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The digital endocast of Necrolemur antiquus
Arianna Harrington, Gabriel Yapuncich and Doug Boyer
Keywords: brain evolution; Eocene; Omomyiforms; Primates

doi: 10.18563/pv.43.2.e1
 
  Abstract

    The study of endocasts, or casts of the endocranial space, have played an important role in shaping understanding of mammalian, and particularly primate, brain evolution. Recently, the reconstructions of three-dimensional virtual endocasts from high-resolution computed tomography images have allowed for the visualization and quantification of endocasts in several Paleocene and Eocene primate species. Here we present the virtual endocast of MaPhQ 289 (informally known as the Montauban 9 skull), a specimen of Necrolemur antiquus Filhol 1873, a middle to late Eocene European primate of the family Microchoeridae. The virtual endocast of MaPhQ 289 reveals a lissencephalic surface morphology with expanded temporal poles and minimal overlap of the cerebellum or olfactory bulb by the cerebrum, which closely resembles the morphology of the endocast of its contemporary relative, Microchoerus erinaceus (Primates, Microchoeridae). MaPhQ 289 yields an endocranial volume (ECV) of 2.36 cm3, about 60% smaller than the volume of the most commonly cited ECV of N. antiquus. Thus, the size of the brain of N. antiquus relative to its body size is likely to be smaller than has been reported in previous literature, highlighting the importance of corroborating older ECV estimates with new evidence using 3-D imaging techniques. 



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  Article infos

Published in 43-2 (2020)

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Pterosaurs (Pterosauria) from the Cerro del Pueblo Formation (Late Campanian) of Coahuila, Mexico
Hector Rivera-Sylva, David Hone, Martha Aguillón-Martínez, Rubén Guzmán-Gutiérrez, David Morales-Flores, Iván Sánchez-Uribe, José Flores-Ventura and Rafael Vivas-González
Keywords: Azhdarchoidea; Coahuila; Mexico; Pterodactyloidea; Pterosauria

doi: 10.18563/pv.48.2.e1
 
  Abstract

    The Late Campanian Cerro del Pueblo Formation, located in southeastern Coahuila, Mexico, has produced a diverse array of vertebrate fossils. However, pterosaur remains from this unit are notably scarce. In this study, we describe new pterosaur material from the formation. The specimens include a fragmentary vertebra identified as belonging to an indeterminate, but derived pterodactyloid, along with the distal condyle of a left metacarpal, referable to an azhdarchoid pterosaur, and a left manus print. While these specimens provide additional evidence of pterosaur presence in the region during the Late Cretaceous, their fragmentary nature limits precise taxonomic and ichnotaxonomic identification. Nevertheless, they highlight the potential for future discoveries that could refine our understanding of the diversity and distribution of pterosaurs in Mexico.
      


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in press

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Preliminary evolution of paleosols and implications for interpreting vertebrate fossil assemblages, Kuldana formation, Northern Pakistan
Andres Aslan and J. G. M. Thewissen
Keywords: Eocene; Kuldana Formation; Pakistan; Paleosols; Pedogenic Carbonate; taphonomy; Time Averaging; Vertebrate Fossils
 
  Abstract

    Paleosols and the taphonomy of vertebrate fossils in the Eocene Kuldana Formation of northern Pakistan provide important information on the preservation and time-averaging of fossil assemblages. Morphologic, mineralogic, and chemical data as well as comparisons with Quaternary soils suggest that Kuldana paleosols formed under generally dry and oxidizing conditions over time intervals of less than 100 000 years and perhaps as short as 1000 years. The distribution of carbonate in Kuldana paleosols further indicates that the upper half of the profiles were acidic whereas the lower halves were alkaline. Vertebrate fossils are rare in Kuldana paleosols and occur primarily in well-cemented sandstones and conglomerates with abundant micritic and iron-stained nodules that were reworked from floodplain soils. The scarcity of vertebrate remains in Kuldana paleosols probably reflects a combination of acidic, dry, and oxidizing conditions in the upper half of the profiles and rapid floodplain sedimentation. Comparisons between the taphonomic characteristics of Kuldana channel fossil assemblages and bone accumulations in modem rivers provide a basis for estimating the length of time represented by Kuldana fossils from several important localities. Vertebrate fossil assemblages from Barbora Banda are characterized by a low-diversity paleofauna, partially articulated skeletons, and bones that are sorted by size and shape. Comparison with bone accumulations in modern rivers suggests that the fossils from Barbora Banda accumulated in 1 to 10 years. Vertebrate fossils from the Lower Kuldana in the Kala Chitta Hills region, typified by locality H-GSP 62, are characterized by a high-diversity paleofauna and generally random and unsorted fossil bone distributions, which suggest that the fossils from these localities represent longer time intervals than the Barbora Banda fossils. Based on the time estimates for Kuldana paleosol development, fossil assemblages in Kuldana channel deposits in the Kala Chitta Hills region probably represent time intervals of about 1000 years. 


  Article infos

Published in Vol. 25, Fasc. 2-4 (1996)

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Etude du crâne de Pachynolophus lavocati n. sp. (Perissodactyla, Palaeotheriidae) des Phosphorites du Quercy
Jean-Albert Remy
Keywords: Perissodactyla; Quercy Phosphorites

doi: 10.18563/pv.5.2.45-78
 
  Abstract

    The genus Pachynolophus, one of the poorest known of the Palaeotheriidae, includes the brachyodont forms with reduced and non-molariform premolars and with upper molars lacking a mesostyle. Quantitative characters (divers surface indications and elongation of the teeth), while demonstrating a close relationship to Hyracotherium, permit a better differentiation of the genus, confirm its specific splitting, and permit the distinction of three lineages. The skull from Memerlein is taken as the type of a new species, P. Iavocati, of which the dentition is extremely characterized by its lophiodonty, the strong reduction of the premolars and the reduction of the cingula. This characterization testifies to a late age which extends the existence of the genus quite near to the Eocene-Oligocene limit. Compared with the only two skulls known of related species (Hyracotheríum vulpiceps and Pachynolophus Iivinierensis), that from Memerlein is distinguished by progressive characters affecting diferent regions but most particularly the braincase; it is not possible, however, to isolate within this evolution the part which leads to a systematic differentiation. Modernization is translated by a considerable increase in size of the braincase, principally in the frontal region, a development of the facial region with anterior displacement of the dental series and a greater specialization of the masticatory apparatus. This evolution parallels the history of the Equidae of the North American early Tertiary, but certain particularities, the form of the alisphenoid, the presence of an anterior frontal foramen, and the structure of the paroccipital apophysis, testifies to the independance of the European forms. 


  Article infos

Published in Vol. 05, Fasc. 2 (1972)

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Observations sur des remaniements structuraux post-mortem dans des dents de mammifères fossiles provenant des phosphorites du Quercy
Jean-Albert Remy
Keywords: Quercy Phosphorites; rearrangements; Teeth
 
  Abstract

    Deux types de remaniements post mortem me paraissent caractéristiques de l'état de conservation des dents de mammifères fossiles dans les Phosphorites du Quercy :

    1) Des destructions localisées d'origine biologique, sous forme de galeries de morphologie très variable creusées dans la dentine et le cément, et impliquant sans doute la participation de différents types de micro-organismes. Ces altérations se sont développées peu de temps après la mort, avant la fossilísation proprement dite et se sont rapidement arrêtées après l'enfouissement dans le sédiment phosphaté.

    2) Des perturbations dans les structures de la dentine liées aux variations locales de minéralisation, provoquées par une imprégnation diffuse des zones les moins calcifiées par divers minéraux et probablement surtout de l`apatite. 


  Article infos

Published in Vol. 06, Fasc. 3-4 (1975)

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Rongeurs du Miocène inférieur et moyen en Languedoc. Leur apport pour les correlations Marin-Continental et la Stratigraphie.
Jean-Pierre Aguilar
Keywords: Languedoc; Miocene; Rodents; Southern France
 
  Abstract

    The rodents (Cricetidae, Gliridae, Sciuridae) found in lacustrine, brackish marine and karstic sediments of Miocene age in Languedoc, assign the position of the different localities in the scale of "niveaux repères" used by mammalogists. Some detailed stratigraphical studies bring several correlations between this continental biochronological scale and the marine scale ; the most important results are the Aquitanian age of the "niveaux repères" of Coderet and Paulhiac, the Burdigalian age of Laugnac, Estrepouy, Vieux-Collonges, La Romieu and Sansan and the Langhian or Lower Serravallian age of La Grive M. The correlations between the Tethys and the Central Paratethys for the Lower Neogene profit also of these results, since the locality of Neudorf Spalte 1, 2 (Czechoslovakia) is shown to be younger than Sansan (France). The paleontological study has also several geological inferences for the Miocene of Languedoc ; with the calibration of this Miocene, we know quite precisely that the Lower Miocene is chiefly a time lacustrine sedimentation, and also that the marine Miocene sedimentation ends early in the Miocene Period, in Langhian or lower Serravallian times. 


  Article infos

Published in Vol. 09, Fasc. 6 (1980)

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Observations sur l'anatomie crânienne du genre Palaeotherium (Perissodactyla, Mammalia): mise en évidence d'un nouveau sous-genre, Franzenitherium
Jean-Albert Remy
Keywords: Palaeotherium; Paléogène; Perissodactyla; skull anatomy; Systematics
 
  Abstract

    The skull remains referred to the genus Palaeotherium are recorded and described. Biometrical tests are made to elucidate intrageneric allometric relationships and to allow comparisons with various other perissodactyls. Apart from the well known shortness of post canine diastems and deepness of the narial opening, the genus is characterized by a great lengthening of the splanchnocranium, owing to a spreading of the post-orbital facial region, by a reduced area of the eye-socket and by the prevalence of the temporal muscle with regard to the masseter; this original shape of the masticatory apparatus needs to be related to the morphology of the jugal teeth and particularly to their  asymmetrical semi-hypsodonty.
        These animals, whose running ability was evidently poor, appear to have been adapted to rather closed environments, feeding on relatively soft vegetable matter; olfactory sense was likely to play a leading part in interindividual and environmental relationships. Such evolutionary trends might explain the disappearance of most of them, as clirnatic conditions deteriorated at the end of the Eocene, before the "Grande Coupure" which affected mammalian faunas at that time.
          Although the present paper is not directly concemed with phylogenetics, it invalidates the supposed ancestor-descendant relationship between P. castrense and P. magnum, and it suggests a possible emergence of the P. medium lineage from a P. siderolithicum stock. Moreover, the structure of the post-orbital facial area allows the  erection of a new sub-genus, Franzenitherium, for the  species lautricense and duvali.

      


  Article infos

Published in Vol. 21, Fasc. 3-4 (1992)

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The new Algerian locality of Bir el Ater 3: validity of Libycosaurus algeriensis (Mammalia, Hippopotamoidea) and the age of the Nementcha Formation
Fabrice Lihoreau, Lionel Hautier and Mahammed Mahboubi
Keywords: Dispersal event; Miocene; North Africa; Tetralophodon

doi: 10.18563/pv.39.2.e1
 
  Abstract

    The description of original material of anthracothere and proboscidean in the new locality of Bir el Ater 3 from East Algeria, and a thorough review of early Libycosaurus remains of Bir el Ater 2 allows us validating L. algeriensis as the smallest and earliest species of Libycosaurus and probably the earliest migrant of the genus from Asia. The presence of a Tetralophodon in the Neogene Nementcha formation might represent the earliest occurrence of the genus in Africa. These original fossil remains allow us to discuss the age of the Neogene part of the Nementcha formation close to the Serravalian/Tortonian boundary. 


  Article infos

Published in Vol.39-2 (2015)

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Les rongeurs de l'Eocène d'Afrique Nord-Occidentale [Glib Zegdou ( Algérie) et Chambi (Tunisie)] et l'origine des anomaluridae.
Monique Vianey-Liaud, Jean-Jacques Jaeger, Jean-Louis Hartenberger and Mahammed Mahboubi
Keywords: Africa; Eocene; New taxa; Paleobiogeography; PHYLOGENY; Rodents
 
  Abstract

    This paper is about the oldest African rodents faunas, from the late Early Eocene, or early Middle Eocene, Glib Zegdou (Algeria) and Chambi (Tunisia) localities. Five species are described and figured, belonging to a new family here created, the Zegdoumyidae.

    This family is compared to the Early and Middle Eocene rodents families from Asia, Europe and North America (Chapattimyidae, Yuomyidae, Gliridae, Theridomyidae, lschyromyidae and Sciuravidae), as well as to those known from the Late Eocene African locality Bir El Ater (Anomaluridae and Phiomyidae).

    On the one hand, it seems clear that the African endemic Anomaluridae arise from the Zegdoumyidae. On the other hand, the lschyromyidae, or primitive Sciuravidae, may be the most reliable ancestral groups for the Zegdoumyidae. Thus, this new family can be considered as the sister group for the American Sciuravidae on the one hand, and for the European Gliridae on the other hand.

    The biogeographical consequences of these phylogenetic hypotheses are discussed. A new phase of communication between Europe and North Africa is inferred, during the Early Eocene. It has been followed by a short period of endemism, allowing the adaptive radiation for the Zegdoumyidae, preceding the immigration of the Phiomyidae, during the Late Eocene, probably from Asian relatives. 


  Article infos

Published in Vol. 23, Fasc. 1-4 (1994)

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Un nouveau genre de ?Palaeotheriidae (Perissodactyla, Mammalia) décelé dans les phosphorites du Quercy (Eocène supérieur ou Oligocène) d'après un arrière crâne sans dents.
Jean-Albert Remy
Keywords: endocranial cast; Epitympanic sinus; Palaeotheriidae; Paléogène; Quercy Phosphorites; skull anatomy
 
  Abstract

    A rear skull from the Quercy Phosphorites is described. It documents a new perissodactyl genus, likely assignable to the family Palaeotheriidae and probably paleogene of age. Owing to the lack of any tooth, this family assignment remains however somewhat hypothetical. The specimen is firstly characterised by the presence of a wide epitympanic sinus swelling and hollowing the squamosal shell and the post-glenoid process. This cavity might make up a peculiar pattern of improvement for the hearing apparatus by carrying out a kind of drum near the middle ear, whereas the bony tympanic remains barely bulged and forms but a few developed auditory bulla. This pattern appears an outcome of a trend observed with many palaeotheriids, such as Plagiolophus. Furthermore, the endocranial cast shows a rather high degree of gyrencephaly for a paleogene mammal. The prominent lambdoidal crest points out a powerful nape musculature and a lowered head bearing. Consequently, it is assumed that such an animal was probably living in somewhat open places, at the expense of rather tough vegetables. It might have been accordingly provided with a semi-hypsodont, cement covered, "plagiolophoid" dentition. 


  Article infos

Published in Vol. 28, Fasc. 1 (1999)

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 La poche à phosphate de Ste-Neboule (Lot) et sa faune de vertébres du Ludien Supérieur. 1 La poche et son remplissage
Bernard Gèze
Keywords: Eocene; Quercy Phosphorites
 
  Abstract

    La poche de Ste-Néboule, commune de Béduer (Lot), 15 km environ à l'WSW de Figeac, fait partie du groupe le plus septentrional des gouffres creusés par les ruissellements du Paléogène dans les calcaires jurassiques de la bordure sud-ouest du Massif Central et qui furent comblés à la même époque par des argiles sidérolithiques accompagnées de phosphate de chaux concrétionné ainsi que des restes de la célèbre faune dite «des phosphorites du Quercy» . 


