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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Marine reptiles from the Lower Cretaceous (Aptian) deposits of White Cliffs, southeastern Australia: implications of a high latitude, cold water assemblage
No full textReassessment of Cratochelone berneyi Longman, 1915, a giant sea turtle from the Early Cretaceous of Australia
No full textMacropodoid endocranial casts from the early Miocene of Riversleigh northwestern Queensland
No full textFirst record of a pachycormid fish (Actinopterygii: Pachycormiformes) from the lower cretaceous of Australia
No full textBenjamin J. Kea
Phylogenetic implications of macropodid (Marsupialia: Macropodoidea) postcranial remains from Miocene deposits of Riversleigh northwestern Queensland
No full textReassessment of the Early Cretaceous plesiosaur Cimoliasaurus maccoyi Etheridge 1904 (Reptilia: Sauropterygia)from White Cliffs New South Wales
No full textMarine reptiles from the Lower Cretaceous of South Australia: elements of a high-latitude cold-water assemblage
No full textThe definitive version is available at www.blackwell-synergy.comThe Lower Cretaceous rocks of South Australia have yielded a diverse marine reptile assemblage of up to five families of plesiosaur (including a new cryptoclidid or cimoliasaurid, indeterminate elasmosaurids, a possible polycotylid, rhomaleosaurids, and pliosaurid) and one family of ichthyosaur (ophthalmosaurid). Other common associated vertebrates include chimaerids and osteichthyans. Sharks, dipnoans and dinosaurs are uncommon and marine turtles are notably absent. The main fossil-producing strata belong to the Lower Aptian–Lower Albian Bulldog Shale although the Upper Albian Oodnadatta Formation has produced isolated elements. Both these units comprise finely laminated shaly mudstones and claystones deposited in a transgressive shallow coastal, epicontinental marine environment. Estimates of palaeolatitude place South Australia between 60_ and 70_S, in the late Early Cretaceous. Sedimentary structures (including lonestone boulders and glendonites), fossils, isotope data and climatic modelling also indicate that seasonally cool–cold conditions (possibly with winter freezing) prevailed during deposition of the Bulldog Shale. This contrasts markedly with climate regimes typically tolerated by modern aquatic reptiles but suggests that some of the South Australian Mesozoic taxa may have possessed adaptations (including elevated metabolic levels and / or annual migration) to cope with low temperatures. A high proportion of juvenile plesiosaur remains in the Bulldog Shale might also indicate that nutrient-rich cold-water coastal habitats functioned as both ‘safe calving grounds’ and refuges for young animals prior to their entering the open sea as adults. The occurrence of plesiosaurs and ichthyosaurs in the high-latitude Lower Cretaceous of southern Australia, along with plesiosaurs and mosasaurs in the Upper Cretaceous of South America, Antarctica, New Zealand and the Chatham Islands, demonstrates that Mesozoic marine reptiles utilized southern high-latitude environments over a considerable period of time, and that these records do not represent casual occupation by isolated taxa
Plesiosaur remains from Cretaceous high-latitude non-marine deposits in southeastern Australia
No full textAustralian plesiosaur remains are common although currently poorly documented. At present, most of the described material is derived from extensive Early Cretaceous epicontinental marine rocks in central and northeastern Australia (Kear, 2003). In recent years, however, a number of fragmentary specimens have been recovered from Lower Cretaceous non-marine sequences in the southeastern part of the continent (Fig. 1). The fossil-producing strata are included within the middle Valanginian– early Albian Wonthaggi (Gippsland Basin) and Eumeralla (Otway Basin) formations, southern Victoria, and early–middle Albian Griman Creek Formation (Surat Basin), Lightning Ridge, New South Wales/ Surat region, Queensland. Interestingly, these units were deposited in an Early Cretaceous high-latitude zone (60–80º S), subject to highly seasonal, cool to cold conditions and months of winter darkness near the southern pole. Fossils recorded include a diverse range of freshwater/ terrestrial vertebrates, non-marine invertebrates, and plants (see Dettmann et al., 1992 for summary). Although several previous reports have mentioned plesiosaur material from southeastern Australia (e.g. Rich et al., 1988; Rich and Rich, 1989; Vickers-Rich, 1996; Smith, 1999; Rich and Vickers-Rich, 2000; Kear, 2003), none of the remains have yet been described. It is therefore, the purpose of this paper to present an up-to-date summary of the existing specimens (Table 1) and assess their taxonomic and paleoecological implications
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