ISSN:0272-4634    

DOI:10.1080/02724634.1990.10011787

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

In December 1940, vertebrate paleontologists dissolved the Paleontological Society's Section of Vertebrate Paleontology and formed the Society of Vertebrate Paleontology as the principal professional organization of their discipline. During the months leading to this founding meeting, Simpson wrote a manuscript about the former Section. That manuscript, which Simpson never published, had two purposes: (1) to justify the dissolution of the Section and the formation of the separate Society, and (2) to describe the Section's administrative practices. Presented here in its entirety, with historical notes added by Cain, this manuscript provides insight into the relation between vertebrate paleontologists and the Paleontological Society during the 1930s. Simpson's manuscript also illustrates the extent to which vertebrate paleontologists expressed disciplinary independence during this period.

ISSN:0272-4634    

DOI:10.1080/02724634.1990.10011788

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A new acanthodiform acanthodian is described from the lowermost Pennsylvanian of Utah. The specimen is a primitive acanthodid, as is indicated by the posterior position of pelvic fin spine, and is namedUtahacanthus guntheri, gen. et sp. nov. It is characterized by opposing dorsal and anal fin spines, relatively shorter pelvic and dorsal fin spines compared to other Acanthodidae, and strongly developed gill rays.Utahacanthus, in common with some other acanthodians, possessed three otoliths. A comparative analysis of gnathostome otoliths results in the postulation of aragonite as the basic mineral of otoliths for all gnathostomes, and of three otoliths as a feature common to all teleostomes including acanthodians. Many parallel characters apparently occur involving the mineral composition of statoconia and otoliths. The number of otoliths is reduced within osteichthyans from three (actinopterygians) to two (dipnoans) to one (actinistians), and finally to statoconia (reversal in tetrapods).

ISSN:0272-4634    

DOI:10.1080/02724634.1990.10011789

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Microvertebrates from limestones near the Burmese border town of Mae Sam Lap, northern Thailand, are dated as late Famennian by associated conodonts. The fauna contains the chondrichthyansThrinacodus(Harpagodens)ferox, Symmorium?sp., “Cladodus,” cf.C. acutus, and two new taxa,Phoebodus australiensis, sp. nov., andSiamodus janvieri, gen. et sp. nov. Several types of chondrichthyan scales, actinopterygian scales and teeth, and rare acanthodian scales also occur in the fauna.Phoebodus australiensis, sp. nov., is also recognized from Australia and South China;Siamodus, gen. nov., is also recognized from the Late Devonian of South China.Thrinacodus feroxappears in the Late Devonian of Australia, South China, and Thailand, predating the occurrence of this species in Europe and North America (Carboniferous). These data suggest close affinity between the Shan-Thai, East Gondwana, and South China Terranes at the end of the Devonian.

ISSN:0272-4634    

DOI:10.1080/02724634.1990.10011790

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Leptopterygius tenuirostrisis a long-snouted ichthyosaur which extends from the Upper Triassic (Rhaetian) to the Lower Jurassic (Hettangian and Sinemurian) of England. The species is quite common, but few complete skeletons are known and most of these were collected from the vicinity of Street, in Somerset, during the last century. Some of these skeletons bear a distinctive pattern of chisel marks on their surrounding matrix, and since one such specimen has been shown to be a composite, the authenticity of the others is thrown into question. A survey is made of questionable specimens to alert others to the problem.

ISSN:0272-4634    

DOI:10.1080/02724634.1990.10011791

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A well-preserved pelvis of a large pterodactyloid pterosaur from the Santana Formation (Aptian) of Brazil is described. The pelvis is the first in which the orientation of the acetabulum is unambiguous. The acetabulum is directed laterally and posteriorly, and indicates that the femur could be brought under the body. This would allow bipedal locomotion, and a new model of bipedal locomotion for pterodactyloid pterosaurs is presented.

ISSN:0272-4634    

DOI:10.1080/02724634.1990.10011792

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Freshwater/estuarine organic deposits at Cudmore Grove, Mersea Island, Essex, England, palynologically dated to the Hoxnian Interglacial Substage Ho IIIb, have yielded by far the richest fossil herpetofauna known from the British Pleistocene. Caudates are represented byTriturus cristatusandT. vulgaris; anurans byHylasp.,Bufo bufo, Rana arvalis, R. “esculenta” orR. ridibunda, andR. lessonae;testudines byEmys orbicularis;saurians byAnguis fragilisandLacertasp.; and snakes byElaphe longissima, Natrix mauraorN. tessellata, N. natrix, andVipera berus. Of these 14 taxa, seven do not occur in Britain today, but are found in continental Europe. The fossil assemblage reflects the former connection of Britain to continental Europe and is consistent with a climate of milder winters and warmer summers than today during the later part of the Hoxnian Interglacial (Substage Ho IIIb).

ISSN:0272-4634    

DOI:10.1080/02724634.1990.10011793

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Vertebrates from the Comanche Series (Lower Cretaceous) in central Texas occur in the superposed Twin Mountains, Glen Rose, and Paluxy formations. Stratigraphie position and relationship to marine units are more clearly defined for the central Texas localities than for the classic mammal-producing sites in the Antlers Formation of north-central Texas. The diverse terrestrial to marine faunas include new records for the rayRhinobatos, a ptychodont (cf.Hylaeobatis ornata), and the salmoniformEnchodus. Anurans, salamanders, lacertilians, and mammals representing early forms relevant to the emergence of extant higher taxa are present but fragmentary. Crocodilians are represented by at least three taxa and theropods by more than three. Eight species of mammals have been named from the Comanche Series, with perhaps as many as four other unnamed species represented. Paleoenvironments appear to control the distribution of taxa: dinosaurs are found in coastal settings and are abundant in some terrestrial sites with little aquatic component, while mammals occur in mixed sites with abundant fish faunas. During the Early Cretaceous, the Texas coast was flanked by a broad, flat, carbonate-dominated shelf, and fed by southeast flowing streams in low-relief paleovalleys under a semiarid climate.

ISSN:0272-4634    

DOI:10.1080/02724634.1990.10011794

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The auditory ossicles and tympanic bulla of the Archaeoceti show little intergeneric morphological variation, and are similar to the ossicles of extant cetaceans in most respects. The attachment of the tympanic membrane is separated from its origin indicating that the Archaeoceti possessed an elongated, conical tympanic conus unique to cetaceans. The sigmoid process is an expansion of the anterior limb of the ancestral tympanic bone and is entirely ectotympanic in origin. Expansion of the sigmoid process is partially responsible for the elongation of the tympanic conus by spatially separating the manubrium of the malleus out of the plane of attachment of the tympanic membrane. Elongation is further augmented by the reduction of the manubrium of the malleus, and by the evolutionary rotation of the malleus-incus system about its physiologic axis of rotation. Evolutionary rotation, reduction of the manubrium, and an expanded sigmoid process all contributed to a system of angular amplification that is still present in extant cetaceans. The specific gravity of the ossicles is greater than that of any extant cetacean for which it is known. This could have resulted from the systemic increase in bone density experienced by archaeocetes in their adaptation to the marine environment. These adaptations appear in the earliest cetacean,Pakicetus inachus, and are well developed by the Late Eocene in the Basilosauridae. Such adaptations could have laid the foundation for the development of underwater echolocation by enabling the middle ear to transmit high-frequency sound.

ISSN:0272-4634    

DOI:10.1080/02724634.1990.10011795

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

ISSN:0272-4634    

DOI:10.1080/02724634.1990.10011796

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor