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Our revision of the type material of Liodesmus led to significant adjustments in our understanding of the taxon when the original type specimen of Pholidophorus gracilis, which was later determined as the type species of the genus Liodesmus, was recently found in the collection in Berlin. It had been confused with a specimen that was described as the type specimen of the species Liodesmus gracilis in the collection in Munich. Moreover, the Munich specimen was mistakenly considered by all authors who have studied Liodesmus as a type specimen for the genus Liodesmus. However, the original holotype of Pholidophorus gracilis and this Munich specimen of Liodesmus gracilis belong to two different families. Caturus brevicostatus, whose holotype was recently found in Berlin as well, is described in detail here for the first time. Liodesmus sprattiformis is now described under the new genus Nasrinsotoudehichthys outside Caturidae but within the Caturoidea. Since all specimens that have been described so far under Liodesmus either belong to other, previously described genera, belong to new genera clearly outside the description of the genus Liodesmus, or are nomina dubia (including the type species Pholidophorus gracilis), the genus Liodesmus and the Liodesmidae are nomina dubia as well. [ABSTRACT FROM AUTHOR]

Ginglymodians (e.g. gars) are a group of holostean fishes with a rich fossil history in the Mesozoic. The resolution of interrelationships among extinct ginglymodians is central to the problem of understanding the origin of this clade. Here, a new fossil ginglymodian, Diandongichthys ocellatus gen. et sp. nov. is described based on 13 well-preserved specimens from the Early-Middle Triassic (Anisian) marine deposits exposed in Luoping, eastern Yunnan, China. The discovery documents one of the oldest and smallest ginglymodians hitherto known from the Middle Triassic, with a maximum standard length of 41 mm. Diandongichthys , although displaying several synapomorphies of ginglymodians, retains some primitive states with respect to other early ginglymodians (e.g. a short snout without anterior infraorbitals, a maxilla ending below the orbit, and a median gular); consequently, it is nested at the base of the Ginglymodi in this phylogenetic study. Besides body shape, some autapomorphies on the cranial bones and caudal fin easily distinguish Diandongichthys from other members of this clade. The discovery provides new insights into the origin and early diversification of ginglymodian fishes. [ABSTRACT FROM AUTHOR]

Globally, the Middle Jurassic records of pycnodonts are extremely scarce. Here we report the discovery of pycnodont remains (prearticular dental plate, isolated teeth) from the Middle Jurassic (Bathonian, ~ 162 Ma) Fort Member of Jaisalmer Formation, Rajasthan state, western India. The specimens from Jaisalmer, assigned to cf. Eomesodon sp., represent the earliest record of East Gondwanan pycnodonts, and suggest a relatively rapid dispersal and a much wider Middle Jurassic distribution after their first appearance in the Late Triassic of the Western Tethys. The new Indian find predates the next younger (Late Cretaceous) record of pycnodont fishes in India by about a hundred million years, and necessitates a re-evaluation of the current ideas favoring a restricted occurrence of these remarkable fishes during the Late Triassic–Middle Jurassic. [ABSTRACT FROM AUTHOR]

Neopterygii is a taxonomically diverse clade of ray-finned fishes, including Teleostei, Holostei and closely related fossil taxa. The Colobodontidae is a stem group of large-sized neopterygians with a durophagous feeding adaption from the Middle to Late Triassic marine ecosystems in Europe and South China. Here, we report the discovery of a new colobodontid, Feroxichthys panzhouensis sp. nov., based on a well-preserved specimen from the early Middle Triassic (Anisian) of Panzhou (formerly known as Panxian), Guizhou, China. The discovery extends the geographical distribution of Feroxichthys from eastern Yunnan into western Guizhou, and demonstrates a more rapid diversification of early colobodontids than previously thought. The new species possesses diagnostic features of Feroxichthys (e.g., a fused lacrimal-maxilla), but it is easily distinguished from the type species Feroxichthys yunnanensis and other colobodontids by some derived features on the skull and, especially, the relatively short and deep body with a prominent postcranial hump. This body form, previously unknown in colobodontids, implicates a morphological adaptation to structurally complex habitats in light of ecological studies of modern ray-finned fishes with a similar body form. In addition, the feeding apparatus suggests a more obligate durophagous diet for F. panzhouensis sp. nov. than other colobodontids. Results of a cladistic analysis recover the new species as a sister taxon of F. yunnanensis within the Colobodontidae, and suggest that a hump-backed body form has independently evolved multiple times in Triassic neopterygians. As such, the new finding provides an important addition for our understanding of the morphological and ecological diversity of neopterygian fishes from the Triassic marine ecosystems in South China. [ABSTRACT FROM AUTHOR]

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The previously alleged ‘perleidid’ genus Peltoperleidus is a stem-neopterygian fish taxon with two or three horizontal rows of notably deepened flank scales. Until recently, members of this genus were known only from the Ladinian (late Middle Triassic) or near the Anisian/Ladinian boundary (~242 Ma) in southern Switzerland and northern Italy. Here, I report the discovery of a new species of the genus, Peltoperleidus asiaticus sp. nov., based on three well-preserved specimens from the Anisian (early Middle Triassic, ~244 Ma) of Luoping, eastern Yunnan, China. The discovery extends the geological range of Peltoperleidus by approximately two million years and documents the first record of the genus in Asia. Similar to its relatives (represented by P. macrodontus) from Europe, P. asiaticus sp. nov. is likely a small-sized durophagous predator with dentition combining grasping and crushing morphologies. Results of a cladistic analysis unite four species of Peltoperleidus as a monophyletic group within the Louwoichthyiformes, and suggest that the presence of two horizontal rows of notably deepened scales was independently evolved in Peltoperleidus and another stem-neopterygian taxon Altisolepis. P. asiaticus sp. nov. is nested at the base of Peltoperleidus, and a new family Peltoperleididae is proposed for the genus, contrasting the previous placement of Peltoperleidus in the poorly defined, paraphyletic ‘Perleididae’. Comparative studies of the basal peltoperleidid from China with its younger relatives from Europe provide new insights into the evolutionary origin and paleogeographic distribution of this clade. [ABSTRACT FROM AUTHOR]

Four complete platysiagid fish specimens are described from the Luoping Biota, Anisian (Middle Triassic), Yunnan Province, southwest China. They are small fishes with bones and scales covered with ganoine. All characters observed, such as nasals meeting in the midline, a keystone-like dermosphenotic, absence of post-rostral bone, two infraorbitals between dermosphenotic and jugal, large antorbital, and two postcleithra, suggest that the new materials belong to a single, new Platysiagum species, P. sinensis sp. nov. Three genera are ascribed to Platysiagidae: Platysiagum , Helmolepis and Caelatichthys. However, most specimens of the first two genera are imprints or fragmentary. The new, well-preserved specimens from the Luoping Biota provide more detailed anatomical information than before, and thus help amend the concept of the Platysiagidae. The Family Platysiagidae was previously classed in the Perleidiformes. Phylogenetic analysis indicates that the Platysiagidae is a member of basal Neopterygii, and its origin seems to predate that of Perleidiformes. Moreover, platysiagid fishes are known from the Middle Triassic of the western Tethys region. The newly found specimens of platysiagids from Luoping provide additional evidence that both eastern and western sides of the Tethys Ocean were biogeographically more connected than previously thought. [ABSTRACT FROM AUTHOR]

Crude oil is one of the most widespread pollutants released into the marine environment, and native species have provided useful information about the effect of crude oil pollution in marine ecosystems. We consider that the lined sole Achirus lineatus can be a useful monitor of the effect of crude oil in the Gulf of Mexico (GoM) because this flounder species has a wide distribution along the GoM, and its response to oil components is relevant. The objective of this study was to compare the transcriptomic changes in liver and gill of adults lined sole fish (Achirus lineatus) exposed to a sublethal acute concentration of water-accommodated fraction (WAF) of light crude oil for 48 h. RNA-Seq was performed to assess the transcriptional changes in both organs. A total of 1073 differentially expressed genes (DEGs) were detected in gills; 662 (61.69%) were upregulated, and 411 (38.30%) were downregulated whereas in liver, 515 DEGs; 306 (59.42%) were upregulated, and 209 (40.58%) were downregulated. Xenobiotic metabolism and redox metabolism, along with DNA repair mechanisms, were activated. The induction of hypoxia-regulated genes and the generalized regulation of multiple signaling pathways support the hypothesis that WAF exposition causes a hypoxia-like condition. [ABSTRACT FROM AUTHOR]

Our understanding of the ecology and phylogenetic relationships of Pachycormiformes, a group of Mesozoic stem teleosts including the iconic Leedsichthys, has often been hindered by a lack of comprehensive morphological information. Micro‐CT scanning of an articulated, although flattened, cranium of the edentulous Martillichthys renwickae from the Middle Jurassic (Callovian) Oxford Clay of the UK reveals previously unknown internal details of the most complete suspension‐feeding pachycormiform skull known, including the palate, braincase and branchial skeleton. The latter preserves gill rakers with elongate, pointed projections similar to those of Asthenocormus, in contrast to the finer fimbriations associated with Leedsichthys. We also reinterpret some previously described features, including dermal bone patterns of the snout, skull roof and lower jaw, and the morphology of the ventral hyoid arch. These new anatomical data reinforce the phylogenetic placement of Martillichthys as part of the Jurassic clade of edentulous pachycormiforms. The elongate skull geometry of these Jurassic taxa is strikingly similar to that of Ohmdenia, the sister taxon to edentulous pachycormiforms, but contrasts sharply with the morphology of the Late Cretaceous edentulous pachycormiform Bonnerichthys, raising questions over the phylogenetic relationships among these taxa. Most significantly, Martillichthys shows specialized characters with a restricted phylogenetic distribution among suspension‐feeding pachycormiforms, including the distinctive gill rakers and a greatly extended occipital stalk. Our analysis of Martillichthys supports past interpretations of a close relationship with Asthenocormus, and provides a model for interpreting the less complete remains of other members of this enigmatic group of fishes. [ABSTRACT FROM AUTHOR]

Early Mesozoic halecomorphs are highly diverse, but their taxonomy and phylogenetic relationships are still controversial. We describe here a new halecomorph taxon from the Late Jurassic (Kimmeridgian) Nusplingen Lithographic Limestone, southern Germany. Sanctusichthys rieteri, gen. et sp. nov., is characterized by the peculiar patterns of skull roofing bones and cephalic sensory canals, and a unique squamation made of tiny lepisosteoid-type scales with extremely or completely reduced ganoin layer. Very peculiarly, S. rieteri presents a series of bones placed between the frontals and the anamestic supraorbitals, one of them carrying a portion of the main supraorbital sensory canal between the frontal and nasal bones. These bones, here called parafrontals, are so far unknown in other actinopterygians. The new taxon resembles most closely several Late Jurassic Furo-like halecomorphs, which have been classified in the family Furidae and are currently placed in either of the controversial orders Ophiopsiformes or Ionoscopiformes. The close phylogenetic relationships between these taxa are confirmed in a cladistic analysis that retrieves Sanctusichthys within a broadly defined Ionoscopiformes, including the potentially independent Ophiopsiformes. Interestingly, these Furo-like halecomorphs are highly diverse in the Late Jurassic deposits of southern Germany, and they are especially well represented—with four species accounting for 15% of the actinopterygian taxa—in the Nusplingen quarry, which yields one of the three most diverse Jurassic assemblages of these fishes. The paleoecological significance of this high diversity can only be explored after solving the β-taxonomy and phylogenetic relationships of these Furo-like taxa. [ABSTRACT FROM AUTHOR]

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Background: The pycnodontiform fish Pycnodus is one of the representatives of the highly diverse actinopterygian fish fauna from the early Eocene Bolca Lagerstätte, representing one of the youngest and thus last occurrences of this extinct neopterygian clade. This genus has historically been used as a wastebasket taxon in regards to poorly known pycnodontiform fossils. Authors have argued over the specific status of the Bolca Lagerstätte Pycnodus in terms of how many species are contained within the genus with some arguing for multiple species and others suggesting lumping all Bolca specimens together into one species. Methods: Here, we use a quantitative approach performing biometric and geometric morphometric analyses on 52 specimens of Pycnodus in order to determine if the morphological variability within the sample might be related to inter- or intraspecific variation. Results: The analyses revealed that the variations of body shape, morphometric and meristic characters cannot be used to distinguish different morphotypes. On the contrary, our results show a remarkable link between shape and size, related to ontogeny. Discussion: Differences in body shape of small (juvenile) and large (adult) individuals is probably related to different microhabitats occupation on the Bolca reef with juveniles sheltering within crevices on the reef and adults being more powerful swimmers that swim above the coral. Taxonomically, we suggest that the Bolca Pycnodus should be referred to strictly as Pycnodus apodus as this was the name given to the holotype. Additionally, an overview of species assigned to Pycnodus is given. [ABSTRACT FROM AUTHOR]

Living holosteans, comprising 8 species of bowfins and gars, form a small monophyletic group of actinopterygian fishes, which are currently considered as the sister group to the enormously numerous teleosts and have largely been neglected in neuroanatomical studies. We have studied the catecholaminergic (CAergic) systems by means of antibodies against tyrosine hydroxylase (TH) and dopamine (DA) in the brain of representative species of the 3 genera included in the 2 orders of holostean fishes: Amia calva (Amiiformes) and Lepisosteus platyrhincus, Lepisosteus oculatus, and Atractosteus spatula (Lepisosteiformes). Different groups of TH/DA-immunoreactive (ir) cells were observed in the olfactory bulb, subpallium, and preoptic area of the telencephalon. Hypothalamic groups were labeled in the suprachiasmatic nucleus, tuberal (only in A. calva), retrotuberal, and retromamillary areas; specifically, the paraventricular organ showed only DA immunoreactivity. In the diencephalon, TH/DA-ir groups were detected in the prethalamus, posterior tubercle, and pretectum. In the caudal hindbrain, the solitary tract nucleus and area postrema presented TH/DA-ir cell groups, and also the spinal cord and the retina. Only in A. calva, particular CAergic cell groups were observed in the habenula, the mesencephalic tegmentum, and in the locus coeruleus. Following a neuromeric analysis, the comparison of these results with those obtained in other classes of fishes and tetrapods shows many common traits of CAergic systems shared by most vertebrates and in addition highlights unique features of actinopterygian fishes. [ABSTRACT FROM AUTHOR]

The Upper Cretaceous (Cenomanian) limestone quarry of Haqel, Lebanon, is home to one of the largest diversities of fossil actinopterygians in the Mesozoic, particularly of pycnodontiform fishes. Here, we describe a pycnodontiform fish, Flagellipinna rhomboides, gen. et sp. nov., from this locality based on four specimens. It is considered a member of the derived family Pycnodontidae due to the presence of a postparietal process. This taxon is distinct from other pycnodontids due to its diamond-shaped body, whip-like dorsal fin, postcloacal scales with forward-pointing spines, and acute anterior profile with a concave slope, giving it a 'hunchback' appearance. The prognathous snout armed with molariform teeth suggests that this pycnodont preyed on a variety of shelled animals from crevices. The smallest specimen is distinct in that it has a larger orbit size, no spines on the contour scales, poorly ossified skull roof bones, a notochord partially covered by arcocentra, and lacks whip-like filament on the dorsal fin, which suggest that it is a juvenile/subadult. The differences between the juvenile/subadult and other larger specimens suggest a change in ecological niche occupation during ontogeny, going from a generalized forager that lived in complex, reef habitats to moving into deeper waters to feed from crevices on the reef edge. These findings provide a more complete picture of the possible life history strategies that pycnodontiforms may have used in order to exploit different resources throughout their lives. [ABSTRACT FROM AUTHOR]

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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 forDapediumLeach, 1822 and other deep-bodied Mesozoic neopterygians. The species diagnosis ofD. pholidotumis amended. Comparison withD. stollorumThies & Hauff, 2011 andD. caelatumQuenstedt, 1858, also from the Lower Jurassic Posidonia Shale, shows thatD. pholidotumis unique in having: (1) a length/height ratio of the operculum ofc. 0.73, whereas inD. stollorumandD. caelatumthis value reaches onlyc. 0.58; (2) a length/width ratio of the gular plate ofc. 1.6, whereas inD. stollorumandD. caelatumthis value is 1.3; (3) 27 or more caudal fin lepidotrichia, whereas inD. stollorumandD. caelatumthere are 24 and 25 lepidotrichia, respectively; (4) at least 26 dorsal fin lepidotrichia, whereasD. stollorumandD. caelatumpossess only 24 dorsal fin lepidotrichia each; and (5) a length/height ratio of the flank scales immediately behind the operculum of 0.37, whereas inD. stollorumandD. caelatumthis ratio ranges around 0.31 and 0.5, respectively. A cladistic analysis based on modification of a previously published taxon–character matrix shows thatDapediumis the sister group of the ginglymodian fishes [Semionotiformes + Lepisosteiformes]. The generic diagnosis ofDapediumLeach, 1822 is amended. [ABSTRACT FROM AUTHOR]

Background: The pycnodontiform fish Pycnodus is one of the representatives of the highly diverse actinopterygian fish fauna from the early Eocene Bolca Lagersta¨tte, representing one of the youngest and thus last occurrences of this extinct neopterygian clade. This genus has historically been used as a wastebasket taxon in regards to poorly known pycnodontiform fossils. Authors have argued over the specific status of the Bolca Lagersta¨tte Pycnodus in terms of how many species are contained within the genus with some arguing for multiple species and others suggesting lumping all Bolca specimens together into one species. Methods: Here, we use a quantitative approach performing biometric and geometric morphometric analyses on 52 specimens of Pycnodus in order to determine if the morphological variability within the sample might be related to inter- or intraspecific variation. Results: The analyses revealed that the variations of body shape, morphometric and meristic characters cannot be used to distinguish different morphotypes. On the contrary, our results show a remarkable link between shape and size, related to ontogeny. Discussion: Differences in body shape of small (juvenile) and large (adult) individuals is probably related to different microhabitats occupation on the Bolca reef with juveniles sheltering within crevices on the reef and adults being more powerful swimmers that swim above the coral. Taxonomically, we suggest that the Bolca Pycnodus should be referred to strictly as Pycnodus apodus as this was the name given to the holotype. Additionally, an overview of species assigned to Pycnodus is given. [ABSTRACT FROM AUTHOR]

The halecomorph fishPanxianichthys imparilis, from the Pelsonian (Anisian, Middle Triassic) of Panxian County, Guizhou Province, South China, was recently described in brief. Here we present a thorough revision of this taxon based on 22 specimens, which allows a much better understanding of its anatomy and, consequently, its phylogenetic relationships. Newly recognized anatomical features include a flat quadratojugal, a symplectic articulating with the lower jaw ventral to the quadrate articulation, five infraorbitals, up to three suborbitals, and a large tail body lobe.Panxianichthysrepresents the oldest known non-parasemionotiform halecomorph and has a crescent-shaped preopercle and a maxillary branch of infraorbital sensory canal, but it is excluded from the ‘Ionoscopiformes–Amiiformes’ clade mainly by the presence of a quadratojugal, a dermosphenotic hinged to the side of the skull roof with a smooth innerorbital flange bearing no sensory canal, and a symplectic articulation much more ventral than that of the quadrate. A comparison with other Triassic non-parasemionotiform halecomorphs, together with the phylogenetic analysis, supports the erection of a new halecomorph order, Panxianichthyiformes, which is the sister group to the post-Triassic ‘Ionoscopiformes–Amiiformes’ clade. In addition,Robustichthys, also from the Anisian and previously ascribed to Ionoscopiformes, is recognized here as a new stem-group Ginglymodi. http://zoobank.org/urn:lsid:zoobank.org:pub:5594E962-985F-466D-AC52-2E9A5AC07787 [ABSTRACT FROM PUBLISHER]

The actinopterygian fish †Hemicalypterus weiri Schaeffer, 1967 is herein redescribed and rediagnosed based on new information collected from reexamination of museum specimens as well as examination of recently collected specimens from the Upper Triassic Chinle Formation of San Juan County, Utah, United States. †Hemicalypterus is distinguishable by its deep, disc-shaped compressed body; ganoid-scaled anterior half and scaleless posterior half; spinose, prominent dorsal and ventral ridge scales anterior to dorsal and anal fins; hem-like dorsal and anal fins with rounded distal margins; small mouth gape; and specialized, multicuspid dentition. This type of dentition, when observed in extant fishes, is often associated with herbivory, and †Hemicalypterus represents the oldest known ray-finned fish to have possibly exploited an herbivorous trophic feeding niche. A phylogenetic analysis infers a placement of †Hemicalypterus within †Dapediiformes, with †Dapediiformes being recovered as sister to Ginglymodi within holostean actinopterygians. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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Copyright of Paläontologische Zeitschrift is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The lower jaw of Lepisosteus osseus has been described as containing a U-shaped cartilaginous structure identified as a detached portion of Meckel's cartilage. We investigated this structure through study of a growth series of L. osseus, including cleared-and-stained specimens and histological preparations. Meckel's cartilage is well developed by 17.2 mm SL, and is formed by typical hyaline cartilage. The left and right Meckel's cartilage are continuous across the anterior midline in most small specimens (<35 mm SL), although the robustness of this continuity is variable and in some specimens the two sides are separate. In larger individuals (>85 mm SL) the left and right sides are separate from one another and end far posterior to the tip of the dentaries. In specimens between 17.6-22.1 mm SL, there is a diffuse, V-shaped patch of connective tissue between the rami of the lower jaws. By 35 mm SL this patch becomes more consolidated and in histological sections of a 44.6 mm SL specimen, it is revealed to contain chondrocytes. In even larger individuals, this becomes a well-defined U-shaped structure. Because both this structure and a Meckel's cartilage that crosses the anterior midline are present in the same individuals, we conclude that this cartilage is not homologous to the anterior portion of Meckel's cartilage (i.e., it fails the test of conjunction) but is rather a neomorphic structure, herein termed the rostrohyal. [ABSTRACT FROM AUTHOR]

A new species of hump-backed semionotiform fish,Lophionotus sanjuanensis, gen et sp. nov., is described based on specimens recently and previously collected from the Upper Triassic Church Rock Member of the Chinle Formation of southeastern Utah. It is characterized by a deep body with a large postcranial hump, and dense tuberculation on the posterodorsal margin of the skull that continues into the dorsal ridge and dorsolateral flank scales. The vertical preoperculum bears a short and broad paddle-like ventral process. The infraorbital series expands ventral to the suborbital and contacts the anterior ramus of the preoperculum, although this character has also been observed in other deep-bodied semionotiform taxa. This taxon represents the first newly described semionotiform fish species from the western United States in over 45 years, and adds to knowledge of Triassic fishes biodiversity. [ABSTRACT FROM PUBLISHER]

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. [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 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. [ABSTRACT FROM AUTHOR]

The Ginglymodi is one of the most common, though poorly understood groups of neopterygians, which includes gars, macrosemiiforms, and "semionotiforms."In particular, the phylogenetic relationships between the widely distributed "semionotiforms,"and between them and other ginglymodians have been enigmatic. Here, the phylogenetic relationships between eight of the 11 "semionotiform"genera, five genera of living and fossil gars and three macrosemiid genera, are analysed through cladistic analysis, based on 90 morphological characters and 37 taxa, including 7 out-group taxa. The results of the analysis show that the Ginglymodi includes two main lineages: Lepisosteiformes and †Semionotiformes. The genera †Pliodetes, †Araripelepidotes, †Lepidotes, †Scheenstia, and †Isanichthys are lepisosteiforms, and not semionotiforms, as previously thought, and these taxa extend the stratigraphic range of the lineage leading to gars back up to the Early Jurassic. A monophyletic †Lepidotes is restricted to the Early Jurassic species, whereas the strongly tritoral species previously referred to †Lepidotes are referred to †Scheenstia. Other species previously referred to †Lepidotes represent other genera or new taxa. The macrosemiids are well nested within semionotiforms, together with †Semionotidae, here restricted to †Semionotus, and a new family including †Callipurbeckia n. gen. minor (previously referred to †Lepidotes), †Macrosemimimus, †Tlayuamichin, †Paralepidotus, and †Semiolepis. Due to the numerous taxonomic changes needed according to the phylogenetic analysis, this article also includes formal taxonomic definitions and diagnoses for all generic and higher taxa, which are new or modified. The study of Mesozoic ginglymodians led to confirm Patterson's observation that these fishes show morphological affinities with both halecomorphs and teleosts. Therefore, the compilation of large data sets including the Mesozoic ginglymodians and the re-evaluation of several hypotheses of homology are essential to test the hypotheses of the Halecostomi vs. the Holostei, which is one of the major topics in the evolution of Mesozoic vertebrates and the origin of modern fish faunas. [ABSTRACT FROM AUTHOR]

