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Contributions à l'étude du gisement Miocène supérieur de Montredon (Hérault). Les grands mammifères. 4 - Les artiodactyles Suidae.
Léonard Ginsburg
Keywords: Artiodactyla; France; Mammalia; Montredon; Upper Miocene
 
  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. 


  Article infos

Published in Vol. 18, Ext (1988)

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

doi: 10.18563/pv.39.2.e1
 
  Abstract

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


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Published in Vol.39-2 (2015)

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Cervus elaphus rossii (Mammalia, Artiodactyla), a new endemic sub-species from the Middle Pleistocene of Corsica
Elisabeth Pereira
Keywords: Cervus elaphus; Corsica; Endemism; Pleistocene
 
  Abstract

    Several endemic deer remains from the Middle Pleistocene deposits of the Castiglione cave (Oletta, Haute-Corse) are examined here. A morphometric analysis allows to relate them to a new insular subspecies Cervus elaphus rossii. The bones were compared with those of the mainland early Middle Pleistocene subspecies Cervus elaphus acoronatus Beninde and the European species Cervus elaphus Linné (Late Middle Pleistocene and Upper Pleistocene forms (continental and insular)). The Castiglione fossil shows peculiar morphofunctional features in its appendicular skeleton suggesting a morphological convergence with certain Bovidae. 


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

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Les traces de pas de Dinosaures et autres Archosaures du Lias inférieur des grands Causses, Sud de la France
Georges Demathieu, Georges Gand, Jacques Sciau, Pierre Freytet and Jacques Garric
Keywords: Dinosauroid footprints; France; Grands-Causses; Hettangian; ichnostratigraphy; paleoenvironments; Sinemurian; statistical results

doi: 10.18563/pv.31.1-4.1-143
 
  Abstract

    The Causses" is a near 3400 km2 large plateau located in the south of France. Here the first dinosaur footprints where found in 1935. After this, this area has yielded an ever-increasing number of ichnites now in excess of 500 specimens. These latter, 15 to 50 cm long, tridactyl or tetradactyl footprints of generally biped animals, were discovered at the surface of Hettangian to lower Sinemurian dolomite layers within 4 distinct stratigraphic units. The 35 sites bearing ichnites are located on the plateau margin. For the first time, morphologic characters studied through descriptive statistic methods with the usual parameters and classical Student and Snédecor tests, allowed us, to divide the whole set of biped traces into 6 ichnospecies. Their definitions are further constrained by multivariate statistical results using Principal Component Analysis (PCA), Factor Analysis of correspondances (FAC) and Discriminant Analysis (DA). All have confirmed the morphologic observations. So that now, the following taxa are identified : Grallator variabilis, G. lescurei, G. sauclierensis, G. minusculus, Eubrontes giganteus, Dilophosauripus williamsi, cf. Moraesichnium, Orníthopus fabrei nov ichnosp. The more immediately visible differences relate to the interdigital II-IV divarication and the digit length ratio. To this panel, we must add Batrachopus deweyi and shapes suggesting Trisauropodichnus and/or Anomoepus. Among all ichnite associations described in the lower Liasic, the New England assemblage presents the most affinities with ours. It shows the ichnotaxa Grallator, Dilophosauripus, Eubrontes, Batrachopus without forgetting Ornithopus fabrei nov. ichnosp. which is close to Ornithopus gallinaceus from the Massachusetts and Connecticut basins. On comparing the present early Jurassic ichnofauna of the Causses with the ones of the Middle and Upper Triassic formations of the eastem border of the Massif Central (France), it appears that tridactyl footprints become more and more numerous and large from Triassic to Early Jurassic. In the Causses, these latest are prevalent but in Quercy (France), Poland, Italy, USA, they are also associated with Omithopoda, Thyreophora and Sauropoda ichnites. Footprint areas considered here were generaly under an arid climate. Animals that passed by were heavy and bulky possible Megalosaur trackmakers, and lighter and slender Coelophysids or Ceratosaurs. For all, these areas were pathways as the orientations of the trackways seem point out. The directions followed by these reptiles were without any important variation during the Hettango-Sinemurian stages. These areas were also used from time to time by Crocodilomorpha and may be tetradactyl (I-IV) bipedal avian Theropods. However, the number of such trackways in sites, sometimes substantial, should not lead us to overestimate the trackmakers populations. These last were probably relatively moderately abondant in this inter-supratidal swamp environment. In the Causses, ichnites are connected with former algo-laminated deposits (Algal mats) which were rapidly hardened by means of calcitisation of cyanobacteria. The result has been a moderate depth of footprints; autopodia disturbing only a few cm of the carbonate substrate. Other fossils have been discovered : invertebrates with thin bivalve and gastropod shells, crustaceans tests and plants. These latter suggest the existence of paleomangroves like environments but also continental vegetation periodically overruning the swamp environment during regression/transgression cycles. At these times, wooded parts of it, could become protecting, feeding, resting and nesting places.

      


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Published in Vol. 31, Fasc. 1-4 (2002)

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Systematic revision of Ctenodactylidae (Mammalia, Rodentia) from theMiocene of Pakistan.
J.A. Baskin
Keywords: Ctenodactylidae; Miocene; Prosayimys; Rodents; Sayimys; Siwalik
 
  Abstract

    Extensive sampling of the Siwalik deposits of the Potwar Plateau of northem Pakistan and from the Zinda Pir dome of central Pakistan has produced a fossil record of Miocene ctenodactylids that can be correlated with the paleomagnetic time scale. The early Miocene Prosayimys flynni (n. gen., n. sp.) is recognized as the first ctenodactylid in the Indian subcontinent. Prosayimys is ancestral to Sayimys. From the late early Miocene to the early late Miocene, there is an anagenetic succession of three species of Sayimys: S. cf. S. intermedius, S. sivalensis, and S. chinjiensis (n. sp.). Sayimys chinjiensis gave rise to the late late Miocene S. perplexus. A second lineage is represented by Sayimys minor, S. sp. A, and S. sp. B. 


  Article infos

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

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A primitive Emballonurid bat (Chiroptera, Mammalia) from the Earliest Eocene of England
Jerry J. Hooker
Keywords: bats; Early Eocene; Emballonuridae; Origins; PHYLOGENY
 
  Abstract

    A new genus, Eppsillycteris, is erected for Adapisorex? allglicus COOPER, 1932, from the earliest Eocene Blackheath Beds of Abbey Wood, London, England. Various derived character states indicate that it belongs to the order Chiroptera (bats) rather than to the extinct "insectivore" family Adapisoricidae. Other derived character states are shared with fossil and modern members of the family Emballonuridae. Placement of the new genus in this family extends the record of the Emballonuridae back in time by about 10 million years. It is the earliest record of a modern bat family and one of the earliest bats. This implies that the differentiation of at least some modern bat families took place in the Palaeocene, where no authenticated records of bats yet exist. The primitive characters of the earliest bats make the family Nyctitheriidae an unlikely stem group for the order Chiroptera. A tentative plausible alternative exists in some unnamed upper molars from the Palaeocene of Walbeck, Germany. Wyollycteris chalix, described as a bat from the Late Palaeocene of Wyoming, U,S.A., fits better in the family Nyctitheriidae. 


  Article infos

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

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Lower Paleogene crocodilians from Silveirinha, Portugal.
Miguel T. Antunes
Keywords: ?Upper Paleocene / Lowermost Eocene; Crocodilians; Ecology; Portugal
 
  Abstract

    The presence at Silveirinha of one of the earliest, ? Late Paleocene or Lowermost Eocene, european representatives of the genus Diplocynodon is based mostly on isolated bones and teeth (often from juveniles). This small-sized form is the only crocodilian so far recognized in this site. The longevity of Diplocynodon in Portugal becomes much extended; the genus survived there until the Middle Miocene at least. A discussion on the possible affinities with other eocene Díplocynodon and especially those from Cubillos-Valdegallina (Zamora, Spain) is presented. On the other hand, differences have been detected in comparison with: Díplocynodon tormis, from the middle Eocene of the Douro basin in Spain, which may belong to another phyletic line; and the aff. Diplocynodon from Dormaal (Belgium) and Le Quesnoy (France), nearly contemporaneous of Silveirinha. The Silveirinha Diplocynodon and many other data strongly suggest moist, subtropical, quite limited in space environments related to an alluvial plain crossed by small, meandering channels. 


  Article infos

Published in Vol. 32, Fasc. 1 (2003)

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

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

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

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

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


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

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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 and Jean-Yves Crochet
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. 


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

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Types dentaires adaptatifs chez les sélaciens actuels et post-paléozoïques.
Henri Cappetta
Keywords: Dental types; evolution; Fossil selachians; Recent selachians; Trophic adaptations
 
  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. 


  Article infos

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

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The evolution of the molar pattern of the Erethizontidae (Rodentia,Hystricognathi) and the validity of Parasteiromys Ameghino, 1904.
Adriana M. Candela
Keywords: Argentina; Erethizontidae; Hystricognathi; Miocene; Molar evolution; Porcupines; Rodentia; Systematics
 
  Abstract

    The genus Parasteiromys AMEGHINO, 1904 is revalidated, and P. friantae sp. nov. (Hystricognathi, Erethizontidae) from Colhuehuapian (early Miocene) sediments of the southern cliff of Colhue-Huapi Lake (Province of Chubut, Argentina), is described. The molar morphology of these taxa and of living porcupines adds new elements to understand the dental evolution of the Erethizontidae, and to propose the hypothetical ancestral molar pattern for this family. This pattern does not correspond to any of the morphologies traditionally proposed as ancestral for South American hystricognathous rodents. The proposed pattern is characterized by a metaloph disconnected from the posteroloph and oriented towards the hypocone, and the third loph incompletely developed with the lingual portion homologous to the mesolophule of Baluchimyinae (Chapattimyidae) from the Miocene of Pakistan. The inferred steps of the molar evolution of erethizontids towards the pentalophodont condition, considered derived for the family, are illustrated. This study strengthens the hypothesis placing erethizontids in a basal position among rodents of the suborder Hystricognathi.

      


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

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

doi: 10.18563/pv.5.2.45-78
 
  Abstract

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


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

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A new Ardynomys (Rodentia,Cylindrodontidae) from the Eocene of the eastern Gobi Desert, Mongolia.
Demberelyin Dashzeveg
Keywords: Ardynomys; Eocene; Mongolia; Rodentia; Systematics
 
  Abstract

    A partial skull of Ardynomys russelli sp. nov. (Rodentia, Cylindrodontidae) is described. This was collected in the late Eocene of Alag Tsab locality in the eastem Gobi Desert, Mongolia. Ardynomys russelli sp. nov. is characterized by small size, brachyodont molars, and retention of P3. It represents the earliest record of the genus Ardynomys MATTHEW & GRANGER, 1925, in Asia. 


  Article infos

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

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Nouveaux gisements à rongeurs dans les molasses oligo-miocènes de la région toulousaine
Francis Duranthon
Keywords: Cricetidae; Eomyidae; GIiridae; Miocene; Oligocene; Rodents; Sciuridae; Southern France
 
  Abstract

    The fauna from three new rodent localities (Castelmaurou, Grépiac-carrière et Grépiac-rive gauche) from Oligo-Miocene molasses of the Toulouse area is described. The one from Colomiers is completed. 11 species belonging to 4 families (Cricetidae, Eomyidae, Gliridae, Sciuridae) are present. The Miocene localities of Grépiac-carrière and Colomiers are correlated with Balizac, La Brète, Lambert and Lespignan. Grépiac-rive gauche is just a little older than these sites. Castelmaurou is somewhat younger than La Milloque and belongs to Oligocene. 


  Article infos

Published in Vol. 22, Fasc. 2-3 (1993)

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Contributions à l'étude du gisement Miocène supérieur de Montredon (Hérault). Les grands mammifères. 2 - les carnivores
Gérard de Beaumont
Keywords: anatomy; Carnivora; France; Montredon; Systematics; Upper Miocene
 
  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.
      


  Article infos

Published in Vol. 18, Ext (1988)

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Historical and new perspectives on the parataxonomyof fossil eggs.
Monique Vianey-Liaud and Darla Zelenitsky
Keywords: amniotic eggshells; Parataxonomy
 
  Abstract

    A critical review on the literature about the parataxonomy of amniote eggshells reasserts the great interest of this systematics tool for the progress of dinosaur eggshell paleontology. However, shedding light on its limits, we propose to give up the use of the basic types - morphotypes key system. 


  Article infos

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

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Die Referenzfauna des Geiseltalium, MP levels 11 bis 13 (Mitteleozan, Lutetium)
Hartmut Haubold
Keywords: Eocene; Geiseltal; Land mammal ages; Mammalian reference levels
 
  Abstract

    The Middle Eocene Fossillägerstätte of the Geiseltal lignite beds near Halle/S. (German Democratic Republic) is the reference locality of the European land mammal age Geiseltalian and of the Mammalian Paleogene reference levels MP 11 - MP 13. Due to this importance a reinvestigation is given of the lithostratigraphical development of the Geiseltal beds and of their vertebrate sites. The last are genetically related to the southwest border of the Geiseltal depression and the influx of carbonate-rich waters. The geographical distribution and stratigraphical position of the fossiliferous sites depends on subrosive and tectonically controlled distribution of coal seams. The geological factors and the known stratigraphical guide of some mammalian species suggest corrections of the age of some sites. Four of the alltogether five coal bearing phases contain the 35 sites with mammalian remains. By the distribution of the around 69 mammal species are characterized, with 5 faunal steps ranging from MP 11 to MP 14 or over the Geiseltalian up to the Lower Robiacian. Well distant are the faunas of MP 11 and MP 12. Beginning with MP 12 up to MP 13/14, the fossil record is very frequent by 27 sites. This evidence coincides somewhat more with the concept of land mammal ages compared to that of the punctual mammalian reference levels. 


  Article infos

Published in Vol. 19, Fasc. 3 (1989)

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Batoids (Rajiformes, Torpediniformes, Myliobatiformes) from the Sülstorf Beds (Chattian, Late Oligocene) of Mecklenburg, northeastern Germany: a revision and description of three new species
Thomas Reinecke
Keywords: Batoids; Chattian; Elasmobranchii; North Sea Basin; Oligocene

doi: 10.18563/pv.39.2.e2
 
  Abstract

    Bulk-sampling of fossil-rich tempestites from the Chattian Sülstorf Beds of
    Mecklenburg, north-eastern Germany, yielded a rich selachian fauna in which batoids
    predominate by the abundance of teeth but are subordinate by the number of taxa. Thirteen
    taxa are identified, among which rajiform batoids are the most diverse (six species). One
    genus and three species are newly described: Raja thiedei sp. nov., Oligoraja pristina gen. et
    sp. nov., and Torpedo chattica sp. nov. Two species are reallocated: Atlantoraja cecilae
    (Steurbaut & Herman, 1978) new comb., and Dipturus casieri (Steurbaut & Herman, 1978)
    new comb. Ontogenetic heterodonty is documented for the first time in the dental pattern of
    Myliobatis sp. Stratigraphical ranges of batoid taxa in the period from Rupelian to Langhian
    are presented and partly discussed in context with the palaeoclimatic evolution and
    palaeogeographic situation of the North Sea Basin. 


  Article infos

Published in Vol.39-2 (2015)

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An unusual cranial fossil of the giant lower Pliocene shrew (Paranourosorex gigas Rzebik-Kowalska, 1975) from Podlesice, Poland
David L. Harrison and Barbara Rzebik-Kowalska
Keywords: Mammalia; Paranousorex gigas; Pliocene; Poland; Ruscinian; Soricidae
 
  Abstract

    A well-preserved anterior cranium of Paranourosorex gigas RZEBIK-KOWALSKA, 1975 from Podlesice, Poland, provides additional knowledge of this rare shrew, including almost complete maxillary dentition. The systematic status of this species as a relative of recent Anourosorex MILNE-
    EDWARDS, 1870 is confirmed 


  Article infos

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

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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
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). 


  Article infos

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

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