摘要:

The Chinaman Gully Formation in South Australia is a regressive non-marine to marginal marine unit previously correlated with the ‘Eocene/Oligocene boundary’ type 1 Sequence Boundary Ta 4.3/4.4. It is barren of ostracods. Cytherellid, krithiid, pontocypridid, paracypridid and trachyleberidid ostracods are abundant in the underlying Blanche Point Formation (BPF), whereas bairdiids, xestoleberidids, hemicytherids and loxoconchids are more abundant in the Port Willunga Formation (PWF) which overlies the Chinaman Gully Formation. A major contrast in trachyleberidid, loxoconchid and hemicytherid species composition is evident between the BPF and PWF. A bootstrap variety of correspondence analysis identifiedParacypris, Kuiperiana, Krithe, Tasmanocypris?, Argilloecia, Trachyleberis, CytherellaandBythocyprisas significant genera (indicating a palaeodepth of 120–200 m) in the BPF andQuadracythere, Hornibrookella?, Loxoconcha, Microcytherura, bairdiids,Schizocythere, Cytheralison, KangarinaandXestoleberisas significant genera (indicating a palaeodepth of ≤ 50 m) in the PWF. The generic diversity and the adult/juvenile ratio is higher in the PWF than in the BPF, reflecting a greater number of niches in a shallower environment with higher hydrodynamic stress. The many autochthonous cytherellids in the BPF probably signify low oxygen conditions during deposition.

ISSN:0311-5518    

DOI:10.1080/03115519608619470

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

New interpretations are available from recently published appendages ofEoredlichia intermedia(Early Cambrian Chengjiang fauna), the most primitive trilobite for which appendages are known. The basis (formerly identified as the coxa) is preserved in one appendage. An allegedly long proximal podomere in the endopod is actually subdivided into two and, at least in posterior appendages, each of these podomeres bears a strong, angular endite. The large, subquadrate basis, angular endite on the first podomere of the endopod, and attachment of the exopod along the whole length of the basis are features shared with naraoiids, for whichNaraoia longicaudataZhang & Hou is exemplar. The long line of attachment of the exopod to the basis works as a hinge joint inE. intermediaand is a feature shared byOlenoides serratus. This joint allows rotation of the basis and endopod around the hinge line, permitting extensive leg movement without forcing the large exopod fan out of position. The shape of the basis inO. serratusis reinterpreted here, and a new reconstruction of the exopod shows detailed similarity toE. intermedia. The limbs ofEoredlichiashow that appendage structure in primitive trilobites is little altered from shared ancestry with naraoiids.

ISSN:0311-5518    

DOI:10.1080/03115519608619471

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Two further finds ofKeratobrachyops australisWarren (Amphibia, Temnospondyli, Chigutisauridae) from the Early Triassic Arcadia Formation of Queensland provide new information concerning skull characters not noted in the holotype. The holotype ofXenobrachyops allosHowie (Amphibia, Temnospondyli, Brachyopidae) from the same locality is redescribed following the discovery of several features not previously noted. In addition, new but fragmentary brachyopoid material from the Arcadia and overlying Glenidal Formations provides information on derived character states within the superfamily. Controversy surrounds the correct familial composition of the superfamily Brachyopoidea, with the family Brachyopidae being allied by various authors with a diversity of other Triassic and Permian families. A cladistic analysis of a number of these families has been performed in an attempt to determine interfamilial relationships. Our results support a brachyopid-chigutisaurid dichotomy within the Brachyopoidea, but also suggest the families Tupilakosauridae, Dvinosauridae and Saurerpetontidae are plesiomorphous members of the clade. Further analysis of genera within the superfamily shows that several brachyopid genera cannot be distinguished by cladistic means, indicating a need for revision of its members. Future analysis may support the erection of a new brachyopoid family for species ofSinobrachyopsandXenobrachyops.

ISSN:0311-5518    

DOI:10.1080/03115519608619472

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A large rock slab collected in 1913 from the roof of the Bellambi Colliery in the southern Sydney Basin bears fossil tracks that are now known from recent radiometric and chemostratigraphic dating to be earliest Triassic, rather than latest Permian, in age. The tracks show two distinctive features of reptiles: scale impressions and claw marks. Both manus and pes are pentadactyl, ectaxonic, semidigitigrade and have an outer interdigital angle (digits IV–V) greater than inner interdigital angles. Digit proportions are consistent with a phalangeal formula of 23333. The fossil tracks are referred to the ichnospeciesDicynodontipus bellambiensissp. nov. They are similar to the kinds of tracks thought to be produced byLystrosaurusspecies. Given the abundance of these species in Early Triassic faunas of low diversity and the occurrence of members of theLystrosaurusfauna in Queensland and Antarctica, chances are good that this is indeed a trackway ofLystrosaurus. If considered to be made by an animal of that type, the trackway was produced using the primitive alternate gait, rather than the mammalian amble, by an animal about 84 cm long and some 22 cm high. Preservation of bones of these creatures would not be expected given the non-calcareous nature of associated fossil soils in the Sydney Basin Triassic. Herbaceous lycopods, locally common in these and other Early Triassic strata worldwide, are among the most likely foods of these tusked, low-browsing herbivores.

ISSN:0311-5518    

DOI:10.1080/03115519608619473

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Two bryozoan species have been found in the Kahuitara Tuff (Piripauan-Haumurian Stages; equivalent to Campanian-Maastrichtian) of Pitt Island, in the Chatham Islands, about 900 km east of the South Island of New Zealand. Cretaceous bryozoans are rare in Australasia, and the two species in this paper are the first to be formally described from New Zealand. Both species have thick dendroid colonies but whereasCeriocava maculatasp. nov. is an unequivocal cerioporine cyclostome, the other species —Chiplonkarina campbellisp. nov. — is more problematical and is interpreted as an aberrant ‘malacostegan’ cheilostome. Like previously described species ofChiplonkarina, C. campbellihas interzooidal walls with a central crenulated layer, indicating the former presence of an intercalary cuticle of the type found in many cheilostomes but unknown in cyclostomes. The anomalous global biogeographical distribution of bryozoans during the Cretaceous is briefly discussed.

ISSN:0311-5518    

DOI:10.1080/03115519608619474

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

ISSN:0311-5518    

DOI:10.1080/03115519608619475

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor