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International audience; A pleuropholid fish is described for the first time from the Upper Cretaceous (Cenomanian) Akrabou Formation, Agoult locality, southeastern Morocco. The new material, consisting of a single complete specimen, is attributed to a new species, Pleuropholis danielae, and is diagnosed by its slender body shape, the absence of a leptolepid notch in the dentary, a broad maxilla, covering almost the entirely lower jaw, and flank scales with an unserrated posterior margin. This species represents the last known occurrence of Pleuropholidae, a group so far unknown from the Late Cretaceous.

Acipenseriformes (sturgeons and paddlefishes) are currently recognized as sister-group of Neopterygii (bowfin, gars and teleosts) and along with Polypteriformes (bihirs) constitute the two most basal taxa among living ray-finned fishes. Acipenseriforms uniquely possess a large preoral snout which distinguishes them from other actinopterygians. It is covered ventrally by a longitudinal series of exoskeletal elements which extends along the middle part of the snout from the parasphenoid to the very anterior tip of the head. These cranial elements, highly variable in size, number and proportions, are generally referred to as ventral rostral bones. The homologies of these bones remain unresolved. The issue is getting even more complicated because of vague nature of the parasphenoid of acipenseriforms, with which the ventral rostral series is in a contact. Paradoxically, the homology of this bone of acipenseriforms has never been subjected to thorough survey based on the early development and morphology of this bone. Here, the development of the parasphenoid and the ventraI rostral bones in Siberian sturgeon Acipenser baerii and American paddlefish Polyodon spathula is investigated based on a large sample of specimens of both species ranging from larvae just posthatching to juveniles of 50 days posthatching. Data obtained in this study allowed to establish primary homologies of the parasphenoid and the ventral rostral bones of Acipenseriformes and to address the evolutionary history of the snout in these fishes.

Acipenseriformes (Actinopterygii) are commonly recognized as a sister group of Neopterygii. They represent the basal-most taxa of extant ray-finned fishes, along with Polypterus (Polypteriformes). This position on the cladogram determines the key importance of sturgeons for an understanding of the evolutionary history of actinopterygians, as well as bony fishes in general. However, their unique morphology and the absence of any reliable homologies (in particular, for the snout region and jaw arch) make these fishes ineffective for the testing of phylogenetic hypotheses and the reconstruction of the evolution of Osteichthyes. This article presents the results of a comparative anatomical analysis of the jaw arch and snout region in sturgeons. The homologies of these parts are established, and an evolutionary scenario is proposed to explain the transformation of the mandibular arch and snout region during the presumed transition from palaeoniscoid ancestors to Acipenseriformes. It is shown that these transformations were triggered by paedomorphosis, which caused, inter alia, underdevelopment of the lower jaw. This underdevelopment resulted in a release of the anterior ends of the upper jaw rami and the entire snout region from restrictions concerning the functioning of the jaw apparatus.

In teleost fishes there are three immunoglobulin isotypes named immunoglobulin M (IgM), D (IgD) and T (IgT). IgT has been the last to be described and is considered a teleosts-fish specific isotype. From the recent availability of genome sequences of fishes, an in-depth analysis of Actinopterygii immunoglobulin heavy chain genes was undertaken. With the aid of a bioinformatics pipeline, a machine learning software, CHfinder, was developed that identifies the coding exons of the CH domains of fish immunoglobulins. Using this pipeline, a high number of such sequences were obtained from teleosts and holostean fishes. IgT was found in teleost and holostean fishes that had not been previously described. A phylogenetic analysis reveals that IgT CH1 exons are similar to the IgM CH1. This analysis also demonstrates that the other three domains (CH2, CH3 and CH4) were not generated by recent duplication processes of IgM in Actinopterygii, indicating it is an immunoglobulin with an earlier origin.

Here we describe new pycnodontiform fish material recovered from the marine Agrio Formation (lower Valanginian–lower Hauterivian) of the NeuquØn Province in the south-western of Patagonia, Argentina. The new material include an incomplete skull and an incomplete prearticular dentition. The incomplete skull consists of some dermal and endochondral elements as well as dental remains and represents a new large-sized gyrodontid that is referred to a new species, Gyrodus huiliches. Gyrodus huiliches sp. nov. is characterized by a unique combination of tooth crown ornamentations and tooth shape separating it easily from all known Gyrodus species. The incomplete prearticular dentition shows a tooth arrangement and sculpture that resembles that of “Macromesodon” agrioensis –the previously only known pycnodontiform in the area. This allows revising this species, which was based on an isolated vomerine dentition and which we refer to a new genus, Tranawuen. The new Patagonian fishes reported here expand the knowledge of South American pycnodontiforms. We hypothesize that meanwhile the new Patagonian genus – Tranawuen– diverged from Gyrodus after it migrated into the eastern Pacific through the Hispanic Corridor during the Late Jurassic, the new species –Gyrodus huiliches– most likely diverged from a Central or South American species of Gyrodus. Both represent the youngest gyrodontid records and simultaneously the southernmost Early Cretaceous occurrences of pycnodontiform fishes., Facultad de Ciencias Naturales y Museo

Endocasts of the osseous labyrinth have the potential to yield information about both phylogenetic relationships and ecology. Although bony labyrinth morphology is well documented in many groups of fossil vertebrates, little is known for early Neopterygii, the major fish radiation containing living teleosts, gars and the bowfin. Here, we reconstruct endocasts of the bony labyrinth and associated structures for a sample of Mesozoic neopterygian fishes using high-resolution computed tomography. Our sample includes taxa unambiguously assigned to either the teleost (Dorsetichthys, "Pholidophorus," Elopoides) and holostean ("Aspidorynchus," "Caturus," Heterolepidotus) total-groups, as well as examples of less certain phylogenetic position (an unnamed parasemionotid and Dapedium). Our models provide a test of anatomical interpretations for forms where bony labyrinths were reconstructed based on destructive tomography ("Caturus") or inspection of the lateral wall of the cranial chamber (Dorsetichthys), and deliver the first detailed insights on inner ear morphology in the remaining taxa. With respect to relationships, traits apparent in the bony labyrinth and associated structures broadly support past phylogenetic hypotheses concerning taxa agreed to have reasonably secure systematic placements. Inner ear morphology supports placement of Dapedium with holosteans rather than teleosts, while preserved structure in the unnamed parasemionotid is generalized to the degree that it provides no evidence of close affinity with either of the crown neopterygian lineages. This study provides proof-of-concept for the systematic utility of the inner ear in neopterygians that, in combination with similar findings for earlier-diverging actinopterygian lineages, points to the substantial potential of this anatomical system for addressing the longstanding questions in the relationships of fossil ray-finned fishes to one another and living groups. J. Morphol. 279:426-440, 2018. © 2016 Wiley Periodicals, Inc.

Secondary sexual characteristics are features that appear at sexual maturity and distinguish the two sexes of a species. They are readily observed and studied in living animals, but the phenomenon is rather more difficult to identify in fossil taxa. Here we report a new sexually dimorphic stem-neopterygian fish, Venusichthys comptus gen. et sp. nov., based on 30 exceptionally well-preserved specimens from the Middle Triassic (Pelsonian, Anisian) Luoping Lagerstatte of eastern Yunnan, China. The discovery represents the oldest known secondary sexual characteristics in Neopterygii. These characteristics, including pointed tubercles on cranial bones, scales and fins, and hook-like contact organ anterior to the anal fin, have three inferred primary functions: maintenance of body contact between the sexes during prespawning behavior or spawning; stimulation of the females during breeding; and defense of nests and territories. Lacking a specialized anal fin in the presumed males, Venusichthys would likely have a different reproductive strategy from peltopleurids and other potentially viviparous stem-neopterygians. Moreover, Venusichthys shows a unique character combination distinguished from any other stem-neopterygian families and consequently represents a new family of this clade. As such, the new finding provides an important addition for understanding the behavior, reproduction, and early diversification of Neopterygii.

Background The facial musculature is a remarkable anatomical complex involved in vital activities of fishes, such as food capture and gill ventilation. The evolution of the facial muscles is largely unknown in most major fish lineages, such as the Actinopterygii. This megadiverse group includes all ray-finned fishes and comprises approximately half of the living vertebrate species. The Polypteriformes, Acipenseriformes, Lepisosteiformes, Amiiformes, Elopiformes, and Hiodontiformes occupy basal positions in the actinopterygian phylogeny and a comparative study of their facial musculature is crucial for understanding the cranial evolution of bony fishes (Osteichthyes) as a whole. Results The facial musculature of basal actinopterygians is revised, redescribed, and analyzed under an evolutionary perspective. We identified twenty main muscle components ontogenetically and evolutionarily derived from three primordial muscles. Homologies of these components are clarified and serve as basis for the proposition of a standardized and unifying myological terminology for all ray-finned fishes. The evolutionary changes in the facial musculature are optimized on the osteichthyan tree and several new synapomorphies are identified for its largest clades, including the Actinopterygii, Neopterygii, and Teleostei. Myological data alone ambiguously support the monophyly of the Holostei. A newly identified specialization constitutes the first unequivocal morphological synapomorphy for the Elopiformes. The myological survey additionally allowed a reinterpretation of the homologies of ossifications in the upper jaw of acipenseriforms. Conclusions The facial musculature proved to be extremely informative for the higher-level phylogeny of bony fishes. These muscles have undergone remarkable changes during the early radiation of ray-finned fishes, with significant implications for the knowledge of the musculoskeletal evolution of both derived actinopterygians and lobe-finned fishes (Sarcopterygii).

Most pycnodontiform fishes are represented by their distinctive dentition alone, whereas articulated skeletons are very rare and the systematic position of most taxa based upon isolated teeth and the association of upper and lower dentitions to a specific taxon is still somewhat ambiguous in most cases. The vomerine dentition of the Late Jurassic pycnodontiform Athrodon wittei (Fricke, 1876), which is described here for the first time, is characterised by a high number of lateral tooth rows and the distinct morphology of the teeth. The dentition of Athrodon differs from most other pycnodont dentitions in the peculiar arrangement of the teeth into irregular rows and not well-differentiated principal row. The absence of regular tooth rows is not considered plesiomorphic here but most probably was achieved independently in different pycnodont lineages. The high number of lateral tooth rows (> four) is considered to be autapomorphic for Athrodon. The pycnodont fish Nonaphalagodus from the Albian of Texas, which also is known by isolated dentitions only, resembles Athrodon in the high number of vomerine tooth rows but differs in that this taxon displays the more derived feature of the teeth being arranged more regularly and individualized rows. doi:10.1002/mmng.200800002

Dapedium pholidotum (Agassiz, 1832) (Actinopterygii, Neopterygii) is redescribed based on new material from the Posidonia Shale (Early Jurassic: Early Toarcian) of Germany. Dapediiformes ord. nov. is introduced for Dapedium Leach, 1822 and other deep-bodied Mesozoic neopterygians. The species diagnosis of D. pholidotum is amended. Comparison with D. stollorum Thies & Hauff, 2011 and D. caelatum Quenstedt, 1858, also from the Lower Jurassic Posidonia Shale, shows that D. pholidotum is unique in having: (1) a length/height ratio of the operculum of c. 0.73, whereas in D. stollorum and D. caelatum this value reaches only c. 0.58; (2) a length/width ratio of the gular plate of c. 1.6, whereas in D. stollorum and D. caelatum this value is 1.3; (3) 27 or more caudal fin lepidotrichia, whereas in D. stollorum and D. caelatum there are 24 and 25 lepidotrichia, respectively; (4) at least 26 dorsal fin lepidotrichia, whereas D. stollorum and D. caelatum possess only 24 dorsal fin lepidotrichia each; and (5) a lengt...

Ray-finned fishes (Actinopterygii) constitute approximately half of all living vertebrate species. A stable hypothesis of relationships among major modern lineages has emerged over the past decade, supported by both anatomy and molecules. Diversity is unevenly partitioned across the actinopterygian tree, with most species concentrated within a handful of geologically young (i.e. Cretaceous) teleost clades. Extant non-teleost groups are portrayed as ‘living fossils’, but this moniker should not be taken as evidence of especially primitive structure: each of these lineages is characterized by profound specializations. Attribution of fossils to the crowns and apical stems of Cladistia, Chondrostei and Neopterygii is uncontroversial, but placements of Palaeozoic taxa along deeper branches of actinopterygian phylogeny are less secure. Despite these limitations, some major outlines of actinopterygian diversification seem reasonably clear from the fossil record: low richness and disparity in the Devonian; elevated morphological variety, linked to increases in taxonomic dominance, in the early Carboniferous; and further gains in taxonomic dominance in the Early Triassic associated with earliest appearance of trophically diverse crown neopterygians.

Reconstructing the feeding ecology of fossil fishes can be difficult, but new mechanical approaches enable reasonably reliable inferences by comparison with living forms. Here, the feeding ecology of one of the most iconic and abundant actinopterygians of the Early Jurassic, Dapedium, is explored through detailed anatomical study and functional analyses of jaw mechanics. Mathematical models derived from modern teleost functional morphology are applied, to ascertain the transmission of force through the jaws of Dapedium. A number of features not previously identified in the genus are described, and the dentition is described in full for the first time. The analysis of the functional morphology of Dapedium, in combination with its jaw anatomy and dentition, indicates that the genus was well adapted to a durophagous feeding habit, although indirect evidence suggests a more generalist feeding mode. Being a generalist durophage may explain the success of the genus in the aftermath of the end-Triassic extinction event and its radiation in the Early Jurassic, as indicated by the ubiquity of Dapedium fossils throughout the Lower Lias.

The Permian and Triassic were key time intervals in the history of life on Earth. Both periods are marked by a series of biotic crises including the most catastrophic of such events, the end-Permian mass extinction, which eventually led to a major turnover from typical Palaeozoic faunas and floras to those that are emblematic for the Mesozoic and Cenozoic. Here we review patterns in Permian-Triassic bony fishes, a group whose evolutionary dynamics are understudied. Based on data from primary literature, we analyse changes in their taxonomic diversity and body size (as a proxy for trophic position) and explore their response to Permian-Triassic events. Diversity and body size are investigated separately for different groups of Osteichthyes (Dipnoi, Actinistia, 'Palaeopterygii', 'Subholostei', Holostei, Teleosteomorpha), within the marine and freshwater realms and on a global scale (total diversity) as well as across palaeolatitudinal belts. Diversity is also measured for different palaeogeographical provinces. Our results suggest a general trend from low osteichthyan diversity in the Permian to higher levels in the Triassic. Diversity dynamics in the Permian are marked by a decline in freshwater taxa during the Cisuralian. An extinction event during the end-Guadalupian crisis is not evident from our data, but 'palaeopterygians' experienced a significant body size increase across the Guadalupian-Lopingian boundary and these fishes upheld their position as large, top predators from the Late Permian to the Late Triassic. Elevated turnover rates are documented at the Permian-Triassic boundary, and two distinct diversification events are noted in the wake of this biotic crisis, a first one during the Early Triassic (dipnoans, actinistians, 'palaeopterygians', 'subholosteans') and a second one during the Middle Triassic ('subholosteans', neopterygians). The origination of new, small taxa predominantly among these groups during the Middle Triassic event caused a significant reduction in osteichthyan body size. Neopterygii, the clade that encompasses the vast majority of extant fishes, underwent another diversification phase in the Late Triassic. The Triassic radiation of Osteichthyes, predominantly of Actinopterygii, which only occurred after severe extinctions among Chondrichthyes during the Middle-Late Permian, resulted in a profound change within global fish communities, from chondrichthyan-rich faunas of the Permo-Carboniferous to typical Mesozoic and Cenozoic associations dominated by actinopterygians. This turnover was not sudden but followed a stepwise pattern, with leaps during extinction events.

Ray-finned fishes (Actinopterygii) dominate modern aquatic ecosystems and are represented by over 32000 extant species. The vast majority of living actinopterygians are teleosts; their success is often attributed to a genome duplication event or morphological novelties. The remainder are 'living fossils' belonging to a few depauperate lineages with long-retained ecomorphologies: Polypteriformes (bichirs), Holostei (bowfin and gar) and Chondrostei (paddlefish and sturgeon). Despite over a century of systematic work, the circumstances surrounding the origins of these clades, as well as their basic interrelationships and diagnoses, have been largely mired in uncertainty. Here, I review the systematics and characteristics of these major ray-finned fish clades, and the early fossil record of Actinopterygii, in order to gauge the sources of doubt. Recent relaxed molecular clock studies have pushed the origins of actinopterygian crown clades to the mid-late Palaeozoic [Silurian-Carboniferous; 420 to 298 million years ago (Ma)], despite a diagnostic body fossil record extending only to the later Mesozoic (251 to 66 Ma). This disjunct, recently termed the 'Teleost Gap' (although it affects all crown lineages), is based partly on calibrations from potential Palaeozoic stem-taxa and thus has been attributed to poor fossil sampling. Actinopterygian fossils of appropriate ages are usually abundant and well preserved, yet long-term neglect of this record in both taxonomic and systematic studies has exacerbated the gaps and obscured potential synapomorphies. At the moment, it is possible that later Palaeozoic-age teleost, holostean, chondrostean and/or polypteriform crown taxa sit unrecognized in museum drawers. However, it is equally likely that the 'Teleost Gap' is an artifact of incorrect attributions to extant lineages, overwriting both a post-Palaeozoic crown actinopterygian radiation and the ecomorphological diversity of stem-taxa.

Living ray-finned fishes number approximately 30,000 species, roughly equal to modern lobe-finned fishes plus tetrapods combined. The fossil record of ray-finned fishes extends to the Early Devonian (ca. 415 Ma), although the oldest taxa for which the morphology of the otic region is known in any great detail are 35 million years younger. Early actinopterygians have consolidated saccular otoliths, open vestibular fontanelles, and a persistent otico-occipital fissure. These general osteichthyan conditions are joined by specializations like the lateral cranial canal, a diverticulum that extends through the loop of the posterior semicircular canal and is thought to be unrelated to hearing. This anatomy persists into early members of the dominant modern radiation of ray-finned fishes, Neopterygii. Neopterygian subclades, including teleosts, show parallel losses of persistent fissures, fragmentation of the endocranium into separate ossification centers, and reduced bony enclosure of the inner ear. Teleosts show remarkable specializations for hearing based on connections between the gas-filled swim bladder and the otic capsule. Cretaceous fossils of clupeomorphs (herrings) and otophysans (catfishes, minnows, characins, and Neotropical knifefishes) document the assembly of the specialized anatomical features associated with hearing in both groups.

We report on a new semionotiform taxon, Scheenstia zappi gen. et sp. nov., from Schamhaupten in the Late Jurassic limestones of the Franconian and Swabian Alb, southern Germany. Although the taxon is so far represented by a single specimen, excellent preservation allows a detailed description of its skeletal anatomy. Scheenstia zappi is distinguished by the presence of a sensory canal in the supraorbital bones and a saddle-like articular surface in the quadratojugal, both features so far unknown in other semionotiforms. The new taxon is further diagnosed by a unique combination of characters: More than three pairs of extrascapular bones; frontals less than three times longer than their maximal width; semitritorial dentition; four anterior infraorbitals; middle pit line contained in a groove in the dermopterotic and parietal; concave posterior border of the angular, robust bugle-like process of the posttemporal bone; large basal fulcra; eleven fin rays in the lower lobe of the caudal fin (below the lateral line); and a first, scale-like caudal fin ray reduced. Among semionotiforms it most closely resembles Lepidotes, in particular the large tritorial forms of the Late Jurassic and Early Cretaceous of Europe, such as L. mantelli, L. maximus and L. laevis. The peculiar shape of the quadratojugal in Scheenstia zappi resembles the condition in some basal teleosts in which a ventral articular surface of the quadrate probably served in the rotation of the lower jaw. Copyright © 2011 The Natural History Museum. Fil: López-Arbarello, Adriana. Bayerische Staatssammlung fur Palaontologie und Geologie; Alemania Fil: Sferco, Marta Emilia. Bayerische Staatssammlung fur Palaontologie und Geologie; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; Argentina

A new scanilepiform, Beishanichthys brevicaudalis gen. et sp. nov., is named and described based on fossils from the Lower Triassic lake deposits exposed in Beishan area, Gansu Province, China. The discovery documents a new record of this group, which is significantly older than other known scanilepiforms from China, and is slightly younger than Evenkia from the Lowest Triassic of Central Siberia. Although the Beishan beds were previously interpreted as Late Permian in age, based on megaplant fossils, this new discovery supports the reinterpretation of the deposits as Early Triassic in age, based on vertebrate fossils from the same locality and horizon. Phylogenetic analysis was conducted to resolve the relationships of Scanilepiformes with other actinopterygian clades, and the inter-relationships within Scanilepiformes. Contrary to previous thought that scanilepiforms are closely related to the Amiidae, the phylogenetic results of this study recognize the Scanilepiformes as stem-group neopterygians. Relationships of the Scanilepiformes and Australosomus with other neopterygians remain unresolved. With a characteristic long-based dorsal fin, scanilepiforms represent a small group that emerged in Early Triassic freshwater environments, inhabited Eurasia and North America during the Middle–Late Triassic, briefly invaded the marine environment by the Late Triassic in Europe, and became extinct at the end of Triassic. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 161, 595–612.

Microstructural scanning electron microscope investigation was performed on sectioned and surface-etched isolated, prehensile teeth of the Late Triassic semionotiform species Sargodon tomicus and Pycnodontidae incertae sedis from the Late Cretaceous. The teeth of both taxa display a system of vascular canals penetrating the dentine and the overlying hypermineralized acrodin cap; small tubules are radiating at an angle to the long axis of the canals, interpreted as residual spaces left by odontoblast cell processes. This is the first detailed account of vascular acrodin encountered in a pycnodont species. New information is revealed also about Sargodon dental histology in the shape of mineralized remnants of the basal lamina at the acrodin–dentine junction. This implies that deposition of the acrodin organic matrix proceeded centrifugally by the cells of the inner dental epithelium, probably with minor collagen contribution from odontoblasts. This is contrary to the more typical centripetal formation (beneath the basal lamina) of the acrodin layer implied for the studied pycnodontid teeth. The rare occurrences of vascular acrodin within Actinopterygii, and the demonstrated differences in its histogenesis, do not suggest the usefulness of the tissue as systematic character but rather point to its adaptive significance. The superficial increase in the order of acrodin bundle orientation, observed in both species, is similarly regarded as convergently acquired mechanical adaptation. The observed uneven shape of crystallite rows and lesser degree of mineralization of the inner collariform ganoin, compared to its outer portion, is indicative of epithelial-ectomesenchymal interaction and qualifies the tissue as enameloid. Microsc. Res. Tech., 2011. © 2010 Wiley-Liss, Inc.

The continental deposits of the Cuyana Basin, western Argentina, have yielded the most diverse, but so far almost unstudied, Triassic ichthyofaunas of South America. Here, we review these faunas and show that only eight of the 29 named taxa can be considered valid, includ- ing the chondrostean Neochallaia, the acrolepid Challaia, Guaymayenia, a taxon of uncertain affinities, and five species of the perleidiform family Pseudobeaconiidae. The first three taxa most probably come from Middle Triassic sediments, while the pseudobeaconiids are of Late Triassic age. Other material, although not diagnostic, probably rep- resents other species, and thus, the diversity of actinoptery- gians in the Cuyana basin is certainly higher than currently recognized. For the Late Triassic fish fauna, the absence of crown-group neopterygians and a single record of a sarcop- terygian is noteworthy and probably indicates some degree of endemism in this fauna, also supported by the high abundance of pseudobeaconiids, which are unknown from other areas. Furthermore, on the basis of the age indicated by the fishes and the available geological information, we discuss the age of the local fauna of the Cerro Bayo, close to the city of Mendoza, and the Agua de la Zorra Forma- tion, Uspallata. The oldest articulated actinopterygian remains are known from the Middle Devonian, but actinopterygians are still rare during that time (Friedman and Blom 2006). They evolved rapidly during the Carboniferous and Perm- ian, and several actinopterygian lineages went to extinc- tion at the Permo ⁄ Triassic boundary. However, the actinopterygian faunas recovered very rapidly during the Triassic, especially diversifying in shallow marine and brackish environments, giving rise to the very rich and diverse actinopterygian faunas of the Middle and Late Triassic. The Triassic is, therefore, a very important per- iod in actinopterygian evolution (Benton 2004). Several major evolutionary events happened during the Triassic actinopterygian radiation. A very important event in the evolution and history of these fishes is the origin of the Neopterygii, which is marked by the acquisition of a better control of the movements of both dorsal and anal fins, and consequently the improvement in their swim- ming capabilities. Although the Neopterygii appear in the fossil record already in the Permian, their first and rapid radiation occurred during the Triassic, producing a new variety of fishes with very distinct feeding specializations

A recent collection of actinopterygian fossil fishes from a previously unreported locality in the Cenomanian or Turonian of southeastern Morocco includes a single specimen of a macrosemiid fish. Macrosemiids are more common in Jurassic and Early Cretaceous deposits, with the previously known range of the family being Late Triassic through Aptian or Albian. This discovery therefore extends the temporal range of the family into the Late Cretaceous. Moreover, macrosemiids had not previously been reported from northern Africa or the Moroccan area of the Tethys basin; therefore, this fossil also increases the geographical range of the family. The Moroccan macrosemiid is described in a new genus and species, Agoultichthys chattertoni. A phylogenetic analysis places it basal to all other genera of the family with the exception of Notagogus. Diagnostic characters of the new species include the high number of scales laterally along the body and the greater number of dorsal fin rays than in other members of the family.

Semionotus bergeri Agassiz, 1833, from the Upper Triassic (Carnian) of southern Germany, the type species ofSemionotus, is here described in detail for the first time, including so far unstudied material in the Naturkunde-Museum Coburg, which allows a fairly complete reconstruction of this fish. The species is diagnosed by the presence of long frontals, about 4 times longer than wide, with antorbital lateral processes, 6–7 posterior infraorbitals, infraorbital at the posteroventral corner of the orbit notably larger than adjacent ones, infraorbitals at the posterior border of the orbit being as deep as long, and the middle element anteroventrally expanded, dorsal fin base about two times the anal fin base.S. elegans from the Late Triassic-Early Jurassic of the Newark Supergroup in North America, is so far the best know species ofSemionotus and is the only species of this genus that has been included in phylogentic analyses. However, the comparison ofS. bergeri with other proposed speciesof Semionotus, such asS. elegans, and other semionotids casts doubt on the monophyly of this genus as currently understood, since these species exhibit a mosaic distribution of characters.

Three Late Jurassic actinopterygian species are commonly placed in the genus Eurycormus: E. egertoni, E. grandis and E. speciosus. A detailed comparison supports an earlier assignment to two different genera, Eurycormus Wagner, 1863 (speciosus) and Eurypoma Huxley, 1866 (E. egertoni and E. grande). Systematically, the two genera are only distantly related; Eurycormus belongs to the Teleosteomorpha, whereas Eurypoma is a halecomorph closely related to or a member of the Caturoidea within the Amiiformes. Drei oberjurassische Actinopterygier-Arten, egertoni, grandis und speciosus, werden gewöhnlich zur Gattung Eurycormus gestellt. Ein detaillierter Vergleich der drei Arten bestätigt eine frühere Zuordnung zu zwei verschiedenen Gattungen, Eurycormus Wagner, 1863 (speciosus) und Eurypoma Huxley, 1866 (E. egertoni und E. grande), die zwei höheren Taxa innerhalb der Neopterygii zugeordnet werden: Eurycormus zu den Teleosteomorpha und Eurypoma zu den Amiiformes innerhalb der Halecomorphi, möglicherweise nahe oder innerhalb der Caturoidea. doi:10.1002/mmng.200600016

One of the main pending, unsolved problems concerning the study of the pycnodont fishes is their phylogenetic relationships with other major actinopterygian groups. The Pycnodontiformes have often been proposed as the sister group of the Telostei or the Teleosteomorpha. The first extensive cladistic analysis on pycnodont relationships is hereby attempted by coding Pycnodontiformes into a previously existing data matrix with major neopterygian groups: Lepisosteiformes, Semionotiformes, Macrosemiiformes, Halecomorphi, and Teleostei. This analysis has resulted on the Pycnodontiformes having an unexpected position as the most basal Neopterygii among the groups included. Therefore, pycnodonts are not the sister-group of teleosteans, and they are not holosteans either. The phylogenetic relationships and the definition of the Holostei and the Gynglimodi are not affected by the inclusion of the Pycnodontiformes, but the basal position of the latter among Neopterygii may affect the definition of this traditional major actinopterygian group. A collateral consequence of these results is that the Halecostomi can be re-defined as the clade formed by [Holostei + Teleostei]. The phylogenetic relationships of pycnodonts should, consequently, be solved among basal neopterygian groups, mostly from the Triassic, as well as relevant non-neopterygian actinopterygians in order to confirm the neopterygian affinities of the Pycnodontiformes and to verify the definition and diagnosis of the Neopterygii and the Halecostomi., Rivista italiana di Paleontologia e Stratigrafia, Vol 121, No 3

Jurassic fishes from the Southern Hemisphere are poorly known in comparison with those of the Northern Hemisphere. The Tithonian (Late Jurassic) deposits of Argentina have yielded a rich and taxonomically diverse ichthyofauna. However, these fishes have been only partially described and need to be revised or studied. In this paper, the putative ichthyodectiform actinopterygian Notodectes argentinus is redescribed. The holotype comes from the Vaca Muerta Formation, in the southwestern part of Mendoza Province, Argentina. It consists of an incomplete, partially articulated skull in which some of the bones are preserved in three dimensions. The specimen has a unique character combination that allows us not only to diagnose the genus Notodectes but also confirm that it is a member of the actinopterygian order Pachycormiformes. At present, Notodectes represents the first endemic pachycormiform from the Southern Hemisphere and the first specimen found in Mendoza Province (northwestern region of the Neuqu en Basin). Also, Notodectes is the first fastswimming and clearly ichthyophagous pachycormid reported from the Jurassic of South America. Fil: Gouiric Cavalli, Soledad. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Cione, Alberto Luis. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

A new semionotiform fish, Isanichthys palustris gen. et sp. nov., is described from the Late Jurassic – Early Cretaceous Phu Kradung Formation, north-east Thailand. I. palustris is known from a single, nearly complete specimen found alongside abundant Lepidotes specimens at the Phu Nam Jun locality. I. palustris shows a mixture of semionotid-like characters, such as the pattern of cheek ossifications, and lepisosteid-like characters, such as the body shape and a dorsal fin opposed by an anal fin. I. palustris possesses only some of the characters currently used to define the Semionotidae. Cladistic analyses including various semionotid and gar taxa, together with Amia calva and Leptolepis coryphaenoides, suggest that the Semionotiformes (Lepisosteidae and ‘Semionotidae’) form a monophyletic clade, but the ‘Semionotidae’ taxa form an unresolved polytomy. The relationships between Semionotiformes, Halecomorphi and Teleostei are unresolved. When restricted to the best-known taxa, however, the analysis shows the monophyly of the Semionotidae sensu stricto (Semionotus + Lepidotes) and a sister-group relationship between halecomorphs and teleosts. These last two results are regarded as the preferred hypothesis for further studies. I. palustris is the only known example of a predaceous, probably piscivorous, ‘semionotid’. It illustrates the great diversity and ecological adaptation of the semionotiforms during the Late Jurassic – Early Cretaceous. We question the phylogenetic relationships of ‘ancient fishes’ founded on molecular-based trees because we suspect that the use of very few Recent taxa as representatives of previously diverse lineages is an inevitable, but important, bias in the construction of such trees.

A new semionotid fish, Lepidotes buddhabutrensis n. sp., is described from the continental Late Jurassic–Early Cretaceous Phu Kradung Formation, Phu Nam Jun, Kalasin Province. L. buddhabutrensis is characterized notably by the pattern of its cheek bones, by its short preorbital region, and by its numerous and well-developed premaxillary teeth. L. buddhabutrensis is provisionally placed in the genus Lepidotes; it shares, however, derived characters with other semionotids, such as Araripelepidotes and Pliodetes. To cite this article: L. Cavin et al., C. R. Palevol 2 (2003).

La presente tesis doctoral constituye una contribución al conocimiento de la ictiofauna marina del Jurásico de la Cuenca Neuquina de Argentina. Teniendo en cuenta que el Jurásico representa un momento crucial en la historia de los peces óseos y cartilaginosos, ya que durante este período comienzan a delinearse los grandes taxones que actualmente dominan los mares y ríos, resulta de sumo interés su estudio. Las asociaciones de peces fósiles marinos jurásicos mejor conocidas se encuentran en Europa. Contrariamente, los peces marinos del Jurásico del Hemisferio Sur, con la excepción de los peces del Oxfordiano de Chile, son pobremente conocidos. En Argentina las principales localidades jurásicas portadoras de peces marinos se encuentran en las provincias de Mendoza y Neuquén en sedimentos de la Formación Vaca Muerta (hallándose además en sedimentitas de la Fm. Picún Leufú); en esta unidad los peces constituyen el grupo de vertebrados más abundante y diverso. Los primeros hallazgos fueron primariamente estudiados por Dolgopol de Sáez quien identificó numerosas especies nuevas basándose en materiales en general fragmentarios. El material estudiado en esta tesis se encuentra depositado en las colecciones de los museos “Dr. Prof. Juan Augusto Olsacher” de Zapala, Neuquén (colección Paleovertebrados [MOZ-Pv]) y Museo de La Plata, Buenos Aires (colección de la División Paleontología de Vertebrados [MLP]). Estos materiales principalmente proceden de los yacimientos jurásicos de Neuquén, de los cuales, las calizas litográficas del Miembro Los Catutos y las concreciones de la localidad Cerro Lotena son particularmente informativas. Parte del material allí colectado fue citado y figurado previamente en algunas publicaciones, aunque no fue descripto en detalle. La preservación general de los materiales es buena, encontrándose incluso ejemplares en tres dimensiones. Los taxones jurásicos identificados con anterioridad al desarrollo de esta tesis corresponden a condrictios: Batomorphii indet. e Hybodontidae indet. así como numerosos osteictios: Semionotiformes, Pachycormiformes, Aspidorhynchiformes, Teleostei sensu stricto y posibles Coelacanthiformes. Todos estos grandes grupos se encuentran presentes en algunas localidades de las calizas de Solnhofen (Kimmeridgiano-Titoniano) de Alemania y las calizas de Cerin (Kimmeridgiano) de Francia, en donde las faunas tetianas están bien representadas. En síntesis, se puede afirmar que al comienzo de la presente tesis doctoral, la situación de la ictiofauna del Jurásico marino de Argentina se encontraba en una etapa temprana de desarrollo, faltando el estudio detallado de las formas previamente descritas así como de las nuevas formas halladas. Una excepción la constituyen los condrictios. Con este panorama en vista y teniendo en cuenta que el Jurásico es un momento crucial para la comprensión de la fauna actual y que los peces de esa antigüedad son pobremente conocidos fuera de Europa, se planteó como objetivo principal la descripción anatómica detallada y comparativa de las formas presentes en el Jurásico marino de Argentina. Dada la abundancia y calidad de preservación de los ejemplares de los Órdenes Aspidorhynchiformes y Pachycormiformes, éstos fueron seleccionados como objeto de estudio. Además, se planteó analizar los patrones biogeográficos de estos dos grupos de peces, hipotetizando sobre las posibles rutas de migración/dispersión utilizadas. Para cumplir con los objetivos propuestos se ha realizado un estudio sistemático, anatómico, descriptivo de los Aspidorhynchiformes y Pachycormiformes del Jurásico de Argentina integrándolo con estudios comparativos de los peces del Jurásico de Europa (Halecomophii, Pachycormiformes, Aspidorhynchiformes, Semionotiformes, Teleostei). De los resultados de este trabajo de tesis surgen: la redescripción de ejemplares tipo (Notodectes argentinus Dolgopol de Saez y Pholidophorus argentinus Dolgopol de Saez) y su reasignación taxonómica. Notodectes argentinus es asignado aquí al Órden Pachycormiformes. Pholidophorus argentinus es asignado aquí al Órden Aspidorhynchiformes. A estas redescripciones se suman: la descripción de dos nuevas especies de Aspidorhynchiformes del género Belonostomus. Dentro del Órden Pachycormiformes se presenta la diagnosis del género Notodectes y la descripción de dos nuevos géneros y especies (Pachycormiformes gen. et sp. nov A y B). Partiendo de estas descripciones y tomando como base una matriz de datos previamente publicada. Se construyó una nueva matriz de datos de 49 taxones por 152 caracteres que fue utilizada en el análisis filogenético. El objetivo principal del análisis filogenético fue dilucidar la posición de los paquicórmidos y aspidorrínquidos en el contexto de los neopterigios; analizando además las relaciones entre los distintos taxones que componen cada clado. Los resultados del análisis de las topologías más parsimoniosas sugieren que: Aspidorhynchiformes y Pachycormiformes son grupos monofiléticos, en concordancia con hipótesis previas. Teniendo en cuenta el análisis filogenético se enmendaron las diagnosis de los Órdenes Aspidorhynchiformes y Pachycormiformes de acuerdo a las sinapomorfías halladas. Por otro lado, el estudio de la ictiofauna presente en sedimentos marinos jurásicos de la Cuenca Neuquina demuestra una riqueza y calidad notable, lo que ha dado pie al planteo de un proyecto de investigación, actualmente en evaluación, que consiste en el estudio anatómico detallado de otras formas presentes (o que fueran halladas en futuras campañas) en sedimentos marinos de la Cuenca Neuquina. Asimismo, se ha planteado como objetivo para el desarrollo del postdoctorado, actualmente aprobado, el estudio biomorfodinámico, paleoecológico y ecomorfológico de los peces paquicórmidos y aspidorrínquidos hallados (o que sean hallados en futuras campañas) en la Cuenca Neuquina. Por otro lado, partiendo del estudio de los patrones de distribución observados en los peces estudiados en esta tesis se concluye que los mismos habrían utilizado principalmente el Corredor Hispánico como ruta de dispersión y/o migración, aunque algunas formas podrían haber utilizado también el Corredor o pasaje Transeritreo. Del análisis tafonómico de los peces presentes en las calizas litográficas del Miembro Los Catutos de la Formación Vaca Muerta de Argentina se desprende que las formas predominantes corresponden a representantes de los Órdenes Pachycormiformes y Aspidorhynchiformes, encontrándose también otros osteictios como Semionotiformes, cf. “Pholidophoriformes” y Teleostei. Los peces se habrían depositado en ambiente abierto, disaeróbico, con buen aporte de carbonato debido a la presencia de aguas superficiales oxigenadas. El sepultamiento habría sido rápido en un fondo oceánico cuyo contenido en oxígeno disuelto por litro era de aproximadamente 0,1-1 ml (disaeróbico) o bien carente de oxígeno disuelto (anóxico) y hostil lo que inhibió la presencia de organismos carroñeros., Facultad de Ciencias Naturales y Museo