BMC Evolutionary Biology 2013, 13:41 (14 February 2013)
Adaptation to different ecological environments is thought to drive ecological speciation. This phenomenon culminates in the radiations of cichlid fishes in the African Great Lakes. Multiple characteristic traits of cichlids, targeted by natural or sexual selection, are considered among the driving factors of these radiations. Parasites and pathogens have been suggested to initiate or accelerate speciation by triggering both natural and sexual selection. Three prerequisites for parasite-driven speciation can be inferred from ecological speciation theory. The first prerequisite is that different populations experience divergent infection levels. The second prerequisite is that these infection levels cause divergent selection and facilitate adaptive divergence. The third prerequisite is that parasite-driven adaptive divergence facilitates the evolution of reproductive isolation. Here we investigate the first and the second prerequisite in allopatric chromatically differentiated lineages of the rock-dwelling cichlid Tropheus spp. from southern Lake Tanganyika (Central Africa). Macroparasite communities were screened in eight populations belonging to five different colour morphs.
Parasite communities were mainly composed of acanthocephalans, nematodes, monogeneans, copepods, branchiurans, and digeneans. In two consecutive years (2011 and 2012), we observed significant variation across populations for infection with acanthocephalans, nematodes, monogeneans of the genera Gyrodactylus and Cichlidogyrus, and the copepod Ergasilus spp. Overall, parasite community composition differed significantly between populations of different colour morphs. Differences in parasite community composition were stable in time. The genetic structure of Tropheus populations was strong and showed a significant isolation-by-distance pattern, confirming that spatial isolation is limiting host dispersal. Correlations between parasite community composition and Tropheus genetic differentiation were not significant, suggesting that host dispersal does not influence parasite community diversification.
Subject to alternating episodes of isolation and secondary contact because of lake level fluctuations, Tropheus colour morphs are believed to accumulate and maintain genetic differentiation through a combination of vicariance, philopatric behaviour and mate discrimination. Provided that the observed contrasts in parasitism facilitate adaptive divergence among populations in allopatry (which is the current situation), and promote the evolution of reproductive isolation during episodes of sympatry, parasites might facilitate speciation in this genus.
March 2013, Volume 705, Issue 1, pp 159-171
An initial assessment of drought sensitivity in Amazonian fish communities
Carlos E. C. Freitas, Flávia K. Siqueira-Souza, Robert Humston, Lawrence E. Hurd
The Amazon River Basin encompasses the world’s largest remaining tropical rainforest, and the largest freshwater system with the highest fish species diversity on earth, but global climate change is predicted to cause the loss of 7–12% of fish species by 2070. The severe drought anomaly of 2005, caused by warming of Atlantic surface waters, provided a unique opportunity to examine the impact of a major climatic disturbance on a tropical fish assemblage. We monitored fish species diversity in six Brazilian floodplain lakes along the Solimões River from 2004 to 2007 (before, during, and after drought). Statistical analysis revealed changes in species composition of these lakes following the drought, with both positive and negative responses observed. The response to drought was not uniform among species with regard to trophic guild or migratory behavior. SIMPER analysis showed that planktivores on the average increased in abundance in the years following the drought, carnivores and omnivores decreased, and herbivores and detritivores increased. Some of these changes were transitory, others persisted through monitoring. Migratory species disproportionately increased in abundance post-drought compared to non-migratory species. Interlake (β) diversity of fish declined during the drought year, indicating that lakes were becoming less heterogeneous in species composition, but showed a trend toward recovery of pre-drought level in the following years. According to both global climate change models and recent experience, the intensity and frequency of droughts in this region of the world is increasing. Given the sensitivity of resident fish species to the single, short-term, perturbation reported here, assessment of how tropical freshwater fish populations respond to drought will be crucial to understanding the consequences of this kind of perturbation to these communities and to the human inhabitants who depend upon this important protein source.
March 2013, Volume 36, Issue 3, pp 343-348,
Potentially pathogenic yeast isolated from the throat and cloaca of an Arctic colonial seabird: the little auk (Alle alle)
Maria Dynowska, Katarzyna Wojczulanis-Jakubas, Justyna A. Pacyńska, Dariusz Jakubas, Elżbieta Ejdys
Yeasts are a distinctive group of microfungi, but compared to other microorganisms, their ecological function and biodiversity are poorly known. This is especially so where polar ecosystems are concerned. With climate changes and increasing pollution levels in the Arctic, it can be anticipated that there will be an increase in the prevalence and diversity of fungi colonizing live organisms. With these changes, it is crucial to investigate and monitor species diversity and prevalence of fungi in this fragile environment. In this study, yeasts were examined from throat and cloaca of a small colonial seabird, the little auk (Alle alle), a keystone species in the Arctic ecosystem. Samples were collected from 94 adults and 17 nestlings in breeding colony in Magdalenefjorden (NW Spitsbergen) in 2009. In total, twelve species of yeast from eight genera were found in 12 % of the samples, with the Dipodascus genus being the most prevalent. All yeast species were found in the adults, but only one species, Cryptococcus macerans, was found in a single nestling. In individuals where fungus was isolated, it was only isolated from either the throat or the cloaca, except for two cases, where fungus was found in both throat and cloaca. The presence of yeast was not related to sex but age of the birds, with adults being more prone to colonization by yeasts than the nestlings. The relatively low prevalence and diversity of yeast in little auks suggest that these birds are random carriers of fungi, with minor health impacts.
March 2013, Volume 36, Issue 3, pp 305-320
Harp seal foraging behaviour during summer around Svalbard in the northern Barents Sea: diet composition and the selection of prey
Ulf Lindstrøm, Kjell T. Nilssen, Line M. S. Pettersen, Tore Haug
The harp seal Pagophilus groenlandicus is a major high trophic level predator in the Barents Sea, and to better understand their function in the Barents Sea ecosystem, we need to understand their foraging behaviour during their most intensive feeding period. We analysed the diet composition and prey preference of 184 harp seals and 94 faeces samples, sampled in the northern Barents Sea (around Svalbard) during the period May–August in 1996, 1997, and 2004–2006. Concurrent with the sampling of seals, prey availability was assessed in one area in 1996 and 1997 and in two areas in 2006 using standard acoustic methods. Our study showed that harp seal diet composition varied significantly both in time (year) and space, and that their diets appeared to be size dependent. Both subadult (
March 2013, Volume 36, Issue 3, pp 363-372,
Guano deposition and nutrient enrichment in the vicinity of planktivorous and piscivorous seabird colonies in Spitsbergen
Adrian Zwolicki, Katarzyna Małgorzata Zmudczyńska-Skarbek, Lech Iliszko, Lech Stempniewicz
The crucial role of seabirds in the enrichment of nutrient-poor polar terrestrial ecosystem is well-known. However, no studies have examined the potentially different impacts associated with piscivorous and planktivorous bird colonies on the surrounding tundra soils. Therefore, we compared guano deposition and physical and chemical parameters of soil near two large seabird colonies, one of planktivorous little auks (Alle alle) and the other comprising piscivorous Brunnich’s guillemots (Uria lomvia) and kittiwakes (Rissa tridactyla). The two colonies generated similar levels of guano deposition, with the intensity of deposition decreasing away from the colony. Guano deposition adjacent to both colonies was considerably higher than that in control areas. The increased guano supply around colonies significantly enhanced soil conductivity, nitrogen (NO3 −, NH4 +), potassium (K+), and phosphate (PO4 3−) ion concentrations and led to reduced pH values. Guano deposition explained 84 % (piscivorous colony) and 67 % (planktivorous colony) of the total variation in the tested soil parameters. Planktivore and piscivore colonies affected adjacent tundra in different ways. The phosphate content and pH value of soil influenced by piscivores were significantly higher than values measured in planktivore-influenced soil. The gradient of guano deposition and associated ion content in the soil decreased more rapidly with distance from the piscivore colony. Climate-induced changes in populations of planktivorous and piscivorous seabirds are expected in the study region and may therefore have substantial consequential effects on Arctic terrestrial ecosystems.
March 2013, Volume 36, Issue 3, pp 437-443
Winter diet of striated caracara Phalcoboenus australis (Aves, Polyborinae) at a farm settlement on the Falkland Islands
Kalinka Rexer-Huber, Keith L. Bildstein
Striated caracaras occur only on the Falkland Islands and the outer islands of southern Chile and Argentina. In summer, the species associates with seabirds and seals and depends heavily upon them for food. The winter diet is less well understood. We studied the diet of 90–130 mainly juvenile and sub-adult striated caracaras overwintering at a farm on Saunders Island, Falkland Islands, in mid-winter (July–August) 2011. Direct observations of feeding and regurgitation pellets collected at a roost indicate that the winter diet of the striated caracaras at the site is mainly native geese, beetles and other invertebrates, and the carcasses of domestic sheep. This study illustrates seasonal shifts in the diet of this near-threatened South Atlantic endemic and suggests an important nutritional link between juvenile and subadult caracara survival in winter and traditional human activities at sheep farms.
March 2013, Volume 36, Issue 3, pp 453-456
Residence of the leopard seal in the Magellan Strait: a potential sub-Antarctic population inhabiting the waters of Southern Chile?
Jorge Acevedo, Francisco Martinez
The leopard seal is widely distributed on the Antarctic pack ice, but a number of individuals are also thought to displace north from the pack ice to the sub-Antarctic Islands or venture even farther north. In Chile, the leopard seal has been reported mainly in the Fueguian Archipelago, with individuals sighted year-round; however, the data to date have been unable to determine whether it is the same individuals who remain year-round. Thus, one of the questions to be resolved is whether there is a northward dispersion of individuals from the Southern Ocean returning to the Antarctic continent, or alternatively if there is a potential sub-Antarctic population that delay or suspend their migration toward the Antarctic region. Opportunistic sightings of a solitary seal at Ballena Sound, Magellan Region, Chile, were documented in photographs on six occasions from January to May 2012. Based on the review of the photographs, the leopard seal was identified as the same individual. This finding provides the first evidence of a long occupation by a leopard seal in the fjords and channels of Fueguian Region, suggesting the existence of a small population inhabiting the waters of Southern Chile year-round.
Proc. R. Soc. B 7 April 2013 vol. 280 no. 1756 20122071
The fish tail motion forms an attached leading edge vortex
Iman Borazjani and Mohsen Daghooghi
The tail (caudal fin) is one of the most prominent characteristics of fishes, and the analysis of the flow pattern it creates is fundamental to understanding how its motion generates locomotor forces. A mechanism that is known to greatly enhance locomotor forces in insect and bird flight is the leading edge vortex (LEV) reattachment, i.e. a vortex (separation bubble) that stays attached at the leading edge of a wing. However, this mechanism has not been reported in fish-like swimming probably owing to the overemphasis on the trailing wake, and the fact that the flow does not separate along the body of undulating swimmers. We provide, to our knowledge, the first evidence of the vortex reattachment at the leading edge of the fish tail using three-dimensional high-resolution numerical simulations of self-propelled virtual swimmers with different tail shapes. We show that at Strouhal numbers (a measure of lateral velocity to the axial velocity) at which most fish swim in nature (approx. 0.25) an attached LEV is formed, whereas at a higher Strouhal number of approximately 0.6 the LEV does not reattach. We show that the evolution of the LEV drastically alters the pressure distribution on the tail and the force it generates. We also show that the tail’s delta shape is not necessary for the LEV reattachment and fish-like kinematics is capable of stabilising the LEV. Our results suggest the need for a paradigm shift in fish-like swimming research to turn the focus from the trailing edge to the leading edge of the tail.
Boonzaier, J., Van der Merwe, E. L., Bennett, N. C. and Kotzé, S. H. (2013), Comparative gastrointestinal morphology of three small mammalian insectivores: Acomys spinosissimus (Rodentia), Crocidura cyanea (Eulipotyphla), and Amblysomus hottentotus (Afrosoricida). J. Morphol.. doi: 10.1002/jmor.20118
The gastrointestinal morphology was investigated in three mammalian insectivorous species, namely Acomys spinosissimus, Crocidura cyanea, and Amblysomus hottentotus. The aim of the study was to provide a comprehensive morphological comparison between the different species and to explore whether anatomical gastrointestinal adaptations are associated with the insectivorous diet of these species. The shape, proportional length, and proportional surface areas of the different gastrointestinal regions were recorded and compared in the three insectivores. Hematoxylin and Eosin (H&E) and Alcian Blue/Periodic Acid Schiff (AB/PAS) were used for morphological assessment. In all three species, the stomach was simple and uncompartmentalized. The internal aspect of the stomach in A. spinosissimus was hemi-glandular, containing stratified squamous epithelium in the fundus, with glandular epithelium in the body and pyloric region. However, C. cyanea and A. hottentotus had wholly glandular stomachs. Paneth cells were not observed in the intestinal tracts of C. cyanea and A. hottentotus. Acomys spinosissimus was the only species studied that had a cecum. The proximal colonic region of A. spinosissimus had V-shaped mucosal folds. Histologically, C. cyanea had villi throughout the entire gastrointestinal tract (GIT), whereas for A. hottentotus villi were not present in the most distal gastrointestinal regions. In both C. cyanea and A. hottentotus, longitudinal mucosal folds were present in the distal part of the colon. The GITs of C. cyanea and A. hottentotus showed little morphological differentiation namely, a simple, glandular stomach and the lack of a cecum.
James D. Pampush, Ana C. Duque, Brittany R. Burrows, David J. Daegling, William F. Kenney, W. Scott McGraw, Homoplasy and thick enamel in primates, Journal of Human Evolution, Available online 13 February 2013, ISSN 0047-2484, 10.1016/j.jhevol.2013.01.009.
Traditionally, thick enamel has often been used to infer durophagy (i.e., hard nut and seed consumption) in extinct hominins. These inferences are based on the hypothesis that thick enamel is primarily an adaptation to prevent tooth fracture or chipping resulting from high-stress loads produced during the mastication of large hard foods. An alternative view argues that thick enamel may aid in maintaining tooth function in the face of gradual dental wear from grit, phytoliths and acid, which may be found in foods of widely varying hardness. We use estimates of primate dietary abrasiveness and recorded lifespan to test the hypothesis that enamel thickness is selectively responsive to lifetime dental wear resistance. We use data from the literature to relate enamel thickness to measures of dietary abrasiveness, diet profiles, and longevity for 17 primate species and performed linear regression using several combinations of these variables. We found a positive association between lifetime dietary wear and enamel thickness, suggesting that thick molar enamel in primates may have evolved as a means to resist wear apart from selection to resist tooth fracture. Assuming our estimates of lifetime dietary wear are accurate, we caution against ascribing thick enamel solely to the presence of hard-object feeding in paleoanthropological contexts without also considering primate lifespan and other aspects of feeding ecology.
Farmland conservation in West Africa: how do hedgerow characteristics affect bird species richness?
Hope O. Usieta, Shiiwua A. Manu, Ulf Ottosson
Vol. 60, Iss. 1, 2013
The value of farmland for birds at a site in Nigeria, West Africa, was highly dependent upon the habitat structure, with wider and more continuous hedges supporting more bird species.
To understand the value of hedges in Nigerian farmland to bird species richness.
We used line transects to survey birds and vegetation on 166 systematically selected hedgerows on fallow, cultivated and harvested fields in Jos East, Nigeria.
Wider hedges supported higher species richness. Plant species composition was a weak predictor of bird species richness compared to hedge width. There was no observed difference in distribution of bird richness across field types, suggesting that the value of hedgerows for biodiversity is comparable, regardless of farming method. Continuous hedgerows (hedgerows with vegetation gap < 1.5 m) held higher species richness compared with discontinuous (hedgerows with vegetation gap > 1.5 m) hedges.
This result suggests that hedge size and structure, rather than plant species composition, is an important predictor of avian species richness in hedgerows surrounding farmland. Therefore, the value of farmland for birds in this part of Africa is highly dependent upon the habitat structure, with wider and more continuous hedges supporting more bird species.
The Osteology of Balaur bondoc, an Island-Dwelling Dromaeosaurid (Dinosauria: Theropoda) from the Late Cretaceous of Romania
Stephen L. Brusatte, Mátyás Vremir, Zoltán Csiki-Sava, Alan H. Turner, Akinobu Watanabe, Gregory M. Erickson, and Mark A. Norell
Bulletin of the American Museum of Natural History 2013 374, 1-100
The Haţeg Island fauna of the terminal Late Cretaceous (ca. 71–65 million years ago) of Romania is one of the most unusual dinosaur assemblages in the global fossil record. It has long been recognized that many herbivorous dinosaurs from the Haţeg fauna were dwarfed, morphologically aberrant, and/or primitive relative to mainland contemporaries, and these taxa are often considered examples of the so-called island effect: the evolutionary phenomenon by which island-dwelling species are often dwarfed and anatomically modified. Very little, however, is known about the carnivorous dinosaurs that inhabited Haţeg Island, and it is unclear whether they were also dwarfed, aberrant, or primitive. In 2009, the discovery of the first substantially complete theropod from the Late Cretaceous of Europe, the holotype of the Romanian dromaeosaurid Balaur bondoc, provided the first clear glimpse at an island-dwelling carnivorous dinosaur. Here we describe and figure this remarkably preserved skeleton in detail. We provide detailed descriptions and photographs of individual bones, and make extensive comparisons with other dromaeosaurids (and other derived coelurosaurian theropods).
This monographic description provides further evidence that Balaur is an unusual derived dromaeosaurid, closely related to Velociraptor, with a remarkably modified hand and foot skeleton, including a stocky and heavily fused distal hind limb, a double set of hyperextensible pedal claws, and a fused and atrophied hand, which are otherwise unknown among derived coelurosaurian theropods. We present an updated diagnosis of Balaur based on additional preparation of the holotype, comparisons with other dromaeosaurids, and careful consideration of postmortem crushing. Histological techniques demonstrate that both the holotype and a referred specimen of Balaur, which is approximately 50% larger than the holotype and from a separate locality, belong to mature individuals. Therefore, we remove the referred specimen from Balaur bondoc and conservatively consider it Balaur sp. We present an updated assessment of the phylogenetic relationships of Balaur based on a comprehensive new coelurosaurian cladistic dataset, which corroborates the close relationship between Balaur, Velociraptor, Deinonychus, Adasaurus, and Saurornitholestes. We review the fossil record of European Late Cretaceous theropods and show that other specimens from the Late Cretaceous of Romania (including the holotype of Elopteryx), France, and Hungary either do not belong to Balaur (due to the lack of Balaur autapomorphies) or cannot be compared to Balaur because of a lack of overlapping material. Finally, we discuss the biogeographic history of European terminal Cretaceous dinosaur faunas and comment on the extreme morphological specializations of Balaur. We conclude that the phylogenetic position of Balaur, a derived dromaeosaurid closely related to Late Cretaceous Laurasian taxa, is inconsistent with previous hypotheses of long-term geographic endemicity of the Romanian island faunas, but argue that the aberrant Bauplan of Balaur is similar to that seen in some living and recently extinct mammals and thus likely due to the “island effect.”
The eusuchian crocodylomorph Allodaposuchus subjuniperus sp. nov., a new species from the latest Cretaceous (upper Maastrichtian) of Spain
E. Puértolas-Pascual, J. I. Canudo, M. Moreno-Azanza
This paper describes the skull of the eusuchian Allodaposuchus subjuniperus sp. nov. This new skull was recovered between the villages of Beranuy and Serraduy del Pon (Huesca, Spain). Stratigraphically, it was located in a level of coarse-grained sandstones in the middle-upper part of the lower red unit (Conqués Formation) of the Tremp Group, in the uppermost Maastrichtian close to the Cretaceous–Paleogene boundary. Until now Allodaposuchus was a monospecific genus. Phylogenetic analysis places the new taxon as a basal member of Eusuchia forming a clade with the other European Allodaposuchus remains and as a sister clade to the endemic European members of Hylaeochampsidae. Furthermore, Allodaposuchus and Hylaeochampsidae are within the stem of Crocodylia, being key taxa to understanding the origin of Crocodylia. The new taxon is the latest record of Allodaposuchus from Europe, and it presents significant enough morphological differences from Allodaposuchus precedens to establish a new species. The morphological variations in the material included in Allodaposuchus, the wide range of age and the geographical separation among the remains from Romania, France and Spain indicate that Allodaposuchus is not a monospecific genus as traditionally established.