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Page 12 of 19, showing 20 record(s) out of 365 total

New late Paleocene rodents (Mammalia) from Big Multi Quarry, Washakie Basin,Wyoming.
Mary R. Dawson and Christopher K. Beard Logo
Published online: 16/12/1996

Keywords: Clarkforkian; North America; Paleocene; Rodentia

  Abstract

    The earliest North American rodents occur in basal Clarkforkian beds of the Fort Union Formation at Big Multi Quarry near Bitter Creek, northern Washakie Basin, Sweetwater County, Wyoming, and in closely correlative Fort Union beds formerly accessible in the Eagle Coal Mine near Bear Creek, northern Clark's Fork Basin, Carbon County, Montana. Two new species of early Clarkforkian rodents, Paramys adamus and Alagomys russelli, are described from Big Multi Quarry. Paramys adamus is represented by virtually complete upper and lower dentitions, which demonstrate that this species is one of the most primitive North American paramyids yet discovered. These specimens form the basis for a reevaluation of the content and stratigraphic range of P. atavus, which is known with certainty only from Bear Creek. Alagomys russelli is the first North American record for the enigmatic rodent family Alagomyidae, otherwise known from ?late Paleocene-early Eocene localities in Mongolia and China. Phylogenetic analysis of dental and gnathic traits suggests that Alagomyidae form the sister group of all other undoubted rodents. At least two rodent clades, alagomyids and basal paramyids, seem to have invaded North America from Asia at the beginning of Clarkforkian time, but only the paramyids persisted to undergo a significant evolutionary radiation in North America. 


  PV article infos

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

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Functional aspects of the evolution of rodent molars
Percy M. Butler
Published online: 01/10/1980

Keywords: Chewing; Muridae; Rodents; Wear facets

https://doi.org/10.18563/pv.9.ext.249-262

  Abstract

    The wear facets of primitive rodents can be homologized with those of primitive primates and ungulates. As in primates, the jaw movement was ectental, with an increased anterior component in the lingual phase (phase ll). The buccal phase (phase I) in rodents approaches the horizontal and it tends to be reduced in importance in comparison with the lingual phase. ln more advanced rodents the efficiency of grinding is increased by the development of additional cutting edges of enamel (e.g. enlargement of hypocone, development of mesoloph and lingual sinus). The buccal phase movement becomes lined up with the lingual phase movement to form a single oblique chewing stroke,resulting in planation of the crown. As the stroke becomes more longitudinal (propalinal) the enamel edges become more transverse. In Muridae propalinal chewing evolved before the loss of cusps, facets were reorientated and additional cusps developed. 


  PV article infos

Published in Vol. 9, Ext (1980)

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On the genus Dikkomys (Geomyoidea, Mammalia)
Morton Green and Philip R. Bjork
Published online: 01/10/1980

Keywords: Dikkomys; Geomyoidae; North America

https://doi.org/10.18563/pv.9.ext.343-353

  Abstract

    The geomyoid genus Dikkomys is well represented in a sample from the Black Bear Quarry Il local fauna of Early Hemingfordian age in Bennett County, South Dakota. Isolated unworn P/4's of Dikkomys matthewi WOOD have a prominent median cristid (sagicristid) with a connection to the metaconid and the hypolophid. With wear, P/4 does not become as molariform as P/4 because of this cristid.
    A large sample of the Whitneyan beteromyid Proheteromys nebraskensis WOOD contains variants of the P/4 with on incipient sagicristid in approximately 18 percent of the population. The upper dentition and lower molars of Proheteromys nebraskensis are sufficiently generalized to indicate probable ancestry to Dikkomys


  PV article infos

Published in Vol. 9, Ext (1980)

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A new species of chimaeroid fish from the upper Paleocene (Thanetian) of Maryland, USA
Gerard R. Case
Published online: 29/10/1991

Keywords: Chimaeroid nov. sp.; Maryland; U.S.A.; Upper Paleocene

  Abstract

    The recent discovery of several mandibular toothplates of a chimaeroid fish at a dig in the area of the Landover Mall, near Landover, Prince Georges County, Maryland, brings to our attention a new species of the chimaeroid, Ischyodus.
     Although superficially reminiscent of the European chimaeroid toothplates of Ischyodus thurmanni (cf. text-fig. 2), I. williamsae nov. sp. probably has a more closer relationship to I. bifurcatus CASE, 1978, of the Upper Cretaceous of New Jersey and Delaware. 


  PV article infos

Published in Vol. 21, Fasc. 1-2 (1991)

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La poche à Phosphate de Ste-Néboule (Lot) et sa faune de vertébres du Ludien supérieur. 5-Squamates
Jean-Claude Rage Logo
Published online: 25/09/1978

Keywords: Eocene; Quercy Phosphorites

https://doi.org/10.18563/pv.8.2-4.201-215

  Abstract

    The Squamates from Sainte-Néboule are charateristic of the Upper Eocene from the Phosphorites du Quercy. Most genera known from this locality do not survive the « Grande Coupure ». Cadurcoboa insolita gen. nov., sp. nov. is a small Boidae very characteristic of the Upper Eocene. 


  PV article infos

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

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Rongeurs muroidés du Néogène supérieur d'Afghanistan, évolution, biogéographie, corrélations
Louis D. Brandy
Published online: 30/09/1981

Keywords: Afghanistan; Muroidea; Neogene

https://doi.org/10.18563/pv.11.4.133-179

  Abstract

    The rodent faunas of five afghan localities found in 1976 and 1977 (Sherullah, Ghazgay, Pul-e Charkhi, Dawrankhel 14 and 15) are studied.
    The rodents (Muridae, Cricetidae and Rhizomyidae) represent 8 genera and 10 species. The detailed description of the 2 new genera and 7 species diagnosed in 1979 is given. An other species is created : Pseudomeriones crapouilloti n. sp. These faunas precise the origin and diversification of Muridae and Cricetidae. A phyletic lineage known in Afghanistan is represented in East Africa by a ramus or a collateral lineage. The five localities are dated from Lower Turolian to Ruscinian. They constitute the frame of a chronologie scale for the Upper Continental Neogene of Afghanistan.
    The study of afghan material brings new data to the biogeography of Old Word's rodents during the Upper Neogene; from Pakistan to Europe and Africa, a rather warm and damp province would have existed till Upper Miocene; after which (in the mio-pliocene epoch) it would have divided into 3 parts, by aridification of the central area. 


  PV article infos

Published in Vol. 11, Fasc. 4 (1981)

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Contributions à l'étude des micromammifères du gisement Miocène supérieur de Montredon (Hérault). 3- Les insectivores
Jean-Yves Crochet and Morton Green
Published online: 30/06/1982

Keywords: Hérault; Insectivora; Late Miocene; Micromammals; Montredon

https://doi.org/10.18563/pv.12.3.119-131

  Abstract

    This paper presents a preliminary list of insectivores from the Vallesian beds at Montredon (France). The associated rodent fauna has established a Vallesian age for the fauna. Eleven species belonging to the Soricidae, Talpidae, Erinaceidae, and Dimylidae are identified of which four only are referred with certainty to forms already named. 


  PV article infos

Published in Vol. 12, Fasc. 3 (1982)

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Cryptomerix Schlosser, 1886, Tragulidé de l'oligocène d'Europe ; relations du genre et considérations sur l'origine des ruminants.
Jean Sudre
Published online: 01/06/1984

Keywords: Archaic Ruminants; Paleobiogeography; Quercy Phosphorites; Systematics; Tragulids

  Abstract

    The genus Cryptomeryx SCHLOSSER, 1886, inusited during a long period, has been discovered in Lower and Middle Oligocene localities of the Quercy region (South-West France). This new material, as well as specimens from the old collections referred to Cryptomeryx, are described; their study, allows us precising the definition of the genus, and confirming its allocation to the Tragulidae family. The type species of the genus, Crypmmeryx gaudryi (= Lophiomeryx gaudryi FILHOL, 1877), occurs in several localities at the base of the Middle Oligocene (Itardies, La Plante 2, Roqueprune 2, Soulce, Herrlingen 1). The new species C. matsoui n. sp. has been defined in the older locality of Mas de Got (top of Lower Oligocene). It is possible that the species Pseudamphimeryx decedens STEHLIN, 1910 pertains to the same genus. Also to the Tragulids must be referred the monospecific genus Iberomeryx (I. parvus GABOUNIA, 1964) from Upper Oligocene of Benara (Georgie, URSS), with which Cryptomeryx is related. These genera are not direct ancestors of Miocene tragulids; their occurrence in the Western European Oligocene results from a first immigration wawe of the family. These Tragulids are one of the most archaic groups of Ruminants. They are probably derived from a primitive stock which had acquired in Asia the selenodont condition of the dentition. 


  PV article infos

Published in Vol. 14, Fasc. 1 (1984)

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Mammals and stratigraphy : Geochronology of the continental mammal-bearing Tertiary of south America.
Larry G. Marshall, Robert Hoffstetter and Rosendo Pascual
Published online: 15/12/1983

Keywords: Cenozoic; Geochronology; Mammalia; South America; Stratigraphy; Tertiary

https://doi.org/10.18563/pv.13.ext

  Abstract

    The principles and practices employed in establishment and recognition of South American land mammal ages are reviewed along with previous and present concepts of distinguishing time, rock, and faunal units. Previous chronological arrangements of South American Tertiary land mammal faunas are appraised on the basis of recent geological and paleontological data. Twelve South American Tertiary land mammal ages are here recognized [from oldest to youngest, Riochican (middle to late Paleocene); Casamayoran (early Eocene); Mustersan (middle Eocene); Divisaderan (late Eocene); Deseadan (early [to middle?] Oligocene); Colhuehuapian (late Oligocene); Santacrucian (early Miocene); Friasan (middle Miocene); Chasicoan (late Miocene); Huayquerian (latest Miocene); Montehermosan (early to middle Pliocene); and Chapadmalalan (late Pliocene)]. As all except the Friasian were originally defined on the basis of Argentine faunas, these are discussed first and at length, and each is reviewed with discussion of type locality, stratigraphy, type fauna, and faunal correlations. Non-Argentine faunas are then discussed country by country in alphabetical order.

         A review is given of radioisotope dates obtained on volcanic rocks (i.e., basalts, tuffs) associated with mammalbearing beds in Argentina. Based on these age determinations and on correlation of the late Tertiary land mammals involved in the interchange between North and South America, a chronology of South American land mammal ages correlated with North American land mammal ages and European marine stages is proposed.

    It is concluded that South America was an island continent through most of the Tertiary Period (ca 65 to about 3 Ma). As a result, the land mammal fauna of South America developed in isolation and was dominated by autochthonous endemic groups. Toward the end of the Tertiary (i.e., middle Miocene) a unique faunal balance had been achieved by the descendants of the ancient inhabitants (notoungulates, litopterns, condylarths, astrapotheres, edentates, marsupials) and of later (late Eocene) waif immigrants (caviomorph rodents, platyrrhine primates). A prominent feature of this mammal fauna was the combination of carnivorous and omnivorous marsupials with native placental herbivorous ungulates, subungulates, and edentates.

    Sometime during the late Miocene, a limited but important interchange of mammalian taxa between North and South America took place. Procyonids (raccoons and their allies), a group of North American origin, first appear in South America in strata of Huayquerian Age, while members of the extinct South American ground sloth families Megalonychidae and Mylodontidae first appear in North America in early Hemphillian time. These groups dispersed along island arcs before the appearance of the Panamanian land bridge in the Pliocene (ca 3.0 Ma). Cricetine rodents, a group of North American origin, are first known in South America in strata of Montehermosan Age. The known taxa are too advanced and diversified to be considered the first of this group to invade South America. lt is believed by some workers that these rodents arrived before the Montehermosan, possibly in the late Miocene or earlier, by waif dispersal from North America.

    The isolation of South America ended with the appearance of the Panamanian land bridge, which provided a direct, dry land connection between the two Americas. Across this portal an extensive interchange of terrestrial faunas occurred, and the fossil record documents an intermingling of these long-separated land mammals faunas.

          The beginning of this interchange by land route in South America is marked by the appearance of mammals which evolved from North American emigrants in the Chapadmalal Formation of Argentina. These include a mustelid (Conepatus), a tayassuid (Argyrohyus), and four genera (Akodon, Dankomys, Graomys, Reithrodon) of cricetine rodents. The appearance of this contingent of northern animals favors the existence of the Panamanian land bridge by this time. Likewise, a large number of terrestrial vertebrates of South American origin appear in North America in beds of late Blancan Age date around 2.7 Ma. Among the mammals are Neochoerus, Erethizon, Glyptotherium, Glossotherium, Kraglievichia, and Dasypus


  PV article infos

Published in Vol. 13, Ext (1983)

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First report of an Eocene reptile fauna from Florida, USA
Alan J. Holman
Published online: 30/07/2001

Keywords: Eocene; Fauna; Florida; Reptile; USA

  Abstract

    Fossils of the Trionychidae, Bataguridae or Emydidae, Palaeophis and Crocodylia from Chattahoochee, NW Florida, USA, represent the first report of an Eocene reptile fauna from Florida. 


  PV article infos

Published in Vol. 30, Fasc. 1-2 (2001)

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Fossil snakes from the Palaeocene of Sao José de Itaborai, Brazil, Part II. Boidae
Jean-Claude Rage Logo
Published online: 28/12/2001

Keywords: Boidae; Boinae; Brazil; Erycinae; New taxa; Palaeocene; Snakes

  Abstract

    The middle Palaeocene of São José de ltaboraí (State of Rio de Janeiro, Brazil) has produced a rich and diverse fauna of boid snakes. It comprises six or seven species: Hechtophis austrinus gen. et sp. nov., Corallus priscus sp. nov., Waincophís pressulus sp. nov., Waincophis cameratus sp. nov.,"Boinae A", and "Boinae B". Moreover, two dentaries might pertain to either H. austrinus or "Boinae B", or even represent a distinct taxon. Hechtophis austrinus is assigned, with reservation, to the Erycinae. All other taxa are referred to the Boinae. The vertebrae of all taxa have paracotylar foramina, which raises the problem of the apomorphic or plesiomorphic nature of this feature. This fauna also raises the question of the presence of extinct erycine boids in South America, but it does not allow this question to be settled. 


  PV article infos

Published in Vol. 30, Fasc. 3-4 (2001)

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Analyse d'ouvrage: “A.G. SMITH, D.G. SMITH & B.M. FUNNELL: Atlas of Mesozoic and Cenozoic coastlines (1995)”
Jacques Michaux
Published online: 18/03/1996

Keywords: Atlas; Book review; Cenozoic; Coastlines; Mesozoic

  Abstract

    ATLAS OF MESOZOIC AND CENOZOIC COASTLINES, par Alan G. SMITH, David G. SMITH & Brian M. FUNNELL, 1995. Cambridge University Press, 99 p., 31 cartes, 3 tab!., 2 fig. ISBN 0-521-45155-8.

    L' "Atlas of Mesozoic and Cenozoic coastlines" succède avec bonheur aux "Mesozoic and Cenozoic paleocontinental maps" de Smith & Briden, publié en 1977. 


  PV article infos

Published in Vol. 25, Fasc. 1 (1996)

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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: 15/12/2003

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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Preliminary evolution of paleosols and implications for interpreting vertebrate fossil assemblages, Kuldana formation, Northern Pakistan
Andres Aslan and J. G. M. Thewissen Logo
Published online: 16/12/1996

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. 


  PV article infos

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

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Les Amphibiens et les reptiles du Pliocène supérieur de Balaruc II (Herault, France)
Salvador Bailon Logo
Published online: 15/09/1989

Keywords: amphibians; Europe; France; Pliocene; Reptiles

  Abstract

    The late Pliocene site (MN 16) of Balaruc II (Hérault, France) has provided remains of the following amphibians and reptiles: Chelotriton pliocenicus nov. sp. and Triturus marmoratus (Salamandridae), cf. Rana (Ranidae), cf. Blanus (Amphisbaenidae), cf. Agama (Agamidae),  Gekkonidae indet., Lacerta s.l. (Lacertidae), "Ophisaurus" sp. (Anguidae), Michauxophis occitanus (Aniliidae), Erycinae indet. (Boidae), Elaphe cf. E. longissima and Malpolon sp. (Colubridae), cf. Naja (Elapidae) and Vipera sp. (Viperidae). The salamandrid Chelotriton pliocenicus and the aniliid Michauxophis occitanus constitute, up to now, the only records of these groups in the European Pliocene. The fauna is indicative of a warm, dry
    subtropical climate. 


  PV article infos

Published in Vol. 19, Fasc. 1 (1989)

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Revision der Equoidea aus den Eozänen Braunkohlen des Geiseltales bel Halle (DDR).
Jens L. Franzen and Hartmut Haubold
Published online: 15/04/1986

Keywords: Eocene; Europe; Mammalia; Perissodactyla; Stratigraphy; taxonomy

  Abstract

    The dentitions as well as one complete and several partial skeletons of Equoids from the Eocene lignite beds of the Geiseltal locality are revised. Instead of 13 species distinguished up to now 3 chronoclines with 5 species and 3 separate species are recognized (text. fig. 1). Propalaeotherium hassiacum HAUPT, 1925 is evolving into Propalaeotherium isselanum (CUVIER, 1824) between the levels of the « obere Unterkohle ›› and the « untere Mittelkohle ›› of the Geiseltal section. Propalaeotherium argentonicum GERVAIS, 1849 is shown to be present in the « untere Unterkohle ››, whereas Lophiotherium pygmaeum (DEPERET,1901) occurs in the « obere Mittelkohle ›› and in the « oberes Hauptmittel ››. Plagiolophus cartieri STEHLIN, 1904 appears during the transition from the « Mittelkohle ›› into the « Oberkohle ›› as the earliest true Palaeothere. Therefore the « Oberkohle ›› is already regarded as Upper Eocene. This is corroborated by the occurrence of a phyletic descendant of Propalaeatherium parvulum (Propalaeotherium n.sp.) in the middle and upper "Oberkohle " because this species appears otherwise for the first time at the mammal level of Lissieu. On the other hand Propachynolophus gaudryz (LEMOINE, 1878) described by Matthes (1977) from the « untere Unterkohle ›› turns out te be in fact a Phenacodont. Thus the decisive argument for classifying the « untere Unterkohle ›› as Lower Eocene has to be dropped. Biostratigraphically the « Unterkohle ›› and the «Basishauptrnittel ›› correspond with the lower Middle Eocene (mammal level of Messel), whereas the «unteres Hauptmittel ›› and the « untere Mittelkohle ›› are equivalent to the middle part of the middle Eocene (mammal level of lssel), and the « obere Mittelkohle ›› together with the « oberes Hauptmittel ›› coincide with the upper Middle Eocene (mammal level of Bouxwiller). 


  PV article infos

Published in Vol. 16, Fasc. 1 (1986)

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Book review : "Encyclopedia of Paleoherpetology"
Jean-Yves Crochet
Published online: 20/06/1987

Keywords: Book review; Paleoherpetology

  Abstract

    Encyclopedia of Paleoherpetology. In 19 parts ; Initiated by Prof. Dr. Oskar KUHN ; Edited by Dr. Peter WELLNHOFER, München. - Part. 17 A : Pelycosauria, by Dr. Robert R. REISZ, Erindael Campus, University of Toronto. 1986. VIII, 102 pp., 43 fig., 20,5 x 25,5 cm, soft cover : DM 140, - (Pref. - Price for subscribers to the whole series : DM 126, -). ISBN 3-437-30486-0. 


  PV article infos

Published in Vol. 17, Fasc. 2 (1987)

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Cricetid rodents from Siwalik deposits near Chinji village. Part I: Megacricetodontinae, Myocricetodontinae and Dendromurinae.
Everett H. Lindsay Logo
Published online: 15/10/1988

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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La poche à Phosphate de Ste-Néboule (Lot) et sa faune de vertebres du Ludien supérieur. 6- Oiseaux
Cécile Mourer-Chauviré Logo
Published online: 25/09/1978

Keywords: Eocene; Quercy Phosphorites

https://doi.org/10.18563/pv.8.2-4.217-229

  Abstract

    There are very few birds in the site of Sainte-Néboule. They belong to three species already known in the "Phosphorites" : Paraortyx brancoi, Aegialornis broweri, Cypselavus gallicus, and to one new species, Recurvirostra santaeneboulae. The comparison of some different bones of the genus Cypselavus with some Apodiformes and Caprimulgiformes shows that this genus must be classified in the order Apodiformes. 


  PV article infos

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

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Experimental taphonomy inavian eggs and eggshells: effects on early diagenesis.
Ana M. Bravo, D. A. Buscalioni Logo, Lauro Merino and B. G. Müller
Published online: 15/12/2003

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. 
      


  PV article infos

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

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Page 12 of 19, showing 20 record(s) out of 365 total