Entity

Time filter

Source Type


Blanco R.E.,Institute Fisica | Rinderknecht A.,Museo Nacional de Historia Natural
Comptes Rendus - Palevol | Year: 2012

Recently discovered stapes of Pleistocene South American ground sloths of the genera Lestodon and Glossotherium are studied. Available body mass estimates are larger for Lestodon (4100. kg) than for Glossotherium (1500. kg), reflecting the obvious difference in the overall size of the skull and other bones. However, as previously reported, the absolute size of incus and malleus is very similar in both genera. In a previous work, the frequency range of Glossotherium (from 44. Hz to 15,489. Hz) was estimated quantitatively from well-preserved tympanic ring dimensions. For the first time the frequency ranges of hearing in both genera are estimated by a method based on the footplate area of the stapes. The obtained frequency ranges are consistent with the previous estimation for Glossotherium and are similar in both genera, giving evidence of a frequency range of hearing independent of body size in this group of mammals. Some possible paleobiological implications of the results may include adaptation to some specific sound source, fossoriality, or long-range communication. © 2012 Académie des sciences. Source


A new genus and 13 new species of Scaphopoda (ten Dentaliida and three Gadilida) are described from the tropical Pacific Ocean in the Coral Sea, Solomon Islands, Vanuatu, Fiji, Wallis Island and Tonga. Th e new genus is named Boissevainia n. gen. and the new species are Paradentalium choneides n. sp., P. danielleae n. sp., Fustiaria electra n. sp., F. diaphana n. sp., Gadilina lauensis n. sp., Episiphon joanae n. sp., E. wallisi n. sp., E. indefensum n. sp., E. kantori n. sp., E. lacteum n. sp. (Dentaliida); Bathoxiphus kathieae n. sp., Annulipusellum aenigmaticum n. sp. and Boissevainia mossiae n. gen., n. sp. (Gadilida). Th e new taxa not only highlight the diversity of the class in the tropical Pacific Ocean, but also indicate the presence of morphologies not yet recorded for the region or described for the class. © Publications Scientifiques du Muséum national d'Histoire naturelle, Paris. Source


Otero R.A.,Museo Paleontologico de Caldera | Soto-Acuna S.,University of Chile | Rubilar-Rogers D.,Museo Nacional de Historia Natural
Acta Palaeontologica Polonica | Year: 2010

The revision by Hiller et al. (2005) of the species Mauisaurus haasti Hector (Plesiosauroidea, Elasmosauridae) from the Late Cretaceous of New Zealand, has provided reliable postcranial characters that permit recognition of this taxon as distinct among Late Cretaceous elasmosaurid plesiosaurs from both the Northern and Southern hemispheres. Particularly, in adult specimens, the femur displays a large, hemispherical capitulum that seems to be autapomorphic. This unique morphology is present in at least two specimens recovered from Late Cretaceous (Maastrichtian) beds in central Chile, which these fossils may be referred to the same taxon with confidence. The Chilean fossils are considerably larger than those from New Zealand, suggesting either difference in ontogenetic age or interspecific variation. The studied material constitutes the second accurate generic identification of elasmosaurid plesiosaurs from the eastern margin of the Pacific Ocean, thus complementing the known south-gondwanic paleodistribution of Mauisaurus during the Late Cretaceous. Source


Bustamante D.E.,Chosun University | Won B.Y.,Chosun University | Ramirez M.E.,Museo Nacional de Historia Natural | Cho T.O.,Chosun University
Botanica Marina | Year: 2012

Approximately 29 species of Neosiphonia are currently recognized worldwide. We describe our unidentified samples collected from the Pacific coast of South America as a new species, N. peruviensis sp. nov., based on morphological and molecular data. Neosiphonia peruviensis sp. nov. is characterized by erect and prostrate thalli, rhizoids cut off from proximal ends of pericentral cells by cross walls, six peri-central cells that are totally ecorticate, abundant trichoblasts forked once or twice, prominent scar cells and tetrasporan-gia spirally arranged. Our new species is similar to several Neosiphonia/ Polysiphonia species having more than four pericentral cells: N. notoensis, N. porrecta, "N. tepida", N. teradomariensis, and "P. forfex". However, N.peruviensis sp. nov. is distinguished from these similar species by having six pericentral cells through all of the thallus. Phylogenetic analyses of rbcL indicate that our N. peruviensis is placed in genus Neosiphonia and is also distinguishable from other Neosiphonia species. © 2012 by Walter de Gruyter Berlin Boston. Source


Parham J.F.,California State University, Fullerton | Papenfuss T.J.,University of California at Berkeley | Dijk P.P.V.,Wildlife Conservation Society | Wilson B.S.,University of the West Indies | And 3 more authors.
Molecular Phylogenetics and Evolution | Year: 2013

Determining whether a conflict between gene trees and species trees represents incomplete lineage sorting (ILS) or hybridization involving native and/or invasive species has implications for reconstructing evolutionary relationships and guiding conservation decisions. Among vertebrates, turtles represent an exceptional case for exploring these issues because of the propensity for even distantly related lineages to hybridize. In this study we investigate a group of freshwater turtles (Trachemys) from a part of its range (the Greater Antilles) where it is purported to have undergone reticulation events from both natural and anthropogenic processes. We sequenced mtDNA for 83 samples, sequenced three nuDNA markers for 45 samples, and cloned 29 polymorphic sequences, to identify species boundaries, hybridization, and intergrade zones for Antillean Trachemys and nearby mainland populations. Initial coalescent analyses of phased nuclear alleles (using *BEAST) recovered a Bayesian species tree that strongly conflicted with the mtDNA phylogeny and traditional taxonomy, and appeared to be confounded by hybridization. Therefore, we undertook exploratory phylogenetic analyses of mismatched alleles from the " coestimated" gene trees (Heled and Drummond, 2010) in order to identify potential hybrid origins. The geography, morphology, and sampling context of most samples with potential introgressed alleles suggest hybridization over ILS. We identify contact zones between different species on Jamaica (T. decussata×T. terrapen), on Hispaniola (T. decorata×T. stejnegeri), and in Central America (T. emolli×T. venusta). We are unable to determine whether the distribution of T. decussata on Jamaica is natural or the result of prehistoric introduction by Native Americans. This uncertainty means that the conservation status of the Jamaican T. decussata populations and contact zone with T. terrapen are unresolved. Human-mediated dispersal events were more conclusively implicated for the prehistoric translocation of T. stejnegeri between Puerto Rico and Hispaniola, as well as the more recent genetic pollution of native species by an invasive pet turtle native to the USA (T. scripta elegans). Finally, we test the impact of introgressed alleles using the multispecies coalescent in a Bayesian framework and show that studies that do not phase heterozygote sequences of hybrid individuals may recover the correct species tree, but overall support for clades that include hybrid individuals may be reduced. © 2013 Elsevier Inc. Source

Discover hidden collaborations