106 research outputs found
DĂ©couverte de Poissons fossiles dans le Tortonien diatomitique du bassin de HellĂn (Province d'Albacete, Espagne)
The finding of fossil fishes in the Tortonian diatomites of the HellĂn basin (Province of Albacete, Spain), shows that this fish-fauna, characterized by the occurrence of the genus Spratelloides BLEEKER, exhibits great similarities with some fish-faunas from the diatomitic Messinian of the Westem Mediterranean
Sur la présence de "Percichthyidae" (Poissons Téléostéens) dans l'EocÚne moyen du Bassin du Duero (Province de Zamora, Espagne)
La prĂ©sence d'os isolĂ©s de Percoidei est signalĂ©e dans l'EocĂšne moyen du bassin du Duero. Bien que leur dĂ©termination prĂ©cise soit difficile, il est possible de mentrer que des reprĂ©sentants de la famille des "Percichthyidae" vivaient Ă cette Ă©poque dans douces de la pĂ©ninsule ibĂ©rique.Se señala la presencia de huesos aislados de Percoides en el Eoceno medio de la cuenca del Duero, y aunque su determinaciĂłn precisa es bastante difĂcil, es posible demostrar que representantes de la familia "Percichthyidae" vivĂan en esta Ă©poca en las aguas continentales de la penĂnsula IbĂ©rica
Contributions à la Paléontologie du MiocÚne moyen continental du Bassin du Tage. II - Observations sur les dents pharyngiennes de poissons cyprinidés - Póvoa de Santarém.
The study of Cyprinid fish pharyngeal teeth, collected by M. Telles Antunes in continental "Helvetian" sediments from Póvoa de Santarém, makes possible to demonstrate the occurrence of two distinct species. One remains undetermined. The other belongs to the recent genus Leuciscus CUV. Several dental types of this genus are described and figured as Leuciscus antunesi nov. sp. Palaeoclimatical and palaeoecological interpretations are proposed
Poissons du PaléogÚne inférieur de Silveirinha (Portugal)
Fragmentary skeletal remains of Percoid fishes (Teleostei, Percoidei) are described from the Upper Paleocene? or Lowermost
Eocene(MN7) from Silveirinha. It is suggested that they belong to some primitive Percoids which are already known in the Iberian peninsula. They bear witness of an ancient westwards extension of the geographical distribution of Percoid fishes that are common in the lower levels of the Eocene in the Douro Basin in Spain
The phylogenetic origin and evolution of acellular bone in teleost fishes: insights into osteocyte function in bone metabolism
Vertebrate bone is composed of three main cell types: osteoblasts, osteoclasts and osteocytes, the latter being by far the most numerous. Osteocytes are thought to play a fundamental role in bone physiology and homeostasis, however they are entirely absent in most extant species of teleosts, a group that comprises the vast majority of bony âfishesâ, and approximately half of vertebrates. Understanding how this acellular (anosteocytic) bone appeared and was maintained in such an important vertebrate group has important implications for our understanding of the function and evolution of osteocytes. Nevertheless, although it is clear that cellular bone is ancestral for teleosts, it has not been clear in which specific subgroup the osteocytes were lost. This review aims to clarify the phylogenetic distribution of cellular and acellular bone in teleosts, to identify its precise origin, reversals to cellularity, and their implications. We surveyed the bone type for more than 600 fossil and extant rayâfinned fish species and optimised the results on recent largeâscale molecular phylogenetic trees, estimating ancestral states. We find that acellular bone is a probable synapomorphy of Euteleostei, a group uniting approximately twoâthirds of teleost species. We also confirm homoplasy in these traits: acellular bone occurs in some nonâeuteleosts (although rarely), and cellular bone was reacquired several times independently within euteleosts, in salmons and relatives, tunas and the opah (Lampris sp.). The occurrence of peculiar ecological (e.g. anadromous migration) and physiological (e.g. redâmuscle endothermy) strategies in these lineages might explain the reacquisition of osteocytes. Our review supports that the main contribution of osteocytes in teleost bone is to mineral homeostasis (via osteocytic osteolysis) and not to strain detection or bone remodelling, helping to clarify their role in bone physiology
â Kenyaichthyidae fam. nov and â Kenyaichthys gen. nov - First Record of a Fossil Aplocheiloid Killifish (Teleostei, Cyprinodontiformes)
The extant Cyprinodontiformes (killifishes) with their two suborders Cyprinodontoidei and Aplocheiloidei represent a diverse and well-studied group of fishes. However, their fossil record is comparatively sparse and has so far yielded members of the Cyprinodontoidei only. Here we report on cyprinodontiform fossils from the upper Miocene Lukeino Formation in the Tugen Hills of the Central Rift Valley of Kenya, which represent the first fossil record of an aplocheiloid killifish. A total of 169 specimens - mostly extraordinarily well preserved and a sample of ten extant cyprinodontiform species were studied on the basis of morphometrics, meristics and osteology. A phylogenetic analysis using PAUP was also conducted for the fossils. Both the osteological data and the phylogenetic analysis provide strong evidence for the assignment of the fossils to the Aplocheiloidei, and justify the definition of the new family dagger Kenyaichthyidae, the new genus dagger Kenyaichthys and the new species dagger K. kipkechi sp. nov. The phylogenetic analysis unexpectedly places dagger Kenyaichthys gen. nov. in a sister relationship to the Rivulidae (a purely Neotropical group),a probable explanation might be lack of available synapomorphies for the Rivulidae, Nothobranchiidae and Aplocheilidae. The specimens of dagger K. kipkechi sp. nov. show several polymorphic characters and large overlap in meristic traits, which justifies their interpretation as a species flock in statu nascendi. Patterns of variation in neural and haemal spine dimensions in the caudal vertebrae of dagger Kenyaichthys gen. nov. and the extant species studied indicate that some previously suggested synapomorphies of the Cyprinodontoidei and Aplocheiloidei need to be revised
Los CiprĂnidos (Pisces) del sistema lacustre OligocĂ©nico-MiocĂ©nico de los Monegros (sector SE de la cuenca del Ebro, provincias de Lleida, Tarragona, Huesca y Zaragoza)
El material de dientes faringeos de Ciprinidos procedentes de las sucesiones lacustres del Oligoceno superior y Aquitaniense inferior del sector SE de la cuenca del Ebro es atribuido a Rutilus antiquus n.p. Esta nueva especie es morfologicamente proxima a R. pachecoi (ROYO) y ccLeuciscusa antunesi GAUDANT, reconocidas en el Mioceno de la Pennsula Ibrica, asi como a la especie actual R. alburnoides (STEINDACHNER). R. antiquus n.p. habito durante el Oligoceno superior y probablemente durante el Aquitaniense 1os lagos someros endorreicos de salinidad variable (Sistema lacustre de Los Monegros) del sector SE de la cuenca del Ebro
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