The oldest sarcopterygian fish

The study of basal sarcopterygians is crucial to an understanding of the relationships and interrelationships of sarcopterygians, including their relationship to tetrapods. The new material from Qujing, Yunnan, southwestern China, represents the oldest known sarcopterygian fish and extends the record of sarcopterygians to the Late Silurian, or about 410 Ma. The new form is close to Youngolepis and Powichthys at the base of the Crossopterygii. Similarities among the lower jaws of onychodonts, porolepiforms, Youngolepis, Powichthys and the new form support a position of onychodonts within the Crossopterygii. Four characters in the character matrix of Cloutier & Ahlberg (1996, in Stiassny et al: Interrelationships of Fishes , Academic Press) are reviewed, and sarcopterygian interrelationships are studied on the basis of their data with minor modifications. The new scheme of sarcopterygian interrelationships differs markedly from Cloutier & Ahlberg's scheme. Neither actinistians nor onychodonts are situated at the base of Sarcopterygii, but within the Crossopterygii. Youngolepis and Powichthys are at the base of the Crossopterygii, instead of being the sister group of dipnoans plus Diabolepis.     

Stem sarcopterygians have primitive polybasal fin articulation

Among osteichthyans, basal actinopterygian fishes (e.g. paddlefish and bowfins) have paired fins with three endoskeletal components (pro-, meso- and metapterygia) articulating with polybasal shoulder girdles, while sarcopterygian fishes (lungfish, coelacanths and relatives) have paired fins with one endoskeletal component (metapterygium) articulating with monobasal shoulder girdles. In the fin–limb transition, the origin of the sarcopterygian paired fins triggered new possibilities of fin articulation and movement, and established the proximal segments (stylopod and zeugopod) of the presumptive tetrapod limb. Several authors have stated that the monobasal paired fins in sarcopterygians evolved from a primitive polybasal condition. However, the fossil record has been silent on whether and when the inferred transition took place. Here we describe three-dimensionally preserved shoulder girdles of two stem sarcopterygians (Psarolepis and Achoania) from the Lower Devonian of Yunnan, which demonstrate that stem sarcopterygians have polybasal pectoral fin articulation as in basal actinopterygians. This finding provides a phylogenetic and temporal constraint for studying the origin of the stylopod, which must have originated within the stem sarcopterygian lineage through the loss of the propterygium and mesopterygium.     

Endocranial preservation of a Carboniferous actinopterygian from Lancashire,UK, and the interrelationships of primitive actinopterygians

The gross brain structure of an Upper Carboniferous (ca. 310 Myr ago) ray-finned fish (Actinopterygii) is described from exceptionally well-preserved fossil material from the Burnley region of Lancashire, UK. Previously identified as ''Rhadinichthys'' planti, the species is reassigned to the genus Mesopoma. Morphological characters derived from these data are combined with reviews of cranial skeletal anatomy, enamel composition, oculomoter muscle insertion and paired fin morphology to test and reanalyse hypotheses of primitive actinopterygian interrelationships. Results indicate that ancestral chondrostean (sturgeon and paddlefish) and neopterygian (teleost, amiid and gar) lineages diverged earlier than current theories suggest. Palaeonisciformes, a taxonomic group widely used to include most Palaeozoic actinopterygians, include a significant number of primitive neopterygians, several of which may form a distinct monophyletic clade. Within this revised phylogenetic context, changes in gross brain morphology from primitive conditions, as revealed by fossil data, highlight likely specializations in extant non-teleostean actinopterygians.     

A primitive ornithischian dinosaur from the Late Triassic of South Africa, and the early evolution and diversification of Ornithischia

Although the group played an important role in the evolution of Late Mesozoic terrestrial ecosystems, the early evolutionary history of the ornithischian dinosaurs remains poorly understood. Here, we report on a new primitive ornithischian, Eocursor parvus gen. et sp. nov., from the Late Triassic (?Norian) Lower Elliot Formation of South Africa. Eocursor is known from a single specimen comprising substantial cranial and postcranial material and represents the most complete Triassic member of Ornithischia, providing the earliest evidence for the acquisition of many key ornithischian postcranial characters, including an opisthopubic pelvis. A new phylogenetic analysis positions this taxon near the base of Ornithischia, as the sister taxon to the important and diverse clade Genasauria. The problematic clade Heterodontosauridae is also positioned basal to Genasauria, suggesting that an enlarged grasping manus may represent a plesiomorphic ornithischian condition. This analysis provides additional phylogenetic support for limited ornithischian diversity during the Late Triassic, and suggests that several major ornithischian clades may have originated later than generally believed. There are few morphological differences between Late Triassic and Early Jurassic ornithischians, supporting previous suggestions that the Early Jurassic ornithischian radiation may simply represent the filling of vacant ecological space following Late Triassic terrestrial extinctions.     

A revision of xinjiangchelyid turtles from the Late Jurassic of Sichuan Basin,China

The type specimens of the Jurassic turtles from the Sichuan Basin (China) previously referred to plesiochelyid Plesiochelys are revised, which confirm that they belong to the family Xinjiangchelyidae. The study of a large number of additional shell material shows, as the dominant group, the Xinjiangchelyidae were greatly diversified in the Late Jurassic of the Sichuan Basin. By the absence of mesoplastron and other shell characters, Chengyuchelys baenoides is moved to Xinjiangchelyidae and considered as a valid taxon. Of the xinjiangchelyids from the Late Jurassic of Sichuan Basin, four genera are recognized: Chengyuchelys, Tienfuchelys, Yanduchelys and cf. Protoxinjiangchelys. The phylogenetic analysis results in that Chengyuchelys includes C. baenoides, C. latimarginalis and C. radiplicatus, and Tienfuchelys consists of T. tzuyangensis, T. chungkingensis and T. zigongensis. All xinjiangchelyids from the Sichuan Basin are more primitive than Xinjiangchelys in the plastron sutured to the carapace.     

Presence of the large aquatic snake Palaeophis africanus in the middle Eocene marine margin of the Congo Basin,Cabinda, Angola

Ten isolated snake vertebrae from Landana and Sassa-Zao, Cabinda Exclave, Angola, present a “primitive” grade morphology with a weak lateral compression and do not belong to Palaeophis aff. typhaeus as originally referred to. They well belong to a single taxon and are here attributed to Palaeophis africanus for which the intracolumnar variation is described and illustrated. This species is Lutetian (middle Eocene) in age and originates from a marine coastal environment confirming again the aquatic capabilities of palaeophiid snakes. It represents the third largest species of Palaeophis with P. colossaeus and P. maghrebianus to which it is closely related in our tentative phylogenetic analysis, indicating that these three taxa could belong to an African clade. This study also contributes to the debate on the existence of primitive and advanced grades among palaeophiid snakes. Palaeophis presents laterally compressed anterior trunk vertebrae that could have been often erroneously considered as representing advanced grade species and potential parataxonomy.     

Lung ventilation in salamanders and the evolution of vertebrate air-breathing mechanisms

Functional analysis of lung ventilation in salamanders combined with historical analysis of respiratory pumps provides new perspectives on the evolution of breathing mechanisms in vertebrates. Lung ventilation in the aquatic salamander Necturus maculosus was examined by means of cineradiography, measurement of buccal and pleuroperitoneal cavity pressures, and electromyography of hypaxial musculature. In deoxygenated water Necturus periodically rises to the surface, opens its mouth, expands its buccal cavity to draw in fresh air, exhales air from the lungs, closes its mouth, and then compresses its buccal cavity and pumps air into the lungs. Thus Necturus produces only two buccal movements per breath: one expansion and one compression. Necturus shares the use of this two-stroke buccal pump with lungfishes, frogs and other salamanders. The ubiquitous use of this system by basal sarcopterygians is evidence that a two-stroke buccal pump is the primitive lung ventilation mechanism for sarcopterygian vertebrates. In contrast, basal actinopterygian fishes use a four-stroke buccal pump. In these fishes the buccal cavity expands to fill with expired air, compresses to expel the pulmonary air, expands to fill with fresh air, and then compresses for a second time to pump air into the lungs. Whether the sarcopterygian two-stroke buccal pump and the actinopterygian four-stroke buccal pump arose independently, whether both are derived from a single, primitive osteichthyian breathing mechanism, or whether one might be the primitive pattern and the other derived, cannot be determined. Although Necturus and lungfishes both use a two-stroke buccal pump, they differ in their expiration mechanics. Unlike a lungfish (Protopterus), Necturus exhales by contracting a portion of its hypaxial trunk musculature (the m. Iransversus abdominis) to increase pleuroperitoneal pressure. The occurrence of this same expiratory mechanism in amniotes is evidence that the use of hypaxial musculature for expiration, but not for inspiration, is a primitive tetrapod feature. From this observation we hypothesize that aspiration breathing may have evolved in two stages: initially, from pure buccal pumping to the use of trunk musculature for exhalation but not for inspiration (as in Necturus); and secondarily, to the use of trunk musculature for both exhalation and inhalation by costal aspiration (as in amniotes).     

Molecular systematics of small-eared shrews (Soricomorpha,Mammalia) within Cryptotis mexicanus species group from Mesoamérica

Cryptotis mexicanus species group is the most diverse group of Cryptotis shrews in the Mesoamerican highlands (ca.13 species). In México, eight endemic species occurs and several taxa are endangered. The species’ limits and phylogenetic relationships of these taxa have been recently examined using morphology; nevertheless, little is known about phylogenetic relationships among Cryptotis species at the molecular level. Therefore, our research included a mitochondrial DNA marker as a source of additional information to corroborate taxonomic identification and produce a phylogenetic hypothesis of the C. mexicanus species group. We were particularly interested in the status of Cryptotis magnus, a species considered as relict on the basis of primitive characters. Based on the analyses of genetic sequences of a high number of Cryptotis species, outgroups, and phylogenetic analyses of parsimony and Bayesian inference, we confirmed that Cryptotis genus consists of different lineages that represent species groups. A detailed analysis suggests that C. magnus is a species that shares an evolutionary history with the C. mexicanus species group because it is imbedded within this group. In particular, our data strongly support that C. magnus and Cryptotis phillipsii are sister groups, a pair of species that inhabit allopatrically Southern México.     

Whole Genome Sequence Typing to Investigate the Apophysomyces Outbreak following a Tornado in Joplin,Missouri, 2011

Case reports of Apophysomyces spp. in immunocompetent hosts have been a result of traumatic deep implantation of Apophysomyces spp. spore-contaminated soil or debris. On May 22, 2011 a tornado occurred in Joplin, MO, leaving 13 tornado victims with Apophysomyces trapeziformis infections as a result of lacerations from airborne material. We used whole genome sequence typing (WGST) for high-resolution phylogenetic SNP analysis of 17 outbreak Apophysomyces isolates and five additional temporally and spatially diverse Apophysomyces control isolates (three A. trapeziformis and two A. variabilis isolates). Whole genome SNP phylogenetic analysis revealed three clusters of genotypically related or identical A. trapeziformis isolates and multiple distinct isolates among the Joplin group; this indicated multiple genotypes from a single or multiple sources. Though no linkage between genotype and location of exposure was observed, WGST analysis determined that the Joplin isolates were more closely related to each other than to the control isolates, suggesting local population structure. Additionally, species delineation based on WGST demonstrated the need to reassess currently accepted taxonomic classifications of phylogenetic species within the genus Apophysomyces.     

Early Cretaceous Enantiornithine Birds (Aves,Ornithothoraces) and Establishment of the Ornithuromorpha Morphological Type

New data on the taxonomic and morphological diversity of Early Cretaceous Enantiornithes are reviewed. A new hypothesis concerning the phylogenetic position of Pengornithidae is proposed. These birds traditionally treated as primitive enantiornithines may in fact be more closely related to Ornithuromorpha. This phylogenetic placement implies that the fan-shaped tail and modern-type humeral joint was formed once in the early evolution of birds. Hence, the similarity between Pengornithidae and other enantiornithines may be plesiomorphic. The ecology of Early Cretaceous enantiornithines is discussed. The increased mobility of neck in Holbotia is possibly accounted for by the cranioinertial swallowing mechanism, as in modern ratites. The hypotheses of scansorial adaptations in Parapengornis and Fortunguavis are criticized. In addition, the phylogenetic position of Mystiornis is discussed.     

First discovery of a primitive coelacanth fin fills a major gap in the evolution of lobed fins and limbs

The fossil record provides unique clues about the primitive pattern of lobed fins, the precursors of digit-bearing limbs. Such information is vital for understanding the evolutionary transition from fish fins to tetrapod limbs, and it guides the choice of model systems for investigating the developmental changes underpinning this event. However, the evolutionary preconditions for tetrapod limbs remain unclear. This uncertainty arises from an outstanding gap in our knowledge of early lobed fins: there are no fossil data that record primitive pectoral fin conditions in coelacanths, one of the three major groups of sarcopterygian (lobe-finned) fishes. A new fossil from the Middle-Late Devonian of Wyoming preserves the first and only example of a primitive coelacanth pectoral fin endoskeleton. The strongly asymmetrical skeleton of this fin corroborates the hypothesis that this is the primitive sarcopterygian pattern, and that this pattern persisted in the closest fish-like relatives of land vertebrates. The new material reveals the specializations of paired fins in the modern coelacanth, as well as in living lungfishes. Consequently, the context in which these might be used to investigate evolutionary and developmental relationships between vertebrate fins and limbs is changed. Our data suggest that primitive actinopterygians, rather than living sarcopterygian fishes and their derived appendages, are the most informative comparators for developmental studies seeking to understand the origin of tetrapod limbs.     

New material of Diacodexis (Mammalia,Artiodactyla) from the early Eocene of Southern Europe

Diacodexeidae are the first representatives of Artiodactyla in the fossil record. Their first occurrence is at the very base of the Ypresian (earliest Eocene, 56.0 Ma) with Diacodexis, a genus well diversified during the early Eocene in Europe, especially during the MP7–MP8 + 9 interval. However, most of European species are documented by scarce material, retrieved from single localities. In this work, we describe new Diacodexis material from ～MP7 and ～MP8 + 9 localities of Southern Europe, including material of D. antunesi from Silveirinha, considered as the most primitive European Diacodexis species, and material from three localities from Southern France (Fordones, Palette, and La Borie). The new material documents Diacodexis premolar morphology and deciduous dentition which bear potentially important phylogenetic information, as well as astragali, including a specimen from Silveirinha that constitutes the earliest occurrence of an astragalus of the genus Diacodexis in the European fossil record. Investigation of the enamel microstructure reveals that early European species had a simple enamel pattern with one-layered Schmelzmuster composed of ‘basic’ radial enamel only, instead of the two-layered Schmelzmuster (thin radial enamel + thick layer of Hunter-Schreger bands) observed on North American species and so far considered to represent the primitive condition within Artiodactyla. In accordance with previous studies, our observations highlight that Diacodexis gigasei from Belgium is morphologically closer to the North American species D. ilicis than to D. antunesi from Portugal. The latter species, together with D. aff. antunesi from Fordones, appears to be morphologically closer to the Asiatic taxa D. indicus and D. pakistanensis. Finally, we found numerous similarities between D. cf. gigasei from Palette and D. gigasei, a result that challenges the intra-European provincialism that characterizes the earliest Ypresian. Diacodexis gigasei could be one of the rare species shared by the northwestern and southwestern European bioprovinces.     

