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Les rongeurs du Miocène moyen et supérieur du Maghreb
Jean-Jacques Jaeger
Keywords: Neogene; North Africa; Rodentia
 
  Abstract

         The Faunas of Rodents from seven north-african fossiliferous beds distributed from the Middle up to the Uppest Miocene are studied. One genus, seventeen species, one subspecies described are new.
           A detailed description is given of the evolution of the numerous specific lines, systematic groups and communities. The evidence of the strong endemism of the North African faunas of that time compared with those of Europe as well as of Tropical Africa is clearly shown. Special relationships with Asia clearly also appear, mostly in the Middle Miocene and the beginning of the Upper Miocene.
           Using the specific lines with a biostratigraphic purpose gives the opportunity to establish a biochronological scale for the continental formations of the Maghreb. This scale is calibrated by a few absolute datations. These datations, as well as the stratigraphical study of several fossiliferous localities have given the possibility to establish precise correlations with the corresponding scales of Europe and of Tropical Africa, as well as with the marine formations of the Neogene of occidental Mediterranean sea.
           The paleoclimatic data connected with this period in North Africa are explained and the contribution of the micromammals is discussed. 


  Article infos

Published in Vol. 08, Fasc. 1 (1977)

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La morphologie dentaire des Thalattosuchia (Crocodylia, Mesosuchia).
Patrick Vignaud
Keywords: Dental morphology; Dental types; feeding habits.; Jurassic; Metriorhynchidae; Systematics; Teleosauridae; Thalattosuchia
 
  Abstract

    The tooth morphology of the Thalattosuchia (marine crocodilians from the Jurassic and the Early Cretaceous) is analysed. The Callovian from Poitou and the Kimmeridgian from Quercy have yielded many remains of Metriorhynchus, Steneosaurus and Machimosaurus. These remains allow us to study the variations of tooth morphology during ontogenic growth, tooth replacement and the location of the teeth. We have defined different tooth types for these genera. In Metriorhynchus, the two tooth types defined do not coincide with the two groups recognized in the Callovian (broad-skulled and narrow-skulled metriorhynchids) but reflect the prey preferences of these forms. In Steneosaurus and Machimosaurus the five tooth types deñned are in agreement with the main taxa known from the Bathonian to the Early Cretaceous. This study allows to precise the function and the prey preference of the Thalattosuchia during the Jurassic and the Early Cretaceous.

      


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Published in Vol. 26, Fasc. 1-4 (1997)

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Contributions à l'étude du gisement Miocène supérieur de Montredon (Hérault). Les grands mammifères. 5 - Les périssodactyles Equidae
Véra Eisenmann
Keywords: Equidae; Hipparion; Late Vallesian; Mammalia; Montredon; Perissodactyla
 
  Abstract

    Revision of the hipparion material from Montredon, including newly excavated and other unpublished specimens brings evidence of specific heterogeneity.
    A fragmentary very small MC III seems very close to H. macedonicum from the upper Vallesian of Ravin de la Pluie, Greece. In that same site was also found a large hipparion.
    Most of the Montredon material is referred to H. depereti. This species associates characters usually found in Vallesian hipparions (highly plicated upper cheek teeth, deep vestíbular grooves on the lower cheek teeth, robust metapodials) with characters more frequent in Turolian forms (middle size, lack of confluence in the upper premolar fossettes, lack of ectostylids on the adult lower cheek teeth, well developped keel on the MC III, facette for the 2nd cuneiform present on all MT III). H. depereti shares some of these characters with the Spanish and Portuguese hipparions transítional between the Vallesian and the Turolian (Masia del Barbo, Azambujeira) but is not identícal to any of them. The upper Vallesian hipparion material from Diavata, Greece, probably belongs to H. depereti but not the large hipparion rests from Ravin de la Pluie.
    Thus, Montredon and Ravin de la Pluie may well share the same small species, H. macedonicum, but they differ in the associated one: middle-sized H. depereti at Montredon, large-sized H. primigenium at Ravin de la Pluie. Both sites, however, give evidence of small hipparions during the Vallesian, coexisting with other larger species.
    The present paper also proposes an adaptation of the Kiesewalter's indices that calculates the height at the withers using the metapodial length, and discusses indices proposed by Gromova and by Sen et al. to express the relative development of the metapodial keel. 


  Article infos

Published in Vol. 18, Ext (1988)

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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, Daniel Goujet and Alain Blieck
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. 


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

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Designating a lectotype for Mesacanthus pusillus (Gnathostomata: Acanthodii)
Matthew Baron and Kevin Seymour
Keywords: acanthodians; Chordata; Devonian; Midland Valley; Orcadian Basin

doi: 10.18563/pv.44.1.e2
 
  Abstract

    The early gnathostome genus Mesacanthus is well represented in both Lower Old Red Sandstone and Middle Old Red Sandstone assemblages of northern and central Scotland. This ‘acanthodian’ taxon is currently thought to comprise two valid species: M. mitchelli and M. pusillus. Although the whereabouts of the holotype of M. mitchelli (NHMUK PV P560) is known, the syntype material for M. pusillus has long been thought lost. Here we identify at least one specimen that formed part of the original syntype material for M. pusillus, albeit in a slightly different condition than when it was originally figured. This specimen is ROM 25872, which is here designated as the lectotype. A second specimen – ELGNM 1978.191.1 – could represent another of the syntype specimens, but poor preservation quality makes it impossible to be certain. 


  Article infos

Published in 44-1 (2021)

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Les Paramyidae (Rodentia) de l'Eocène inférieur du bassin de Paris.
Jacques Michaux
Keywords: Ailuraviinae; Eocene; Paramyinae; Rodents

doi: 10.18563/pv.1.4.135-193
 
  Abstract

    The exploitation of new early Eocene localities in the Paris Basin has resulted in the collecting of  numerous mammalian remains, among which are about 300 isolated teeth representing the rodents. They belong, for the most part, to the paramyid group. Only the latest level of the early Eocene has yielded rodents belonging to the pseudosciurid group. The paramyids, the object of this study, are represented by at least 5 genera and 10 species; they are distributed among 4 clearly dilferentiated subfamilies : Paramyinae Simpson 1945, Pseudoparamyinae Michaux 1964, Ailuraviínae n. subf., Microparamyinae Wood1962.
    It results from this study that the principal types of rodents in the middle and late Eocene of Europe are clearly related to the forms described here: Plesiarctomys Bravard 1850 is related to Pseudoparamys Michaux 1964, Ailuravus Rütimeyer1891 to Meldimys n. gen., Gliravus hammeli Thaler 1966 to Microparamys nanus (Theilard1927), and some Masillamys Tobien 1954 to Microparamys russelli Michaux 1964 and to M. sp. 1. Gliravus and Masillamys are the oldest representatives of the Gliridae and the Pseudosciurídae, respectively, families which will progressively replace the Paramyidae in the course of the middle and late Eocene.
    Two stages can be recognized in the history of te European Paramyidae fauna during the course of the early Eocene: the older is characterized by the Mutigny fauna, the younger by the Cuis fauna.
    The Mutigny fauna appears already rather diversified and does not completely correspond, point by point, to the homologous fauna of North America. A geographic differentiation seems to have been manifested rapidly, unless the fauna established in Europe was already a little different from that which established itself in North America. 


  Article infos

Published in Vol. 01, Fasc. 4 (1968)

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Lissamphibians from Dams (Quercy, SW France): Taxonomic identification and evolution across the Eocene-Oligocene transition
Alfred Lemierre and Maeva J. Orliac
Keywords: Eocene-Oligocene; Grande Coupure; Lissamphibia; Quercy Phosphorites

doi: 10.18563/pv.48.1.e3
 
  Abstract

    The locality of Dams (Quercy, southwestern France) has yielded two fossil assemblages, one from the late Eocene and another from the early Oligocene, making it one of the few localities with infillings across the Eocene-Oligocene transition. At least 24 taxa (13 mammals, 11 snakes) have been identified in this locality. Study of the lissamphibian remains from Dams yields an Eocene and an Oligocene assemblage, with a total of eight taxa. The Eocene assemblage includes two unnamed salamandrine species, one unnamed pelobatid species and one pyxicephalid species (Thaumastosaurus). The Oligocene assemblage includes two unnamed pleurodeline species, one salamandrine species (Salamandra sansaniensis) and an unnamed pelobatid species. Among the eight taxa from Dams, one Eocene salamandrine and one Oligocene pleurodeline are identified for the first time in the Quercy. A review of the lissamphibians from the Quercy area identifies eleven taxa for the Late Eocene (MP19) and eight taxa for Early Oligocene (MP22), with a major turnover at the Eocene-Oligocene transition. This turnover occurs in a time of major climatic changes, with a significant decrease in temperature and precipitation and concurrent increase in seasonality in Europe, likely affecting specialized taxa.
      


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in press

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Les Périssodactyles (Mammalia) du gisement Bartonien supérieur de Robiac (Éocène moyen du Gard, Sud de la France)
Jean-Albert Remy
Keywords: Chasmotherium; new species; Palaeotheriidae; paleoenvironments

doi: 10.18563/pv.39.1.e3
 
  Abstract

    We present here a new updated counting of the perissodactyls of Robiac, the type locality of the MP 16 level of the biochronological scale of paleogene mammals and that of the Robiacian stage of Eocene Land Mammals Ages in Western Europe.
    The outcrop of Robiac consists actually of two 500m apart loci, Robiac-Nord and Robiac-Sud, considered of the same age according to the current discriminating power, and is dated from -38,7 MA after the last faunal, magnetostratigraphic and climatic calibrations.
    It has yielded a very abundant and rich of 21 taxa perissodactyl fauna, topped by the giant Lophiodon lautricense, last representative of the family Lophiodontidae, of which it is the last proved deposit. The Palaeotheriidae are much diversified with 5 genera and 9 species of "Pachynolophinae", 3 genera and 10 species of Palaeotheriinae. Nine taxa have been defined from Robiac: Chasmotherium depereti n. sp., Palaeotherium castrense robiacense Franzen, 1968, the genus Leptolophus Remy, 1965 with the species L. stehlini Remy, 1965 and L. magnus Remy, 1998, Anchilophus (Paranchilophus) jeanteti Remy, 2012, Metanchilophus chaubeti Remy, 2012, Lophiotherium robiacense Depéret, 1917 and Pachynolophus gaytei n. sp.
    The faunal Robiac cenogram with the associated flora testify to a hot, wet and forestal environment, likely corresponding to a short warming climatic phase; the broken up fossil bones should have been carried away and then gathered in swamp areas along the banks of a meandering river.
    The swarm of mammals of Robiac, the richest of contemporaneous deposits, has been followed by a drastic drop in perissodactyl diversity at the MP 17A level; a crisis which could have originated in a renewal of the global Eocene cooling. Fons 4, the type-locality of this level, is largely scarcer in perissodactyls and its cenogram testifies to a less diversified fauna, with on the whole smaller species, that likely means a cooler and drier climatic environment; a new perissodactyl diversification occurred but later.
      


  Article infos

Published in Vol.39-1 (2015)

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Reflections on some Russian eotheriodonts (Reptilia, Synapsida, Therapsida)
Denise Sigogneau-Russell and P. K. Tchudinov
Keywords: Reptilia; Russia; Synapsida; Therapsida

doi: 10.18563/pv.5.3.79-109
 
  Abstract

    As a result of the enrichment of eotheriodont material by one of us (P.K.T.), these specimens (essentially Biarmosuchur and Eotitanosuchur) are reexamined and refigured. A reevaluation of their particularities supports the distinction of two families, for which new diagnoses are proposed. This leads us to discuss the affinities of these families, with respect to the sphenacodonts on one hand, and to the South African primitive theriodonts on the other (gorgonopsids and ictidorhinids). This study contains inherent paleogeographic consequences which are considered in conclusion. 


  Article infos

Published in Vol. 05, Fasc. 3 (1972)

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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 and Bernard Marandat
Keywords: Eocene; new species; Palaeotheriidae; Propalaeotherium

doi: 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. 


  Article infos

Published in Vol.40-2 (2016)

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Mammifères de l'Ilerdien Moyen (Eocène inférieur) des Corbières et du Minervois (Bas-Languedoc, France). Systématique, Biostratigraphie, Corrélations.
Bernard Marandat
Keywords: Biostratigraphy; Corbières; correlations; Early Eocene; Ilerdian; Mammalia; Minervois; Paleobiogeography; Southern France
 
  Abstract

    Mammal-bearing localities have been discovered in the marine and lacustrine series of the middle Ilerdian (Lowermost Eocene) from Southem France (Minervois and Corbières). In the localities of Fordones, Monze, Fournès, and La Gasque, thirty mammal species have been identified. Among others, they include ischyromyid rodents (Microparamys and Pseudoparamys), paromomyid and adapid primates (Arcius and Donrussellia), new insectivores, condylarths, and a dyspternine pantolestid. These faunas provide new informations on the early Eocene Mesogean faunas of Rians and Palette. The assemblages of primates and rodents from Fordones support good  correlations with Palette which was recently placed near the standard-level of Dormaal (MP 7). In fact, Palette and Fordones could be even older than Dormaal. Consequently, there seems to be a relatively important temporal gap between the late Paleocene of Cernay and the Sparnacian of Dormaal. This gap could be partly filled with the Mesogean faunas of Palette, Fordones, and Silveirinha. On the basis of these new mammal faunas the marine middle Ilerdian is proved to be older than the Cuisian stage of the Paris Basin. With regards to the position of the Fordones fauna at the top of the NP 10 calcareous nannoplankton biozone, the westem European paleomammalogists Paleocene/Eocene boundary could be situated between the NP 9 and NP 10 biozones. 


  Article infos

Published in Vol. 20, Fasc. 2-3 (1991)

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Une faunule de vertébrés sous la base de grès de Celas (Eocène supérieur) à ST Dresery (Gard)
Jean-Albert Remy
Keywords: Artiodactyla; Biostratigraphy; Eocene; Mammals
 
  Abstract

    The St-Dézéry local fauna (3 reptile-, 4 mammal species) is approximately of the same age as the La Débruge or the Ste-Néboule faunas. It conduces to a better dating of the limestones underlying the Célas sandstones. A large part of a mandible of Amphimeryx was found there, which documents the record of this family of small artiodactyls 


  Article infos

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

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The paramyid rodent Ailuravus from the middle and late Eocene of Europe, and its relationships
Albert E. Wood
Keywords: Ailuravinae; Rodentia
 
  Abstract

    The complex taxonomic history of the paramyid rodent genus Ailuravus is reviewed. It has been described as Hyracotherium, as a creodont carnivore and as a lemuroid primate - errors at the ordínal level that are most unusual for a rodent. The genus is a member of the poorly known subfamily Ailuravinae, probably derived from some European Early Eocene species of Paramys. Aíluravus was a large arboreal paramyid with highly rugose cheek teeth, very well developed hypocone, and a remarkably weak lower incisor. It was tropical to subtropical. Three named species are recognized, A. macrurus from the Lutetian of Messel; the genotype, A. picteti, from Egerkingen, Buchsweiler and the Geiseltal, slightly later in the Lutetian; and A. stehlinschaubi, new name, from the Bartonian of Mormont-Eclépens and Robiac. One or more unnamed species are present in the Ypresian of Cuis. The species are close to a phyletic sequence. No later representatives of the genus are known. The late Eocene to earliest Oligocene North American paramyid Mytonomys, whose relationships have been obscure, is tentatively referred to the Ailuravinae. 


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Published in Vol. 07, Fasc. 1-2 (1976)

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Evolution de la lignée Megacricetodon collongensis-Megacricetotodon roussillonensis (Cricetidae, Rodentia, mammalia) au cours du Midocène inférieur et moyen dans le Sud de la France.
Jean-Pierre Aguilar
Keywords: Cricetids rodents; Evolutionary lineage; Lower and Middle Miocene; Mammalian biochronology; Megacricetodon new species; Southern France
 
  Abstract

    New populations of the genus Megacricetodon have recently been discovered in Southern France.Two new species are defined: M. lemartineli n. sp. and M. fournasi n. sp., their stages of evolution are intermediate between those of M. gersii and M. roussillonensis. Morphological and biometrical analysis indicate the presence of only one lineage: M. collongensis--M. collongensis-gersii--M. gersii--M.lemartineli nov. sp.--M. fournasi nov. sp. and M. roussillonensis. This observation allows to refine the chronology based on rodents, for the Late Early Miocene and the Middle Miocene in the Southern France.
    Comparisons with some iberian species are done. The validity of the French species M. bezianensis and M. bourgeoisi is discussed. 


  Article infos

Published in Vol. 24, Fasc. 1-2 (1995)

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Pantolestidae nouveaux (Mammalia, Insectivora) de l'Eocène moyen de Bouxwiller (Alsace).
Jean-Jacques Jaeger
Keywords: Bouxwiller; Insectivora; Mammalia; Middle Eocene; Pantolestidae

doi: 10.18563/pv.3.3.63-82
 
  Abstract

    The Pantolestidae from the middle eocene of Bouxwiller are the subject of a detailed study. Buxolestes hammeli (n. g., n. sp.) is not closely related to any other European or North American form described until now; it presents, however, some characters in common with Pantolestes, a form of the same age from North America. A parallel evolution from a common ancestral form could explain this ressemblance.
    Another form (gen. and sp. indet.) accompanies Buxolertes hammeli in the Bouxwiller fauna.
      


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Published in Vol. 03, Fasc. 3 (1970)

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First evidence of an early Miocene marine teleostean fish fauna (otoliths) from la Paillade.(Montpellier,France)
Bettina Reichenbacher and Henri Cappetta
Keywords: Aquitanian; Biostratigraphy; La Paillade; marine deposits; Miocene; otoliths; Palaeoecology; Palaeogeography; Southern France; Teleostei
 
  Abstract

    A fossil fish fauna, based on 5533 otoliths, from the La Paillade locality at Montpellier is described and figured. The otolith-bearing marls correlate to mammal zone MN l (Aguilar, 1982), and thus represent the earliest Miocene. The fish fauna consists of 30 taxa belonging to 20 families. Two species are new: Dussumieria sittigi and Liza gaudanti. The predominant faunal element is the Lesueurigobius vicínalis-species complex, composing 73% of all investigated otoliths. The palaeoecological analysis reveals a marine to euryhaline fish fauna living under tropical to subtropical conditions in the transition zone littoral - sublittoral. Water depth probably was more than 10 m. The scarcity of pelagic físhes suggests that the habitat was either a sheltered bay and/or far away from the open sea. Furthermore, some genera represented in the La Paillade fish fauna presently live exclusively in the Indopacific realm. Their presence strongly supports a broad connection between the Indian Ocean, the Mediterranean, and the Paratethys Seas during the Early Miocene (Aquitanian). From a palaeobiogeographical point of view, faunal relationships were found between the La Paillade fish fauna and both the Paratethys fish fauna and the fish fauna from the deposits in the Upper Rhinegraben and the Mayence and Hanau Basins (Germany).



      


  Article infos

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

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Mammals and stratigraphy : the Paleocene of Europe
Donald E. Russell, Jean-Louis Hartenberger, Charles Pomerol, Sevket Sen, Norbert Schmidt-Kittler and Monique Vianey-Liaud
Keywords: Europe; Mammalia; Mammalian biochronology; Paléogène; Stratigraphy
 
  Abstract

    The mammalian faunas of the Paleogene of Europe and their localities are reviewed with comments on problems of European stratigraphy (epoch, stage and substage limits) and on the possibilities of faunal migrations. Radiometric dating is discussed. A stratigraphic scale for the Paleogene is presented, as well as a refined system of sequential faunal levels. 


  Article infos

Published in Vol. 12, Ext (1982)

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Les serpents des phosphorites du Quercy
Jean-Claude Rage
Keywords: Grande Coupure; Quercy Phosphorites; Serpents
 
  Abstract

    A short review of the genera and species of snakes from the Quercy's phosphorites described by former authors is followed by the study of specimens recently collected. Most of these latter specimens belong to the Aniliidae, Boidae, Colubridae and to the Scolecophidia; the precise systematic position of some of them is not defined yet. The following genera and species are described: Eonilius europae nov. gen. and nov. sp., Platyspondylia lepta nov. gen. and nov. sp., Coluber cadurci nov. sp. and Dunnophis cadurcensis nov.  sp.; a species described by de Rochebrune (Palaeopython filholi) is revised. One of the most important conclusions of this study is that the Colubridae appear as early as the Upper Eocene. The stratigraphic repartition of these snakes shows that the rich Upper Eocene fauna is followed by the very reduced fauna of the Lower Oligocene; then the oligocene «Grande Coupure» corresponds to a very important faunistic renewal. The fauna remains poor and little diversified during the beginning of the Middle Oligocene after which there is a new faunistic explosion. 


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

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Nouvelle quantification de l'Hypsodontie chez les Theridomyidae : l'exemple de Theridomys ludensis nov. sp.
Monique Vianey-Liaud
Keywords: Dental morphology; evolution; Hypsodonty; Oligocene; Theridomyidae
 
  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. 


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

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Schmelzmikrostruktur in den inzisiven alt-und neuweltlicher histricognather nagetiere
Thomas Martin
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.
      


  Article infos

Published in Vol. 21, Ext (1992)

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