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Marcelo S. De La Fuente - One of the best experts on this subject based on the ideXlab platform.

  • New remains of Condorchelys antiqua (Testudinata) from the Early-Middle Jurassic of Patagonia: anatomy, phylogeny, and paedomorphosis in the early evolution of turtles
    2019
    Co-Authors: Juliana Sterli, Marcelo S. De La Fuente, Guillermo W. Rougier
    Abstract:

    ABSTRACT—New cranial and postcranial remains of the Early–Middle Jurassic turtle, Condorchelys antiqua, are described here in detail, providing new insights into the early evolution of turtles. Unconstrained and constrained cladistic analyses in addition to newly developed total-evidence Bayesian analysis were performed to explore large-scale turtle relationships and evolutionary trends. All the analyses show a similar resolution at the base of the tree, recovering several species of small-sized, fresh water turtles of the Early–Middle Jurassic at the base of the tree following the most basal, large-sized, terrestrial turtles from the Late Triassic. The calibration of the cladistic analyses and the tip-dating analysis provided similar results in the main nodes Testudines, Pan-Cryptodira, Cryptodira, Pan-Pleurodira, and Pleurodira, corroborating that the Jurassic is a key period for turtle evolution. The significant reduction in size in Early–Middle Jurassic stem turtles and the combination of certain characters (e.g., presence of fontanelles, loss of bones, loss of scutes) shown by those taxa suggests heterochronic changes, paedomorphosis in particular, at the base of the turtle tree. These morphological novelties could have trigged, or facilitated, the occupation of the aquatic niche as seen in Jurassic stem turtles. SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP Citation for this article: Sterli, J., M. S. de la Fuente, and G. W. Rougier. 2019. New remains of Condorchelys antiqua (Testudinata) from the Early–Middle Jurassic of Patagonia: anatomy, phylogeny, and paedomorphosis in the early evolution of turtles. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2018.1480112.

  • A NEW TURTLE FROM THE LA COLONIA FORMATION (CAMPANIAN-MAASTRICHTIAN), PATAGONIA, ARGENTINA, WITH REMARKS ON THE EVOLUTION OF THE VERTEBRAL COLUMN IN TURTLES
    Palaeontology, 2011
    Co-Authors: Juliana Sterli, Marcelo S. De La Fuente
    Abstract:

    Patagoniaemys gasparinae gen. et sp. nov. is a new stem turtle found in central Patagonia, Chubut Prov- ince, Argentina, in outcrops of the La Colonia Formation (Campanian-Maastrichtian). This is a turtle of relatively large size (carapace length c. 70 cm), and the preserved remains of the holotype consist of skull fragments and sev- eral postcranial elements including a nearly complete verte- bral column. A phylogenetic analysis shows Patagoniaemys gasparinae gen. et sp. nov. forming a monophyletic group with Otwayemys cunicularius and Mongolochelys efremovi ,a s a sister group to Meiolaniidae. A comprehensive review confirms that formed cervical vertebrae appeared indepen- dently several times during turtle evolution: in the clade that includes Patagoniaemys gasparinae gen. et sp. nov. and Meiolaniidae, in some baenids, in the total group Pleurodira and in crown group Cryptodira. Likewise, formed caudal vertebrae appeared several times in turtle evolution.

  • an eocene leatherback turtle Cryptodira dermochelyidae from seymour island antarctica
    Studia geologica salmanticensia, 2009
    Co-Authors: Marcelo S. De La Fuente, Sergio Santillana, Sergio A Marenssi
    Abstract:

    RESUMEN: Se describen los primeros restos fosiles de tortugas Dermochelyidae en la Peninsula Antartica. Los mismos proceden de afloramientos de la Formacion La Meseta (Eoceno) en tres localidades de la Isla Marambio (Seymour). Los materiales fosiles consisten en placas aisladas y un pequeno fragmento de la coraza, de naturaleza epitecal, correspondientes a diversos especimenes. Esta armadura epitecal es solo conocida entre los miembros de la familia Dermochelyidae registrados desde el Eoceno medio hasta la Actualidad. Los especimenes antarticos son tentativamente referidos al genero Psephophorus, taxon cuyas especies se registran desde el Eoceno medio - superior hasta el Plioceno en Europa, Nueva Zelanda y America del Norte. ABSTRACT: The outcrops of La Meseta Formation from Seymour Island yielded the first Antarctic fossil remains of Dermochelyid. It consist of isolated platelets and a small portion of the shell of epithecal nature. This epithecal armor is only known in Middle- Upper Eocene to Recent members of the family Dermochelyidae among the turtles. The Antarctic specimens are tentatively referred to Psephophorus, a genus whose species are recorded from Middle - Upper Eocene to Pliocene of Europe, New Zealand and North America.

  • Trachemys dorbigni (Dúmeril y Bibron, 1835) (Cryptodira: emydidae) en el Pleistoceno tardío de la provincia de Entre Ríos, Argentina
    2008
    Co-Authors: Marcelo S. De La Fuente, Noriega, Jorge Ignacio, Piña, Carlos Ignacio
    Abstract:

    El objetivo de la presente nota es presentar el hallazgo reciente de un caparazón completo de un Emydidae recuperado de sedimentitas de antigüedad Pleistoceno tardío expuestas en la localidad de Cañada Las Achiras (provincia de Entre Ríos) que permite referir este ejemplar a Trachemys dorbigni, confirmando el registro de la especie actual en el Pleistoceno tardío de nuestro territorio.Asociación Herpetológica Argentin

  • Trachemys dorbigni (Duméril y Bibron, 1835) (Cryptodira: Emydidae) en el Pleistoceno tardío de la provincia de Entre Ríos, Argentina
    Asociación Herpetológica Argentina, 2002
    Co-Authors: Marcelo S. De La Fuente, Noriega Jorge, Piña Carlos
    Abstract:

    El objetivo de la presente nota es presentar el hallazgo reciente de un caparazón completo de un Emydidae recuperado de sedimentitas de antigüedad Pleistoceno tardío expuestas en la localidad de Cañada Las Achiras (provincia de Entre Ríos) que permite referir este ejemplar a Trachemys dorbigni, confirmando el registro de la especie actual en el Pleistoceno tardío de nuestro territorio

Marton Rabi - One of the best experts on this subject based on the ideXlab platform.

  • total evidence analysis and body size evolution of extant and extinct tortoises testudines Cryptodira pan testudinidae
    Cladistics, 2018
    Co-Authors: Marton Rabi, Evangelos Vlachos
    Abstract:

    Fil: Vlachos, Evangelos. Consejo Nacional de Investigaciones Cientificas y Tecnicas; Argentina. Museo Paleontologico Egidio Feruglio; Argentina

  • lower cretaceous fossils from china shed light on the ancestral body plan of crown softshell turtles trionychidae Cryptodira
    Scientific Reports, 2017
    Co-Authors: Donald B Brinkman, Marton Rabi, Lijun Zhao
    Abstract:

    Pan-trionychids or softshell turtles are a highly specialized and widespread extant group of aquatic taxa with an evolutionary history that goes back to the Early Cretaceous. The earliest pan-trionychids had already fully developed the “classic” softshell turtle morphology and it has been impossible to resolve whether they are stem members of the family or are within the crown. This has hindered our understanding of the evolution of the two basic body plans of crown-trionychids. Thus it remains unclear whether the more heavily ossified shell of the cyclanorbines or the highly reduced trionychine morphotype is the ancestral condition for softshell turtles. A new pan-trionychid from the Early Cretaceous of Zhejiang, China, Perochelys hengshanensis sp. nov., allows a revision of softshell-turtle phylogeny. Equal character weighting resulted in a topology that is fundamentally inconsistent with molecular divergence date estimates of deeply nested extant species. In contrast, implied weighting retrieved Lower Cretaceous Perochelys spp. and Petrochelys kyrgyzensis as stem trionychids, which is fully consistent with their basal stratigraphic occurrence and an Aptian-Santonian molecular age estimate for crown-trionychids. These results indicate that the primitive morphology for soft-shell turtles is a poorly ossified shell like that of crown-trionychines and that shell re-ossification in cyclanorbines (including re-acquisition of peripheral elements) is secondary.

  • a new xinjiangchelyid turtle from the middle jurassic of xinjiang china and the evolution of the basipterygoid process in mesozoic turtles
    BMC Evolutionary Biology, 2013
    Co-Authors: Marton Rabi, Changfu Zhou, Oliver Wings, Walter G Joyce
    Abstract:

    Background Most turtles from the Middle and Late Jurassic of Asia are referred to the newly defined clade Xinjiangchelyidae, a group of mostly shell-based, generalized, small to mid-sized aquatic froms that are widely considered to represent the stem lineage of Cryptodira. Xinjiangchelyids provide us with great insights into the plesiomorphic anatomy of crown-cryptodires, the most diverse group of living turtles, and they are particularly relevant for understanding the origin and early divergence of the primary clades of extant turtles.

Torsten M Scheyer - One of the best experts on this subject based on the ideXlab platform.

  • turtle shell bone and osteoderm histology of mesozoic and cenozoic stem trionychian adocidae and nanhsiungchelyidae Cryptodira adocusia from central asia mongolia and north america
    Fossil Record, 2017
    Co-Authors: Torsten M Scheyer, Elena V Syromyatnikova, Igor G Danilov
    Abstract:

    Abstract. The record of fossil turtles from the Cretaceous and Cenozoic of Asia and North America is very rich, including several lineages of Cryptodiran turtles. Here we survey the shell bone histology of two important closely related groups of stem trionychians, the Adocidae and Nanhsiungchelyidae, which have representatives in both Asia and North America. All studied taxa show shell bones in which the diploe is framed by well-developed cortical compact bone layers. Taxa of both groups also express external regular surface sculpturing of their shell bones, and in the case of the nanhsiungchelyid genus Basilemys also on the osteoderms, which is also reflected in the internal histological bone structures. Besides similarities of the regular ornamentation patterns, both groups share a number of microanatomical and histological characters such as the zonation of external cortex with rather homogeneous fine-fibred interwoven structural fibres (ISF) in the more internal zone and a dominance of vertically oriented fibres in the ISF and the presence of growth marks in the more external zone. On the other hand, growth marks, i.e. lines of arrested growth, which are visible as wavy lines in thin sections, extend subparallel to the external bone surface in adocids, but they are not parallel/subparallel in nanhsiungchelyids. Thickness and structure of bone trabeculae in the cancellous interior regions depends on the shell bone thickness of the individual samples. The internal cortices of all taxa except the North American samples of Adocus usually consist of parallel-fibred bone that locally grades into lamellar bone. Secondary bone remodelling is more frequent in nanhsiungchelyids compared to adocids, and Sharpey's fibres that extend perpendicular to the bone margins extending across subparallel growth marks are more commonly found in adocids. In addition, bone histology served to identify trionychid specimens in the adocid and nanhsiungchelyid samples, especially as bone surface sculpturing patterns were weathered or eroded in those cases. The histological data present thus supplement the numerous previously reported differences in external shell morphology between adocids and nanhsiungchelyids on the one hand and trionychids and carettochelyids on the other.

  • the turtles from the uppermost jurassic and early cretaceous of galve iberian range spain anatomical systematic biostratigraphic and palaeobiogeographical implications
    Cretaceous Research, 2013
    Co-Authors: Adan Perezgarcia, Torsten M Scheyer, Xabier Murelaga
    Abstract:

    The faunal associations of the uppermost Jurassic and Early Cretaceous Villar del Arzobispo, El Castellar, and Camarillas formations of the Spanish town of Galve (Maestrazgo Basin of the Iberian Range) are composed of more than fifty taxa belonging to Chondrichthyes, bony fishes, lissamphibians, mammals, and reptiles. Although the presence of turtles has been recognized in these three formations, being very abundant, the published information is limited. The detailed study of these turtles allows us to recognize at least nine taxa, several of them previously not identified in the Spanish record. These taxa correspond to stem Testudines (Solemydidae), members of ParaCryptodira (Pleurosternidae), several representatives of Plesiochelyidae and taxa closely related with this clade, representatives of the stem group of Cryptodira (Xinjiangchelyidae) and members of crown Cryptodira. The chelonian fauna of Galve increases the systematic, anatomical, biostratigraphic, and paleobiogeographic knowledge on several clades, represented by taxa shared with other European regions, clades also present in Early Cretaceous sites of North America or Asia, as well as taxa exclusive of the Iberian record.

  • three ways to tackle the turtle integrating fossils comparative embryology and microanatomy
    Scheyer Torsten M; Werneburg Ingmar; Mitgutsch Christian; Delfino Massimo; Sánchez-Villagra Marcelo R (2013). Three Ways to Tackle the Turtle: Integra, 2013
    Co-Authors: Torsten M Scheyer, Ingmar Werneburg, Christian Mitgutsch, Massimo Delfino, Marcelo R Sanchezvillagra
    Abstract:

    Herein we review a series of case studies covering the evolution and phylogenesis of turtles, and the ontogenetic development of one of the most peculiar body plans within the Craniota. Comparative analyses of skeletal development, ontogenetic timing, and bone microstructure in both extant and extinct taxa are used to document patterns and make inferences about the origin of turtles, turtle ingroup relationships, and the evolution of turtle ontogenetic development. The need for a balanced sampling of both Cryptodiran and pleurodiran turtle species for future comparative studies is highlighted.

  • first record of soft shelled turtles Cryptodira trionychidae from the late cretaceous of europe
    Journal of Vertebrate Paleontology, 2012
    Co-Authors: Torsten M Scheyer, Thomas Mors, Elisabeth Einarsson
    Abstract:

    ABSTRACT Fossil soft-shelled turtles (Trionychidae) have so far been recognized in all continents except Antarctica, based largely on remains preserving their diagnostic sculptured shell bones. The origin of the group is generally assumed to be in the Early Cretaceous of Asia, whereas they first appear in North America and Europe during the Late Cretaceous and Paleocene, respectively. Here we describe the first record of an indeterminate trionychid from the late early Campanian from southern Sweden, a part of the paleobiogeographically isolated Fenno-Scandian Shield, thus extending the stratigraphic record of the group in Europe back about 15 Ma into the Late Cretaceous. Our finding provides evidence against the currently favored dispersal scenario in which trionychid turtles are interpreted to have come to Europe first during the Paleocene either directly from North America or via Asia. The described indeterminate trionychid possibly represents a relic of a pre-Cretaceous endemic radiation of North Europ...

  • a plywood structure in the shell of fossil and living soft shelled turtles trionychidae and its evolutionary implications
    Organisms Diversity & Evolution, 2007
    Co-Authors: Torsten M Scheyer, Walter G Joyce, Martin P Sander, Wolfgang Bohme, Ulrich Witzel
    Abstract:

    Abstract The shell of soft-shelled turtles (Cryptodira: Trionychidae) can be characterised by a flexible bridge region, the loss of peripherals and a flattened carapace that is covered not with keratinous shields but with a leathery dermis. Here, we give a detailed description of the bone histology of this natural body armour that is unique not only among turtles but also among all known vertebrates. The flat bone elements have a sandwich-like morphology, with an internal and external compact bone layer framing inner cancellous bone. The external cortex is subdivided into two separate zones. The outer zone of the external cortex, which encompasses the ornamentation pattern typical for trionychid turtle shell bones, is comprised of lamellar bone. Similarly, the whole of the internal cortex is comprised of lamellar bone. The inner zone of the external cortex, however, consists of a highly ordered, plywood-like arrangement of structural collagen fibre bundles within the bone and skin of the shell. The orientation of the collagenous fibres also prescribes the orientation of the mineral phase of the bone, the hydroxyl-apatite crystallites. Strikingly, this peculiar fibre bundle arrangement strongly resembles artificial reinforced fibre-strengthened polymeric materials that combine superior mechanical strength with low weight. We hypothesise that the evolutionary success of soft-shelled turtles is tied to this plywood-like structure of the skin and bone. It may have been the key adaptation that allowed trionychids to greatly reduce and flatten their protective shell, resulting in decreased mineral needs for hard tissues, improved camouflage and hunting performance, biomechanical stability of the shell, as well as overall increased agility and short-term swimming boosts. Significantly, it also may have enabled more efficient cutaneous breathing while still retaining effective armour in both the fossil and Recent trionychid turtles.

Evangelos Vlachos - One of the best experts on this subject based on the ideXlab platform.

Gabe S Bever - One of the best experts on this subject based on the ideXlab platform.

  • the postnatal skull of the extant north american turtle pseudemys texana Cryptodira emydidae with comments on the study of discrete intraspecific variation
    Journal of Morphology, 2009
    Co-Authors: Gabe S Bever
    Abstract:

    This study describes the postnatal morphology of the skull in the extant testudinoid turtle Pseudemys texana. The material basis of this study is drawn from a single population and therefore provides the opportunity to document cranial variation expressed at multiple levels of inference (e.g., ontogeny, sexual dimorphism, individual) within a taxonomically restricted sample. Such descriptions are exceedingly rare for reptiles but are important for evaluating the inherent biological information that skeletal morphology provides to more inclusive biological questions. Results indicate that postnatal variation in Pseudemys texana for discrete cranial characters is considerable, especially when recognizing the taxonomically conservative nature of the sample and the fact that most of the examined characters were drawn from published phylogenetic analyses. Results demonstrate a complex relationship between size, skeletal maturity, and the expression of discrete skeletal characters in this sexually dimorphic reptile. Such complexity potentially could affect our interpretation of evolutionary history based on discrete characters. This study emphasizes the need for increasing the numbers and taxonomic breadth of morphological descriptions based on expanded samples so that a better understanding of the phylogenetic distribution and modular expression of anatomical variability can be achieved. The available empirical data lag seriously behind recent theoretical advances that broaden the application of intraspecific variation data for discrete characters to phylogenetic and evolutionary questions. J. Morphol., 2009. © 2008 Wiley-Liss, Inc.

  • comparative growth in the postnatal skull of the extant north american turtle pseudemys texana testudinoidea emydidae
    Acta Zoologica, 2007
    Co-Authors: Gabe S Bever
    Abstract:

    Bever, G.S. 2007. Comparative growth in the postnatal skull of the extant North American turtle Pseudemys texana (Testudinoidea: Emydidae). —Acta Zoologica (Stockholm) 88: 000–000 Postnatal growth is one of the many aspects of developmental morphology that remains distinctly understudied in reptiles. Variation and ontogenetic scaling within the skull of the extant emydid turtle, Pseudemys texana is described based on 25 continuous characters. Results indicate that skull shape in this species changes little during postnatal growth relative to the only cryptodire taxa for which comparable datasets are available (Apalone ferox and Sternotherus odoratus). This relative lack of change results in the paedomorphic retention of a largely juvenile appearance in the adult form of P. texana. The skulls of males and females, despite the presence of distinct sexual dimorphism in size, grow with similar scaling patterns, and the few observed differences appear to reflect alteration of the male growth trajectory. Comparisons with A. ferox and S. odoratus reveal a number of similarities and differences that are here interpreted within a phylogenetic context. These preliminary hypotheses constitute predictive statements that phylogenetically bracket the majority of extant cryptodire species and provide baseline comparative data that are necessary for the future recognition of apomorphic transformations. Plasticity of ontogenetic scaling as a response to the homeostatic needs and behaviour of individuals commonly is evoked as a limitation of ontogenetic scaling as a means to inform phylogenetic studies. These evocations are largely unfounded considering that variability itself can evolve and thus be phylogenetically informative.