摘要:

Tamiobatis vetustusis a very rare Paleozoic shark, originally based on a well-preserved, isolated brain-case of somewhat doubtful provenance from Eastern Powell Co., Kentucky. A second much larger braincase has been referred to the genus but, like the holotype, is completely isolated. The latest specimen, found on a bedding plane in the Late Devonian Cleveland Shale, is associated with partial jaws, teeth, scales, and a spine impression which demonstrates that it is a ctenacanthoid shark, herein assigned to the familyTamiobatidaeHay, 1902. The well-preserved basicranial region reveals details of the blood circulation pattern not previously seen.

ISSN:0272-4634    

DOI:10.1080/02724634.1998.10011054

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A new sarcopterygian fish,Psarolepis, gen. nov. (Sarcopterygii, Osteichthyes) is described from the Lower Devonian of Eastern Yunnan, China. The new genus manifests many porolepiform-like features that are commonly used to distinguish porolepiforms from osteolepiforms, such as internasal cavity well developed, parasphenoid not protruding forward to ethmoidal region, vomeral area rectangular in shape and not meeting at median line, dorsal part of interorbital wall broad and tectum orbitale well developed, external surface of lower jaw with three large fossae, and well developed parasymphysial plates at anterior tip of lower jaws.

ISSN:0272-4634    

DOI:10.1080/02724634.1998.10011055

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Gars (Lepisosteidae, Actinopterygii) are reported from Madagascar for the first time, from exposures of the Upper Cretaceous (?Campanian) Maevarano Formation in the Mahajanga Basin, northwestern Madagascar. The material includes relatively common isolated scales, and vertebral centra, teeth, fin rays, and dermal cranial elements, all assigned toLepisosteussp. This new record from Madagascar adds to previously documented Cretaceous Gondwanan gar occurrences in India, Africa, and South America, as well as in Laurasia. The overall pattern points to a Pangean distribution in the Cretaceous and a Jurassic or earlier origin for the gar clade. The extant endemic fishes of Madagascar are not phylogenetically close to gars or to other Late Cretaceous fishes known from the island, suggesting that the ichthyofauna now there likely evolved from post-Mesozoic colonizers.

ISSN:0272-4634    

DOI:10.1080/02724634.1998.10011056

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The morphology of †Kuntuluniais reviewed based mainly on well preserved specimens from Madongshan Formation of Liupanshan Group, Ningxia province. Some anatomical features of †Kuntuluniaare revised, and the basisphenoid, basioccipital, exoccipital, autosphenotic, palatine, sclerotic bone, postcleithrum and separated third and fourth ural centra are described for the first time. A smooth bone lying anteriorly to the maxilla is named the antemaxilla.

ISSN:0272-4634    

DOI:10.1080/02724634.1998.10011057

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A new acanthomorph genus is described from the Greenhorn Formation (Turonian) of north eastern Nebraska. The type and only specimen of this genus is a nearly complete skull and postcranial skeleton characterized by an interesting combination of features such as a prominent, anteriorly thickened supraoccipital crest, protrusile upper jaw with well developed premaxilla, opercular bones without spines, 39 vertebral centra, pectorals very low on the flank, pelvic fins in abdominal position, medial pelvic process distally ossified, true dorsal fin-spines present, and spinoid scales covering the trunk. The Late Cretaceous acanthomorph †Aipichthysshares a few characters with the new genus including deeply cleft caudal fin and nine principal caudal rays on the upper lobe of the caudal fin. Characters are shared also with †Araripichthysfrom the Early Cretaceous of Brazil. The material described resembles in certain characters (e.g., supraneurals, abdominal vertebrae and probably paired fin placement) the acanthomorph †Ferrifrons rugosus, represented by a single incomplete specimen from the Niobrara Chalk (Santonian). Based on a few synapomorphies, the new genus and †Ferrifronsare included in the new fossil family Ferrifronsidae.

ISSN:0272-4634    

DOI:10.1080/02724634.1998.10011058

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

We report here the discovery of a new taxon of Paleozoic tetrapod from the Late Mississippian of Nevada (330–340 Ma). It has a unique vertebral column with principal centra having vertical anterior and posterior faces, ventrally incomplete accessory centra located antero-dorsally in each centrum, and enlarged presacral/sacral vertebrae. The head and pectoral girdle were not preserved but the large femur, robust pelvic girdle and enlarged sacral vertebrae possibly indicate a terrestrial mode of life. This new form significantly extends the western geographic range of known Mississippian tetrapods. It presents a mosaic of primitive and derived features, indicating that continued revision of traditional accounts of vertebral homology and the early diversifications of Paleozoic tetrapods will be necessary.

ISSN:0272-4634    

DOI:10.1080/02724634.1998.10011059

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Rhadinosteus parvusis a small anuran whose diagnosis is based on several partial skeletons and some isolated bones representing metamorphic to newly transformed ontogenetic stages from the Late Jurassic Morrison Formation at the Rainbow Park Microsite, Utah. This frog is a member of the Pipoidea on the basis of an azygous frontoparietal and parasphenoid that lacks lateral alae and is an important addition to the poorly known Jurassic frog fauna. Although other members of the Pipoidea have skeletal specializations for burrowing or swimming,Rhadinosteuspossesses an unspecialized skeleton. Presence of ectochordal vertebrae suggest thatRhadinosteusis a member of the Rhinophrynidae, and if so, it is the most primitive member known. Being from the Late Jurassic,Rhadinosteuspredates both the previous pipoid, Early Cretaceous, and rhinophrynid, Late Paleocene, records.

ISSN:0272-4634    

DOI:10.1080/02724634.1998.10011060

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A new genus and species of sphenodontian lepidosaur,Zapatadon ejidoensis, is described, based upon a nearly complete skull of a posthatchling specimen from the late Early Jurassic La Boca Formation, Tamaulipas, México. It is diagnosed by its extremely small size, the presence of a depression around the hatchling tooth series on the dentary, an expanded prefrontal that surrounds most of the dorsal process of the maxilla, and a broad jugal that nearly excludes the maxilla from the orbit. A phylogenetic analysis of its relationships supports the hypothesis that it is among the closest relatives of the only extant sphenodontian,Sphenodon. However, the relationships ofZ. ejidoensiscould not be resolved with respect to Eilenodontinae,Opisthias, and aCynosphenodon-Sphenodonclade. The most significant character diagnosing the clade composed of these five taxa is wear facets indicative of propalinal mandibular movement.

ISSN:0272-4634    

DOI:10.1080/02724634.1998.10011061

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Four different species belonging to three genera of South African proterosuchids have been described:Proterosuchus fergusi(Broom, 1903),Chasmatosaurus vanhoepeni(Haughton, 1924),Elaphrosuchus rubidgei(Broom, 1946), andChasmatosaurus alexandri(Hoffman, 1965). The specimens and descriptions suggest that all four are subjective synonyms for the same concept. The type specimen is specifically determinable and the senior synonym,Proterosuchus fergusiBroom, 1903, is selected as the valid name for the South African proterosuchid species. The diagnosis for the species includes features such as: the dentigerous borders of the premaxilla and maxilla form an angle of about 120 degrees; the palatal teeth are arranged in a specific pattern; the laterosphenoid is not reduced in its anterior development; and the epipterygoid is axe-shaped and has an anteroventral medial process.

ISSN:0272-4634    

DOI:10.1080/02724634.1998.10011062

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A large number of dinosaur nesting sites have been documented from the Upper Cretaceous (Maestrichtian) Lameta Formation of India. A remarkable diversity is noticeable in the eggshells. Based on the general morphology and the histostructure, they are parataxonomically assignable to oofamily Megaloolithidae (Tubospherulithic morphotype) and Elongatoolithidae (Ratite morphotype). Ten new oospecies of these eggshells are described in the present paper. Of these, the eight oospecies are assignable to oogenusMegaloolithus, one to the newly established oogenusEllipsoolithusand the remaining one has been categorised as Incertae sedis. In addition, associated chelonian eggshells are also described.

ISSN:0272-4634    

DOI:10.1080/02724634.1998.10011063

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor