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Details of the endolymphatic structures are described for the first time in the headshields of the osteostracan genus Tremataspis from the Silurian of Estonia. Tiny platelets, here termed covering platelets, are located within the openings of the endolymphatic duct. The details of their shapes and arrangements differ among the four studied species. In Tremataspis schmidti Rohon and Tremataspis milleri Patten, the covering platelets are usually arranged in an oval or circular shape around the opening of the endolymphatic duct. These species can have smooth, flat covering platelets at the mouth of an irregularly funnel-shaped aperture in the dorsal shield; the funnel often has a posterior extension. In Tremataspis rohoni Robertson and Tremataspis mammillata Patten, a distinct circular arrangement of platelets does not occur; instead, their funnel was capped with a few (2-3) smooth, flat covering platelets. The funnel of T. milleri sometimes has a long postero-lateral extension, while that of T. mammillata can have a short extension; no extensions of the funnel have been observed in T. schmidti or T. rohoni. The diameter of the pores in the covering platelets is larger than that of the pores in the superficial layer of the headshield and much larger than the diameter of the pores in the porous fields (these are thin perforated bony septa subdividing the sensory canals horizontally into lower and upper parts). In T. milleri, the larger pores are located on the side of the covering platelets that is closer to the body midline. The discovered system of covering platelets possibly functioned as a sieve for allowing in suitable grains of material and preventing material that is too fine or too coarse, or not sufficiently dense, from entering the inner ear. [ABSTRACT FROM AUTHOR]

The larger-bodied fish fauna of the Kishenehn Formation's Coal Creek Member (Eocene, 43.5 Ma), northwestern Montana, is understudied because of a sampling bias towards small specimens. Small specimens (<10 cm length) of taxa are usually found as mostly to fully complete compression fossils. Relatively larger-bodied fishes, such as amiids (the bowfin Amia calva and close relatives), are only known from fragmentary remains for which taxonomic resolution is only possible to the family level. Here we describe the most complete amiid fossil (USNM 618000) from the Kishenehn Formation. We assign this specimen to the genus Amia based on the presence of pointed coronoid teeth and a long preural region (81 preural centra). The specimen exhibits a combination of features from multiple species, including a total of 89 centra (like Amia calva and Amia scutata), eight ural centra (like Amia scutata and Amia pattersoni), and a concave anteroventral margin on the first postinfraorbital (like Amia hesperia). The lack of more complete specimens of amiids and other larger-bodied taxa is most often attributed to a preservation bias; however, this could also reflect a rarity of amiids in the ecosystem overall or a partitioning of habitat preference away from the shallow, near-shore regions of the ancient lake. This new specimen enhances the known biodiversity of relatively larger-bodied fishes from this region during the Eocene epoch. [ABSTRACT FROM AUTHOR]

The larger-bodied fish fauna of the Kishenehn Formation's Coal Creek Member (Eocene, 43.5 Ma), northwestern Montana, is understudied because of a sampling bias towards small specimens. Small specimens (<10 cm length) of taxa are usually found as mostly to fully complete compression fossils. Relatively larger-bodied fishes, such as amiids (the bowfin Amia calva and close relatives), are only known from fragmentary remains for which taxonomic resolution is only possible to the family level. Here we describe the most complete amiid fossil (USNM 618000) from the Kishenehn Formation. We assign this specimen to the genus Amia based on the presence of pointed coronoid teeth and a long preural region (81 preural centra). The specimen exhibits a combination of features from multiple species, including a total of 89 centra (like Amia calva and Amia scutata), eight ural centra (like Amia scutata and Amia pattersoni), and a concave anteroventral margin on the first postinfraorbital (like Amia hesperia). The lack of more complete specimens of amiids and other larger-bodied taxa is most often attributed to a preservation bias; however, this could also reflect a rarity of amiids in the ecosystem overall or a partitioning of habitat preference away from the shallow, near-shore regions of the ancient lake. This new specimen enhances the known biodiversity of relatively larger-bodied fishes from this region during the Eocene epoch. [ABSTRACT FROM AUTHOR]