  Article infos

Published in Vol. 08, Fasc. 2-4 (1978)

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Les gisements de Robiac (Eocène supérieur) et leurs faunes de Mammifères.
Jean Sudre
Keywords: Fauna; Late Eocene; Mammalia; Robiac

doi: 10.18563/pv.2.3.95-156
 
  Abstract

    Designated the type-locality of a late Eocene paleomammal zone, Robiac has recently been the object of important excavations. The first results of the new collecting, as  well as a revision of the material in old collections, are given in this work.
    Two stratigraphic section, cutting through the two sites presently distinguished (Robiac-Nord and Robiac-Sud) reveal the lithologic variation at the base of the Fons Limestone and the localization of three fossiliferous beds at Robiac-Sud.
    The molluscan fauna and the flora (charophytes), which have already been described, as well as that of the lower vertebrates, have been listed.
    A list of 46 mammalian species (only 16 species were known previous to 1964) has been established. The micro-mammals, nearly all new in this fauna (marsupials, insectivores, bats, rodents, primates, and some smallsized artiodactyls), Were obtained only after screen-washing of the matrix; about 4 tons of sediment were thus treated.
    The artiodactyls have been the most extensively analyzed; 6 genera, of which one is new, have been recognized. The latter is described as Robiacina minum n.g., n.sp., and represents a very small artiodactyl of the family Anoplotheriidae. The taxonomie status of certain species formerly described has been clarified by the designation of lectotypes (Cebochoerus robiucensis, Catodonerium robiacense, Xiphodon castrense).
    The paleontologic corrélations at present possible between the late Eocene faunas have allowed the relative positions of te different French localities of this age to be established; the Guépelle locality, it seems, could define in the future a new paleomammal zone.
      


  Article infos

Published in Vol. 02, Fasc. 3 (1969)

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L'anatomie de Lyrocephaliscus euri (wiman), Trématosaure du Trias inférieur du Spitsberg : arrière-crâne, squelette axial et ceinture scapulaire.
Jean-Michel Mazin and Philippe Janvier
Keywords: skull anatomy; Spitsbergen; Trematosaurs; Trias
 
  Abstract

    The formic acid preparation of a nodule collected from the Lower Triassic of Spitsbergen, and containing a skull with some associated postcranial elements of Lyrocephaliscus euri (WIMAN), precises and enriches previous descriptions of the reputedly well-known trematosaur. lt permits more detailed descriptions of the occipital region, of the course of the carotid arteries and collateral vessels, and refutes the previous description of a stapedial foramen in trematosaurs. The discovery of pleurocentres associated with the other vertebral components confirms the primitive rhachitomy of trematosaurs. 


  Article infos

Published in Vol. 13, Fasc. 1-2 (1983)

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Late Campanian theropod trackways from Porvenir de Jalpa, Coahuila, Mexico
Hector E. Rivera-Sylva, Eberhard Frey, Christian Meyer, Anne S. Schulp, Wolfgang . Stinnesbeck and Valentin Vanhecke
Keywords: Dinosaur tracks; Late Cretaceous; Mexico.; Tetanura; Theropod

doi: 10.18563/pv.41.2.e1
 
  Abstract

    Confident attribution of bipedal tridactyl dinosaur tracks to theropods or ornithopods can be challenging. Here we describe trackways produced by tetanuran dinosaurs, previously attributed to hadrosaurs, from Coahuila State, northeastern Mexico. Multiple trackways headed in the same direction suggest gregarious behaviour in these late Campanian theropods.  


  Article infos

Published in Vol 41-2 (2018)

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Sur le plus ancien Lagomorphe Européen et la "Grande Coupure" Oligocène de Stehlin
Nieves Lopez-Martinez and Louis Thaler
Keywords: Grande Coupure; Lagomorphe; Oligocene
 
  Abstract

    Pour la première fois un spécimen de lagomorphe a été récolté en Quercy. L'intérêt de ce fossile tient surtout à son âge géologique inattendu, qui recule considérablement la date de première apparition en Europe de cet ordre de mammifère, Ceci nous paraît justifier une nouvelle réflexion sur la « grande coupure» oligocène, 


  Article infos

Published in Vol. 06, Fasc. 3-4 (1975)

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Mammals and stratigraphy of the continental mammal-bearing Quarternary of South America
Larry G. Marshall, Annalisa Berta, Robert Hoffstetter, Rosendo Pascual, Osvaldo A. Reig, Miguel Bombin and Alvaro Mones
Keywords: Geochronology; Mammalia; Quaternary; South America; Stratigraphy
 
  Abstract

    Previous chronological arrangements of South American Quaternary land mammal faunas are appraised on the basis of current geological and paleontological data. Three South American late Pliocene-Pleistocene land mammal ages are conventionally recognized, from oldest to youngest, the Uquian, Ensenadan, and Lujanian ; all are defined on Argentine faunas.

         The Uquian is based fundamentally and historically on the fauna from the Uquía Formation in Jujuy Province, northwestern Argentina. Important known formations in Argentina yielding Uquian Age faunas include the sub-surface Puelche Formation (or Puelchense) near the city of Buenos Aires, and the Barranca de Los Lobos and Vorohué Formations between Mar del Plata and Miramar, Buenos Aires Province. A tentative subdivision is propos-ed for the Uquian into three subages based on knowledge of the Mar del Plata-Miramar sequence, from oldest to youngest, the Barrancalobian, Vorohuean, and Sanandresian. In Argentina the Uquian is presently marked by the first known record of Scelidodon, Hydrochoeropsis, Ctenomys, Canidae, Ursidae, Gomphotheriidae, Equidae, Tapiridae, Camelidae, Cervidae, and the last known record of Thylatheridium, Thylophorops, Dankomys, Eumysops, Pithanotomys, Eucoelophorus, Hegetotheriidae, Sparassocynidae, and Microtragulidae.

    The Ensenadan Age is based on the fauna from the Ensenada Formation near the city of Ensenada, Buenos Aires Province. In Argentina the Ensenadan is marked by the first known record of Lomaphorus, Neothoracophorus, Plaxhaplous, Cavia, Lyncodon, Lutra, Galera, Smilodon, Dicotyles, Lama, Vicugna, the last known record of Orthomyctera, and the only known record of Brachynasua.

         Typícal beds of late Lujanian Age in Argentina consist of fluvial deposits occupying stream channels, and shallow basins, often incised into beds of early Lujanian (i.e. Bonaerian of early workers) and Ensenadan Age. The Lujanian Age is based on a fauna from beds along the Rio Luján, about 65 km west of the city of Buenos Aires, Buenos Aires Province. The Lujanian in Argentina is marked by the first record of Equus, Chlamyphorus, and Holochilus, and the last record of Megatherioidea, Glyptodontoidea, Arctodus (=Arctotherium), Smilodon, Litopterna, Notoungulata, Proboscidea, Equidae, Morenelaphus, and Palaeolama.

       These land mammal ages are often difficult to recognize in other South American countries. The compositions of South American Pleistocene faunas vary with the environment. Some taxa were widely distributed in fossil deposits throughout the continent, but their occurrences need not reflect synchroneity. This is a result of changing climates and habitats in time. Consequently, proposed intracontinental correlations need confirmation based on magnetostratigraphy and a radioisotope time scale. Paleontologic characterizations of these land mammal ages (i.e. first and last record, and guide fossils) are useful for much of Argentina, but extensions to most of the other parts of South America are at best tenuous.

    The majority of known non-Argentine Pleistocene faunas are believed to be Lujanian in age. Possible non Argentine early Pleistocene (Uquian) faunas include Ayo Ayo and Anzaldo in Bolivia, and Cocha Verde in southern Columbia. A possible middle Pleistocene (Ensenadan or early Lujanian) fauna is the Chichense of Ecuador. Paleomagnetic and radioisotopic date (MacFadden et al., 1983) clearly indicate that the greater part of the Tarija fauna (Bolivia) is Ensenadan in age.

      The end of the Pleistocene and beginning of the Holocene in South America is marked by extinction of nearly all large mammalian herbivores and their specialized large predators. Radiocarbon age determinations suggest that large scale extinctions of megafauna occurred between 15,000 and 8,000 yrs. B.P. (years before present). 


  Article infos

Published in Vol. 14, Ext (1984)

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A new hypothesis for the origin of African Anomaluridae and Graphiuridae (Rodentia)
Monique Vianey-Liaud and Jean-Jacques Jaeger
Keywords: Africa; Anomaluridae; Gliridae; Graphiuridae; Paleontology; PHYLOGENY; Rodentia
 
  Abstract

    A new hypothesis for the phylogenetic relationships of recent anomalurids and graphiurids is proposed, based on information from evolutionary lineages of Paleogene European rodents, particularly Gliridae, and Eocene Algerian Zegdoumyidae. Differences in first occurrences, in paleogeography, and in infraorbital structure in glirids (protrogomorphy and pseudomyomorphy) and graphiurids (hystricomorphy) separate Graphiuridae from Gliridae (Graphiurinae is here raised to family rank). Similar considerations, and dental morphology, suggest that Anomaluridae (appearing in the late Eocene) and Graphiuridae (appearing in the Pliocene) are related to early Eocene Zegdoumyidae. 


  Article infos

Published in Vol. 25, Fasc. 2-4 (1996)

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La poche à phosphate de Ste-Néboule (Lot) et sa faune de vertébres du Ludien Supérieur. 2- Amphibiens. Etude Preliminaire
Jean-Claude Rage and Colette Vergnaud-Grazzini
Keywords: Eocene; Quercy Phosphorites
 
  Abstract

    The Caudata are known by two Salamandridae ; one of them is attributed to the genus Megalotriton. The Pelobatidae form the major part of the Anura ; a few bones indicate also the presence of Neobatrachia. 


  Article infos

Published in Vol. 08, Fasc. 2-4 (1978)

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Comparative bone histology of rhabdodontid dinosaurs
Edina Prondvai
Keywords: bone histology-based ontogeny; Mochlodon; Rhabdodon; skeletal maturation; Zalmoxes

doi: 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.   


  Article infos

Published in Vol.38-2 (2014)

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Experimental taphonomy inavian eggs and eggshells: effects on early diagenesis.
Ana M. Bravo, D. A. Buscalioni, Lauro Merino and B. G. Müller
Keywords: archosaurian eggshells; avian egg; Experimental taphonomy; geochemical analysis; pyritisation; Upper Cretaceous
 
  Abstract

    We experimentally explore the early taphonomic stages involving the decay and biodegradation of buried eggs and eggshells. Unfertilised commercial chicken eggs and eggshell fragments were buried in plastic containers and were kept under controlled conditions for eight months. Half of the containers were filled with marl, and the remainder with sand. All were saturated with fresh tap water, acidified water, sulphate water, or seawater. They were kept in the dark at 23.4-26 °C, except one, which was kept in a heating chamber at 37.4°C. We expected that different burial conditions would produce distinct taphonomic outcomes. Instead, the taphonomic alterations of buried eggs parallel that of the alteration of egg proteins (i.e., denaturation and/or putrefaction) with an additional role played by the eggshell. Mummification, encrustation, distortion and fragmentation, and necrokynesis (vertical displacement) depend on organic matter decay. The experiment identifies environmental conditions that may favour or actively promote these taphonomic processes. Of these, early pyritization is one of the most relevant. For comparative purposes, samples of fossil and extinct eggshell representing three distinct environmental burial conditions were examined. These included Megaloolithus, Caiman crocodilus, and Struthio camelus ootypes. The geochemical analysis of these eggshells showed no significant differences among the chemical variables of these fossil and extant ootypes. Eggshells exhibited a stable composition over a range of experimental conditions. 
      


  Article infos

Published in Vol. 32, Fasc. 2-4 (2003)

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