Citation for this article: Ebert, M., and J. A. Lane. 2018. Rediscovery of the missing type specimen of ‘Ophiopsis’ aequalis (Neopterygii: Halecomorphi), a small paleontological mystery solved. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2018.1440235. [ABSTRACT FROM AUTHOR]

A new genus and species of pycnodontiform fishes,Grimmenodon aureum, from marginal marine, marine-brackish lower Toarcian (Harpoceras exaratumammonite subzone) clay deposits of Grimmen in northeastern Germany is described. The single specimen represents a diagnostic left prearticular dentition characterized by unique tooth arrangement and ornamentation patterns.Grimmenodon aureum, gen. et sp. nov., is the second unambiguously identified pycnodontiform species from the Early Jurassic, in addition toEomesodon liassicusfrom the early Lower Jurassic of western Europe. We also report an indeterminate pycnodontiform tooth crown from the upper Pliensbachian (Pleuroceras apyrenumammonite subzone) of the same site. The material expands the Early Jurassic range of pycnodontiforms significantly northwards and confirms their presence before and immediately following the onset of the Toarcian Oceanic Anoxic Event (T-OAE) in the marginal marine ecosystems south of the Fennoscandian Shield. Moreover, the new records indicate that the Early Jurassic diversity of pycnodontiform fishes was greater than previously assumed and probably equaled that of the Late Triassic. Therefore, it is hypothesized that the Triassic-Jurassic mass extinction event did not affect pycnodontiform fishes significantly. Micro-computed tomography was used to study the internal anatomy of the prearticular ofGrimmenodon aureum, gen. et sp. nov. Our results show that no replacement teeth were formed within the tooth-bearing bone but rather were added posteriorly to functional teeth. http://zoobank.org/urn:lsid:zoobank.org:pub:A56BDE9C-40C4-4CFA-9C2E-F5FA35A66F2 Citation for this article: Stumpf, S., J. Ansorge, C. Pfaff, and J. Kriwet. 2017. Early Jurassic diversification of pycnodontiform fishes (Actinopterygii, Neopterygii) after the end-Triassic extinction event: Evidence from a new genus and species,Grimmenodon aureum. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2017.1344679. [ABSTRACT FROM PUBLISHER]

Simple Summary: This research aimed to define intestinal DCs from myxines to teleosts by using immunohistochemistry with TLR-2, Langerin/CD207, and MHC II. In particular, we analyzed intestinal DCs in several species of fish phylogenetically organized: Eptatretus cirrhatus (myxines), Scyliorhinus canicula (Chondrichthyes), Polypterus senegalus (Osteichthyes, Brachiopterygii), Lepisosteus oculatus (Osteichthyes, Holostei), and Clarias batrachus (Osteichthyes, Teleostei). The findings show that intestinal DCs and DC-like cells are positive to all the antibodies tested, demonstrating the presence of these cells phylogenetically from myxines to teleosts. These results could improve the state-of-the-art on the evolution of the immune system and the importance of sentinel cells in the body's defense. In addition, we demonstrated with immunohistochemistry the presence of MHC II in myxines (Eptatretus cirrhatus) for the first time. Dendritic cells (DCs) are antigen-presenting cells (APCs) that regulate the beginning of adaptive immune responses. The mechanisms of tolerance to antigens moving through the digestive tract are known to be regulated by intestinal DCs. Agnatha and Gnathostoma are descendants of a common ancestor. The Ostracoderms gave rise to Cyclostomes, whereas the Placoderms gave rise to Chondrichthyes. Sarcopterygii and Actinopterygii are two evolutionary lines of bony fishes. Brachiopterygii and Neopterygii descend from the Actinopterygii. From Neopterygii, Holostei and Teleostei evolved. Using immunohistochemistry with TLR-2, Langerin/CD207, and MHC II, this study aimed to characterize intestinal DCs, from myxines to teleosts. The findings reveal that DCs are positive for the antibodies tested, highlighting the presence of DCs and DC-like cells phylogenetically from myxines, for the first time, to teleosts. These findings may aid in improving the level of knowledge about the immune system's evolution and these sentinel cells, which are crucial to the body's defense. [ABSTRACT FROM AUTHOR]

We describePalaeomacrosemius thiollieri, gen. et sp. nov., a new genus of Macrosemiidae (Neopterygii: Ginglymodi), from the Upper Jurassic (late Kimmeridgian to early Tithonian) of the Solnhofen Archipelago (Germany) and Cerin (France).Palaeomacrosemius, gen. nov., is characterized primarily by the following features: presence of vertical scale rows that do not dichotomize dorsal to the lateral line (unlike members of the genusMacrosemiusAgassiz); a long dorsal fin with 32–33 dorsal fin rays; and a smaller scale-free area immediately ventrolateral to the dorsal fin compared withMacrosemius. Small, hook-like spines located on the posterolateral border of the principal dorsal fin rays may have functioned in reproductive behavior. We also review the currently known species ofMacrosemius(M.rostratusAgassiz andM.fournetiThiollière) from the Upper Jurassic plattenkalk of southern Germany and Cerin, France.Macrosemius rostratus, which we here restrict to the German plattenkalk basins of Eichstätt and Solnhofen (Tithonian above the eigeltingense horizon), is mainly characterized by the presence of 37–39 dorsal fin rays, which are very long in adult specimens.Macrosemius fournetiis mainly characterized by the presence of 34–35 dorsal fin rays, which are broader in the posterior part of the fin. AlthoughM.fournetiwas previously known only from Cerin, France, we here describe it for the first time from the older plattenkalk of Brunn (southern Germany, late Kimmeridgian). Citation for this article: Ebert, M., J. A. Lane, and M. Kölbl-Ebert. 2016.Palaeomacrosemius thiollieri, gen. et sp. nov., a new Macrosemiidae (Neopterygii) from the Upper Jurassic of the Solnhofen Archipelago (Germany) and Cerin (France), with a revision of the genusMacrosemius. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2016.1196081. http://zoobank.org/urn:lsid:zoobank.org:pub:414EFC70-C0FC-4CE7-919C-20ACB28A709D [ABSTRACT FROM PUBLISHER]

Neopterygii is the largest clade of ray-finned fishes, including Teleostei, Holostei, and their closely related fossil taxa. This clade was first documented in the Early Carboniferous and underwent rapid evolutionary radiation during the Early to Middle Triassic. This article describes a new perleidid neopterygian species, Teffichthys elegans sp. nov., based on 13 well-preserved specimens from the lower Daye Formation (Dienerian, Induan) in Guizhou, China. The new species documents one of the oldest perleidids, providing insights into the early diversification of this family. The results of a phylogenetic analysis recover Teffichthys elegans sp. nov. as the sister taxon to Teffichthys madagascariensis within the Perleididae. T. elegans sp. nov. shares three derived features of Perleididae: the length of the anteroventral margin of the dermohyal nearly half the length of the anterodorsal margin of the preopercle; the anteroventral margin of the preopercle nearly equal to the anterior margin of the subopercle in length; and the anteroventral margin of the preopercle one to two times as long as the anterodorsal margin of the preopercle. It possesses diagnostic features of Teffichthys but differs from T. madagascariensis by the following features: presence of three supraorbitals; six pairs of branchiostegal rays; relatively deep anterodorsal process of subopercle; absence of spine on the posterior margin of the jugal; and pterygial formula of D26/P14, A22, C36/T39-41. The Perleidiformes are restricted to include only the Perleididae, and other previously alleged 'perleidiform' families (e.g., Hydropessidae and Gabanellidae) are excluded to maintain the monophyly of the order. Similar to many other perleidids, T. elegans sp. nov. was likely a durophagous predator with dentition combining grasping and crushing morphologies. The new finding also may indicate a relatively complex trophic structure of the Early Triassic marine ecosystem in South China. [ABSTRACT FROM AUTHOR]

Simple Summary: MicroRNAs regulate gene expression and, in particular, the miR-430 family plays an important role in the early development of fishes. In this study we have observed that this family appeared early in the evolution of fishes and all the studied species have multiple copies of miR-430. In some fishes that diverged early on, we have found three different versions of miR-430, yet as fishes evolved over time, some groups seem to have lost some of these versions. These findings could lead to more studies on the different functions of these versions, which could be preserved in farmed species. This knowledge could help improve aquaculture methods. The miR-430 microRNA family has been described in multiple fish species as one of the first microRNAs expressed by the zygote. It has been suggested that this family is implicated in maternal mRNA elimination, but may also play a role in steroidogenesis, sexual differentiation, and flatfish metamorphosis. The miR-430 sequences have been found in multiple-copy tandem clusters but evidence of their conservation outside of teleost fishes is scarce. In the present study, we have characterized the tandem repeats organization of these microRNAs in different fish species, both model and of interest in aquaculture. A phylogenetic analysis of this family has allowed us to identify that the miR-430 duplication, which took place before the Chondrostei and Neopterygii groups' divergence, has resulted in three variants ("a", "b", and "c"). According to our data, variant "b" is the most closely related to the ancestral sequence. Furthermore, we have detected isolated instances of the miR-430 repeat subunit in some species, which suggests that this microRNA family may be affected by DNA rearrangements. This study provides new data about the abundance, variability, and organization of the miR-430 family in fishes. [ABSTRACT FROM AUTHOR]

Semionotiformes is a diverse extinct group in Neopterygii. It is well represented in the Mesozoic, occurring in marine and continental strata worldwide. However, some diagnostic characters of Semionotiformes and, in particular, of Semionotidae, have been under debate, due to the description of new taxa or revision of previously known ones. In this paper, we provide a detailed description of the first unequivocal record of Semionotidae from Gondwana, i.e., Lophionotus parnaibensis, sp. nov. from the Pastos Bons Formation, Upper Jurassic, in the Parnaíba Basin, northeastern Brazil. It was included in the genus Lophionotus mainly due to the presence of smooth cranial bones, triangular lateral expansion of antorbital portion of frontal, and ratio length/width of frontals lower than three times. It was recovered as a new species due to a unique combination of characters. This discovery represents the most recent occurrence of the genus, which was previously recorded only in the U.S.A. up to the Early Jurassic. [ABSTRACT FROM AUTHOR]

The basic knowledge about the development and formation of the body plan of vertebrates (Vertebrata) was obtained while working with traditional and generally accepted model objects, such as the embryos of mice (Muridae), chickens (Gallus), bony fish (Teleostei), clawed frogs (Xenopus). At the same time, for understanding the evolutionary history of vertebrates, studies of so-called "non-model" objects are of particular value. These animals represent important phylogenetic branches on the evolutionary tree of vertebrates, but do not possess a set of qualities that make them convenient for laboratory work. First of all, such objects include the most ancient living representatives of the taxa, basally diverged from the common evolutionary trunk. These are cyclostomes (Cyclostomata) in the case of vertebrates in general, cartilaginous fish (Chondrichthyes) in the case of gnathostomes (Gnathostomata) and bone ganoids (Holostei) as representatives of new-finned fish (Neopterygii). The research value of these ancient groups lies in the fact that morphological features that are later characteristic of the entire taxon appear in their evolution for the first time, for example, the telencephalon and neural crest cells in cyclostomes, paired fins and the jaws in cartilaginous fish. Representatives of these groups provide an opportunity to study the evolutionary premieres of individual structures and features and mechanisms that ensured their emergence. This article presents an overview of studies of whole-genome duplications at the early stages of vertebrate evolution and the emergence of a unique forebrain region, the telencephalon, which we studied on lampreys, as the most ancient representatives of vertebrates available for laboratory research today. [ABSTRACT FROM AUTHOR]

Fossil evidence suggests that ray-finned fishes (Actinopterygii) diversified greatly after the largest mass extinction event at the Permian-Triassic boundary. This radiation resulted in a diversity peak in the Middle Triassic, which is manifested in diverse feeding specializations, especially among small-bodied Neopterygii. We present new material from an early Spathian (Early Triassic) outcrop in northern Dobrogea, southeast Romania. The material includes isolated jaw and palatal bones that evidently belong to a single individual, a durophagous actinopterygian, and isolated scales referred to the same taxon. A systematic evaluation of this material indicates affinities with Polzbergiidae, and provides a first glimpse of internal aspects of the feeding apparatus of that group. A pair of ectopterygoids with crushing dentition show a well-developed lateral process, a feature that was previously proposed to be a synapomorphy uniting Cladistia (bichirs) with the Triassic? Scanilepiformes. The recognition of this structure in various Triassic ray-fins (summarized herein) indicates that it was probably widespread among stem neopterygians. The new material belongs to a large individual with a heterodont dentition, therefore representing the earliest large, specialized, durophagous neopterygian. It increases the group's morphological diversity in the Spathian, and hints at an earlier trophic diversification after the mass extinction. Based on new data, we analyse changes in body size of bony fishes through the Early and Middle Triassic. Current evidence suggests that body size distribution remained skewed towards larger sizes in the late Early Triassic, and that the diversification of small-bodied stem neopterygians had not yet been in full swing. [ABSTRACT FROM AUTHOR]

Based on specimens from the Lower Cretaceous Tlayua Formation of Mexico, we describe a new genus and species of Halecomorphi, Cipactlichthys scutatus gen. et sp. nov, which exhibits several diagnostic characters such as the dermal bones and the scales with ganoin and highly ornamented by numerous tubercles and ridges; parietal slightly longer than wide with approximately the same length as the frontal; jaws extending far, below the posterior orbital margin, reaching the posterior third of the postorbital plate; maxilla with a convexly rounded posterior margin; pectoral fin margins slightly convex; first ray of pectoral fin very long, reaching the posterior edge of the pelvic fin; about 37 preural vertebrae and 7 Ural centra; a series of hypertrophied scales just posterior to the cleithrum; arrangement of flank scales with two rows of deep scales; a series of dorsal and ventral scutes forming the dorsal and ventral midline, between the dorsal and anal fins and the caudal fin. A phylogenetic analysis including two outgroups and eleven neopterygians confirmed the monophyly of the Holostei as well as the monophyly of the Halecomorphi, although this last clade is weakly supported. Cipactlichthys scutatus was hypothesised as the sister-group of the (Ionoscopiformes + Amiiformes). [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]