A new and previously cryptic fish species, Polymixia hollisterae, new species, proposed common name "Bermuda Beardfish," is described from two voucher specimens collected in 1997 at a depth of about 280 fm or 512 m on the NW slope of the Bermuda Platform, and a third voucher collected by a midwater trawl in the north-central Gulf of Mexico. The species belongs to the paracanthopterygian acanthomorph genus Polymixia, family Polymixiidae, order Polymixiiformes, and is named after pioneering ichthyologist, ocean explorer, and conservationist Gloria E. Hollister (Anable). It is distinguished from all other species in the genus by its greater dorsal and anal fin heights (19% and 14% of SL, respectively), its extremely long pectoral and pelvic fins (22% and 14% of SL, respectively), its relatively large eye diameter (34% of total head length), and its morphologically distinctive first anal-fin radial. It has a unique pigmentation pattern on the dorsal, anal, and caudal fins consisting of narrow, dark black patches near the tips of the longest few soft dorsal- and anal-fin rays, and a caudal-fin margin with a dark black fringe covering the distal fourth of the fin. Based on an earlier molecular study that revealed it to be a cryptic species, P. hollisterae, new species, is closely related to P. japonica, but it differs by 20-33 nucleotides in a total alignment of 4,983 nuclear and mitochondrial sites. The new species shares a distinctive scale morphology with P. japonica and P. nobilis (the type species); an intermediate number of dorsal-fin rays (V,31-32), like P. japonica (V,31-34); a distinctive preopercle shape with P. japonica, P. lowei, and P. berndti; and a low number of pyloric caeca with P. lowei and P. berndti. Pored lateral-line scales number 35, an intermediate number compared to reported counts of other species (31-39). The three supraneurals are sigmoidshaped like those of P. nobilis, while dorsal-fin proximal radials interfinger with neural spines in a unique pattern. Body shape, as studied with measurement proportions and multivariate morphometrics, is distinguished by a relatively large head, large eyes, long jaws, and a more streamlined pre-dorsal body profile than its congeners. Further research and additional collecting will be needed to ascertain the geographic distribution and conservation status of the new species. [ABSTRACT FROM AUTHOR]

In this microichthyological study the teeth and bony cores of gill rakers of three pleuronectiform species [European plaice Pleuronectes platessa Linnaeus, 1758 and European flounder Platichthys flesus trachurus (Duncer, 1892), both in the Pleuronectidae, and turbot Scophthalmus maximus (Linnaeus, 1758) in the Scophthalmidae] of the Baltic Sea are SEM imaged, described and compared for the first time. The shape and number of teeth in jaws and on pharyngeal tooth plates as well as the shape, size and number of the bony cores of gill rakers in these taxa differ. The European plaice and European flounder carry incisiform teeth anteriorly in their jaws and smoothly rounded, molariform teeth on pharyngeal tooth plates; the teeth of the plaice are more robust. The gill rakers have similar gross morphology, occurring as separate conical thornlets on gill arches. The bony cores of these thornlets (rakers) consist of vertical ribs with connective segments between them. The cores of gill rakers of the plaice and flounder reveal some differences in details. The plaice has cores with one peak, simple vertical ribs, and nodules on their lower thicker parts, while the flounder has cores with a side-branch and fine vertical ribs, which have parallel ribbing and tend to twist around the lower part of cores. The teeth of the jaws and pharyngeal tooth plates and the raker cores of the turbot are completely different from those of the plaice and flounder. In the turbot two main types of complex gill rakers are attached to the gill arches: one type has 'sail'-shaped, high elements with one to two rows of fine conical teeth set in sockets; the other type has low tubercles with the same type of teeth. The differences among the species can be useful for studies of taxonomy and phylogeny, as well as for understanding their feeding habits. [ABSTRACT FROM AUTHOR]

The fish genus Esox (Teleostei, Esocidae) has been recorded from thirty late Miocene, Pliocene, and Pleistocene localities where forty-one bone-bearing strata are exposed in the territory of Ukraine, Russian Federation, and Republic of Moldova. From eight localities the genus is reported or described for the first time. A detailed description and morphological analysis of the currently available osteological material demonstrates the presence of four species in the studied area: (i) Esox sibiricus (late Miocene-early Pliocene); (ii) Esox moldavicus (early Pliocene-early Pleistocene); (iii) Esox nogaicus sp. nov. (early Pleistocene, Calabrian); (iv) Esox lucius (early-middle Pleistocene). The Northern Pike (Esox lucius) is recorded for the first time in the early Pleistocene fossil record of southeastern Europe. The new species E. nogaicus is characterized by a massive dentary with deep symphysis and the possible presence of a pair of fixed canine-like teeth near the anterior end of the vomer. Such canine teeth are seen also in certain species known only from North America, the extant Esox masquinongy, the fossil species E. columbianus, and an unnamed Miocene form. However, unlike in E. nogaicus, in the three North American species fixed canines also occur anteriorly on the palatines. The Miocene, Pliocene, and Pleistocene pikes from southeastern Europe document a greater diversity of morphologies in the past than exists today in the pike species of Europe. Changes in the predominant species of Esox in southeastern Europe are hypothesized to be driven by changing global and regional climates. [ABSTRACT FROM AUTHOR]

The fish genus Esox (Teleostei, Esocidae) has been recorded from thirty late Miocene, Pliocene, and Pleistocene localities where forty-one bone-bearing strata are exposed in the territory of Ukraine, Russian Federation, and Republic of Moldova. From eight localities the genus is reported or described for the first time. A detailed description and morphological analysis of the currently available osteological material demonstrates the presence of four species in the studied area: (i) Esox sibiricus (late Miocene-early Pliocene); (ii) Esox moldavicus (early Pliocene-early Pleistocene); (iii) Esox nogaicus sp. nov. (early Pleistocene, Calabrian); (iv) Esox lucius (early-middle Pleistocene). The Northern Pike (Esox lucius) is recorded for the first time in the early Pleistocene fossil record of southeastern Europe. The new species E. nogaicus is characterized by a massive dentary with deep symphysis and the possible presence of a pair of fixed canine-like teeth near the anterior end of the vomer. Such canine teeth are seen also in certain species known only from North America, the extant Esox masquinongy, the fossil species E. columbianus, and an unnamed Miocene form. However, unlike in E. nogaicus, in the three North American species fixed canines also occur anteriorly on the palatines. The Miocene, Pliocene, and Pleistocene pikes from southeastern Europe document a greater diversity of morphologies in the past than exists today in the pike species of Europe. Changes in the predominant species of Esox in southeastern Europe are hypothesized to be driven by changing global and regional climates. [ABSTRACT FROM AUTHOR]

Three new species in two new genera of cornuate Osteostraci are described here based on specimens from the Early Devonian (Lochkovian) Man on the Hill (MOTH) locality in the Mackenzie Mountains, Northwest Territories, Canada. The new taxa share several characteristics withSuperciliaspis gabrielsei.Glabrapeltagen. nov., and its two species,G. cristatasp. nov. andG. minimasp. nov., are based on four previously undescribed specimens.Dentapelta loeffleraegen. et sp. nov. is based on one newly recovered specimen, along with another specimen originally referred by earlier workers to ‘Cephalaspidinae indet.’ Together withSuperciliaspis, these new genera are subjected to a phylogenetic analysis, building on earlier work by R. Sansom. The results indicate that all four species in three genera belong to a single clade that is here named as the new family Superciliaspididae. The Superciliaspididae are characterized by a long, narrow median field with a border of raised ridges of fused plates, by narrow and posteriorly pointing cornua, and by orbits close together. A laterally expanded pineal opening and raised orbital rims place the Superciliaspididae as sister to the clade Scolenaspididae + Zenaspididae in the Order Zenaspidida. Internal anatomy of the nasohypophysial opening confirms separate internal nasal and hypophysial ducts. To date, the Superciliaspididae have been found only at the MOTH locality in the Mackenzie Mountains of northern Canada, whereas related taxa are distributed more widely in North America, Spitsbergen and Europe. http://zoobank.org/urn:lsid:zoobank.org:pub:F69DDE22-311A-4F2A-9B5D-8E59D13341E2 [ABSTRACT FROM AUTHOR]

The Silurian thelodont Phlebolepis elegans Pander from Saaremaa, Estonia, is one of the most-often illustrated early vertebrates, yet its external morphology has remained poorly known and experts seldom agree about its probable body form. We examined hundreds of articulated specimens from the type locality (Himmiste Quarry) to reconstruct its morphological features. We found that a reconstruction published more than four decades ago by A. Ritchie was the best available till now. We disagreed mostly in that the mouth is not terminal, but subterminal, and there is a slight development of a rostrum dorsal to the mouth. The pectoral fin originates close behind the orbits, but is otherwise similar to Ritchie's reconstruction. We also found the caudal fin to be much larger, more flexible and more symmetrical (though not perfectly symmetrical) than earlier reconstructions, with a large dorsal lobe and an even larger ventral lobe, and a fin web supported by slender 'ray-like' scale-covered lobes. The shape, number and location of the branchial openings are notably still not certainly known. Our preferred morphological features are represented by an artist's restoration. With this revised understanding, future representations of Phlebolepis elegans can be based on more reliable information and its morphology can be compared more accurately with that of other early vertebrates. [ABSTRACT FROM AUTHOR]

Knowledge of the Thelodonti has improved greatly in recent years, but phylogenetic relationships remain poorly understood. We revised the data from an earlier phylogenetic study and added 15 scale-based species. Maximum parsimony analysis gives a well-resolved tree in which Archipelepis and Boothialepis form a basal clade, recognized here as the order Archipelepidiformes, sister group to two large clades also recognized as orders. The first is recognized as the order Furcacaudiformes, including Nikolivia, Lanarkia, Phillipsilepis, Pezopallichthys, Drepanolepis (in the new family Drepanolepididae), Barlowodus, Apalolepis, and Furcacaudidae. The second, here recognized as the Thelodontiformes, contains Turinia, Thelodus, Stroinolepis, Loganellia, Longodus, Helenolepis, Phlebolepis, Erepsilepis, Trimerolepis, Eestilepis, Valiukia, Paralogania, and Shielia. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A new genus and species of osteoglossomorph fish is described from the Eocene Mahenge site in north central Tanzania. The new species is sympatric with the previously described osteoglossomorph† Singida jacksonoides, but is easily distinguished from it by the presence in the new species of teeth on the jaws and entopterygoid. The new species shares characters with the Heterotidinae, such as the two arms of the preopercle being of similar length and the posterior end of the maxilla lying on the dentary, and other characters with the Osteoglossinae (including† Phareodus), for example the enlarged pectoral fin ray and the shape of the opercular bone. New specimens of† S. jacksonoidesalso have been recovered from the site, providing more information on the osteology of this fish. The relationships of these two Mahenge osteoglossomorphs are assessed, with both fishes placed within the Osteoglossidae, but of uncertain position in the family. Addition of the new species to previous cladistic data sets, and the revised information for† S. jacksonoides, causes the subfamily Osteoglossinae to be nonmonophyletic. © 2005 The Linnean Society of London,Zoological Journal of the LinneanSociety, 2005,144, 213–228. [ABSTRACT FROM AUTHOR]

The Eocene Horsefly locality in British Columbia has yielded many fossil fishes, insects, and plants. Its varved sediments make it ideal for study of temporal changes in environment and fish morphology. Several intervals of diatomaceous varves indicate a deep, stratified lake setting. Earlier studies focused on morphological and taphonomic change during the 700-year H2 interval and morphological change during the 10 000-year H3 interval. The present study uses taphonomy as an index for environmental change during the ten millennia represented by H3, comparing taphonomic changes with the morphologic changes found earlier. The H3 interval records deposition in deep water, indicated by dominance of the fish genera Amyzon and Eohiodon. Quiet water conditions are indicated by minimal fin disarticulation. Hypoxia at the time of fish death is confirmed by open mouths of most fish specimens, while cool water on the lake floor prevented full flotation of fish carcasses. Water depth, temperature, and oxygenation fluctuated during H3 deposition. Periods of cooler, deeper, more hypoxic water are indicated by greater numbers and size of Amyzon specimens and by less disarticulation of skull and abdominal bones. Periods of warmer, shallower, more oxygenated waters are indicated by more disarticulation, less fin tetany, smaller fish specimens, and greater diversity of species. Correlations between the taphonomic changes and morphological changes in A. aggregatum are weak. Therefore, the morphological changes are not easily explained as ecophenotypic or short-term evolutionary responses to changes in physical lake conditions. [ABSTRACT FROM AUTHOR]

The genus Polymixia is the only survivor of a Late Cretaceous marine fish radiation and is often said to be the most primitive living acanthomorph (i.e., Polymixia possesses the greatest number of primitive character states for Acanthomorpha). Recent studies, including this one, place Polymixia as the sister to all other Paracanthopterygii. Despite its importance, most species of Polymixia are extremely difficult to discriminate on the basis of morphology. As a result, the number of valid species is uncertain. Moreover, there has never been a phylogenetic analysis of the genus. Thus, a molecular phylogenetic study was needed to clarify species boundaries and to resolve relationships within the genus. Tissue or DNA samples backed by museum vouchers were obtained for most species, with additional samples from new geographic areas representing specimens with distinctively different meristics and uncertain identifications. Seven loci (five nuclear and two mitochondrial) were sequenced, from which Bayesian and maximum-likelihood trees were generated. Results reveal nine species-level clades, of which five represent previously known species (Polymixia berndti, P. japonica, P. longispina, P. lowei, and P. nobilis). Surprisingly, results also reveal four previously unknown species-level clades, one close to P. lowei, one close to P. nobilis, and two new species clades related to P. japonica. The species clades are distinguished by their phylogenetic histories, sequence differences, geographic distributions, and morphologies. The clade containing P. berndti is recovered as the sister to all other species of Polymixia. Its genetic variability suggests that it might contain two or more species and it is referred to here as a “species complex”. Polymixia nobilis, the type species, was previously thought to be restricted to the Atlantic, but is now shown to be widespread in the Pacific and possibly in the Indian Ocean. Specimens from waters off Australia identified as P. busakhini actually belong to P. nobilis. In contrast, P. japonica is confirmed only in the area near Japan and the East China Sea; other more distant records are misidentifications. Wide (antipodal) geographic distributions are seen in several clades, including P. nobilis, the P. berndti species complex, and the P. japonica species group. The new phylogeny helps explain the evolution of some morphological characters previously used to distinguish groups of species, particularly dorsal-fin soft-ray count, shape of rows of scale ctenii, and number of pyloric caeca. [ABSTRACT FROM AUTHOR]

The Early Devonian (Lochkovian) Man On The Hill (MOTH) locality in the Northwest Territories has yielded hundreds of exquisitely preserved specimens of over 72 different species of early vertebrates, greatly increasing our understanding of the diversity of this period. In this paper, we describe three new genera comprising four new species of ischnacanthid acanthodian, based on their dentigerous jaw bones and teeth. This taxonomic diversity reflects some of the diversity of dentition found among ischnacanthiform acanthodians at the MOTH locality, in contrast to their highly conservative body forms. This high diversity of related forms suggests an early radiation in jaw and tooth morphology in Early Devonian ischnacanthiform acanthodians in this region. All ischnacanthiform specimens from MOTH were originally assigned to Ischnacanthus gracilis. However, study of the unique jaw and tooth morphology of MOTH ischnacanthiform specimens indicates that it is unlikely that Ischnacanthus was present at the MOTH locality. [ABSTRACT FROM AUTHOR]

Lees, J., Märss, T., Wilson, M. V. H., Saat, T. and Špilev, H. 2011. The sculpture and morphology of postcranial dermal armor plates and associated bones in gasterosteiforms and syngnathiforms inhabiting Estonian coastal waters. - Acta Zoologica (Stockholm) 93: 422-435. Five fish species inhabiting Estonian coastal waters ( Gasterosteus aculeatus L., Pungitius pungitius (L.), and Spinachia spinachia (L.) of the order Gasterosteiformes and Syngnathus typhle L. and Nerophis ophidion (L.) of the order Syngnathiformes) are described on the basis of the sculpture and morphology of their postcranial dermal armor plates, as revealed and illustrated by SEM images. This study shows that the shapes of these superficial skeletal elements vary by species as well as by their position on the body, whereas the sculpture on the bones is taxon specific. The detailed features allow the identification of isolated fossil and subfossil remains and show promise for future systematics studies. [ABSTRACT FROM AUTHOR]

Sedimentary and faunal characteristics of the Lower Devonian Man On The Hill (MOTH) vertebrate-bearing succession, Mackenzie Mountains, Northwest Territories, Canada provide insights to the paleoenvironmental conditions. Based on sedimentological and petrographic analyses of a 6-m vertical section of the vertebrate-bearing strata, three depositional scenarios for the MOTH locality are proposed, the favoured interpretation being that the vertebrate-bearing interval was deposited on the outer margin of a carbonate platform within an intra-shelf topographic low below storm-wave base. This interpretation is supported by the presence of fine, alternating laminae of light grey argillaceous limestone, or calcareous shale, and dark grey silt to sand-rich calcareous shale, as observed in thin section, and the characterization of the lithology for the vertebrate-bearing strata as an interlaminated argillaceous limestone and calcareous shale. An abundant, low-diversity association of cryptic trace fossils, previously unrecognized at MOTH, is described. These trace fossils and the presence of pyrite suggest that the intra-shelf topographic sag at MOTH had restricted circulation and was generally hypoxic. Based on the instability of such a restricted environment, a cause of death for the cyathaspids Dinaspidella and Nahanniaspis is unclear. However, turbidite deposition and seasonal turnover can be eliminated as possible causes of death, as vertebrates were not located frequently enough within light or dark grey layers and minimal signs of skeletal abrasion or fracturing were observed in Dinaspidella and Nahanniaspis. The high preservation potential of the fossils at MOTH likely was enhanced by the hypoxic nature of the bottom waters within the intra-shelf topographic low below storm-wave base. [ABSTRACT FROM AUTHOR]

A correction to the article "A New Family of Cypriniformes (Teleostei, Ostariophysi) Based on a Redescription of † Jianghanichthys Hubeiensis (Lei, 1977) From the Eocene Yangxi Formation of China," by John Liu and colleagues is presented.

The fossil cypriniform fish †Jianghanichthys hubeiensisfrom Eocene mudstones in Songzi, Hubei, China, was originally assigned to the extant cyprinid genusOsteochilus, then later to the new genus †Jianghanichthysby its original author, but with its familial status uncertain. Other authors subsequently assigned it to the cypriniform family Catostomidae. A detailed comparison of osteological characters shows that †Jianghanichthysis distinguished from all other cypriniforms by having (1) first principal anal fin ray branched; (2) supraorbital sensory canal largely exposed in frontal but roofed by longitudinal flange; (3) supraorbital sensory canal meeting the temporal sensory canal within the parietal; (4) maxilla bearing three dorsal processes; (5) dorsal surface of anterior end of dentary triangular and broad; and (6) the first centrum of †Jianghanichthyshas a similar size and prominent posterior concavity to the second centrum. A computed tomography (CT) scan of a matrix-covered skull confirmed these unique characters, as well as that the pharyngeal teeth are either absent or not well formed. A series of phylogenetic analyses, using parsimony criteria and morphological characters, consistently recovers †Jianghanichthysin a polytomy with the non-loach cypriniform families, but it could not be placed within any recent family. Among osteological characters, few unique synapomorphies are shared byJianghanichthysand recent families of Cypriniformes, whereas a large number of symplesiomorphies with the Catostomidae, Cyprinidae, and Gyrinocheilidae were found, indicating thatJianghanichthysis a stem taxon of Cypriniformes. Therefore, the first family of Cypriniformes known only from fossils, †Jianghanichthyidae, is erected to contain this Eocene cypriniform fish. http://zoobank.org/urn:lsid:zoobank.org:pub:42C2E6E4-9E85-406B-A892-8998735F200D Citation for this article: Liu, J., M.-M. Chang, M. V. H. Wilson, and A. M. Murray. 2015. A new family of Cypriniformes (Teleostei, Ostariophysi) based on a redescription of†Jianghanichthys hubeiensis(Lei, 1977) from the Eocene Yangxi Formation of China. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2015.1004073. [ABSTRACT FROM AUTHOR]

Teeth of a new freshwater dasyatoid ray recovered from the latest middle Eocene Brian Head Formation of southern Utah represent the youngest freshwater stingray so far known in the fossil record of North America. The crown morphology of Saltirius utahensis n. gen. n. sp. exhibits strong sexual dimorphism, with the presumed males bearing two prominent margino-labial protuberances and a bifid cusp that produces a saltire-like outline. This unique crown separates this genus and species from any known extinct or extant myliobatiform, but does have some resemblance to the crown of Asterotrygon maloneyi from the lower Eocene Green River Formation of Wyoming. The occurrence of S. utahensis in the Brian Head Formation provides additional evidence for the persistence of warm subtropical temperatures during the late Eocene in southern Utah. [ABSTRACT FROM AUTHOR]

Aim The aim of this study was to determine the contributions of Gondwanan vicariance and marine dispersal to the contemporary distribution of galaxiid fishes. This group has been central in arguments concerning the roles of dispersal and vicariance in the Southern Hemisphere, as some taxa have marine life history stages through which transoceanic dispersal may have been facilitated, yet other galaxiids are entirely restricted to freshwaters. Location Southern Hemisphere land masses of Gondwanan derivation. Methods Biogeographic hypotheses of Gondwanan vicariance and marine dispersal were tested using four lines of evidence: (1) concordance of species-area phylogenetic relationships, (2) molecular estimates of lineage divergence times with a priori expectations based on plate tectonics, (3) reconstructions of ancestral dispersal capabilities, and (4) reconstructions of distribution inheritance scenarios (using the dispersal-extinction-cladogenesis model to infer historical ranges and dispersal and extinction events). Results Phylogenetic relationships were reconstructed from 4531 mitochondrial and nuclear nucleotide characters, and 181 morphological characters, across 53 of the 56 presently recognized species. Phylogenetic relationships were generally well resolved and supported among galaxiids using the combined dataset, and conflicting relationships between molecular and morphological datasets typically received low topological support from either or both datasets. Transoceanic disjunctions were exhibited at 16 nodes, but only three pre-dated relevant continental fragmentation events; furthermore, ancestral distribution inheritance scenarios for two of these nodes reflected cladogenesis within, rather than between, Gondwanan land masses, and ancestral marine dispersal capability could not be rejected for all three. Instead, the four lines of evidence surveyed suggest that Gondwanan vicariance occurred twice, but in both instances was preceded by marine dispersal between land masses, and in at least one instance was initiated by the cessation of marine dispersal subsequent to continental fragmentation. Main conclusions Gondwanan vicariance appears to have been preceded by marine dispersal in the few instances where it may explain contemporary galaxiid distribution, such that these biogeographic mechanisms may sometimes have a synergistic relationship. [ABSTRACT FROM AUTHOR]

Horseshoeichthys armaserratus, gen. et sp. nov., (Clupeomorpha: Ellimmichthyiformes: Sorbinichthyidae) is described from the Horseshoe Canyon Formation (Maastrichtian), Albertosaurus bonebed locality, Alberta, Canada. Horseshoeichthys armaserratus is classified as an ellimmichthyiform based on the following characters: the presence of a sixth infraorbital with a sensory canal that leads to the fifth infraorbital, absence of a supraorbital bone, subrectangular predorsal scutes, parietals in contact with each other at the midline, and two supramaxillae. The specimen is classified in the Sorbinichthyidae Family as it has abdominal ribs articulating in pits on the centra, posterior spines on predorsal scutes, and absence of a median spine on predorsal scutes. A new genus and species is proposed based on the presence of (anteriorly) Y-shaped mesethmoid, supraorbital, subrectangular predorsal scutes with coarse, rounded serrae on the posterior margin and a large anterior projection, scales with serrae on the circuli, and two postcleithra. This specimen represents the first freshwater ellimmichthyiform from the Upper Cretaceous of North America and the highest paleolatitude (59°N) occurrence known for the family. Furthermore, the dentary and centra have distinctive morphologies that are matched by specimens in microvertebrate localities from three underlying formations, including the Milk River Formation (Santonian), which indicates at least a 14 million year history for this lineage. Horseshoeichthys armaserratus, gen. et sp. nov., (Clupeomorpha: Ellimmichthyiformes: Sorbinichthyidae), de la localité du gisement d'ossements d'Albertosaurus de la Formation de Horseshoe Canyon (Maastrichtien), en Alberta, au Canada, est décrit. Horseshoeichthys armaserratus est affecté aux ellimmichthyiformes à la lumière des caractères suivants : la présence d'un sixième sous-orbitaire présentant un canal sensoriel qui mène au cinquième sous-orbitaire, l'absence d'un os sus-orbitaire, des plaques osseuses pré-dorsales sub-rectangulaires, des pariétaux en contact les uns avec les autres au niveau de la ligne médiane et deux sus-maxillaires. Le spécimen est affecté aux sorbinichthyidés puisqu'il présente des côtes abdominales s'articulant dans des fosses sur le centrum et des épines postérieures sur les plaques osseuses pré-dorsales, et que ces dernières n'ont pas d'épine médiane. Un nouveau genre et une nouvelle espèce sont proposés à la lumière de la présence d'un mésethmoïde (antérieurement) en forme de Y, d'un sus-orbitaire, de plaques osseuses pré-dorsales sub-rectangulaires présentant des stries arrondies et épaisses sur leur bord libre postérieur et une grande projection antérieure, d'écailles avec des stries sur le circulus et de deux postcleithra. Ce spécimen représente le premier ellimmichthyiforme d'eau douce du Crétacé supérieur de l'Amérique du Nord et l'exemple connu de cette famille provenant de la plus haute paléolatitude (59oN). En outre, le dentaire et le centrum présentent des morphologies particulières semblables à celles de spécimens trouvés dans des localités de microvertébrés de trois formations sous-jacentes, dont la Formation de Milk River (Santonien), ce qui indique une histoire d'au moins 14 millions d'années pour cette lignée. [ABSTRACT FROM AUTHOR]

The extinct clupeomorph genusArmigatushas been included in a number of phylogenetic analyses, with disagreement about its placement and relationships among the fishes of the extinct clupeomorph order Ellimmichthyiformes. There are currently four species known, all from the Late Cretaceous Tethys Sea. Here we describe a fifth species ofArmigatusfrom Campanian deposits of Dalmatia and present a phylogenetic analysis of the genus. The new species is found to be sister group toA. oligodentatusfrom Morocco, and the two together form the sister group to the species from Lebanon,A. namourensisplusA. brevissimus(A. alticorpuswas excluded because of lack of data). The genusArmigatusis found to be monophyletic, as are the included members of its sister group,Diplomystus, and the analysis supports the grouping of these two genera in the family Armigatidae. The relationships among the species ofArmigatusindicate that these fishes arose in the eastern part of the central Tethys, then from there reached more northern (Dalmatian) and western (Morocco) areas. http://zoobank.org/urn:lsid:zoobank.org:pub:178B49D2-8D68-4C88-937E-EE93E3C424F7 Citation for this article: Murray, A. M., O. Vernygora, S. Japundžić, J. Radovčić, M. V. H. Wilson, D. Bardack, and T. Grande. 2016. Relationships of the species ofArmigatus(Clupeomorpha, Ellimmichthyiformes) and the description of a new species from the Cretaceous of Dalmatia, Croatia. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2017.1226851. [ABSTRACT FROM AUTHOR]