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Page 9 of 19, showing 20 record(s) out of 365 total

Fossil snakes from the Palaeocene of Sao José de Itaborai, Brazil.Part 1 Madtsoiidae, Aniliidae.
Jean-Claude Rage Logo
Published online: 12/15/98

Keywords: Aniliidae s.l.; Brazil; Coniophis; Hoffstetterella; Madtsoia; Madtsoiidae; middle Palaeocene; New taxa; Snakes

  Abstract

    The middle Palaeocene of São José de Itaboraí (State of Rio de Janeiro, Brazil) has yielded a very rich and diverse snake fauna which includes Madtsoiidae, Aniliidae s.l., Boidae, Tropidophiidae s.l., Booidea incertae sedis, and Russellophiidae. The present article (part I) deals with Madtsoiidae and Aniliidae s.l. Madtsoiidae are represented by many vertebrae and a few skull bones. They comprise one new species assigned to the genus Madtsoia (M. camposi sp. nov.). However, the definition of the genus Madtsoia is unsatisfactory and the generic allocation might be provisional. A few elements, vertebrae only, belong to the Aniliidae s. l. Two taxa are referred to this latter group: Coniophis cf. C. precedens and Hoffstetterella brasiliensis gen. et sp. nov. The forthcoming part II will deal with Boidae.

      


  PV article infos

Published in Vol. 27, Fasc. 3-4 (1998)

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Eurodexeinae, eine neue unterfamilie der Artiodactyla (Mammalia) aus dem unter- und mitteleozän europas
Jorg Erfurt and Jean Sudre
Published online: 12/16/96

Keywords: Artiodactyls; Eocene; evolution; Germany; Lutetian; new genus; New subfamily

  Abstract

    Dichobunoid artiodactyls are described in this paper from the middle Eocene Geiseltal lignite deposits near Halle (Sachsen-Anhalt, Germany). The genera Eurodexis and Parahexacodus are established based on odontologica1 studies. The type-species are E. ceciliensis (FRANZEN & KRUMBIEGEL, 1981) and P. germanicus n. sp. from the "obere Mittelkohle" (see text), MP 13. The genera are referred to the new subfamily Eurodexeinae (Dichobunidae, Artiodactyla, Mammalia), which also contains the monospecific genus Eygalayodon SUDRE & MARANDAT, 1993. These new genera show many features similar to North American homacodontids and antiacodontids. They exemplify a high degree of diversity in European dichobunids. Moreover, the family Dichobunidae includes the Dichobuninae and the Hyperdichobuninae. The connection of the posthypocristid with the postentocristid, the shift of a medial to a lingual position of the hypoconulid on the lower molars and the development of a large, caniniform P1 are regarded as the principal tendencies of the eurodexeines. The entoconid is larger and more mesially situated compared to that of Diacodexis. The hypoconulid has a lingual position on a broad postcingulid. The elongation of the premolars and the presence of diastemata are considered associated with extension of the muzzle. This and the acute tubercles of the molars could indicate a limited degree of insectivory. Protodichobune cf. oweni and Diacodexis cf. varleli, first reported here from the "untere Unterkohle" (MP 11) of the Geiseltal, demonstrate the existence of forms in the basal part of the middle Eocene, that are direct descendants of lower Eocene ones. Eurodexis russelli n. sp. from MP 10 of Premontre is the most primitive representative of Eurodexis. A further part of this lineage could be Messelobunodon sp. from MP 11 of Messel (Germany). Another form from Premontre, referred to Eurodexeinae indet., represents the origin of the lineage to Parahexacodus germanicus n. sp. from the Geiseltal (MP 13). The identification of several lineages in MP 10 is evidence of an adaptive radiation during this time. Unfortunately the history of the earlier species of Diacodexis is not known well enough to exclude earlier diversifications. Our study shows the independent development of artiodactyls at the end of the lower Eocene in Europe, North America (and maybe in Asia) with much convergence. The question of the geographic origin of the genus Diacodexis is still open. 


  PV article infos

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

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Les Tayassuidés des phosphorites du Quercy
Léonard Ginsburg
Published online: 11/15/74

Keywords: Quercy Phosphorites; Tayassuidae

  Abstract

    Revision of the Tayassuidae from the old collections of the Quercy leads to interesting facts about taxonomic and phylogenetic problems. It could not have been well done without constant comparison with contemporaneous Tayassuidae from stratified series, as well as with European Miocene Tayassuidae and Hyotheriinae. The result is that only three species are present in the Phosphorites of Quercy: Doliochoerus quercyi FiLHOL (represented by two sub-species: the older, D. quercyi quercyi and the more recent, D. quercyi aquensis), Palaeochoerus gergorianus CROIZET et BLAINVILLE and Palaeochoerus purillus nov. sp. The two former species disappeared with Stampian time, while the third is the direct ancestor of the Aquitanian Palaeochoerus typus POMEL, which became extinct before the beginning of Burdigalian.

    The comparison with Hyotheriinae brought to light new criteria for determinations, based on the study of lower premolars. These observations are condensed in a table of keys for determinations.

    As a result of these studies, it came to light that the Suoidea of the Oligo-Miocene of Europe have never given rise to, except in rare cases, very long lineages. The different forms of pigs are replaced constantly in Europe by the simple game of extinctions and migrations. The reason of that discontinuity is considered here. 


  PV article infos

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

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Second international symposium on Dinosaur, Eggs and Babies (Montpellier-Aix-en-Provence, 25-29 Août 2003).
Monique Vianey-Liaud Logo
Published online: 12/15/03

Keywords: amniotic eggshells; dinosaurs

  Abstract

    Le premier Symposium International sur les ceufs de dinosaures et leurs petits a connu un francs succès, à Isona, en Catalogne (Espagne) en 1999. I1 faisait suite à la publication en 1994 d'un premier ouvrage "Dinosaurs eggs and babies" édité par K. Carpenter, K. Hirsch et J. Homer. Entre 1994 et 1999, les nouvelles découvertes ont augmenté significativement, notamment celles d'ceufs embryonnés, et le nombre de chercheurs impliqués dans ce domaine a accompagné cet accroissement. Jusque là, l'étude de ces objets, les coquilles d'ceufs, est restée longtemps marginale, faute d'une méthodologie scientifique appropriée. 


  PV article infos

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

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Diversity among north african dinosaur eggshells.
Monique Vianey-Liaud Logo and Géraldine Garcia Logo
Published online: 12/15/03

Keywords: Cretaceous; Dinosaurs diversity; Eggshells; Maastrichtian; Morocco; North Africa; taxonomy

  Abstract

    Until the discovery of dinosaur eggshells locality in the Oukdiksou syncline, (Middle Atlas, Morocco) in 1999 (Garcia et al. this volume) the maastrichtian reptiles faunas were unknown in North Africa. Additional material from Achlouj-2 allows us to describe five oospecies, belonging to four oofamilies. The Megaloolithidae is recorded by Megaloolithus maghrebiellsis Garcia el al. and Pseudomegaloolithus atlasi oogen. novo oospec. nov. Tipoolithus achloujensis Garcia et al. is questionably considered as a Subtiliolithidae. A relatively small Elongatoloolithidae is represented by Rodolphoolithus arioul oogen. nov. oospec. nov. A thin Prismatoolithidae is described as a new oospecies of ? Pseudogeckoolithus Vianey-Liaud & Lopez-Martinez, 1997: P. tirboulensis. The diversity of these oospecies indicates that the dinosaur fauna comprises at least five dinosaur oospecies, with perhaps one sauropod and three theropods. 


  PV article infos

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

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Les mammifères Montiens de Hainin (Paléocène moyen de Belgique) Part II : Les Condylarthres
Jean Sudre and Donald E. Russell
Published online: 12/30/82

Keywords: Belgium; Condylarths; Louisininae; Oxyclaeninae; Paleocene

  Abstract

    The Condylarths from Hainin (Hainault, Belgium) show no affinity at the generic level to those known in other Paleocene localities of Europe and North America ; they are described as new forms : Monshyus praevius n. gen., n. sp. and Prolatidens waudruae n. gen., n. sp. Monshyus praevius, discovered in only one of the levels in the excavation at Hainin, is similar to the genera Microhyus TEILHARD and Louisina RUSSELL ; with them it is included in the subfamily Louisininae (Hyopsodontidae). With respect to Microhyus and Louisina, Monshyus is distinguished by the precociously modern aspect of its upper molars, the only teeth that are referable. Prolatidens waudruae, known only by lower molars, was found in several levels in the pit at Hainin. It is an arctocyonid presenting possible relationships to the North American form Oxyprimus galadrielae ; it therefore has been provisionally attributed to the subfamily Oxyclaeninae. If this attribution is confirmed, this species will constitute the first and only representative of the group in Europe. 


  PV article infos

Published in Vol. 12, Fasc. 6 (1982)

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Norselaspis glacialis n.g., n.sp, et les relations phylogénétiques entre les kiaeraspidiens (Osteostraci) du dévonien inférieur du Spitsberg.
Philippe Janvier Logo
Published online: 6/15/81

Keywords: Devonian; kiaeraspids; Osteostraci; Spitsbergen

  Abstract

    The anatomy of Norselaspis glacialis n.g., n.sp., a primitive kiaeraspidian from the Lower Devonian of Spitsbergen, is described on the basis of spécimens studied by grinding sections or prepared with dilute formic acid. This study yielded some new anatomical details, including the presence of a canal prolonging posteromedially the canal alloted to the facial nerve by Stensiö. This posterior prolongation of the « facial canal ›› into the posterolateral part of the labyrinth cavity is consistent with the hypothesis put forward by Allis, Lindström, Jefferies and Whiting, that this canal housed the glossopharyngeus nerve. Furthermore, in N. glacialis, the foramen usually referred to as the foramen for the œsophagus opens posteriorly into a cavity in the postbranchial wall, referred to here as the intramural cavity, and which is interpreted as having housed the heart. Consequently, the œsophagus probably accompanied the dorsal aorta through the aortic canal. Finally, the foramen generally interpreted as having transmitted the ventral afferent arterial trunk is here considered as having housed the hepatic vein, which emptied into the venous sinus of the heart. The ventral afferent arterial trunk may thus have passed through the former «œsophageal ›› foramen.
    The problem of the position of the dorsal nerves in the Osteostraci is discussed, and it is suggested that the three foremost nerve canals opening into the oralobranchial cavity housed the maxillary ramus of the trigeminus, the facial nerve and the glossopharyngeus nerve respectively. The mandibular ramus of the trigeminus must have accompanied one of the two foremost nerves, but for the moment it is impossible to decide which.
    The problem of the nature of the interbranchial crests of the Osteostraci is briefly discussed. Comparison with the branchial apparatus of the Petromyzontida does not support the hypothesis that the interbranchial crests are part of the branchial arches, incorporated into the endoskeletal shield. A different hypothesis is proposed, that the branchial skeleton of the Osteostraci was situated entirely inside the oralobranchial cavity, and was attached to the endoskeletal shield only by the ventromedial processes. The grooves classically allotted to the efferent branchial arteries would thus have housed extrabranchial arteries, branching off from the dorsal aorta, and irrigating the ventral branchial musculature.
    A phylogeny and a classification of the kiaeraspidians are proposed. The evolution of this monophyletic group is characterized by, e.g., reduction of cornual processes, shortening of the abdominal division of the shield, subdivision of the lateral fields, and enlargement of the supraoral fossae.
    The phylogenetic position of the kiaeraspidians within the Osteostraci remains uncertain. Their sister-group may be either the benneviaspidiens or the thyestidians, or Thyestes alone (in which case they would have to be included within the thyestidians). 


  PV article infos

Published in Vol. 11, Fasc. 2-3 (1981)

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Dortokid turtle remains from the Upper Cretaceous of Cruzy (Hérault, southern France) and phylogenetic implications
Haiyan Tong, Eric Buffetaut Logo and Julien Claude Logo
Published online: 11/14/22

Keywords: Cruzy; Dortoka vasconica; France; Late Cretaceous; Turtle

https://doi.org/10.18563/pv.45.2.e3

  Abstract

    An isolated right costal 1 from the Late Cretaceous Massecaps locality (Cruzy, Hérault, southern France) is assigned to Dortoka vasconica (Dortokidae). This find adds a new element to the Late Cretaceous turtle fauna of Cruzy and further supports the hypothesis that two distinct lineages of Dortokidae were present in Europe during the Late Cretaceous-Paleogene due to geographical isolation.
      


  PV article infos

Published in 45-2 (2022)

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La poche à phosphate de Sainte-Néboule (Lot) et sa faune de vertébrés du Ludien supérieur. 13-Rongeurs
Jean-Louis Hartenberger and Monique Vianey-Liaud Logo
Published online: 9/25/78

Keywords: Eocene; Quercy Phosphorites

  Abstract

    Sainte-Néboule has yielded only 4 species of Rodents. But the Theridomyids (Blainvillimys rotundidens and Patriotheridomys altus) are very significative of the age of the locality: Ste-Néboule is lower than the marker level of Escamps 


  PV article infos

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

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La poche à phosphate de Ste-Néboule (Lot) et sa faune de vertebres du Ludien supérieur. 10 - Paléothérides (Perissodactyles).
Jean-Albert Remy
Published online: 9/25/78

Keywords: Eocene; Quercy Phosphorites

  Abstract

    La poche à phosphorite de Sainte-Néboule (Lot) a livré au cours des récentes campagnes de fouilles effectuées dans le cadre de la Rep 311 une douzaine de dents ou fragments de dents de paléothéridés à rapporter à 3 taxons. 


  PV article infos

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

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La poche à phosphate de Ste-Néboule (Lot) et sa faune de vertebres du Ludien supérieur. 8- Insectivores et Chiroptères.
Bernard Sigé
Published online: 9/25/78

Keywords: Eocene; Quercy Phosphorites

  Abstract

    The small insectivorous placental mammals from Ste-Néboule are poorly varied. Two orders of insectivores are documented : the Proteutheria by Pseudorhyncocyon cayluxi (leptictids), the Lipotyphla by Saturninia gracilis and S. beata (nyctitheriids). The bats are only rhinolophoids and mostly hipposiderids. Sufficient populations allow us to restrict the original definitions of three previous species (Hipposideros schlosseri, Palaeophyllophora quercyi, P. oltina). From now, these species can be regarded as monophyletíc. 


  PV article infos

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

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Cricetid rodents from Siwalik deposits near Chinji village. Part I: Megacricetodontinae, Myocricetodontinae and Dendromurinae.
Everett H. Lindsay Logo
Published online: 10/15/88

Keywords: Dendromurinae; Megacricetodontinae; Middle Miocene; Myocricetodontinae; Rodents; Siwalik

  Abstract

    Seventeen species of cricetid rodent are recognized and described from lower and middle Siwalik deposits in the Potwar Plateau of Pakistan. These species are grouped in three categories, characterized as subfamilies (e. g., Megacricetodontinae, Myocricetodontinae, and Dendromurinae); an additional and more abundant category of rodents from these deposits, the Democricetodontinae, is excluded from this study, and will be described in a later study. Fifteen of the species are new, and four new genera are described. The Siwalik cricetid taxa are : Megacricetodon aquilari, n. sp.; Megacricetodon sivalensis, n. sp.; Megacricetodon daamsi, n. sp.; Megacricetodon mythikos, n. sp.; Punjabemys downsi, n. gen. & n. sp.; Punjabemys leptos, n. gen. & n. sp.; Punjabemys mikros, n. gen. & n. sp.; Myocricetodon sivalensis, n. sp.;  Myocricetodon sp.; Dakkamyoides lavocati, n. gen. & n. sp.; Dakkamyoides perplexus, n. gen. & n. sp.; Dakkamys asiaticus, n. sp.; Dakkamys barryi, n. sp.; Dakkamys sp.; Paradakkamys chinjiensis, n. gen. & n. sp.; Potwarmus primitivus, n. gen.; and Potwarmus minimus, n. gen. & n. sp. This diverse record of middle Miocene small mammals illuminates a profound radiation of cricetid rodents in southem Asia, the effects of which were felt in Europe and Africa as well as the rest of Asia. 


  PV article infos

Published in Vol. 18, Fasc. 2 (1988)

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Données et hypothèses sur la radiation initiale des rongeurs.
Jean-Louis Hartenberger
Published online: 10/1/80

Keywords: Diversification scheme; Radiation; Rodents

  Abstract

    About the early radiation of Rodents, we have now from the early tertiary of Asia, a new fossil record, and
    we can do new interpretations. First the problem of the origin of Rodents is studied : considered as a sister group of Lagomorpha, it is possible to find their ancestors between the Mixodontia. Second the new facts about the origin of modern groups of Rodents are reviewed. A general scheme of this diversification can be proposed. 


  PV article infos

Published in Vol. 9, Ext (1980)

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Le genre Microstonyx en Espagne et ses relations avec les autres espèces du même genre hors d'Espagne
Juana M. Golpe-Posse
Published online: 10/1/80

Keywords: Microstonyx; Spain; Suidae

  Abstract

    The genus Microstonyx was found only in the north eastern part of Spain : M. antiquus, referable to the
    Eppelsheim type, from the pyrenean basins ; M. antiquus, more progresive, from the Vallès Basin : M. major-erymanthius group, from the Teruel-Ademuz Area and from Pieru (Penedès Basin).

      


  PV article infos

Published in Vol. 9, Ext (1980)

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Les crocodiliens paléogenes du Tilemsi (Mali): un aperçu systématique
Eric Buffetaut Logo
Published online: 10/1/80

Keywords: Crocodilians; Dyrosoridae; Eocene; Mali; Palaeocene

  Abstract

    Abundant crocodilian fossil remains have been collected, mainly by R. Lavocat. from several levels of the
    Palaeogene of the Tilemsi valley (eastern Mali). Several dyrosaurids occur in the Palaeocene (Montian ?) : Phosphatosaurus sp., Hyposaurus bequaerti (Dollo). H. wilsoni (Swinton). H. nopesai (Swinton), Rhabdognathus rarus Swinton, R. compressus n. sp. ln the lower Eocene has been found a dyrosaurid which cannot be accurutely determined.In the middle Eocene were found a dyrosaurid, Tilemsisuchus lavocati n. g., n. sp., and an indeterminate eusuchian. 


  PV article infos

Published in Vol. 9, Ext (1980)

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Une faune du niveau d'Egerkinger (MP 14; Bartonien inférieur) dans les phosphorites du Quercy (Sud de la France)
Jean Sudre, Bernard Sigé, Jean-Albert Remy, Bernard Marandat, Jean-Louis Hartenberger, Marc Godinot Logo and Jean-Yves Crochet
Published online: 12/18/90

Keywords: Biochronology; Early Bartonian; Eocene; evolution; Mammals; New taxa; Quercy

  Abstract

    The Laprade fauna is chronologically situated between those from Egerkingen and Lissieu and consequently, is close to the MP 14 reference-level of the European mammalian biochronological scale (Symposium of Mainz, 1987).
    This new fauna is presently the oldest known in the Quercy phosphorites, formerly the Le Bretou fauna (MP 16) was considered as the oldest one. The Laprade fauna includes 21 species which belong in 7 mammalian orders (Marsupialia: Amphiperatherium bastbergense, Amphiperatherium goethei; Apatotheria: Heterohyus (Gervaisyus) pygmaeus nov. subgen., nov. sp.; Lipotyphla: Saturninia cf. mamertensis, Saturninia cf. intermedia; Chiroptera: Vespertiliavus lapradei nov. sp.; Rodentia: Protadelomys cf. lugdunensis, Elfomys nov. sp.; Primates: Nannopithex cf. filholi, cf. Pseudoloris or Pivetonia; Perissodactyla: ?Palaeotherium ?castrense, small-sized Palaeotherium sp., Plagiolophus sp., Anchilophus sp.; Artiodactyla: Dichobune cf. robertiana, Mouillacitherium cartieri, Tapirulus cf. depereti, Mixtotherium priscum, Pseudamphimeryx schlosseri, and Artiodactyla indet). Sixteen of these species are mentioned for the first time from the Quercy faunas.
    The recognition of a new apatemyid, Heterohyus (Gervaisyus) pygmaeus nov. subgen., nov. sp., attests to an early origin of a lineage known in the Late Eocene. The emballonurid bat Vespertiliavus lapradei nov. sp. is presently the earliest record of this genus and family. This Auversian fauna leads to discuss the age of taxa showing archaic features. These taxa were defined on specimens collected in the Quercy during the last century and have never been found in the Quercy localities recently investigated. This fauna bears also evidence of a karstic filling episode older than those previously dated by fossils in the Quercy Jurassic. 


  PV article infos

Published in Vol. 20, Fasc. 1 (1990)

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Morphotypes dentaires actuels et fossiles des chiroptères vespertilionines. 2ème partie: implications systématique et phylogéniques.
Henri Menu
Published online: 11/15/87

Keywords: Chiroptera; PHYLOGENY; Systematics; Vespertilionine

  Abstract

    The first part of this study was devoted to a descriptive analysis of teeth morphologies among the vespertilionine bats. This leads now to a tentative synthesis, providing views on the systematics of the group. The results could be seen according to three distinct but closely related purposes : 1 - the sorting of the genera contents in order to conform the genera units to homogeneous taxa that could represent natural issues of evolutionary lineages ; 2 - the investigation of relationships between extant genera in order to infer the possibilities of common origin ; 3 - according to the preceeding items and to the observed evolutionary trends, a tentative phylogeny, modest and cautious. The contents of many genera are sorted : Leuconoe is removed from subgeneric to generic position, whereas Myotis becomes a subgenus of it ; the myotodont species are cleared away from the Pipistrellus genus ; Glischropus and Scotozous are synonymized within Pipistrellus ; Hypsugo is raised to the generic level ; some species previously ranged within Pipistrellus will form provisionally a collective group, Attalepharca nov. ; the Eptesicus genus is broken up, the excluded species being grouped within Nycterikaupius gen. nov. ; the Nycticeini tribe is defined again after exclusion of Otonycteris , Scotoecus, Scotophilus , and addition of Hesperoptenus ; the species la io and Pipistrellus tasmaniensis are removed to Eptesicus (n.s.) and Pipistrellus dormeri to Scotoecus. Groupings of genera are stated according to the main evolutionary trends of I1/. The relevance of these is often warranted by close morphologic similarities of other teeth. This leads to a recognition of the major evolutionary radiations which occurred in the group. The filiations schematized at the end of the work show the dental relationships observed between the extant genera, and could represent a phylogenic framework. Two major facts are to be underlined : 1- the early divergence of leuconoids ; 2 - the successives crossings to myotodonty from the nyctaloid flow. Fossil data from the literature are punctually and tentatively incorporated within phylogenic sketches. 


  PV article infos

Published in Vol. 17, Fasc. 3 (1987)

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Les vertébres dévoniens de la Montagne Noire (Sud de la France) et leur apport à la phylogénie des pachyosteomorphes (Placodermes Arthrodires).
Hervé Lelièvre, Raimund Feist Logo, Daniel Goujet and Alain Blieck
Published online: 5/15/87

Keywords: Devonian; Montagne Noire; New taxon; PHYLOGENY; Placoderms; Stratigraphy; Vertebrate

  Abstract

    Several different taxa of jawed vertebrates are reported for the first time from the Devonian of south-eastern Montagne Noire, France. Besides some undeterminable fragments of placoderm fishes from the Pragian and Lower Emsian, the material from the Upper Devonian is mainly represented by Melanosteus occitanus gen. and sp. nov. (Frasnian) and Thoralodus cabrieri LEHMAN, 1952 ("Famennian"). The good state of preservation of Melanosteus allows a detailed anatomical study leading to a phylogenetic analysis of the selenosteid pachyosteomorphs. 


  PV article infos

Published in Vol. 17, Fasc. 1 (1987)

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Schmelzmikrostruktur in den inzisiven alt-und neuweltlicher histricognather nagetiere
Thomas Martin
Published online: 12/15/92

Keywords: Africa; Caviomorpha; Ctenodactyloidea; Deseadan; Enamel microstructure; Hunter-Schreger bands; Hystricognathi; Incisors; Ischyromyoidea; multiserial; Paleobiogeography; pauciserial; Phiomorpha; Rodentia; South America

  Abstract

    Enamel microstructure in the incisors of Old- and New World hystricognath rodents:

    The incisor enamel microstructure in more than 100 genera of fossil and Recent hystricognath and sciurognath rodents was studied. A multiserial schmelzmuster is present in the Hystricognathi, the Ctenodactylidae, advanced Chapattimyidae, and in Pedetes. A redefinition of pauciserial and multiserial HSB is given that makes the two enamel types unambiguously distinguishable which apparently represent well defined evolutionary levels. In the pauciserial Schmelzmuster the IPM is thicker than in the multiserial one. In pauciserial HSB the IPM always surrounds each prism, and the crystallites of the IPM run parallel to prism direction; transition zones between HSB are lacking; the inclination of the HSB is normally very low and the prism cross sections are not flattened but somewhat irregular. The number of prisms per HSB is no good distinctive character for pauciserial and multiserial HSB, since there exists a wide overlap. The pauciserial schmelzmuster is primitive, the multiseiial derived because: 1. the pauciseiial schmelzmuster appears earlier in the fossil record in the most primitive rodents (Paramyids s.l. and Ctenodactyloids); 2. the Eocene Ctenodactyloidea show pauciserial HSB but the Oligocene and younger ones are characterized by multiserial HSB; 3. in the outgroup comparison, the Eurymylidae (Mixodontia) show pauciserial HSB; 4. biomechanically, multiserial HSB strenghten the enamel better than pauciserial HSB, since their IPM runs nearly always in an angle of 45° or more to the prisms.

    In multiseríal HSB three subtypes can be distinguished which are differentiated by the IPM orientation. Primitive is a (rarely strict) parallel or acute angular, anastomozing IPM, and derived is an interrow sheet-like ("plattenartige") IPM. This evolutionary polarity is indicated by enamel evolution in the Ctenodactylidae which show an acute angular IPM in the Oligocene and a rectangular interrow sheet-like IPM since the Miocene. Among the Caviomorpha a rectangular interrow sheet-like IPM is restricted to the Octodontoidea; therefore they must be considered derived in terms of their enamel structure. The first multiserial HSB in rodent incisors appear in phiomyids or chapatrimyids from the Upper Eocene of Algeria. The IPM is acute angular and anastomozing. The worldwide next younger multiserial HSB are found in Lower Oligocene phiomyids of Fayum, Egypt There already a rectangular interrow sheet like IPM is present (in Metaphiomys) besides the acute angular anastomozing IPM.

    The first Caviomorpha from the Deseadan (Oligocene-Miocene) likewise show already acute angular anastomozing IPM (e.g. Scozamys) and rectangular interrow sheet-like IPM (Platypittamys). Therefore the first Caviomorpha cannot be positioned close to a transition from pauciserial to multiserial HSB. In none of the potential caviomorph ancestors from southern North America multiserial HSB or transitional stage between pauciserial and multiserial HSB could be found. The similarities between the enamel types of the Fayum rodents and the rodents from the Deseadan of South America make a derivation of the Caviomorpha from Paleogene North African phiomorph rodents or their direct ancestors most probable. This supports at the same time a descent of the platyrrhine Primates from North African anthropoids.
      


  PV article infos

Published in Vol. 21, Ext (1992)

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Contributions à l'étude du gisement Miocène supérieur de Montredon (Hérault). Les grands mammifères. 6 - Les périssodactyles Rhinocerotidae
Claude Guérin
Published online: 11/15/88

Keywords: Aceratherium; anatomy; Biostratigraphy; Dicerorhinus; Miocene; Montredon; Paleoecology; Upper Vallesian

  Abstract

    The Montredon site has yielded about hundred rhinoceros remains:
    - twenty two of them, including 14 carpal and tarsal bones and 6 complete metapodials, belong to
    Dicerorhinus schleiermacheri at its second evolutionary stage;
    - fifty one remains including a nearby complete but crushed skull, a mandible, 26 isolated cheek-teeth, 10 carpals and tarsals, one metacarpal, are of Aceratherium incisivum, second evolutionary
    stage;
    - fifteen remains belong to Aceratherium (Alicornops) simorrense (among other an upper molar, 8 carpals and tarsals, one metatarsal);
    - six remains are attributed to an undetermined species of what is probably the most recent Prosantorhinus ever found.
    The evolution stages of the two first species allow us to date the deposit back to the Upper Vallesian, MN 10 zone; Montredon is one of the youngest sites in which Aceratherium simorrense was found. The four rhino species indicate a swampy forest biotope 


  PV article infos

Published in Vol. 18, Ext (1988)

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Page 9 of 19, showing 20 record(s) out of 365 total