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Page 19 of 19, showing 5 record(s) out of 365 total

Comparative bone histology of rhabdodontid dinosaurs
Edina Prondvai Logo
Published online: 11/17/14

Keywords: bone histology-based ontogeny; Mochlodon; Rhabdodon; skeletal maturation; Zalmoxes

https://doi.org/10.18563/pv.38.2.e1

  Abstract

    A comparative bone histological study of the three known genera of the endemic European ornithopod dinosaur family, Rhabdodontidae, is presented here in an ontogenetic context. Investigated specimens were assigned to different ontogenetic stages based exclusively on the histological indicators of osteologic maturation during diametrical bone growth; an entirely size-independent method as opposed to most previous studies. Qualitative comparison of bone histology of corresponding ontogenetic stages and elements among the three valid rhabdodontid genera, Mochlodon, Zalmoxes, and Rhabdodon, revealed some consistent patterns. Genus specific histological differences within Rhabdodontidae are most expressed between Rhabdodon and the Mochlodon-Zalmoxes clade. These indicate a prolonged phase of fast growth and a less constrained cyclicity in the growth dynamics of Rhabdodon, as opposed to the slower and more regulated growth strategy reflected in the bones of Mochlodon and Zalmoxes. These genus specific differences are consistent with the phylogenetic interrelation of the genera and are most probably related to the pronounced differences in body size. However, when compared to other ornithopods, most detected histological features in rhabdodontids do not seem to reliably reflect either phylogenetic relations or body size. A notable common feature of all rhabdodontid genera irrespective of body size is the ontogenetically early onset of cyclical growth and secondary remodelling; a pattern that more resembles the condition found in derived ornithopods than that described in more basal taxa which are closer relatives of rhabdodontids. The recognition of taxon-specific histological patterns as well as patterns indicative of ecological and thereby functional traits clearly requires more accurate, preferably quantitative evaluations.   


  PV article infos

Published in Vol.38-2 (2014)

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Les insectivores des phosphorites du Quercy
Jean-Yves Crochet
Published online: 11/15/74

Keywords: Insectivores; Quercy Phosphorites

  Abstract

    Many types of insectivores have been described from specimens found in the Quercy phosphorites. These remains very often were not dated because they came from old collections. Recent excavations have permitted the situation of Amphidozotherium cayluxi FILHOL in the late Eocene. Two new genera are descrlbed based on material both from the old collections (Cryplotopos nov. g.) and from that recently recovered (Darbonetus nov. g., beginning of the middle Oligocene). Their systematic positions are revised and comparisons with American faunas are made. Amphidozotherium is not a talpid, but an erinaceoid belonging to an indeterminate family. Saturninia gracilis STHELIN is classified among the Nyctitheriinae, Myxomygale antiqua FILHOL among the Urotrichini Talpinae, and the genus Geotypus POMEL among the Scaptonichini Talpinae. A new study of the talpids from Auvergne has been rendered necessary. During the late Eocene and Oligocene precise morphology relationships existed between certain insectivores of Europe and North America. 


  PV article infos

Published in Vol. 06, Fasc. 1-2 (1974)

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Sur le remplissage des "poches à phosphorite" d'Aubrelong (commune de Bach, Lot)
Bernard Gèze
Published online: 11/15/74

Keywords: Aubrelong; Quercy Phosphorites

  Abstract

    Abstract not available 


  PV article infos

Published in Vol. 06, Fasc. 1-2 (1974)

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Owls, caves and fossils. Predation, preservation and accumulation of small mammal bones in caves, with an analysis of the Pleistocene cave faunas from Westbury-Sub-Mendip, Somerset, UK, par Peter Andrews, 1990. The University of Chicago Press, 232 p.
Christiane Denys Logo
Published online: 12/17/92

Keywords: caves; owls; preservation; taphonomy

  Abstract

    La taphonomie (science de l'enfouissement et de la fossilisation) des micromammifères a trop souvent été négligée par rapport à celle des grands mammifères. Or, pour expliquer les concentrations parfois très importantes de microfossiles dans les grottes et les sites préhistoriques il faut connaître les mécanismes qui concourrent actuellement à favoriser les accumulations de ces derniers. C'est le but de l'ouvrage de Peter Andrews qui se décompose en deux parties. 


  PV article infos

Published in Vol. 22, Fasc. 1 (1992)

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Analysis of changing diversity patterns in Cenozoic land mammal age faunas, South America
Larry G. Marshall and Richard L. Cifelli
Published online: 3/30/90

Keywords: Cenozoic; Chronofaunas; diversity; Equilibrium theory; Extinction; Land mammal faunas; Origination; South America

  Abstract

    Comparison of various measurements of taxonomic evolution using stratigraphic range data for orders, families and genera of land mammals indicates several means by which deficiencies of the South American fossil record (e.g., presence of hiatuses, unequal temporal and geographic representation of ages, unequal systematic treatment) may be normalized, thus permitting a less distorted appreciation of diversity pattern and trend. Initial radiation of native taxa resulted in a relative equilibrium by early Eocene time. Subsequent increases in absolute diversity were apparently induced by immigration at the family level and by environmental factors at the generic level. Miocene through Pleistocene phases of faunal stability, herein characterized as chronofaunas, are punctuated by rapid turnover events resulting from a complex of factors, including adaptive radiation of immigrant taxa into unoccupied eco-space; environmental and concomitant habitat change induced by orogenic events of the Andes; and biotic interactions between native and immigrant taxa, including competition and prey naivete. The first two factors account for major faunal transitions in the South American middle and late Tertiary; immigration-induced turnover may have been of greater importance in shaping the character of the fauna upon the Great American Interchange and the arrival of man in the Neotropics 


  PV article infos

Published in Vol. 19, Fasc. 4 (1990)

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Page 19 of 19, showing 5 record(s) out of 365 total