Dos ejemplos muy diferentes, invertebrados (moluscos bivalvos) y vertebrados (Osteichthyes, Cladistia Polypteriformes), de ambientes muy distintos (marinas y de aguas dulces) y que se diversificaron en momentos muy distantes (Ordovícico Inferior-Media y Cretácico Superior) permiten plantear algunos de los problemas encontrados en la detección de los factores inductores y en la comprensión de las modalidades de paleodiversificación. Los interrogantes son ¿Cuando, dónde y cómo se han producido las paleodiversificaciones? Establecer el papel de los paleoambientes y evidenciar las innovaciones clave constituyen dificultades importantes. El carácter al parecer súbito de estas radiaciones no concuerda totalmente con el gradualismo del modelo darwiniano clásico

Identification of extant polypterid fishes has commonly been done by describing the morphology of the entire animal. Unfortunately, in the fossil record, these fishes appear frequently only as isolated finlet spines and/or scales, occasionally vertebrae. The present study aims to describe i) the finlet organization, the finlet spine morphology of living Polypteridae, in order to establish diagnosis and to study the finlet spine variability at the species level. The spines are composed of bone and dentine, covered with ganoine on the anterior face. Among the extant Polypteridae, we observed specific variation in several morphological characters of finlet spines, especially the median groove and the basal, lateral, median, and posterior processes of the spine articular head. We show here that differences observed for finlet spines are significant enough to discriminate Polypteridae at the species level and, to a lesser extant, the three Polypterus bichir subspecies. These differences could be applied successfully to the fossil record but with some caution when the fossil material is scarce or/and more or less damaged.

Potobatis semperei gen. et sp. nov. sp. (Myliobatiformes, Dasyatoidea) comes from a level located at the top of the section of the El Molino Formation at La Palca, near Potos. This level is Danian in age according to magnetostratigraphic studies. Close to the African genus Hypolophites (Dasyatoidea, Dasyatidae) by its dental morphology, the new genus differs from the latter by its much smaller size and by its less specialized dentition. The palaeoenvironment was probably an estuarine or a mangrove area.

The fossil record of gonorynchiform fishes provides key information on the diversity, palaeobiogeography, and phylogeny of the group. The first mention of fossil Gonorynchiformes dates back to Cuvier in the early 19th century, and there is still a need for a critical review of the earliest descriptions and of some key taxa today.Fossil gonorynchiform. fishes are known from the earliest Cretaceous (Berriasian-Valanginian) to the earliest Miocene, and the clade has several extant representatives. To date, the fossil record has yielded only about 18 genera and 35 species of Gonorynchiformes. With only 46 known localities, their fossil record is relatively poor compared to that of other groups of Ostariophysi. The distribution of these localities is heterogeneous in both space and time.Debates on the phylogenetic status of Gonorynchiformes have mainly focused on the identity of the basal-most members of the clade and on its sister group. Unfortunately, very few large-scale phylogenetic studies have included the fossil representatives of the clade.Using known fossil occurrences and several phylogenetic proposals, we conducted an exploratory diversity analysis. A traditional taxic approach shows that gonorynchiform diversity rose steadily during the Early Cretaceous and reached a peak in the Aptian-Cenomanian interval. It then declined slightly towards the end of the Cretaceous and it decreased further at the dawn of the Cenozoic. This apparent low diversity level is only interrupted by relative diversity peaks in the first half of the Eocene and in the Oligocene. In the absence of fossils after the earliest Miocene, diversity estimates are conjectural for most of the Neogene.We found a close similarity of the estimates obtained with alternative phylogenetic hypotheses, meaning that the differences among these phylogenies have virtually no impact on inferred diversity patterns. Our diversity analysis points to some major gaps in the known fossil record, and it calls for the integration of most (if not all) fossil taxa in phylogenetic analyses.

Longtemps places dans les clupeiformes, les Gonorynchiformes ont rejoint les Ostariophysi au sein desquels ils representent le groupe-frere des Otophysi. La monophylie du groupe est maintenant bien etablie tant par les donnees morphologiques que moleculaires. De nos jours, quatre familles sont representees par sept genres (dont cinq d'eau douce) et 35 especes (dont 28 d'eau douce). Les Gonorynchiformes fossiles sont connus depuis le Cretace basai (soit 145-140 millions d'annees) jusqu'au Miocene basai (soit 23,5-20 millions d'annees), et plusieurs taxons ont de grandes extensions temporelles. Ils sont representes par environ 18 genres et 34 especes. Avec moins de 50 localites fossiles, les archives paleontologiques des Gonorynchiformes sont relativement pauvres par rapport a celles d'autres groupes d'Ostanophysi. La distribution de ces localites est heterogene a la fois dans l'espace et dans le temps, mais elle concerne tous les continents. Nous avons mene une analyse exploratoire de la diversite globale par l'utilisation conjointe des approches taxique et phylogenetique. Les resultats montrent que la diversite s'installe au cours du Cretace ancien et atteint un maximum dans l'intervalle Albien-Cenomanien (110-95 millions d'annees). Elle decline ensuite jusqu'a la fin du Cretace ou elle semble se stabiliser. En l'absence de fossiles apres le Miocene ancien, la diversite estimee a partir de cette epoque reste conjecturale. D'une maniere plus generale, notre analyse souligne l'heterogeneite et la pauvrete du registre fossile des Gonorynchiformes, mais elle montre aussi que les donnees paleontologiques sont indispensables a la comprehension de l'evolution du groupe dans son ensemble.

Among Ostariophysi, gonorynchiform fishes form the sister-group of Otophysi. The monophyly of the clade Gonorynchiformes is now well-established by both molecular and morphological data. There are four extant families, containing seven genera (among which five live in freshwaters) and about 35 species (among which 28 live in freshwaters). Fossil gonorynchiforms are known from the earliest Cretaceous (Berriasian-Valanginian) to the earliest Miocene. To date, the fossil record has yielded only about 18 genera and 34 species, and we provide an updated list of these valid species. A single extant genus is known in the fossil record: Chanos. With fewer than 50 known localities, the fossil record of gonorynchiform fishes is relatively poor compared to that of other groups of Ostariophysi (e.g., siluriformes have been reported in more than 500 fossil localities, although they appeared in the Late Cretaceous). We show that the distribution of these localities is heterogeneous in both space and time. For example, more than half of the localities are Cretaceous in age, whereas there is no gonorynchiform-bearing site dated from the last 20 million years. Few phylogenetic studies have included most fossil taxa of the clade Gonorynchiformes, and current debates focus essentially on the identity of basal members and on some intra-clade relationships. The palaeobiogeography of the group is poorly known and was apparently complex. Fossil data are scarce in Asia and Australia, but these two continents will certainly reveal key palaeobiogeographic information in the future. Using both the taxic and phylogenetic approaches, we conducted an exploratory diversity analysis. Results show that gonorynchiform diversity rose during the Early Cretaceous and reached a maximum in the Albian-Cenomanian interval. It then declined towards the end of the Cretaceous, where it seemed to have stabilised. In the absence of fossil after the earliest Miocene, diversity estimates are conjectural for most of the Neogene. Overall, our analysis stresses the heterogeneity and the paucity of the fossil record of gonorynchiform fishes, but it also shows that palacontological data are essential to the understanding of the evolution of this clade.

L'osteologie de tHalecopsis insignis de l'Eocene marin de l'Europe est brievement revue. Elle permet de confirmer l'appartenance de ce poisson au sous-ordre des Gonorynchoidei et de proposer sa position phylogenetique entre la famille des †Apulichthyidae et les autres familles de ce sous-ordre.

The order Tselfatiiformes comprises three families, the Protobramidae (three genera and four species), the Eoplethodidae (one genus and one species) and the Plethodidae (seventeen genera and twenty-seven species). Although very specialised, the Protobramidae are the most primitive family within the order. Eoplethodidae, only known by the caudal skeleton, are less evolved than the Plethodidae. Within the Plethodidae, Paranogmius, the only one keeping a subtemporal fossa, is the most plesiomorphic genus. A more apomorphic clade unites together Bananogmius, Niobrara, Syntegmodus and Luxilites. Another clade still more apomorphic joins Martinichthys, Pseudothryptodus, Thryptodus and Plethodus. Pseudanogmius, Pentanogmius, Zanclites and Bachea are successively more and more specialised genera. Enischnorhynchus, Tselfatia and Dixonanogmius, with their skull roof strongly curved in cross-section, represent the most advanced clade. Moorevillia, characterised by its latero-parietal skull, could not be classified unambiguously within the family. The relative positions of the Tselfatiiformes and the Pachyrhizodontoidei within the Clupeocephala are discussed. The latter are considered to be more primitive than the former. The paleozoogeography of the Tselfatiiformes is also considered. They appear in the Eurafrican Mesogea during the Albian and expand there during the Cenomanian and Turonian. During the same period, they get across the Proto-Atlantic Ocean and colonize the north of South America, the Gulf of Mexico, Central America and the North American seaway. During the Coniacian and Santonian, they are abundant in North America but seem to be absent from the Eurafrican Mesogea. A few species subsist in the Gulf of Mexico and in Egypt during the Campanian. The Tselfatiiformes disappear after the Campanian.

L'osteologie de Protobrama avus, d'une nouvelle espece de ce genre, P. woodwardi, et de deux nouveaux genres monospecifiques de Protobramidae, Eusebichthys byblosi et Abisaadichthys libanicus, est etudiee. Les Protobramidae sont de petits teleosteens marins au corps eleve du Cenomanien inferieur du Liban. L'eventuelle synonymie des Protobramidae et des Plethodidae (ou Tselfatiidae) ainsi que l'integration des Protobramidae, des Araripichthyidae et des Ferrifronsidae en un sous-ordre des Protobramoidei sont discutees et rejetees. L'analyse des caracteres des Protobramidae amene a les ranger en tant que famille valable dans l'ordre clupeocephale des Tselfatiiformes aux cotes des Plethodidae.

After the description of Anguillavus and Luenchelys (Belouze and Gayet, 2003), the revision of the last genus Urenchelys WOODWARD, 1900 ends our revision of the first fossil Anguilliformes from the Cenomanian outcrops of Lebanon. Two new genera, Abisaadia and Hayenchelys. are necessarily established to accomodate respectively the species "Urenchelys" hakelensis (DAVIS, 1887) and "Urenchelys" germanus HAY. 1903. which are not specially closed to the type-species Urenchelys avus WOODWARD, 1901. The phyletic relationships of that Cretaceous genera are regarded by cladistic approach. They all form a plesiomorphic and morphologically homogenous group, which shows an explosive diversification based on relatively variable structural pattern and which already announces some specialisations of the Recent Anguilliformes. (C) 2003 Editions scientifiques et medicales Elsevier SAS. Tons droits reserves.

Abstract New genera of characoid fossil fishes are described on the basis of remains from the Maastrichtian El Molino Formation and the early late Paleocene Santa Lucía Formation of Bolivia, and the Mio-Pliocene Solimões Formation of Brazil. Comparisons with the Hepsetidae, Erythrinidae, Ctenoluciidae, Acestrorhynchidae, and the characid Hydrocynus allow the following conclusions to be made: the new Bolivian genus lacks some erythrinid synapomorphies but shows notable resemblance to the Acestrorhynchidae, particularly in the pattern of the replacement teeth. The Brazilian genus is included in the erythrinids.

Une révision complète des premiers poissons du registre fossile à corps anguillimorphe, fondée sur de nouveaux spécimens des gisements cénomaniens du Liban, est réalisée. Elle propose la mise en synonymie de l’espèce Anguillavus bathshebae HAY, 1903 avec l’espèce type A. quadripinnis HAY, 1903, tout en reconnaissant cependant une autre espèce d’anguille à nageoires pelviennes, A. mazeni nov. sp. L’étude conjointe de Luenchelys minimus nov. gen., nov. sp. révèle, chez ces premières formes crétacées, des variations intraspécifiques et une répartition paléobiogéographique potentiellement importantes. Cette révision anatomique donne les bases indispensables pour valider leur appartenance aux Anguilliformes (Teleostei, Elopomorpha) et accéder à l’architecture plésiomorphe d’un ordre ultraspécialisé dans la faune actuelle. New specimens from Cenomanian outcrops of Lebanon permit redescribtion of the first eel-like fossil fishes. Anguillavus bathshebae Hay, 1903 becomes synonymous with the type species A. quadripinnis Hay, 1903. A new fossil eel with pelvic fins, Anguillavus mazeni nov. sp., is furthermore proposed. In the same way, the revision of Luenchelys minimus nov. gen., nov. sp., reveals some morphological variations at the specific level and a widespread biogeographical repartition which potentially can be important. This whole anatomical revision is a necessary basis for integrating these fossils into the Anguilliformes (Teleostei, Elopomorpha) and gives an idea of the plesiomorphic structural pattern of the order, in which the modern forms are particularly specialised.

Une révision complète des premiers poissons du registre fossile à corps anguillimorphe, fondée sur de nouveaux spécimens des gisements cénomaniens du Liban, est réalisée. Elle propose la mise en synonymie de l’espèce Anguillavus bathshebae HAY, 1903 avec l’espèce type A. quadripinnis HAY, 1903, tout en reconnaissant cependant une autre espèce d’anguille à nageoires pelviennes, A. mazeni nov. sp. L’étude conjointe de Luenchelys minimus nov. gen., nov. sp. révèle, chez ces premières formes crétacées, des variations intraspécifiques et une répartition paléobiogéographique potentiellement importantes. Cette révision anatomique donne les bases indispensables pour valider leur appartenance aux Anguilliformes (Teleostei, Elopomorpha) et accéder à l’architecture plésiomorphe d’un ordre ultraspécialisé dans la faune actuelle.

Polypteriformes (or Cladistia) and Lepisosteiformes (or Ginglymodi) are two groups of freshwater fishes with ganoid scales. The earliest fossil records of these taxa are Albian (Lepisosteiformes) and Cenomanian (Polypteriformes) respectively in Gondwana; they are still extant. The ‘first’ appearance of the two groups in the fossil record (explosive in polypteriforms, gradual in lepisosteiforms) as well as their evolutionary mode (diversification/disparity or replacement) is described in detail. The lepisosteiforms appear to show a rapid radiation of post‐Palaeozoic clades immediately upon origination, while the polypteriforms represent a counter‐example with their sudden diversification and their sudden acquisition of several ‘key innovations’.

The Pajcha Pata fossil locality in south central Bolivia, in the upper part of the Lower Member of the El Molino Formation, is the first late Cretaceous fauna in South America which has yielded, in addition to some invertebrates and plants, all kinds of vertebrates except birds, but including dinosaurs and mammals. Its middle Maastrichtian age, indicated by geochronologic data, is consistent with the fauna, including the marine ichthyofauna. The vertebrate fossils reported here come from the main fossiliferous level which includes terrestrial, freshwater and marine taxa: vertebrates, Mammalia (both tribosphenic and non-tribosphenic therians), Theropoda (Coelurosauria and Sauropoda), Crocodylia, Squamata (Serpentes), Chelonia, Amphibia (Anura, Gymnophiona, Caudata) and fish (Dipnoi, Teleostei, Actinopteri, Cladistia, Chondrostei); invertebrates (Gastropoda, Bryozoa) and plants (charophytes). Amongst these taxa are the earliest records of some fish, Amphibia and tribosphenic Mammalia in South America and/or in the world. The fish concerned are: Polypteriformes (Latinopollia suarezi), Siluriformes of the family Andinichthyidae (Andinichthys) and two new families, Osteoglossiformes of the subfamily Heterotidinae (Osteoglossidae), Perciformes of the family Latidae, Dipnoi of the family Lepidosirenidae (Lepidosiren cf. paradoxa). The Amphibia concerned are: indeterminate Gymnophiona, Noterpetontidae (Noterpeton bolivianum). Pajcha Pata is the only known locality in South America with both non-tribosphenic and tribosphenic therian mammals. The depositional environment was probably estuarian or lagoonal as indicated by a mixed continental, freshwater, and marine fauna. Comparison of this local fauna with faunas of the same age at localities belonging to the same proximal part of the El Molino basin on one hand, and with others belonging to the distal part on the other hand, shows that the two continental areas seem to have their own endemic freshwater fish fauna (except the Characidae and the Lepisosteidae, known in all levels of Bolivia). However, these two areas have the same marine taxa. This implies some influence of the sea in the whole basin. Calculated temperatures of the marine waters range from 13 to 17° for a latitute of about 22°S, implying a southern Pacific upwelling. The El Molino Basin could have been also connected with the open sea through present-day Argentina and not only Venezuela as thought until now.

Following the discovery of the first living polypterid, Polypterus bichir, in 1802, almost two centuries later we now know of 15 living species (including four subspecies), 14 belonging to the genus Polypterus and one to the genus Erpetoichthys (Calamoichthys) all inhabiting intertropical Africa. The polypterid fossil record was for a long time reduced to some scarce, disarticulated bones, mainly scales, found in various African deposits covering a wider area than the actual geographical distribution. With the discovery, on one hand, of polypterid scales, vertebrae, dermal bones of the cranium and dorsal spiny rays in South America and, on the other hand, of scales and numerous dorsal spiny rays in Niger and Sudan, and two articulated fossils in Morocco, the story of the polypteriforms has revealed some of its mysteries. The discovery of isopedine between dentine and bony basal plate in the scales of living and fossil polypterid species is considered a synapomorphy of the group, and has been an important aid in discriminating polypterid scales from other ganoid scales. A review of the main findings during the last 20 years is presented.