Gular Plate Research Articles

Reconstructing an ancient fish: Three-dimensional skeletal restoration of the head of Mawsonia (Sarcopterygii, Actinistia) using CT scan, and an adjusted model for body size estimation in fossil coelacanths.

Mawsonia constitutes one of the most conspicuous fossil coelacanth taxa, due to its unique anatomy and possible maximum body size. It typifies Mesozoic coelacanth morphology, before the putative disappearance of the group in the fossil record. In this work, the three-dimensional cranial anatomy and body size estimations of this genus are re-evaluated from a recently described specimen from Upper Jurassic deposits of Uruguay. The 3D restoration was performed directly on the material based on anatomical information provided by the living coelacanth Latimeria and previous two-dimensional restorations of the head of Mawsonia. The montage was then scanned with computed tomography and virtually adjusted to generate an interactive online resource for future anatomical, taxonomic and biomechanical research. In general terms, the model constitutes a tool to improve both the anatomical knowledge of this genus and its comparison with other coelacanths. It also facilitates the evaluation of possible evolutionary trends and the discussion of particular features with potential palaeobiological implications, such as the anterior position of the eye and the development of the pseudomaxillary fold. Regarding the body size, a previous model for body size estimation based on the gular plate was submitted to OLS, RMA, segmented linear and PGLS regressions (including the evaluation of regression statistics, variance analysis, t-tests and residual analysis). The results point to a power relationship between gular and total lengths showing a better support than a simple linear relationship. The new resulting equations were applied to the studied individual and are provided for future estimates. Although an isometric evolutionary growth cannot be rejected with the available evidence, additional models developed with other bones will be necessary to evaluate possible hidden evolutionary allometric trends in this group of fishes, thus avoiding overestimates.

Dermal skeleton of the stem osteichthyan Ligulalepis from the Lower Devonian of New South Wales (Australia)

When first described based on isolated scales, Ligulalepis was assigned to thePalaeoniscoidea, a basal group of actinopterygians (ray-finned fishes). Recent cladisticanalyses, mainly based on skull and neurocranial characters, have mostly recovered thetaxon (or, ‘Ligulalepis’) as a stem osteichthyan. Here we present information on Ligulalepisdermal elements other than scales and skulls, that include a cheek fragment, a premaxilla,other marginal jaw elements and teeth, an accessory vomer, a partial shoulder girdle,incomplete spine-like elements, and a gular plate. The shoulder girdle and premaxilla compareclosely with those of basal actinopterygians, whereas the spine-like element showssome similarity to the distal end of the spines on medial dorsal plates of the Chinese LateSilurian stem osteichthyans Guiyu and Sparalepis, or alternatively to fin rays on the stemosteichthyan Dialipina. One of the jaw elements appears to be a compound jugal plate pluspart of the dentate maxilla, an arrangement not previously known in any Devonian stemosteichthyan, or actinopterygian. Histological structure of dermal plates somewhat resemblesthat of Meemannia, but pore openings in Ligulalepis lead only to the vascular canalnetwork at the base of the ornament layer and not to a pore canal network. Like previousphylogenetic analyses, our analysis incorporating post-cranial dermal skeleton charactersalso recovered Ligulalepis as a stem osteichthyan.

Nusaviichthys nerivelai gen. et sp. nov., an Albian crossognathiform fish from the Tlayúa lagerstätte, Mexico

The fish Nusaviichthys nerivelai gen. et sp. nov. is described here based on well-preserved fossils from the Albian deposits of the Tlayúa quarry, near Tepexi de Rodríguez, Puebla, central Mexico. The occurrence of this new fish from Tlayúa expands the taxonomical and morphological diversity of the crossognathiformes of the Caribbean region of America during the Early Cretaceous. The inclusion of the osteological features of this species into comparative and phylogenetic analyses reveal its belonging to the order Crossognathiformes, suborder Pachyrhizodontoidei, and family Notelopidae; some of the most significant of these features include the presence of a large extrascapula bone; circumorbital bones forming a completely closed ring; medioparietal condition of the skull; posterior infraorbitals hypertrophied, covering the entire cheek, and extended up to the anterior part of the opercular bones; the relative short uroneural 1 anteriorly restricted to the preural 1; and the cycloid scales with a crenulated posterior edge. This new species differs from its relatives in the presence of numerous and small conic teeth in both jaws and vomer; the large triangular gular plate, and the numerous radiating grooves ridges present in the supraorbital, dermosphenotic, skull roof bones, opercular bones, and jaws; and the almost horizontal position of the neural and hemal spines of the last caudal centra. Despite the weak support, the naturalness of this extinct teleost order is recovered in the phylogenetic analysis performed here, which includes this new Mexican fossil fish as well as other crossognathiform genera not included in previous studies.

Increasing the fish diversity of the Triassic faunas of Gondwana: a new redfieldiiform (Actinopterygii) from the Middle Triassic of Argentina and its palaeobiogeographical implications

AbstractA new actinopterygian, Calaichthys tehul gen. et sp. nov. is described on the basis of a few, well‐preserved specimens from the Anisian Cerro de Las Cabras Formation, Cuyo Basin in Mendoza Province. The new genus shows a combination of primitive characters (e.g. deep posterior region of the maxilla contacting the preopercle, a suspensorium backwardly oriented) and more advanced characters (e.g. distally segmented fin rays, hemiheterocercal caudal fin) and is thus considered to be a ‘subholostean’ fish. The new taxon is assigned to Redfieldiiformes on the basis of its single branchiostegal plate‐like ray, a median gular plate, pectoral fins with stout, stiff, mainly non‐segmented and distally branched fin rays, long and robust fringing fulcra in all fins, basal fulcra bordering both lobes of the caudal fin, and opposite dorsal and anal fins. Calaichthys is characterized by a combination of characters some of which are unique among redfieldiiforms (i.e. strongly ornamented but thin scales with a serrated posterior margin, smooth skull roof bones, extrascapulars with a bifid posterior margin, three suborbital bones, a hatchet‐shaped preopercle, rectangular and slender opercle, deep mouth gape, entopterygoid and ectopterygoid with small pointed teeth disposed in several series, unornamented rostral bone, massive pectoral fins and delicate dorsal, pelvic and anal fins). Calaichthys provides novel information about the anatomy of redfieldiiforms, in particular in relation with the fins and associated scaly elements, as well as the scale morphology and their disposition over the body. Our work confirms for the first time that redfieldiiforms occur in South America. Redfieldiiforms seem to have originated in Gondwana and shown two diversity peaks: in the Anisian and the Carnian. Calaichthys is coeval with those redfieldiiforms of the Middle Triassic (Anisian) of Africa and Australia dwelling in ephemeral lakes.

Revision of Kyphosichthys grandei Xu & Wu, 2012 from the Middle Triassic of Yunnan Province, South China: implications for phylogenetic interrelationships of ginglymodian fishes

The hump-backed ginglymodian fish Kyphosichthys grandei, from the Anisian (Middle Triassic) of South China, is re-described. The revised description presents much previously unknown or misidentified anatomical information, such as the presence of a median gular plate; a short, broad, squarish rostral; two pairs of extrascapulars, of which the lateral one is fused with the parietal bone; parasphenoid having relatively large, dorsoposteriorly oriented ascending processes which articulate with the sphenotics; a complete row of scales bordering the body lobe; and supracleithrum with a concave facet for articulation with the posttemporal, etc. Taxonomical comparison clearly distinguishes Kyphosichthys from other known hump-backed ginglymodians – that is, Luoxiongichthys, Lophionotus, Semiolepis and Paralepidotus – and a potential stem-group ginglymodian Dapedium. A more comprehensive cladistic analysis of the Ginglymodi is conducted herein based on incorporation of more morphological characters and taxa, and rectification of the character states of some taxa used in previous analyses after re-description of Kyphosichthys grandei and better knowledge of Luoxiongichthys hyperdorsalis and Sangiorgioichthys sui based on our observations of specimens at the Geological Museum of Peking University, Beijing, China. The results of our analysis produce the most completely resolved and best-supported hypothesis for the monophyletic group Semionotiformes to date, and also support a new hypothesis that the Middle Triassic ginglymodians Luoxiongichthys, Sangiorgioichthys and Kyphosichthys form a monophyletic group at the base of the Ginglymodi, of which Kyphosichthys grandei is the sister group of Sangiorgioichthys sui. The new family Kyphosichthyidae is introduced. The present contribution supplements previous analyses of the Ginglymodi, especially for basal taxa and the clade Semionotiformes, and sheds new light on the origin and early diversification of the Ginglymodi.http://zoobank.org/urn:lsid:zoobank.org:pub:C8ACA263-8658-4A66-BFF9-99F6D5C84E91

Actinistian gular plates from the Cretaceous of Mexico and the problems assigning gular plates taxonomically

Abstract. Two gular plates of an indeterminate actinistian are described from the Cretaceous of Muhi quarry, Hidalgo state, in central Mexico. Their narrow shape belongs to the few actinistian gular plates with a high length / width ratio (above 4) in contrast to most known actinistian gular plates with a length / width ratio below 4. The gulars of Muhi quarry are assigned, with caution, to the actinistian family Mawsoniidae on the basis of the length / width ratio (around 4.5) of the gular, which can be found in three other genera of the family. There are not enough characteristics in actinistian gular plates alone to erect a new genus or species. Noteworthy is the large size of the Muhi gulars that corresponds to a body length of about 1.6 m – the length of Latimeria today. The gulars are preserved in association with a basibranchial tooth plate and a few neural spines. This is the third actinistian record from the Cretaceous of Mexico.

New remarkable Late Jurassic teleosts from southern Germany: Ascalaboidae n. fam., its content, morphology, and phylogenetic relationships

Abstract. Complete morphological descriptions, as preservation permits, are provided for a new Late Jurassic fish taxon (Ebertichthys ettlingensis n. gen. et n. sp.) and a revision of some morphological features of Ascalabos voithii Graf zu Münster from the Solnhofen limestones, southern Germany. A new family, Ascalaboidae, is erected to include the two species. The new family is supported by numerous synapomorphies, e.g., maxilla with external row of small conical teeth increasing in size posteriorly, absence of gular plate, low number of vertebrae (34 to 39), deep and narrow supracleithrum – deeper than opercle, and vertebral centrum formation of caudal region including paired chordacentra (pseudo-diplospondyly) that fuse in early ontogeny forming one chordacentrum that is later surrounded by an autocentrum. A phylogenetic analysis based on 173 characters and 42 taxa was performed. Following the phylogenetic hypothesis, the sister-group relationship [Ascalabos + Ebertichthys] + more advanced teleosts stands above the node of Leptolepis coryphaenoides plus more advanced teleosts and below the node of Tharsis plus more advanced teleosts, and the new taxa are interpreted as extinct and primitive forms within Teleostei. The new genus and species is endemic and restricted to one Upper Jurassic locality – Ettling – whereas Ascalabos is known from different localities in the Solnhofen limestones, with the exception of Ettling.

Sinamia kukurihime, a New Early Cretaceous Amiiform Fish from Ishikawa, Japan

Abstract. A new species of the genus Sinamia of the family Sinamiidae of the order Amiiformes, S. kukurihime is described on the basis of a hyomandibula and many isolated bones and scales found from the Lower Cretaceous freshwater deposits of the Kuwajima Formation, Itoshiro Subgroup, Tetori Group in Kuwajima, Hakusan City, Ishikawa Prefecture, Japan. The new species is distinguished from other congeners by the forms of the hyomandibular, frontal, dermopterotic, maxilla, gular plate, preopercle, supracleithrum and scales. Among the genus Sinamia, S. kukurihime sp. nov. is considered to be closest to S. liaoningensis. This is the first record of the genus Sinamia from Japan. The presence of a new species of the genus from Japan demonstrates the wide distribution and diversity of the genus during the Cretaceous in East Asia.

Evidence for coelacanths in the Late Triassic (Rhaetian) of England

The right gular plate of an indeterminate coelacanth from the Westbury Formation (Upper Triassic, Rhaetian) of Blue Anchor Point, Somerset, southwest England is reported. This occurrence represents the first convincing evidence of coelacanths from the Triassic of the United Kingdom. The new specimen suggests a fish of approximately 0.61 m length.

A new genus of coccolepidid fishes (Actinopterygii, Chondrostei) from the continental Jurassic of Patagonia

Jurassic freshwater fish faunas are still poorly known, with the only assemblage of that age known from southern South America being the of the Canadon Calcareo Formation (Oxfordian-Tithonian) of Chubut, Argentina. This fauna is composed mainly by abundant teleosts and a much rarer basal actinopterygian, originally described as †Oligopleurus groeberi and currently usually placed in the genus †Coccolepis. This taxon is here redescribed on the basis of the original specimens and more numerous and better preserved new material from several localities within the Canadon Calcareo Formation. The species shows several differences to other coccolepidid taxa, including the apomorphic presence of a sensory canal in the gular plate, and cannot be referred to a known genus. Thus, a new genus name, †Condorlepis gen. nov., is proposed. The detailed anatomical description of †Condorlepis gen. nov. groeberi provides further evidence for the chondrostean affinities of the Coccolepididae and their close relationships with the Acipenseriformes, since this species shows six characters that were hitherto considered to be autapomorphies of the latter clade. A comparison of the Almada fauna with other Gondwanan Jurassic freshwater fish faunas shows close similarities with the roughly contemporaneous fauna of Talbragar, Australia, which also includes an abundant basal teleost and coccolepidids. In contrast, there are marked differences with the faunas of the Early to Middle Jurassic Kota Formation of India, the Late Jurassic to Early Cretaceous Stanleyville beds of the Democratic Republic of the Congo, and the probably Late Jurassic Tacuarembo Formation of Uruguay, in which basal, non-teleostean neopterygians and sarcopterygians are abundant. © Palaeontological Association February 2013.

A new Early Cretaceous coelacanth from Texas

Coelacanths have a long fossil record spanning from Early Devonian to the present globally, but until now only from Permian and Triassic sediments in Texas. Reported here is a partial skull, including an articulated lower jaw and disarticulated cranial elements, of a new coelacanth fish (Sarcopterygii: Actinistia) from the Early Cretaceous (Albian) of northern Texas. The presence of a single large pore opening for the supraorbital sensory canal, lack of ornamentation of the cheek and opercular bones, the presence of a few large pore openings in the cheekbones (five or less in the lachrymojugal, one in the other cheekbones) and the presence of small teeth are characters placing this specimen within a new clade along with the genera Libys, Ticinepomis and Diplurus. An upturned symphysis, unornamented gular plates whose posterior margins taper to points, and angular with sinuous dorsal edges reaching the same dorsal extent as the dentary are characters that make this specimen morphologically unique among the new clade. This specimen represents a new species here named as Reidus hilli.

Nova ocorrência de †Mawsoniidae (Sarcopterygii, Actinistia) na Formação Morro do Chaves, Cretáceo Inferior da bacia de Sergipe-Alagoas, nordeste do Brasil

The goal of this paper is to describe a new occurrence of †Mawsoniidae in the Morro do Chaves Formation, Sergipe-Alagoas Basin. This stratigraphical unit is represented by an intercalation of coquina and shale beds, deposited in a lacustrine paleoenvironment during the Upper Barremian (Lower Jiquiá local stage). The description is accomplished on the basis of new and more complete material, represented by articulated bones of the palatoquadrate and lower jaw, as well as by gular plate. It was assigned to the genus Mawsonia based on the presence of a stout angular conspicuously ornamented with wrinkles and ridges, as well as palatoquadrate with a single strengthening ridge on its lateral surface. When this new occurrence of Mawsonia was compared with the other genera of Mawsoniidae occurring in Brazil (i.e., Axelrodichthys and Parnaibaia), it was verified that it differs clearly from Axelrodichthys by the inclination of the suspensorium (obliquely oriented in Mawsonia versus vertically oriented in Axelrodichthys). Regarding Parnaibaia, the ornamentation of the angular and gular plate is more delicate in this genus.

Palaeoctopus pelagicus from the Turonian of Mexico reinterpreted as a coelacanth (Sarcopterygian) gular plate

Abstract: The supposed vestige of a cephalopod gladius from Turonian platy limestones at Vallecillo, north-east Mexico, named Palaeoctopus pelagicus by Fuchs et al. in 2008, is reinterpreted and shown to be a gular plate of a coelacanth fish, possibly of the genus Megacoelacanthus. In addition to the gular plate, two extrascapulars and fin rays of all fins are preserved on one slab and its counterpart. This is the first record of a coelacanth from these lower Turonian strata at Vallecillo, which are rich in fish.

Precision of Hard Structures Used to Estimate Age of Bowfin in the Upper Mississippi River

AbstractThe bowfin Amia calva has traditionally been considered a nuisance species that competes for resources with more desirable fish species. However, an emerging market for bowfin roe has increased the species' economic importance and raised awareness associated with the lack of information on its ecology and population dynamics. Furthermore, few studies have investigated the utility and precision of hard structures used to estimate bowfin age. The objective of this study was to examine the precision of age estimates obtained from sectioned pectoral fin rays, otoliths, scales, gular plates, and branchiostegal rays of bowfin collected from the upper Mississippi River. Structures from 255 bowfin were examined. Otoliths, scales, and branchiostegal rays were excluded from analyses because of poor readability. Sectioned pectoral fin rays provided the highest between‐reader agreement and lowest variation between age estimates.

The Sensory Canal Systems of the Living Coelacanth, Latimeria Chalumnae: A New Instalment

Entire sensory canal systems of the coelacanth, Latimeria chalumnae, are described: not only the course of principal canals with their primary and secondary collaterals, but also the course and branches of the pit-line and reticular canals. The number of pores on the left side of the head were found to be 296 in an early (yolksac) embryo, 321 in a late term fetus, 485 in a juvenile, and 2974 in adults. This means that in latimeria most of the lateral-line canal system develop after parturition. Pit lines of the living coelacanth are not rows of superficial neuromasts but canals covered by a thin epidermis like in other sensory canals of the lateral line. These pit-line canals, however, have a very specific structure and branching pattern: the medial dorsal pit-line canal is connected by fine branches on top of the head. The infra-dentary pit-line canal connects via these branches with canals deep inside the bones. Several fine and richly branched canaliculi of unknown function radiate from each quadratojugal pit-line canal. The gular plate pit-line canal has superficially branching arms as well as connections to numerous deeper canals inside the bone. These canals consist of fine branches that in turn lead to and open on the ventral surface of the gular plates as small pores. The system is reminiscent of the reticular (pore) canal system known only from some fossil agnathans and fishes. Thus latimeria combines the reticular system of ancient vertebrates with the lateral-line system of modern fishes. The significance of this gular (possibly electro-sensory) system for feeding by the coelacanth will be discussed.

Larval head morphology of Phycosecis litoralis (Pascoe) (Coleoptera : Phycosecidae) with phylogenetic implications

The larval head of a Phycosecis species is described and illustrated. Characters are compared to those found in larvae of other groups of Cucujiformia. Monophyly of all cleroid families examined is supported by several apomorphic features at least partly correlated with predacious habits: antennae directed anteriad, absence of the mandibular mola, presence of a pedunculate seta on the mala, presence of a median endocarina, origin of antennal muscles exclusively from the head capsule, and presence of a weakly pigmented, parallel-sided gular plate. A possible apomorphy of Cleroidea excluding Phloiophilidae is the parallel-sided, prognathous head. A sister-group relationship between Phycosecidae and Melyridae is supported by the presence of a plumose lacinia mobilis and secondary loss of the median endocarina. A monophylum comprising Cleridae + Chaetosomatidae is characterised by a strongly elongated, sclerotised larval gula, the strongly protracted position of the ventral mouthparts, and a cardo as long as or longer than the stipes. Monophyly of Trogossitidae is only weakly supported. Several apomorphies indicate a sister-group relationship between Cleroidea and Nitidulidae. These two taxa are characterised by a fully developed maxillolabial complex, an elongated prepharyngeal tube, and tergal sclerotisation restricted to the prothorax and tergite IX. A tentorial bridge completely separated from the remaining tentorium, and a maxillolabial complex with partly restricted motility of the maxilla are shared derived features of larvae of Cleroidea, Nitidulidae, Coccinellidae and Endomychidae. An unusual attachment of a part of the tentoriostipital muscle to the floor of the prepharyngeal tube is found in all cleroid and cucujoid larvae examined. Cleroidea are a well-defined monophyletic group and may form a monophylum together with a paraphyletic assemblage of Cucujoidea. A close relationship between Cleroidea and Lymexylidae is refuted.

An African twin to the BrazilianCalamopleurus(Actinopterygii: Amiidae)

A new species of amiid fish,Calamopleurus africanussp. nov., is described on the basis of fragmentary material from? Albian Kem Kem beds of southern Morocco. The new species shows several derived characters of the genusCalamopleurussuch as ossified dermopterotic ribs, an inferred loose association between the dermosphenotic and the skull roof, a gular plate with a scalloped posterior margin, and a hyomandibular with a very long posterior (opercular) process. It differs from the type species in the proportions of the frontals, supramaxilla and gular. The distribution ofCalamopleurusand some other Lower Cretaceous fishes is discussed in the context of the presumed adjacency of west Africa and eastern Brazil during much of the Mesozoic.

An African twin to the Brazilian Calamopleurus (Actinopterygii: Amiidae)

Abstract A new species of amiid fish, Calamopleurus africanus sp. nov., is described on the basis of fragmentary material from? Albian Kem Kem beds of southern Morocco. The new species shows several derived characters of the genus Calamopleurus such as ossified dermopterotic ribs, an inferred loose association between the dermosphenotic and the skull roof, a gular plate with a scalloped posterior margin, and a hyomandibular with a very long posterior (opercular) process. It differs from the type species in the proportions of the frontals, supramaxilla and gular. The distribution of Calamopleurus and some other Lower Cretaceous fishes is discussed in the context of the presumed adjacency of west Africa and eastern Brazil during much of the Mesozoic.

The dipnoan species, Sorbitorhynchus deleaskitus , from the Lower Devonian of Guangxi, China

A dipnoan species from the Emsian of Guangxi, China, Sorbitorhynchus deleaskitus , which has previously been diagnosed in the appendix to a more general paper on dipnoan phylogeny (Cambell & Barwick 1990), is described in detail. The head is large and heavily ossified, with cosmine on the external dermal bones. The dental plates are thick and have few poorly defined large tuberosities towards their anterolateral edges. It is the only Early Devonian dipnoan for which the full hyoid arch, gular, basibranchial, and submandibular plates are preserved, and in which the parasphenoid is clearly defined. In many features the genus is more advanced than Dipnorhynchus , but in none is it more advanced than Dipterus , apart from the loss of the buccohypophysial foramen. It gives a new perspective on late Emsian evolution of the group, and reinforces our concept of an independently developing dentine-plated line contemporaneous with a true tooth-plated line.

Numerical Analysis of Impact Deformation and Failure in Composite Plates

The analytical problem of transverse impact by a rigid body on a rectan gular composite plate is considered. The calculation of displacements, deformations and stresses in conjunction with the characteristics of impact contact interaction is provided. The analysis of transverse stresses arising under short-time impulse in graphite/epoxy and organic glass/polymeric adhesive laminated plates is performed. The results illustrating dependencies of a contact force on time are given for various levels of mass and velocity of the impactor at the prescribed impact energy. The analysis of impact damage zones in a three-ply and a five-ply graphite/epoxy laminate (particularly, having soft polymeric in terleaves) is presented for the case of 2-2.5 J impact energy and different mass and veloc ity combinations. The changing of the failure mode increasing the impactor velocity (decreasing the mass) is followed up.