摘要:

A new horned turtle (Family Meiolaniidae),Meiolania brevicollissp. nov. from the Mid Miocene Camfield Beds of northern Australia is diagnosed from cranial fragments and three cervical vertebrae. It is morphologically similar toM. platycepsfrom the Pleistocene of Lord Howe Island, but, in addition to more subtle features, has a flatter skull, proportionally elongated cranial ‘B’ horn-cores, vestigial or absent ‘A’ horn-cores, and probably a shorter neck. An hypothesis of systematic relationships within Meiolaniidae, using shared, derived cranial characters, supports the suggestion of Gaffney & McNamara (1990) thatMeiolaniais a monophyletic genus, derived with respect to‘Meiolania’ oweni. Further,M. brevicollisappears to be advanced with respect toM. platyceps, though the latter is known from much younger strata. The stratigraphic ranges ofM. brevicollisandM. platycepsare unknown. The hypothesis thatM. platycepsmight have evolved from aM. brevicollis-like ancestor is not favoured because it requires a structural reversal in horn-core morphology.

ISSN:0311-5518    

DOI:10.1080/03115519208619035

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Temnospondyl amphibians have numerous teeth which are typically internally convoluted. In this paper we look for derived features of the distribution of both cranial and mandibular teeth and also examine the extent of their convolution. We show that some features of the distribution and convolution are family linked. Overall, the degree of complexity as shown by the number of infolds and infold bends, increases with the size of the dental element. Bending of infolds appears to be more frequent within the superfamily Capitosauroidea, while among the trematosaurian group of temnospondyls bending is less pronounced, with two families, the Plagiosauridae and Rhytidosteidae, showing no bends in marginal teeth and only minimal bending in the largest rhytidosteid tusks.

ISSN:0311-5518    

DOI:10.1080/03115519208619036

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A comprehensive taxonomic revision of heteromorph ammonites from the Miria Formation and the uppermost horizon, a nodule bed, of the Korojon Calcarenite is presented, with major rationalisation of earlier nomenclature and new data on the faunal sequence.Eubaculitesis present throughout the succession as three biostratigraphically discrete species andNostoceras, represented by two species, is restricted to the nodule bed. Remaining elements of the heteromorph fauna are known only from the upper part of the Miria Formation, associated with a diverse assemblage of planispiral ammonites and other molluscs. Preservation of ammonites has been strongly influenced by taphonomic factors such that the biostratigraphic pattern now apparent is largely unrelated to life assemblages. Ammonites from the upper Miria Formation are of late Maastrichtian age whereas those from the nodule bed are ascribed to the early Maastrichtian.

ISSN:0311-5518    

DOI:10.1080/03115519208619037

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A new outcrop of the Waiomio Shellbed is described from the west bank of the Rangitikei River, near Porewa. The shellbed comprises cross-bedded pebbly-shell conglomerate containing a rich intertidal assemblage of estuarine (Macomona liliana, Cominella glandiformis, Austrovenus stutchburyi) and shore face (Paphies subtriangulata, Mactra discors, Spisula aequilatera, Dosinia (Phacosoma) subrosea) Mollusca. This site contains previously undescribed units, and the names Waiomio Formation (which includes the basal Waiomio Shellbed) and Reu Reu Formation are introduced. The excellent exposure demonstrates the position of the Waiomio Shellbed within a complete cyclothem, facilitating interpretation in terms of sequence stratigraphic concepts. A basal disconformity (sequence boundary) truncating a palaeosol horizon (lowstand systems tract), is overlain by the Waiomio Formation (transgressive systems tract), and is succeeded by the Reu Reu Formation, comprising anin situshellbed (condensed section) and massive siltstone (highstand systems tract). The complete sequence is compared with its probable equivalent in the Wanganui coast section, which correlates with oxygen isotope stage 15.

ISSN:0311-5518    

DOI:10.1080/03115519208619038

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor