scholarly journals Ontogeny and variation in the skull roof and braincase of Maiasaura peeblesorum from the Two Medicine Formation of Montana, U.S.A.

2021 ◽  
Vol 66 ◽  
Author(s):  
Bradley McFeeters ◽  
David Evans ◽  
Hillary Maddin
Keyword(s):  
Skull Roof

scholarly journals Actinopterygians of The Permian Locality Buxières-Les-Mines (Bourbonl’archambault Basin, France) and Their Relationship to Other Early Actinopterygians

2018 ◽  
Vol 74 (3-4) ◽  
pp. 245-291
Author(s):  
Stanislav Štamberg
Keyword(s):  
Coal Mine ◽  
Shoulder Girdle ◽  
Great Variability ◽  
Anatomical Features ◽  
The Third ◽  
Skull Roof ◽  
New Knowledge ◽  
Main Component ◽  
The Village ◽  
Dermal Bones

Actinopterygians from the large opencast coal mine in the vicinity of the village of Buxières-les-Mines (Bourbonl’Archambault Basin, Allier, France) are revisited and redescribed based on newly studied specimens. The understanding of the anatomy of Progyrolepis heyleri POPLIN, 1999, originally described by Poplin (1999) on the basis of the upper and lower jaws only, is greatly enhanced and is relatively complete. The anatomy of the palatoquadrate, dermal bones of the skull roof, hyoid arch, operculum, suboperculum, shoulder girdle, cheek bones and branchiostegal rays is described. In addition, new observations have been made on changes in the shape of the maxilla during ontogenesis and microstructure of the teeth. Details of Progyrolepis heyleri scales, including their microstructure and morphology of the ridge scales are provided. The collection of whole individuals, body fragments and numerous isolated bones provide confirmation of the presence of Aeduella blainvillei which is the main component of the actinopterygian fauna in Buxières-les-Mines. Additional new knowledge was obtained regarding the great variability in bones of the opercular apparatus and maxilla, presence of the supraorbital, branchiostegal ray with a conspicuous hyoid process and the direction of mutual overlapping of the suboperculum and branchiostegal ray in Aeduella blainvillei (AGASSIZ, 1833). Microsculpture on the scales is redescribed in this species. Paramblypterus cf. duvernoy is the third member of the actinopterygians in the locality Buxières-les-Mines. Fragments of Paramblypterus are very rare and the bones of the skull roof are presented here. Anatomical features of Progyrolepis heyleri, Aeduella blainvillei and Paramblypterus cf. duvernoy were studied and compared with those of other Devonian and Permo-Carboniferous actinopterygians.

An early actinopterygian ichthyofauna from the Scottish Lower Coal Measures Formation: Westphalian A (Bashkirian)

2016 ◽  
Vol 107 (4) ◽  
pp. 351-394
Author(s):  
Francis M. Elliott
Keyword(s):  
Morphological Characteristics ◽  
Carbonaceous Shale ◽  
Additional Information ◽  
Skull Roof ◽  
Coal Measures ◽  
Skull Bones

ABSTRACTTen new early actinopterygian taxa are described from material collected from five North Lanarkshire coal shale tips in the Midland Valley of Scotland. The newly described taxa include Rhadinichthys? ornatocephalum, Rhadinichthys glabrolepis, Pseudogonatodus aurulentum, Pseudohaplolepis argentatum, Rhadinichthys? plumosum and Lanarkichthys gardineri. Also included are the haplolepids Blairolepis wallacei, Parahaplolepis poppaea, Braccohaplolepis fenestratum and Andrewsolepis lochlani. Additional information was also obtained for a further two named species, Rhadinichthys monensis Egerton and Rhadinichthys grossarti Traquair. The material used for this study was obtained from finely laminated slabs of carbonaceous shale containing incomplete and disarticulated specimens, including isolated skull dermal elements and scales preserved en masse. Using this information, the dermal skull bones of a number of taxa were reconstructed and illustrated in dorsal and lateral views. Furthermore, morphological characteristics of the skull roof of each taxon was used to obtain an appropriate dataset, in order to undertake non-vigorous phylogenic analyses to demonstrate possible relationships between the various groups within the assemblage. In addition, ossified endocranial remains from specimens of Rhadinichthys monensis were examined.

Deltaherpeton hiemstrae, a new colosteid tetrapod from the Mississippian of Iowa

2010 ◽  
Vol 84 (6) ◽  
pp. 1135-1151 ◽  
Author(s):  
John R. Bolt ◽  
R. Eric Lombard
Keyword(s):  
Lateral Line ◽  
New Taxon ◽  
Ventral Margin ◽  
Skull Roof ◽  
The Family ◽  
Early Tetrapods ◽  
Relationship Of ◽  
Dermal Bones ◽  
The Relationship

A new colosteid, Deltaherpeton hiemstrae gen. et sp. nov., is described from the Mississippian Upper Viséan site at Delta, Iowa. Deltaherpeton is represented by a skull roof and both jaws. The new taxon is unique among colosteids in having an internasal and single midline postparietal. An additional midline pair of cf. ‘interfrontonasals’ may be present. Characters previously used to define the colosteids are reviewed and a refined diagnosis for the family Colosteidae is presented. Synapomorphies which unite Deltaherpeton, Colosteus, Greererpeton, and Pholidogaster as Colosteidae are: premaxilla with fang pair; dentary with notch for receipt of premaxillary fang; mandible with single elongate exomeckelian fenestra; pre-narial infraorbital lateral line terminating at ventral margin of premaxilla just anterior to external naris; and post-narial infraorbital lateral line terminating at the ventral margin of the maxilla just posterior to the external naris. Our review of dermal bones in the colosteid snout concludes that no specimen is sufficiently free of distortions or breakage to indicate clearly whether or not the prefrontal borders the external naris, or that an anterior tectal is present. The morphology of Deltaherpeton and the revised data presented for colosteids do not clarify the relationship of colosteids to other early tetrapods.

A review of Silvanerpeton miripedes, a stem amniote from the Lower Carboniferous of East Kirkton, West Lothian, Scotland

2006 ◽  
Vol 97 (1) ◽  
pp. 31-63 ◽  
Author(s):  
Marcello Ruta ◽  
Jennifer A. Clack
Keyword(s):  
Cladistic Analysis ◽  
Lower Carboniferous ◽  
Total Group ◽  
Skull Roof ◽  
Lower Jaw ◽  
First Time ◽  
Basal Position

ABSTRACTPreviously described and new specimens of the anthracosaur Silvanerpeton miripedes from the Scottish Viséan of East Kirkton yield important new data which allow us to provide a more complete reconstruction of the skull roof, palate, braincase and lower jaw. A stout sacral rib and an incompletely ossified tarsus with a subquadrangular intermedium are also recorded for the first time. A remarkably well preserved humerus in extensor view shows similarities with humeri of immature specimens of the embolomere Proterogyrinus. A new cladistic analysis, built from combining characters used in two recent matrices, places Silvanerpeton in a basal position relative to embolomeres and more derived stem amniotes. Data from Silvanerpeton inform character polarity near the base of the amniote total group. We discuss some morphofunctional implications of character changes at the root of total group amniotes, acquisition of terrestrial habits, and patterns of early disparity in this clade.

Taxonomic revision of buchanosteoid placoderms (Arthrodira) from the Early Devonian of south-eastern Australia and Arctic Russia

2014 ◽  
Vol 62 (1) ◽  
pp. 26 ◽  
Author(s):  
J. A. Long ◽  
E. Mark-Kurik ◽  
G. C. Young
Keyword(s):  
Taxonomic Revision ◽  
Lateral Plate ◽  
Early Devonian ◽  
South Eastern ◽  
Skull Roof ◽  
New Family ◽  
Eastern Australia ◽  
Marginal Plates ◽  
Severnaya Zemlya ◽  
South Eastern Australia

The ‘buchanosteid’ placoderms are best known from the Early Devonian of Australia, but also occur in China, Russia, Central Asia and the Middle East. Here we rediagnose the type species Buchanosteus confertituberculatus (Hills 1936) from the type locality at Buchan, Victoria, in the light of new material of both head and trunk shields. The superfamily Buchanosteoidea Denison, 1978 is redefined to unite taxa that share a similar skull roof with separate rostro-pineal (ethmoid) bone, and postethmoid skull pattern characterised by a large trapezoidal nuchal, strap-like short and broad preorbitals, large subrectangular centrals, small postorbitals not contacting the paranuchals, and large, elongate marginal plates. The Family Buchanosteidae is redefined on skull roof and parasphenoid shape and trunk armour features as a monotypic family within the Buchanosteoidea. A new family (Parabuchanosteidae nov.) includes taxa with the posterior lateral plate overlapping the anterior dorsolateral plate externally. Two new buchanosteids are described, Richardosteus barwickorum gen. et sp. nov., from Burrinjuck, south-eastern Australia, and Urvaspis lithuanica gen. et sp. nov., from Severnaya Zemlya, Russia.

A reappraisal of the ornithischian dinosaur Amtosaurus magnus Kurzanov and Tumanova 1978, with comments on the status of A. archibaldi Averianov 2002

2004 ◽  
Vol 41 (3) ◽  
pp. 299-306 ◽  
Author(s):  
Jolyon C Parish ◽  
Paul M Barrett
Keyword(s):  
New Genus ◽  
Skull Roof ◽  
Holotype Specimen ◽  
Nomen Dubium ◽  
The Status ◽  
Valid Taxon

A fragmentary braincase from the Baynshirenskaya Svita (Cenomanian–Turonian) of Amtgay, Omnogov, People's Republic of Mongolia was described as the holotype specimen of the ankylosaurid dinosaur, Amtosaurus magnus Kurzanov and Tumanova 1978. However, the validity of this genus has been questioned by several authors. Recently, a second species, based on a fragmentary specimen consisting of a braincase and partial skull roof, was assigned to Amtosaurus as A. archibaldi Averianov 2002. Here we re-assess the status of Amtosaurus and of the referred species, A. archibaldi. We conclude that "Amtosaurus magnus" is a nomen dubium that should be regarded as Ornithischia indeterminate. However, "A." archibaldi is a valid taxon, characterized by an autapomorphic feature of the skull roof, and we refer this species to the new genus Bissektipelta.

scholarly journals New species of Trachycorystes Bleeker, with comments on other species of the genus (Ostariophysi: Siluriformes: Auchenipteridae)

2011 ◽  
Vol 9 (2) ◽  
pp. 273-279 ◽  
Author(s):  
Heraldo A. Britski ◽  
Alberto Akama
Keyword(s):  
New Species ◽  
Equal Length ◽  
Type Locality ◽  
Nominal Species ◽  
Caudal Fin ◽  
Dorsal Fin ◽  
Skull Roof ◽  
Lower Jaw ◽  
Gas Bladder ◽  
A New Species

A new species of Trachycorystes from the rio Aripuanã, above Dardanelos and Andorinhas falls, is described. The new species is distinguished from the only other species of the genus, T. trachycorystes, by the following characteristics: jaws of equal length (vs. lower jaw prognathous in T. trachycorystes); skull roof covered by thick (vs. thin) integument; inner mental barbel very thin and short not reaching base of outer barbel (vs. extending to or beyond base of outer mental barbel); dorsal-fin spine serrated posteriorly, smooth or rough anteriorly (vs. serrated anteriorly and smooth or rough posteriorly); caudal fin shallowly forked (vs. emarginate); and gas bladder simple, without diverticula (vs. with three posterior diverticula). Comments and data on the nominal species Trachycorystes trachycorystes are provided. Trachycorystes cratensis Miranda Ribeiro, 1937, is allocated to the genus Trachelyopterus Valenciennes, 1840, and another local catfish species, Parotocinclus aripuanensis Garavello, 1988, has its type locality reassigned.

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