The eyes of suckermouth armoured catfish (Loricariidae, subfamily Hypostomus): pupil response, lenticular longitudinal spherical aberration and retinal topography

The dilated, round pupils of a species of suckermouth armoured catfish (Liposarcus pardalis) constrict slowly on illumination (over 35-40 min) to form crescent-shaped apertures. Ray tracing of He-Ne laser beams shows that the lenses of a related species (Pterygoplichthys etentaculus), which also has a crescent-shaped pupil, are well corrected for longitudinal spherical aberration, suggesting that the primary purpose of the irregular pupil in armoured catfish is not to correct such aberration. It is suggested that the iris operculum may serve to camouflage the pupil of these substrate-dwelling species. An examination of the catfish retina shows the photoreceptors to be exclusively single cones interspersed with elongate rods and demonstrates the presence of multiple optic nerve head papillae. Two areas of high ganglion cell density, each side of a vertically oriented falciform process, provide increased spatial resolving power along the axes examining the substrate in front of and behind the animal

Fishes from the marine and continental miocene in Entre Ríos, central eastern Argentina

La diversa fauna neógena que se registra en los acantilados orientales del río Paraná cerca de la ciudad de Paraná, Entre Ríos es conocida desde la mitad del siglo XIX. Muchos vertebrados de agua dulce, marinos y terrestres se han colectado allí. La mayoría de los fósiles miocenos viene de la parte superior de la Formación Paraná (taxones marinos y dulceacuícolas) y de la base de la suprayacente y continental Formación Ituzaingó (“Conglomerado osífero”) (taxones dulceacuícolas, terrestres y marinos retrabajados). De acuerdo a los vertebrados, las temperaturas marinas durante la depositación de la Formación Paraná eran similares a aquéllas presentes actualmente en la costa atlántica a la latitud de Paraná. La fauna de agua dulce del “Conglomerado osífero” sugiere un clima más cálido que el presente e importantes conexiones biogeográficas con cuencas norteñas de América del Sur. Durante los últimos años, los afloramientos fueron intensamente explorados. Algunos de los nuevos reportes incluyen el primer registro de caraciformes cinodóntidos para el área, el descubrimiento del grupo hermano de las pirañas (Megapiranha paranensis), el primer registro en el área del tiburón escielorrínido Megascyliorhinus, el registro más antiguo de especies con dientes aserrados del género de tiburón lámnido Carcharodon y una ballena balenoptérida atacada por el tiburón lámnido Carcharodon plicatilis. Finalmente, enfatizamos en que varios de los géneros miocenos de peces de agua dulce y marinos se han extinguido y que varias pseudoextinciones no pueden explicarse por causas climáticas o tectónicas.Fishes of the marine and continental Miocene of Entre Ríos, eastern central Argentina. The diverse Neogene fauna collected in the cliffs exposed along the left bank of the Paraná River near the city of Paraná, Entre Ríos Province, Argentina, has been scientifically known since the middle of the 19th century. Many freshwater, marine, and terrestrial vertebrates were recorded therein. Most of the Miocene fossils come from the upper part of the Paraná Formation (marine and some freshwater taxa) and the base of the overlying continental Ituzaingó Formation (“Conglomerado osífero”) (freshwater, terrestrial, and reworked marine taxa). According to fish and cetacean evidence marine temperatures during the deposition of the upper part of the Paraná Formation were similar to those recorded in the Atlantic coast at the same latitude today. The freshwater fauna of the “Conglomerado osífero” suggests a climate warmer than present and important basin connections with northern South American basins. Recent intense survey of the outcrops has given new information about the icthtyofauna that occupied the Paranian Sea and the subsequent freshwater basins in the area. Some new reports include the first occurrence of cynodontid characifoms and the scyliorhinid shark Megascyliorhinus in the area, the discovery of the sister group of piranhas (Megapiranha paranensis), the oldest occurrence in the Atlantic of serrated species of the lamnid shark genus Carcharodon, and a balaenopterid whale attacked by the shark Carcharodon plicatilis. We found that there are several extinctions of the freshwater and marine Miocene genera and pseudoextinctions that cannot be explained by climatic or tectonic causes.Fil: Cione, Alberto Luis. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Departamento Científico de Paleontología de Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cabrera, Daniel Alfredo. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Departamento Científico de Paleontología de Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Azpelicueta, Maria de Las M.. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Zoología de Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Casciotta, Jorge R.. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Zoología de Vertebrados; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; ArgentinaFil: Barla, María Julia. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; Argentin

Taxonomic Composition and Trophic Structure of the Continental Bony Fish Assemblage from the Early Late Cretaceous of Southeastern Morocco

International audienceThe mid-Cretaceous vertebrate assemblage from south-eastern Morocco is one of the mostdiversified continental vertebrate assemblages of this time worldwide. The bony fish component(coelacanths, lungfishes and ray-finned fishes) is represented by relatively completespecimens and, mostly, by fragmentary elements scattered along 250 kilometres of outcrops.Here we revisit the bony fish assemblage by studying both isolated remains collectedduring several fieldtrips and more complete material kept in public collections. The assemblagecomprises several lungfish taxa, with the first mention of the occurrence of Arganodustiguidiensis, and possibly two mawsoniid coelacanths. A large bichir, cf. Bawitius, is recordedand corresponds to cranial elements initially referred to ‘Stromerichthys’ from coevaldeposits in Egypt. The ginglymodians were diversified with a large ‘Lepidotes’ plus twoobaichthyids and a gar. We confirm here that this gar belongs to a genus distinctive fromRecent gars, contrary to what was suggested recently. Teleosteans comprise a poorlyknown ichthyodectiform, a notopterid, a probable osteoglossomorph and a large tselfatiiform,whose cranial anatomy is detailed. The body size and trophic level for each taxon areestimated on the basis of comparison with extant closely related taxa. We plotted the averagebody size versus average trophic level for the Kem Kem assemblage, together with extantmarine and freshwater assemblages. The Kem Kem assemblage is characterized bytaxa of proportionally large body size, and by a higher average trophic level than the trophiclevel of the extant compared freshwater ecosystems, but lower than for the extant marineecosystems. These results should be regarded with caution because they rest on a reconstructedassemblage known mostly by fragmentary remains. They reinforce, however, theecological oddities already noticed for this mid-Cretaceous vertebrate ecosystem in NorthAfrica

The invisible fish: hydrodynamic constraints for predator-prey interaction in fossil fish Saurichthys compared to recent actinopterygians

Recent pike-like predatory fishes attack prey animals by a quick strike out of rest or slow movement. This fast-start behaviour includes a preparatory, a propulsive and a final phase, and the latter is crucial for the success of the attack. To prevent prey from escape, predators tend to minimise the duration of the interaction and the disturbance caused to surrounding water in order to not be detected by the prey's lateral line sensory system. We compared the hydrodynamic properties of the earliest fossil representative of the pike-like morphotype, the Triassic actinopterygian Saurichthys, with several recent pike-like predators by means of computational fluid dynamics (CFD). Rainbow trout has been used as a control example of a fish with a generalist body shape. Our results show that flow disturbance produced by Saurichthys was low and similar to that of the recent forms Belone and Lepisosteus, thus indicative of an effective ambush predator. Drag coefficients are low for all these fishes, but also for trout, which is a good swimmer over longer distances but generates considerable disturbance of flow. Second-highest flow disturbance values are calculated for Esox, which compensates the large disturbance with its extremely high acceleration performance (i.e. attacks at high speeds) and the derived teleostean protrusible mouth that allows prey catching from longer distances compared to the other fishes. We show CFD modelling to be a useful tool for palaeobiological reconstruction of fossil fishes, as it allows quantification of impacts of body morphology on a hypothesised lifestyle

A new semionotiform actinopterygian fish from the Mesozoic of Spain and its phylogenetic implications

Camerichthys lunae gen. et sp. nov. is a semionotiform actinopterygian fish described from the newly reported locality of San Andrés de San Pedro (province of Soria, Spain). The material, an articulated, partial three-dimensional specimen, was unearthed from the Tithonian-Berriasian beds of the Matute Formation (Tera Group) in the continental Cameros Basin. The new taxon, Camerichthys lunae gen. et sp. nov., differs from other ginglymodians in presenting a unique combination of characters plus: presence of a suprapreopercular bone; antorbital intermediate in depth in relation to the other anterior infraorbitals; and infraorbital placed in the anterior border of the orbit subdivided into two portions (three uniquely derived characters). The results of the cladistic analysis show that the new genus from Soria cannot be assigned to any of the three semionotiform families, Callipurbeckiidae, Macrosemiidae or Semionotidae. It is considered Semionotiformes incertae sedis. In the more resolutive analysis, with ordered characters, Camerichthys lunae gen. et sp. nov. appears as the sister group of the clade formed by the families Callipurbeckiidae plus Macrosemiidae. The effects of the new genus on the phylogeny of these two families and Dapedium, Semionotus and Paralepidotus, are discussed. Camerichthys gen. nov. is the first ginglymodian genus endemic to the Iberian Peninsula. http://zoobank.org/urn:lsid:zoobank.org:pub:BBD15A41-5BFC-4BFF-AD40-ECD1891953F

Fishes from the Upper Jurassic of Torres Vedras, Portugal

In this study, fossil hybodontiform and neopterygian specimens from the Upper Jurassic of Torres Vedras are reported. Material was collected on the surface of the marine deposits at the top of Praia Azul Member, Lourinhã Formation, dating between upper Kimmeridgian-lower Tithonian; and on the surface of the transitional deposits of Cambelas fossil site, Freixial Formation, dating between middle-upper Tithonian, Upper Jurassic. Fossils are housed in the CI2Paleo of Sociedade de História Natural, in Torres Vedras. Hybodontiforms are represented by 30 isolated teeth, which are attributed to Hybodus cf. reticulatus, as per diagnostic evidences on the main cusp, cutting-edges, and, especially, the root. Neopterygians are represented by 29 isolated or partially associated body scale specimens, diagnosed as cf. Ginglymodi; and 64 isolated and partially articulated prearticular and vomerine teeth referred to Pycnodontiformes indet. This work hopefully improves our understanding about the fish diversity and occurrences of the Upper Jurassic of Portugal; Resumo: Neste estudo são reportados exemplares fósseis de hybodontiformes e neopterígios do Jurássico Superior de Torres Vedras. Este material foi recolhido à superfície dos depósitos marinhos no topo do Membro da Praia Azul, Formação da Lourinhã, datando o Kimmeridgiano superior-Tithoniano inferior; e à superfície dos depósitos transicionais da jazida fóssil de Cambelas, Formação do Freixial, datando o Tithoniano médio-superior, Jurássico Superior. Os fósseis estão alojados no CI2Paleo da Sociedade de História Natural, em Torres Vedras. Os hybodontiformes são representados por 30 dentes isolados, atribuídos a Hybodus cf. reticulatus, conforme evidências diagnósticas na cúspide principal, bordo cortante e, especialmente, a raiz. Os neopterígios são representados por 29 espécimes de escamas corporais isoladas ou parcialmente associadas, diagnosticadas como cf. Ginglymodi; e 64 dentes pré-articulares e vomerinos isolados e parcialmente articulados, atribuídos a Pycnodontiformes indet. Esperançosamente, este trabalho aprimora a nossa compreensão acerca da diversidade e ocorrências dos peixes do Jurássico Superior de Portugal