65 research outputs found
The snakes (Reptilia, Serpentes) of the Miocene of Portugal
The ophidian fauna coming from the Miocene of Amor (MN 5), Quinta das Pedreiras and Quinta do Pombeiro (both MN4)
(Portugal) consists of the following taxa: cf. Bavarioboa sp. (Boidae); cf. Coluber sp. (Coluhridae); two unidentified Colubridae;
Vipera sp. ("Oriental vipers" complex) (Viperidae). The assemblage is characteristic for the lower/middle Miocene transition and it resembles snake faunas known from other European localities of similar age
New material of Laophis crotaloides, an enigmatic giant snake from Greece, with an overview of the largest fossil European vipers
Laophis crotaloides was described by Richard Owen as a new and very large fossil viperid snake species from Greece. The type material is apparently lost and the taxon was mostly neglected for more than a century. We here describe a new partial viperid vertebra, collected from the same locality and of equivalent size to the type material. This vertebra indicates that at least one of the three morphological characters that could be used to diagnose L. crotaloides is probably an artifact of the lithographer who prepared the illustration supporting the original description. A revised diagnosis of L. crotaloides is provided on the basis of the new specimen. Despite the fragmentary nature of the new vertebra, it confirms the validity of L. crotaloides, although its exact relationships within Viperidae remain unknown. The new find supports the presence of a large viperid snake in the early Pliocene of northern Greece, adding further data to the diversity of giant vipers from Europe
La fauna del pleistoceno inferior de la sierra de Quibas (Abanilla, Murcia)
El yacimiento kárstico cuaternario de la Sierra de Quibas (Abanilla, Murcia) ha proporcionado
una amplia lista faunística constituida por 53 especies repartidas entre gasterópodos,
miriápodos, anfibios, reptiles, aves y mamíferos. En el conjunto de los gasterópodos
destaca Palaeoglandina, un género que se extingue en el resto de Europa durante el Plioceno
y que se mantiene como relicto en el Pleistoceno de la Península Ibérica. Dos de las
especies de aves determinadas, Gypaetus barbatus y Gerontieus eremita, y una de las serpientes,
Elaphe cf. E. sealaris, apenas se hallan representadas en el registro fósil. Hay además
varias especies de aves cuya aparición en Quibas supone la primera cita en el Pleistoceno
inferior de la Península Ibérica. Entre los mamíferos posee una especial relevancia la
presencia del cercopitécido Macaca sylvanus. La asociación de los taxones Arvieola deuealíon,
Castillomys rivas rivas, Elíomys intermedius, Equus altidens y Capra sp. aff. C.
alba permite la correlación con Plines 1, Orce 3 y Venta Micena, entre otros. El yacimiento
de Quibas puede situarse, por tanto, antes del final del Pleistoceno inferior, con una antigüedad
entre 1.3 y 1 Ma. Por lo que se refiere a las condiciones paleoclimáticas, podemos
inferir a partir de la asociación faunística un régimen xerófilo, muy semejante al actual en
el área geográfica, aunque quizás con valores de humedad y temperatura algo superiores.
El entorno de la cavidad kárstica estaba formado por roquedo calcáreo con áreas abiertas
de matorral, pero en las proximidades se desarrollaron humedales y zonas arboladas, como
así lo atestigua la presencia de aves y micromamíferos típicos de estos hábitats.The Quaternary karstic site of Sierra de Quibas (Abanilla, Murcia, Spain) has provided
a wide faunallist with 53 species distributed among gastropods, myriapods, amphibians,
reptiles, birds and mammals. Especially interesting among the gastropods is
Palaeoglandina that became extinct in Europe during the Pliocene. It remains as a relict
genus in the Pleistocene of the Iberian Peninsula. Two of the birds, Gypaetus barbatus
and Geronticus eremita, and a snake, Elaphe cf. E. sealaris, are scarcely represented in the fossil record. For several birds, it is the first record in the Lower Pleistocene of the
Iberian Peninsula. Among the mammals, the presence of the Cercopithecine Macaca sylvanus
is especially relevant. The assemblage of the taxa Arvicola deucalion, Castillomys
rivas rivas, Eliomys intermedius, Equus altidens and Capra sp. aff. C. alba allows the
correlation with Plines 1, Orce 3 and Venta Micena, among other sites. Therefore Quibas
can be clated before the end of Lower Pleistocene, between 1.3 and 1 Ma. A dry paleoclimatic
regime, very similar to the current climate in the geographical area, though perhaps
slightly wetter and warmer, can be inferred from the faunal assemblage. The environment
of the karstic cavity was a rocky place with open brushwood areas, but in the
proximities there were wetlands and woodlands, as can be inferred from the presence of
birds and micromammals characteristic of these [email protected] [email protected]
Ancient habitat shifts and organismal diversification are decoupled in the African viper genus Bitis (Serpentes: Viperidae)
Aim: The expansion of open habitats during the mid-Miocene has been hypothesized as a driver of allopatric speciation for many African taxa. This habitat-dependent mode of diversification has been implicated in the shift from C3 (e.g. forest/woodland) to C4 dominated systems (i.e. open savanna, grasslands) in a number of African squamates. We examined this hypothesis using a genus of African viperid snakes (Bitis) with both open habitat and forest-dwelling representatives.
Location: Africa.
Methods: A comprehensive multilocus dataset was used to generate a calibrated species tree using a multispecies coalescent model. Individual gene trees and patterns of nuclear allele sharing were used to assess species monophyly and isolation. To test the habitat-dependent evolution hypothesis, we generated an ancestral character state reconstruction for open and closed habitats using the dated phylogeny. This was related to the timing of open habitat expansion and forest/woodland contraction in Africa.
Results: The genus Bitis originated in the Oligocene, with species level diversification in the late Miocene/Pliocene. Four well-supported clades correspond to the recognized subgenera Bitis, Keniabitis, Macrocerastes and Calechidna. Several previously unrecognized lineages potentially represent cryptic species.
Main conclusions Habitat-dependent evolution does not appear to have been a main driver for generic level viperine diversification: the ancestral state for Bitis was open habitat and at least one clade moved into forest in the Miocene, long after forest had contracted and fragmented. Forest-dependent species diversified only in the late Miocene, presumably as forest became further reduced in extent, fitting an allopatric model of speciation. Although our results do not favour a general pattern of habitat-dependent diversification in Bitis, cladogenesis within the subgenus Calechidna for “arenicolous” species (Bitis caudalis complex) and “rupicolous” species (B. Atropos-cornuta complex), corresponds to the aridification of southwest Africa. This suggests there are subtleties not captured in the broad open habitat category, which are relevant for understanding the role of habitat-dependent evolution
The last European varanid: demise and extinction of monitor lizards (Squamata, Varanidae) from Europe
Remains of a varanid lizard from the middle Pleistocene of the Tourkobounia 5 locality near Athens, Greece are described. The new material comprises cranial elements only (one maxilla, one dentary, and one tooth) and is attributed to Varanus, the genus to which all European Neogene varanid occurrences have been assigned. Previously, the youngest undisputed varanid from Europe had been recovered from upper Pliocene sediments. The new Greek fossils therefore constitute the youngest records of this clade from the continent. Despite being fragmentary, this new material enhances our understanding of the cranial anatomy of the last European monitor lizards and is clearly not referable to the extant Varanus griseus or Varanus niloticus, the only species that could be taken into consideration on a present-day geographic basis. However, these fossils could represent a survivor of the monitor lizards of Asian origin that inhabited Europe during the Neogene
First description of a fossil chamaeleonid from Greece and its relevance for the European biogeographic history of the group
The fossil record of Chamaeleonidae is very scarce and any new specimen is therefore considered important for our understanding of the evolutionary and biogeographic history of the group. New specimens from the early Miocene of Aliveri (Evia Island), Greece constitute the only fossils of these lizards from southeastern Europe. Skull roofing material is tentatively attributed to the Czech species Chamaeleo cf. andrusovi, revealing a range extension for this taxon, whereas tooth-bearing elements are described as indeterminate chamaeleonids. The Aliveri fossils rank well among the oldest known reptiles from Greece, provide evidence for the dispersal routes of chameleons out of Africa towards the European continent and, additionally, imply strong affinities with coeval chamaeleonids from Central Europe
Genetic Structure and Demographic History Should Inform Conservation: Chinese Cobras Currently Treated as Homogenous Show Population Divergence
An understanding of population structure and genetic diversity is crucial for wildlife conservation and for determining the integrity of wildlife populations. The vulnerable Chinese cobra (Naja atra) has a distribution from the mouth of the Yangtze River down to northern Vietnam and Laos, within which several large mountain ranges and water bodies may influence population structure. We combined 12 microsatellite loci and 1117 bp of the mitochondrial cytochrome b gene to explore genetic structure and demographic history in this species, using 269 individuals from various localities in Mainland China and Vietnam. High levels of genetic variation were identified for both mtDNA and microsatellites. mtDNA data revealed two main (Vietnam + southern China + southwestern China; eastern + southeastern China) and one minor (comprising only two individuals from the westernmost site) clades. Microsatellite data divided the eastern + southeastern China clade further into two genetic clusters, which include individuals from the eastern and southeastern regions, respectively. The Luoxiao and Nanling Mountains may be important barriers affecting the diversification of lineages. In the haplotype network of cytchrome b, many haplotypes were represented within a “star” cluster and this and other tests suggest recent expansion. However, microsatellite analyses did not yield strong evidence for a recent bottleneck for any population or genetic cluster. The three main clusters identified here should be considered as independent management units for conservation purposes. The release of Chinese cobras into the wild should cease unless their origin can be determined, and this will avoid problems arising from unnatural homogenization
A new Late Agenian (MN2a, Early Miocene) fossil assemblage from Wallenried (Molasse Basin, Canton Fribourg, Switzerland)
Excavations of two fossiliferous layers in the Wallenried sand- and marl pit produced a very diversified vertebrate fauna. New material allows the reassessment of the taxonomic position of the ruminant taxa Andegameryx andegaviensis and endemic Friburgomeryx wallenriedensis. An emended diagnosis for the second species is provided and additional material of large and small mammals, as well as ectothermic vertebrates, is described. The recorded Lagomorpha show interesting morphological deviations from other Central European material, and probably represent a unique transitional assemblage with a co-occurrence of Titanomys, Lagopsis and Prolagus. Rodentia and Eulipotyphla belong to typical and well-known species of the Agenian of the Swiss Molasse Basin. Abundant small mammal teeth have allowed us to pinpoint the biostratigraphic age of Wallenried to late MN2a. The biostratigraphic age conforms to data derived from the charophyte assemblages and confirms the oldest occurrence of venomous snake fangs. The palaeoenvironmental context is quite complex. Sedimentary structures and fauna (fishes, frogs, salamanders, ostracods) are characteristic for a humid, lacustrine environment within a flood plain system
A new species of Varanus (Anguimorpha: Varanidae) from the early Miocene of the Czech Republic, and its relationships and palaeoecology
Skeletal remains of a new early Miocene (Ottnangian, MN 4 mammal zone) monitor lizard, Varanus mokrensis sp. nov., are described from two karst fissures in the Mokrá-Western Quarry (1/2001 Turtle Joint; 2/2003 Reptile Joint), Czech Republic, providing the first documented example of a European varanid for which osteological data permit a well-supported assignment to the genus Varanus. The new species is morphologically similar to the Recent Indo-Asiatic varanids of the Varanus bengalensis group. It differs from all other Varanus species on the basis of a single autapomorphy and a combination of 11 characters. As a distinguishing feature of V. mokrensis, the parietal and squamosal processes of the postorbitofrontal form a narrowly acute angle. The teeth show distinct, smooth cutting edges along the mesial and distal margins of the apical portion of their crowns. This feature is not observed in most extant Asiatic Varanus species and may represent a plesiomorphic condition. The results of parsimony phylogenetic analyses, with and without character reweighting, reveal poor resolution within Varanus. A Bayesian analysis shows V. mokrensis to be closely related to extant representatives of the Indo-Asiatic Varanus clade, with close affinities to the V. bengalensis species group. The topology of the Bayesian tree supports the hypothesis that Miocene monitors from Mokrá are representatives of a lineage that is ancestral to the well-defined clade of extant African varanids, including the early Miocene V. rusingensis. In addition, our results support a Eurasian origin for the varanid clade. The extant African Varanus species probably originated in the late Oligocene. The radiation of African varanids probably occurred during the late Oligocene to early Miocene time interval. The occurrence of Varanus in the early Miocene of Mokrá-Western Quarry corresponds to the warm phase of the Miocene Climatic Optimum. Remains of a diverse aquatic and heliophobe amphibian fauna at the 2/2003 Reptile Joint site indicate more humid conditions than those at the 1/2001 Turtle Joint site
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