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Page 5 of 19, showing 20 record(s) out of 365 total

Rythme et modalités de l'évolution chez les rongeurs à la fin de l'Oligocène-leurs relations avec les changements de l'environnement.
Bernard Comte
Published online: 15/12/2000

Keywords: Environment; evolution; Oligocene; Rodents; Systematics

  Abstract

    The analysis of oxygene isotope variations as well as paleobotanical data suggest that the Oligocene/Miocene boundary corresponds to a transitional period marked by floristical and climatic variations. During this period, the pyreneo-alpine tectonics has contribued to modify the geography and western Europe landscapes. Faunal changes (appearances, extinctions, migrations) are observed in different mammalian groups, notably in the rodents. A study of the evolutionary trends and patterns in paleogene rodents is involved for the period ranging from level MP 28 of the Late Oligocene to the Early Miocene, including the Oligo-Miocene boundary.
    The Rodents fauna from the sites of Venelles (Bouches-du-Rhône District, France) and Thezels (Lot, France), previously mentionned in litterature, have been studied. The first description of the Eomyidae of La Milloque (MP 29) has been completed. These faunas are compared to those from various localities dating from the considered period. In La Milloque, a new representative of the Eomys species is described next to a form close to Rhodanomys hugueneyae ENGESSER, 1987. It is the Eomys milloquensis nov. sp., the likely descendant of Eomys quercyi COMTE & VIANEY-LIAUD, 1987. Two new species are also described in Thezels: Eucricetodon thezelensis nov. sp., resulting from a likely and local evolution of Eucricetodon praecursor (SCHAUB, 1925) from La Milloque, which, in the same geographic area, could be at the origin of Eucricetodon hesperius ENGESSER, 1985 from Paulhiac. Plesiosminthus admyarion nov. sp., quite distinct from Plesiosminthus schaubi VIRET, 1926, which announces Plesiosminthus myarion SCHAUB 1930. Venelles 'Plesiosminthus schaubi population is considered as a sub-species, named Plesiosminthus schaubi meridionalis nov. subsp. New phylogenetic patterns are proposed. Among the Eomyidae, a quantification of various features of the M1-2/ crown (hypsodonty, degree of abrasion, occlusal angle, state of development of the I and V anticlines), and a comparison with the occlusal diagram of the other teeth among various other populations allows a more efficient separation of Eomys and Rhodanomys genera. In Western Europe, and within this period, it finally does not seem possible to gradually connect the genus Eomys to the genus Rhodanomys. The evolution of the Eomys quercyi - milloquensis lineage seems to underline a similar evolution to that which may have led from the Eomys to the Rhodanomys form. The latter which appears totally accomplished at level MP 29 of the Oligocene is considered as an immigrant. If we compare the most representative species of the Venelles, Thezels, and Coderet sites, (i.e. Rhodanomys, Eucricetodon, Adelomyarion, Peridyromys, Plesíosminthus), it becomes impossible to confirm their biochronological separation. The noticeable differences between the populations may be interpreted as geographical variations. An explanation to these variations, and to fauna's evolution during the Late Oligocene and Early Miocene can be found in the environmental modifications, supported by isotopic, paleobotanical and sedimentologic analysis. A tentative reconstruction of the environments is attempted by the cenogram method. The analysis of the fluctuations of fauna's diversity shows variations which may be correlated to a drop in temperature at MP 29, during the Late Oligocene, followed by an increase in temperature along with an aridity phenomenom, during the basal Miocene (MN O).The confrontation of various methods give the opportunity of reconstituting and comparing the evolution of the environment of three sequences of sites chosen from different regions. Ecological affinities of various rodents' species are being examined. It is possible to consider that the integration of all the conclusions resulting from this study should lead to an explanation to the evolution of rodents for the period around the Oligocene-Miocene boundary. The site of Coderet- level 3- would be posterior to the latter, at the beginnig of the Miocene, and would mark the level MN 0 of the Aquitanian.

      


  PV article infos

Published in Vol. 29, Fasc. 2-4 (2000)

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Un gisement à mammifères dans la formation lacustre d'âge Miocène moyen du Collet Redon près de St-Cannat (Bouches-du-Rhone). Implications stratigaphiques
Jean-Pierre Aguilar and G. Clauzon
Published online: 10/04/1979

Keywords: France; Neogene; Rodentia

https://doi.org/10.18563/pv.8.5.327-341

  Abstract

    The new fauna of Collet Redon (Bouches-du-Rhône, France) is dated by three rodents: Megacricetodon aff. bavaricus, Democricetodon affinis mutilus and Peridyromys cf. hamadryas. They correlate this locality with Oggenhof and Ohningen in Bavaria (Western Germany). As the radiometric age of Ohningen is estimated between 14 and 13 M.Y., these three localities are of Serravallian age. This datation brings a complete readjusment of the stratigraphy of the section of Collet Redon formerly described by Collot and Combaluzier. The marine deposits with underly the continental formation with the mammal fauna, are Burdigalian. The angular unconformity between the marine and the continental deposits gives evidence of an episode of emersion on the margin of a sedimentary basin, with deformation and erosion. Owing to the newly discovered fauna, this geodynamical event is clearly settled within the regional geographical and chronological context. Lacustrine and continental deposits of such an age were up to now unsuspected in this area. 


  PV article infos

Published in Vol. 08, Fasc. 5 (1979)

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Types dentaires adaptatifs chez les sélaciens actuels et post-paléozoïques.
Henri Cappetta Logo
Published online: 01/09/1986

Keywords: Dental types; evolution; Fossil selachians; Recent selachians; Trophic adaptations

https://doi.org/10.18563/pv.16.2.57-76

  Abstract

    The dentition of selachians is characterized by an often very pronounced heterodonty involving a great morphological diversity. Despite this fact, the dentitions of selachians can be grouped in a rather reduced number of dental types corresponding to trophic adaptations: grasping, tearing, cutting, crushing, grinding and grasping-grinding type. The numerous exemples of convergence and parallelism that can be observed in fossil selachians and between Recent and fossil ones is the result of this reduced number of dental types. These dental specialisations allow to try a reconstruction of the way of life of fossil forms. 


  PV article infos

Published in Vol. 16, Fasc. 2 (1986)

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Nouvelle quantification de l'Hypsodontie chez les Theridomyidae : l'exemple de Theridomys ludensis nov. sp.
Monique Vianey-Liaud Logo
Published online: 30/12/1985

Keywords: Dental morphology; evolution; Hypsodonty; Oligocene; Theridomyidae

https://doi.org/10.18563/pv.15.3.159-172

  Abstract

    A new example of parallelism in the dental pattern ofthe Theridomyidae is illustrated by the description ofa new species: Theridomys Iudensis from the standard level of Antoingt (middle Oligocene). Considering the occurence ofthis parallelism phenomenon. the use of numerous qualitative and quantitative criteria is essential to characterize the different stages ofthe different evolutive lineages. Thus, a new simple parameter is proposed (CHY = H+l/0,5 L) to estimate hypsodonty of the medium hypsodont Rodentia. 


  PV article infos

Published in Vol. 15, Fasc. 3 (1985)

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New Late Miocene plecotine bats (Chiroptera, Vespertilionidae: Plecotini) from Gritsev, Ukraine
Valentina V. Rosina, Sergei Kruskop Logo and Yuriy Semenov Logo
Published online: 07/03/2019

Keywords: Barbastella; bats; late Neogene; Mammalia; Plecotus

https://doi.org/10.18563/pv.42.1.e2

  Abstract

    The Late Miocene site of Gritsev (MN 9, Ukraine) has yielded a very rich bat fauna, the remains of which are well preserved. Compared to other Neogene bat assemblages of Europe, the Gritsev bat community is unique in preserving plecotine bats, which are rare from Neogene sites. Some peculiar and new bat species, including a large plecotin Otonycteris, already were described from the Gritsev mammal site. Here we report new records of small plecotin bats from Gritsev, including a new taxon, Barbastella maxima nov. sp. This is the earliest reliable fossil record of this genus and it differs from more recent species of Barbastella in being considerably larger. The evolutionary patterns in the odontology within the tribe Plecotini, supported by biostratigraphical distribution of fossil records of Plecotus are discussed. The morphological peculiarities of the new fossils of plecotine bats from Gritsev are discussed in connection with its possible taxonomical affinity. 


  PV article infos

Published in Vol 42-1 (2019)

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The Quaternary avifauna of Crete, Greece.
Peter D. Weesie
Published online: 01/09/1988

Keywords: Avifauna; Crete; Quaternary; Systematics

https://doi.org/10.18563/pv.18.1.1-94

  Abstract

    Pleistocene bird fossils have been studied from nine localities on Crete. Part of this material was described earlier by the author (Weesie, 1982) and will not be treated here in extenso, the results will be incorporated. More than one third of the over 10,000 fossil bird bones available could be identified ; they were found to represent at least 65 bird species. The following species of the Pleistocene Cretan avifauna are new to the fauna of Crete : Branta ruficollis, Haliaeetus albicilla, Gyps melitensis, Aquila chrysaetos simurgh n. ssp., Ketupa zeylomensis, Aegolius funereus, Dendrocopos leucotos, Zoothera dauma, Turdus iliacus and Pyrrhula pyrrhula. The Pleistocene Cretan avifauna differs less from comparable mainland avifaunas than (fossil) avifaunas from oceanic islands do. Still, the Pleistocene Cretan avifauna has two qualities that are characteristic of island avifaunas : the almost complete absence of a group of birds (the Galliformes) and the presence of two endemic (sub)species : the giant eagle Aquila chrysaetos simurgh n. ssp. and the long-legged owl Athene cretensis (Weesie, 1982). The new subspecies is described in the present study.
    These endemic birds of prey were found in association with their supposedly principal prey species (now extinct as well) : endemic mice for the owl and endemic deer for the eagle. Endemic mammals have been found in association with endemic birds of prey on many islands, not only in the Mediterranean. There is evidence that the size of endemic birds of prey becomes optimally adapted to their feeding on certain endemic mammals, especially rodents. Another characteristic of the Pleistocene Cretan avifauna is the great number of species of birds of prey. This appears to be a common characteristic of fossil avifaunas from caves on Mediterranean islands as well as from caves on the European mainland. However, we think that ecological conditions on Pleistocene Crete (especially the abundant presence of mice) helped to account for the high representation of birds of prey. Furthemore, the fossil avifauna enables us to draw some conclusions about the climate and vegetation on Pleistocene Crete : it is concluded that the climate was cooler than today and that Crete was largely covered with forests. Finally, the reasons for the extinction or disappearance from Crete of some bird species of the Pleistocene Cretan avifauna are discussed. 


  PV article infos

Published in Vol. 18, Fasc. 1 (1988)

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Les mammifères Montiens de Hainin (Paléocène moyen de Belgique) Part III : Marsupiaux
Jean-Yves Crochet and Bernard Sigé
Published online: 30/09/1983

Keywords: Belgium; Marsupials; Paleobiogeography; Paleocene

https://doi.org/10.18563/pv.13.3.51-64

  Abstract

    The oldest european marsupials are described from some specimens (isolated upper molars) recently found from the Hainin sediment (Middle Paleocene of Belgium). These fossils document a new species of the Peradectes genus. They give evidence of a much older occurrence of the marsupials in Europe than it was assumed. They allow us to postulate a didelphid dispersal from South America towards the western-holarctic area operating in two phases : the first one of the Peradectes genus at the end of the Cretaceous; the second one of the Didelphíni tribe at the end of the Paleocene. A central american crossing is likely for the first one,  whereas a transafrican way is tentatively argued for the second one. 


  PV article infos

Published in Vol. 13, Fasc. 3 (1983)

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Contributions à l'étude du gisement Miocène supérieur de Montredon (Hérault). Les grands mammifères. 4 - Les artiodactyles Suidae.
Léonard Ginsburg
Published online: 15/11/1988

Keywords: Artiodactyla; France; Mammalia; Montredon; Upper Miocene

https://doi.org/10.18563/pv.18.ext.57-64

  Abstract

    There is only one suid known in the Upper Miocene of Montredon (Hérault): Microstonyx (Limnostonyx nov. subgen.) antiquus (KAUP). It is differenciated from Microstonyx major by the presence of upper and lower canines which are considerably longer and biger. Its presence at Montredon corroborates the palustrine habitat for the species. 


  PV article infos

Published in Vol. 18, Ext (1988)

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Etude de la Variabilité chez Lophiodon lautricense Noulet
Jean Sudre
Published online: 28/02/1971

Keywords: Cheek teeth; Eocene; Lophiodon; variability

https://doi.org/10.18563/pv.4.3.67-95

  Abstract

    The biometric and morphologie variability of the cheek teeth in the end-of-the-phylum species Lophiodon lautricense Noulet studied in this note, reposes on the observation of about 800 teeth. These were revealed to be little variable in absolute dimensions. The considerable morphologie variability in the upper premolars permitted the problem of the molarization process to be taken up. An hypothesis concerning the order of eruption of the cheek teeth is formulated based on an examination of a large number of milk dentitions. In conclusion, it is suggested that reservations be held on the value of dental characters classically used in systematics for the group under consideration. 


  PV article infos

Published in Vol. 04, Fasc. 3 (1971)

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Contribution à l'étude des Cricétidés oligocènes d'Europe occidentale
Monique Vianey-Liaud Logo
Published online: 20/01/1972

Keywords: Cricetidae; Europe; Oligocene

https://doi.org/10.18563/pv.5.1.1-44

  Abstract

    Of the ten cricetid species from the Oligocene of Western Europe, attributed until now to the genus Eucricetodon, only four prove to be utilizable - E. atavus, E. huberi, E. praecursor, E. collatum - to which it is possible to add two forms newly described: E. huerzeleri and E. quercyi. The evolullon of the genus Pseudocricetodon is also the subject of new observations. The study of the dental morphology allows us to distinguish in these two genera three lineages beginning in the middle Oligocene:

    - Lineage P. montalbenensis-P. thaleri (from Montalban to Goderet), of small size, without
    increase in size.
    - LineageE. atavus-E. infralactorensis (from Hoogbulsel to Estrepouy), of middle size, with a regular increase in size.
    - Lineage E. huerzeleri-E. haslachense (level of Montalban to that of Estrepouy), of large size, with an increase in size.

    Two other forms are equally represented in these loealitles: Heterocricetodon aff. helbengi and Melissiodon quercyi. It has been possible to attribute a precise age (zone of "Cournon") to the last species, which has been defined by Schaub (l925) from material in the Old Quercy collections. The genera Pseudocricetodon, Eucricetodon, ? "Cricetodon", Leydimys, Eumys, differentiated at the beginning of the middle Oligocene in Europe, Asia and North America, seem to derive from a common ancestral group. The place of origin of this group could be situated in Asia. 


  PV article infos

Published in Vol. 05, Fasc. 1 (1972)

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Contributions à l'étude du gisement Miocène supérieur de Montredon (Hérault). Les grands mammifères. 2 - les carnivores
Gérard de Beaumont
Published online: 15/11/1988

Keywords: anatomy; Carnivora; France; Montredon; Systematics; Upper Miocene

https://doi.org/10.18563/pv.18.ext.15-42

  Abstract

    The locality of Montredon has provided 8 species of camivores, often little documented, that are discribed and depicted. All the remains are fragmentary and generally badly preserved which lowers very much the possible precision of the taxonomic study; this one has however allowed the creation of a new subspecies. The most richlypdocumented forms are an ursid (Indarctos) and a felid (Machairodus). Issuing often from a westem Europe evolution, the carnivores are well inserted between those of the better known faunas of the "Classical Pontian" and of the lower Vallesian and this situation fits also well with their stratigraphic level, that cannot however be more accurately defined with them alone.
      


  PV article infos

Published in Vol. 18, Ext (1988)

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A new species of Propalaeotherium (Palaeotheriidae, Perissodactyla, Mammalia) from the Middle Eocene locality of Aumelas (Hérault, France).
Jean-Albert Remy, Gabriel Krasovec Logo and Bernard Marandat
Published online: 24/05/2016

Keywords: Eocene; new species; Palaeotheriidae; Propalaeotherium

https://doi.org/10.18563/pv.40.2.e1

  Abstract

    A new Propalaeotherium species, clearly distinct from the genus Eurohippus, is described. It is characterized by having a similar size as P. voigti from the German Geiseltal localities (MP 11 to MP 13 reference-level), but differs in several features suggesting a slighty more derived morphology. It presents indeed less brachyodont crowns with less prominent and less elevated cingula, slightly larger relative surface of premolars, and a more marked metaconid splitting on cheek teeth. This new species is unknown from other European localities except the nearby Saint-Martin de Londres locality which has been considered older than the MP 13 level. 


  PV article infos

Published in Vol.40-2 (2016)

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S.I. Data
Rongeurs nouveaux de l'Oligocène Moyen d'Espagne.
Louis Thaler
Published online: 15/09/1969

Keywords: Cricetidae; Oligocene; Pseudocricetodon; Rodents; Theridomys

https://doi.org/10.18563/pv.2.5.191-207

  Abstract

    Description of four new rodents from a recently discovered locality at Montalban. Theridomys crusafonti nov. sp. is considered as the ancestry of T. Iembronicus. Theridomys varian: nov. sp. includes «Theridomys» morphotypes and «Blainvilllimys» morphotypes; it could be ancestral to B. blainvillei. Pseudoltinomys nanus nov. sp. represents a new lineage paralleling in evolution that of P. gaillardi (which is equally found at Montalban). Pseudocricetodon montalbanensis nov. gen., nov. sp. designates a lineage of very small Cricetidae accompanying Eucricetodon. With these well defined new species and six others present in the locality, Montalban appears as the best faunal reference point within the biochronologic zone of La Sauvetat.
    As an annex, discussion of two rodent specimens from the classic localíty of Tárrega, close in age to that of Montalban. 


  PV article infos

Published in Vol. 02, Fasc. 5 (1969)

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Compléments sur les Chiroptères de l'Eocène moyen d'Europe. Les genres Palaeochiropteryx et Cecilionycteris.
Bernard Sigé and Donald E. Russell
Published online: 01/10/1980

Keywords: Chiroptera; Geiseltal; Messel; Middle Eocene

https://doi.org/10.18563/pv.9.ext.91-126

  Abstract

    New dental and skeletal material referable to Palaeochiropteryx tupaiodon from the Middle Eocene locality of
    Messel (G.F.R.) is studied, which provides additions to the previously gained knowledge of this european genus. Dental specimens from Geiseltal (G.D.R.), also of Middle Eocene age, allow us to analyze Cecilionycteria prisca. Some of these are separated to establish a new genus, Matthesia, and two new species, M. germanica and M. ? insolita


  PV article infos

Published in Vol. 9, Ext (1980)

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New Squalicorax species (Neoselachii: Lamniformes) from the Lower Maastrichtian of Ganntour phosphate deposit, Morocco
Henri Cappetta Logo, Sylvain Adnet Logo, Driss Akkrim and Mohammed Amalik
Published online: 05/12/2014

Keywords: Anacoracidae; Chondrichthyes; Maastrichtian; Morocco; New taxa

https://doi.org/10.18563/pv.38.2.e3

  Abstract

    Two new Squalicorax species, S. benguerirensis nov. sp. and S. microserratus nov. sp. are described from the Lower Maastrichtian of the Benguérir phosphate open mine, Ganntour deposit, Morocco. The species S. benguerirensis nov. sp. was classically assigned to S. yangaensis since Arambourg (1952) and has been also recognized in coeval deposits from eastern USA to Mid-East. The species S. microserratus nov. sp. correspond to the lateral teeth of S. kaupi as reported by Arambourg (1952) and which is now referred in fact to S. bassanii. The comparison of these two new species with other Anacoracids, known in Moroccan or elsewhere, allows highlighting the great taxonomic and ecological diversities of this family during the Cretaceous.
      


  PV article infos

Published in Vol.38-2 (2014)

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An Australian Miocene Brachipposideros (Mammalia, Chiroptera) related to Miocene representatives from France
Bernard Sigé, Suzanne J. Hand Logo and Michael Archer Logo
Published online: 15/12/1982

Keywords: Australia; bats; Chiroptera; Miocene

https://doi.org/10.18563/pv.12.5.149-172

  Abstract

    A new middle Miocene hipposiderid bat is described from a limestone deposit on Riversleigh Station in north-western Queensland. Hipposideros (Brachipposideros) nooraleebus n. sp. is the first record of this subgenus from anywhere in the world outside of France. The palaeoecological setting of the fossil bats appears to have been a relatively quiet, sunny lime-enriched tropical pool that contained tortoises, crocodiles and fish. It is possible that the bats were washed into the pool from an adjacent cave.
    The Riversleigh bat most closely resembles the French Burdigalian (early middle Miocene) bat H. (B.) aguilari. It is also possible that it may have been closely related to the original Australian hipposiderid stock that ultimately gave rise to the endemic monotÿpic Rhinonycteris aurantius. The disjunct distribution of species of H. (Brachipposideros) suggests that representatives of this subgenus will be found in at least tropical southern Asia. 


  PV article infos

Published in Vol. 12, Fasc. 5 (1982)

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A new species of hippopotamine (Cetartiodactyla, Hippopotamidae) from the late Miocene Baynunah Formation, Abu Dhabi, United Arab Emirates
Jean-Renaud Boisserie Logo, Mathieu Schuster Logo, Mark J. Beech Logo, Andrew Hill and Faysal Bibi Logo
Published online: 07/04/2017

Keywords: Arab Peninsula; Hippopotamidae; Hippopotamine event; Systematics

https://doi.org/10.18563/pv.41.1.e2

  Abstract

    The discovery of new hippopotamid material from the late Miocene Baynunah Formation (Abu Dhabi, United Arab Emirates) has prompted the revision of the existing material of this as yet unnamed fossil taxon. The Baynunah hippopotamid appears to be distinct from all other contemporary and later species in having a relatively more elongate symphysis, a feature similar to the earlier (and more primitive) Kenyapotamus. Yet, the Baynunah hippopotamid presents a dentition typical of the Hippopotaminae. It is therefore a distinct species attributed to the later subfamily, described and named in this contribution. This species provides further evidence for a ca. 8 Ma evolutionary event (termed “Hippopotamine Event”) that initiated the spread and ecological significance of the Hippopotaminae into wet habitats across Africa and Eurasia. The morphological affinities of the new species from Abu Dhabi suggest that the Arabian Peninsula was not a dispersal route from Africa toward southern Asia for the Hippopotamidae at ca. 7.5 Ma to 6.5 Ma. 


  PV article infos

Published in Vol 41-1 (2018)

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S.I. Data
Nouvelles données sur les Ichnites de dinosaures d'El Bayadh (Crétacé Inférieur, Algérie)
Mostefa Bessedik Logo, Cheikh Mammeri, Lahcene Belkebir Logo, Mahammed Mahboubi, Mohamed Adaci Logo, Hakim Hebib Logo, Mustapha Bensalah Logo, Bouhameur Mansour Logo and Mohammed E. H. Mansouri Logo
Published online: 16/12/2008

Keywords: Algeria; Brezina; El Bayadh; Ichnites; Lower Cretaceous; Sauropoids; Theropoids

https://doi.org/10.18563/pv.36.1-4.7-35

  Abstract

    Evidence of 350 Lower Cretaceous Dinosaur footprints is pointed out in El Bayadh area. Their preliminary study allow to distinguish four trackway assemblages which reveal vertebrate bipedal presence forms of tri-and tetradactylous Dinosauroïds (Assemblages 1-3) and quadrupidal Sauropoïd (Assemblage 4).

    The analysis of their footprint biometric features will attribute the quadrupidal Sauropoïd form to Brontopodus ichnogenus which is weIl known in the Jurassic and Cretaceous periods. In retum and despite their age, the dinosauroïd forms were approached, temporarily, to Grallator and Eubrontes types.

    The occurrence of the dinosaur traces (Theropoïd and Sauropoïd) constitutes, in the Lower Cretaceous, an important first step of the knowlege of the marshy Reptilian fauna which takes over, from the begining of the Secondary Era, a wide paleogeographie area on the Southem Tethyan margin. 


  PV article infos

Published in Vol. 36, Fasc. 1-4 (2008)

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New datation of the Tafna Basin (Algeria): A combination between biochronological and magnetostratigraphical data
Salamet Mahboubi Logo, Mouloud Benammi Logo and Jean-Jacques Jaeger Logo
Published online: 11/03/2015

Keywords: correlations; Late Miocene; North Africa; Rodentia

https://doi.org/10.18563/pv.39.1.e1

  Abstract

    The Tafna Basin corresponds to the lowlands, which are located in front of Tessala and Traras ranges, below the Tlemcen mountains, Algeria. This basin displays a complete sedimentary cycle dominated by lagoonal-fluvial and marine deposits. The continental formations located at the base of these deposits are mainly composed of alternating sandstones and clays. An early late Miocene age has been previously attributed to them, based on direct correlations with marine deposits. Search for micromammal fossils led to the discovery of three different rodent species from a single level of the Djebel Guetaf section, located at the bottom of these deposits. The rodent assemblage indicates a late Miocene age. Combined magnetostratigraphical and biostratigraphical investigations were carried out to provide a more accurate age control of these continental deposits. Sixty-four oriented rock samples were collected for a magnetostratigraphic study along a 92 meters thick section including the fossiliferous layer. Rock magnetic investigations indicate the presence of both high and low coercivity minerals. Specimens subjected to progressive thermal demagnetization procedures show that the samples exhibit a high temperature magnetization component and display a normal polarity. Based on biostratigraphic constraints, the Guetaf section is correlated with Chron C4An, indicating an age ranging from
    9.1 to 8.7 Myr.
      


  PV article infos

Published in Vol.39-1 (2015)

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Comparative bone histology of rhabdodontid dinosaurs
Edina Prondvai Logo
Published online: 17/11/2014

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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Page 5 of 19, showing 20 record(s) out of 365 total