New Species of Rotundomys (Cricetinae) from the Late Miocene of Spain and Its Bearing on the Phylogeny of Cricetulodon and Rotundomys

The material of Rotundomys (Rodentia, Cricetinae) from the Late Miocene fossiliferous complex of Cerro de los Batallones (Madrid, Spain) is described and compared with all species currently placed in the genera Rotundomys and Cricetulodon. Both the morphology and size variation encompassed in the collection of specimens from Batallones suggest they belong to a single taxon different from the other known species of these genera. A new species Rotundomys intimus sp. nov. is, therefore, named for it. A cladistic analysis, which is the first ever published concernig these taxa, has been conducted to clear up the phylogenetic position of the new species. Our results suggest that Rotundomys intimus sp. nov. inserts between R. mundi and R. sabatieri as a relatively primitive taxon inside the clade Rotundomys. The new taxon is more derived than R. mundi in having a transversal connection between the metalophulid and the anterolophulid on some m1 but more primitive than R. sabatieri and the most evolved species of Rotundomys (R. montisrotuni +R.bressanus) in its less developed lophodonty showing distinct cusps, shallower valleys, and the presence of a subdivided anteroloph on the M1. The species of Cricetulodon do not form a monophyletic group. As a member of Rotundomys, Rotundomys intimus sp. nov. is more derived than all of these taxa in its greater lophodonty and the complete loss of the anterior protolophule, mesolophs, and mesolophids.     

Association between the Presence of Class 1 Integrons, Virulence Genes, and Phylogenetic Groups of Escherichia coli Isolates from River Water

Ninety-six class 1 integron-positive and 96 integron-negative Escherichia coli isolates cultured from the water of the Warta River, Poland, were characterized for their phylogenetic group affiliation and for the presence of genes associated with virulence. Most strains belonged to phylogenetic group A, but phylogenetic group affiliation was not related with the presence of integrons. The occurrence of heat-stable toxin gene of enterotoxigenic E. coli, S fimbriae subunit gene sfaS, and siderophore receptor genes, fyuA and iutA, was associated with the presence of class 1 integrons. Moreover, virulence factor score (the total number of virulence-associated genes) was associated with the presence of integrons in groups. The results bring new insight into relations between the presence of integrons in E. coli, virulence traits, as well as phylogenetic group affiliation.     

Pseudomeriones megistos nov. sp. (Gerbillinae, Mammalia) from the Latest Miocene of Northern Greece and its phylogenetic relationships

The study of the primitive gerbil remains of Pseudomeriones, recovered from the micromammalian sites of Paliambela-B and Monasteri (Latest Miocene, Northern Greece), gives evidence for a new species, which is characterized by its large size and simple molar morphology. A cladistic analysis based on dental characters affiliates this form with P. rhodius and P. pythagorasi and enables an intrageneric phylogenetic scenario.     

Neocometes (Rodentia,Platacanthomyinae) from the early Miocene of Echzell,Germany

The dental material described in this paper represents the largest known sample of molar material of the extinct platacanthomyine rodent Neocometes Schaub and Zapfe. It can be attributed to Neocometes similis Fahlbusch, the stratigraphically oldest and most primitive of the two species recognized in the European Miocene. This rich material provides sufficient samples of all molar positions to evaluate and confirm the morphologic and morphometric characters given for N. similis. The evolutionary stage of the Neocometes population from Echzell is only slightly more derived than the one from the type locality Erkertshofen 2, and supports the biostratigraphic setting of Echzell given by earlier authors. N. similis is the first mammal described in detail from the fossiliferous ash layers of Echzell, a locality situated at the southwestern margin of the Vogelsberg volcanic complex in central Germany.     

基于线粒体ND2基因全序列探讨陕西红碱淖湿地繁殖鸥类的系统发育地位

本文对采自陕西红碱淖湿地繁殖的遗鸥(Larus relictus)、棕头鸥(L.brunnicephalus)、普通燕鸥(Sterna hirundo)和鸥嘴噪鸥(Gelochlidon nilotica)线粒体ND2基因全序列进行了测定和分析.联合已知该基因全序列的其他44种鸟类,重建了48种鸟类51个体之间的系统发育关系,并确定了4种鸥在系统发育中的地位.结果表明,4种鸥ND2基因全长均为1 041 bp;ML、MP和Bayes树拓扑结构大致相同,支持遗鸥划归为黑头鸥族(Black-headed species),棕头鸥划归为面具鸥族(Masked species),棕头鸥较为原始;普通燕鸥和鸥嘴噪鸥均隶属于黑帽族(Black cap species),鸥嘴噪鸥较为原始,处于分支底部,普通燕鸥与黑枕燕鸥(S.sumatrana)及与北极燕鸥(S.paradisaea)、南美燕鸥(S.hirundinacea)、南极燕鸥(S.vittata)聚类分支亲缘关系较近,但未能明确其具体分类地位;由于样品缺乏,鸥科(Laridae)、燕鸥科(Sternidae)和剪嘴鸥科(Rynchopidae)拓扑结构未能正确解析.     

Integrative taxonomy of New Caledonian beetles: species delimitation and definition of the Uloma isoceroides species group (Coleoptera,Tenebrionidae, Ulomini), with the description of four new species

New Caledonia is an important biodiversity hotspot with much undocumented biodiversity, especially in many insect groups. Here we used an integrative approach to explore species diversity in the tenebrionid genus Uloma (Coleoptera, Tenebrionidae, Ulomini), which encompasses about 150 species, of which 22 are known from New Caledonia. To do so, we focused on a morphologically homogeneous group by comparing museum specimens with material collected during several recent field trips. We also conducted molecular phylogenetic analyses based on a concatenated matrix of four mitochondrial and three nuclear genes for 46 specimens. The morphological study allowed us to discover and describe four new species that belong to the group of interest, the Uloma isoceroides group. Molecular analyses confirmed the species boundaries of several of the previously described species and established the validity of the four new species. The phylogenetic analyses also provided additional information on the evolutionary history of the group, highlighting that a species that was thought to be unrelated to the group was in fact a member of the same evolutionary lineage. Molecular species delimitation confirmed the status of the sampled species of the group and also suggested some hidden (cryptic) biodiversity for at least two species of the group. Altogether this integrative taxonomic approach has allowed us to better define the boundaries of the Uloma isoceroides species group, which comprises at least 10 species: Uloma isoceroides (Fauvel, 1904), Uloma opacipennis (Fauvel, 1904), Uloma caledonica Kaszab, 1982, Uloma paniei Kaszab, 1982, Uloma monteithi Kaszab, 1986, Uloma robusta Kaszab, 1986, Uloma clamensae sp. n., Uloma condaminei sp. n., Uloma jourdani sp. n., and Uloma kergoati sp. n. We advocate more studies on other New Caledonian groups, as we expect that much undocumented biodiversity can be unveiled through the use of similar approaches.     

Cranial morphology of the Early Permian mesosaurid Mesosaurus tenuidens and the evolution of the lower temporal fenestration reassessed

The Early Permian mesosaurids are the oldest known aquatic amniotes with an exclusively Gondwanan distribution. Although several hundred of complete skeletons have been discovered and intensively studied, the anatomy and taxonomic composition of the group, as well as its phylogenetic relationships remain controversial. Several well-preserved mesosaurid specimens found in Uruguay justify a new anatomical reconstruction of the skull of Mesosaurus tenuidens, differing from earlier ones especially in the presence of a lower temporal fenestra. The significance of this structure for the evolution of temporal fenestration in amniotes is evaluated according to the two most recent phylogenetic hypotheses, in which mesosaurids are basalmost sauropsids or basalmost parareptiles. A synapsid-like fenestration may be the primitive condition for Amniota, and it may be also a basal condition for parareptiles, because recent phylogenies suggest a basal position for mesosaurids and lanthanosuchoids within that group, and both possess a lower temporal fenestra. Our results also give a moderately strengthened support for diapsid affinities of turtles.