摘要:

The Ordovician Harding Sandstone has played an important role in studies of the environment of the earliest types of “ostracoderms” (armored jawless fish-like vertebrates). Such studies have concentrated on fossil collections from the type locality, a quarry near Canon City, Colorado, which contains a mixed fossil fauna of “ostracoderms” and marine invertebrates. This co-occurrence has been used in the past as evidence that the vertebrates from the Harding Sandstone were marine animals. Fossil associations alone, however, do not provide sufficient data for paleoenvironmental interpretations. It is also necessary to analyze depositional facies. A previously unpublished locality of the Harding Sandstone allows interpretations of depositional environments by sedimentary facies analysis. Vertebrate fossils of the Harding Sandstone are restricted mainly to supratidal and, to a lesser extent, intertidal deposits. They are most abundant in channelized, granular conglomerates, units devoid of marine invertebrate fossils. This suggests that the vertebrates lived in freshwater streams and rivers.

ISSN:0272-4634    

DOI:10.1080/02724634.1992.10011427

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The marine waters of present-day Antarctica contain an exceedingly depauperate elasmobranch fauna. Recent investigations into the Eocene marine sediments of the La Meseta Formation of Seymour Island, Antarctic Peninsula yielded 13 fossil sharks new to the Antarctic region. Two,Stegostoma cf. S. fasciatum and Pseudoginglymostoma cf. P. brevicaudatum, were unknown as fossils.Squalus woodburnei, S. weltoni, andAnomotodon multidenticulataare new species.Heptranchias howelli, Centrophorussp.,Deaniasp.,Dalatias licha, Odontaspis rutoti, O. winkleri, Lamnacf.L. nasus, andScoliodonsp. are reported in Antarctica for the first time. In addition, the new fossil shark material increases the representation of the four previously known fossil sharks from Seymour Island:Squatinasp.,Pristiophorus lanceolatus, Carcharias macrota, andCarcharocles auriculatus.

ISSN:0272-4634    

DOI:10.1080/02724634.1992.10011428

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Fossil teleostean otoliths from the Mississippi River mudlumps are described for the first time. Analysis of the 446 otoliths obtained from the Late Pleistocene-Early Holocene sediment of a Mississippi River mudlump in the South Pass area of Louisiana revealed the presence of a varied teleostean fauna. The otoliths represent at least 25 families and 40 species of marine fishes.Bregmaceros, a small, cod-like fish that is common on the middle shelf of the present Gulf of Mexico, comprised 42 percent of the total number of otoliths recovered. The otoliths represented teleosts that are presently found in marine waters less than 200 meters in depth. Comparison of the otoliths to modern analogues indicated a depositional environment of middle to outer shelf with temperate to tropical conditions.

ISSN:0272-4634    

DOI:10.1080/02724634.1992.10011429

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The new genus and speciesIowadipterus halliis described from the Middle Devonian of Iowa, U.S.A.Iowadipterusis a long-headed but not long-snouted dipnoan with many distinct features: cheek bones 8 and 9 enlarged, bone 8 bordering bones Y1and Y2so that only bones Y2and Z lie dorsal to the operculum; cheek pit line passing from bone 8 directly to bone 9; elongation of B- and C-bones without differentiation of D- or E-bones; narrow submandibular combined with broad gulars; and scales with tubercles with a shallow depression on the overlapped part of scale.Iowadipterusand possiblyHolodipterusare long-headed dipnoans with a short lower jaw, in contrast to long-headed forms with a long snout (Griphognathus, Soederberghia, Rhynchodipterus, andFleurantiawith elongated rami, andRhinodipteruswith an elongated symphysis). The broad cheek offers a wide space for the adductor muscles and indicates a powerful bite.

ISSN:0272-4634    

DOI:10.1080/02724634.1992.10011430

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Four nearly complete eggs from the middle Eocene Bridger Formation (Wyoming) are assigned to the crocodiloid basic organizational group. Similarity in egg shape and size and in the histological structure of the eggshell withCrocodylus johnstoniandCrocodylus porosusjustifies this classification.

ISSN:0272-4634    

DOI:10.1080/02724634.1992.10011431

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Aigialosaurs are known from three nearly complete skeletons from the Upper Cretaceous (Cenomanian-Turonian) of Yugoslavia. The Aigialosauridae is identified as the sister-group of mosasaurs on the basis of the following shared derived characters: fusion of frontal bones; circular configuration of quadrate; well-developed hinge joint between angular and splenial; surangular and articular contributing equally to articulating surface of lower jaw; reduction of transverse processes and zygapophyses of caudal vertebrae. No significant characters of the skull are known that distinguish aigialosaurs from primitive mosasaurs. In contrast, the trunk vertebrae and the limbs are indistinguishable from those of terrestrial varanoids. The tail and the ventral elements of the pelvic girdle resemble those of some other aquatic diapsids. Aigialosaurs share many derived characters with modern varanids (includingLanthanotusandVaranusand the Eocene genusSaniwa), to the exclusion of the Upper Cretaceous varanidsSaniwidesandTelmasaurus. This suggests an earlier Cretaceous dichotomy separating advanced varanids and aigialosaurs from more primitive genera now included in the Varanidae.

ISSN:0272-4634    

DOI:10.1080/02724634.1992.10011432

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Remains of a pterodactyloid pterosaur wing from the Two Medicine Formation (Campanian) of Montana were described by Padian (1984). The bones were preserved in a limestone concretion, which has now been further prepared to expose additional material. This allows some correction and further elaboration of earlier observations. The specimen (YPM-PU 22446) is now referred to the family Azhdarchidae, and provisionally to the genusQuetzalcoatlus.

ISSN:0272-4634    

DOI:10.1080/02724634.1992.10011433

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The Erythrosuchidae are a late Early to early Middle Triassic lineage that represent the first radiation of large terrestrial carnivores within the Archosauriformes.

ISSN:0272-4634    

DOI:10.1080/02724634.1992.10011434

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The genusPaenelimnoecusBaudelot, 1972 and its species have in the course of time been assigned to the subfamilies Limnoecinae, Crocidurinae, Soricinae and Crocidosoricinae; it was still included in both latter subfamilies in the most recent literature. This enigmatic taxonomical situation is discussed. It is concluded thatPaenelimnoecusbelongs to the subfamily Allosoricinae Fejfar, 1966, which subfamily is here resurrected.

ISSN:0272-4634    

DOI:10.1080/02724634.1992.10011435

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A partial cranium with upper dentition and an isolated rib of the extinct short-faced bear,Arctodus simus, were associated with a nearly complete skeleton of the Columbian mammoth,Mammuthus columbi, at a high elevation site in Huntington Canyon in the Wasatch Mountains of central Utah. This largeA. simuswas a decidedly short-faced individual. Radiometric dates for the mammoth cluster around the interval ±11,220–11,400 BP; dates for spruce wood in stratigraphic position above and below the mammoth skeleton cluster around ±9,400 BP. Assuming direct association with the mammoth, the occurrence ofArctodus simusat ≤ 11,400 BP is a new terminal date for the species. The mammoth and bear may have been associated with humans in the Huntington Canyon vicinity. The late Quaternary high elevation fauna of Utah includes 30 genera from sites above 1,950 meters above mean sea level. Late Quaternary high elevation faunas of the central and southern Rocky Mountains included the short-faced bear, and may have persisted as relict populations until 10,000 BP or later.

ISSN:0272-4634    

DOI:10.1080/02724634.1992.10011436

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor