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Australia: The Land Where Time Began |
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Talbragar Fish Beds - aquatic invertebrates Also discovered in the deposits are small bivalve and gastropod molluscs. There were also filamentous aquatic plants, a shallow-water environment near the lake margin is indicated (R. Beattie, pers. comm. to LB). It has been suggested that the insects were trapped by the ash fall that enveloped the water body, as none were present in the lower layers that contained the scattered fish. Talbragar Fish Beds - Shelly marine faunas Marginal basins in Western Australia are the only known deposits containing shelly marine faunas, studied onshore assemblages being confined to the Middle and Late Jurassic (e.g. Playford et al., 1975; Playford et al., 1976; and see references in Grant-Mackie et al., 2000). Important tie points between biostratigraphic zones in Australia and the international chronostratigraphic stages have been provided by the assemblages, especially the ammoinds (Helby et al., 1987). Offshore marine sequences of Jurassic age are more continuous, though detailed macroinvertebrate studies are made mere difficult by the limited material recovered from bore holes. There is potential for studies of microinvertebrates and shelly protists (e.g. Brown, 1992, Grant-Mackie et al., 2002, Howe, 2002), though the scope for identifying diverse faunas of some groups may be limited by the restricted marine conditions at the time of deposition of some major units (e.g. the Dingo Claystone) as well as the generally impoverished condition in carbonate facies. On the neighbouring terranes of New Zealand, New Caledonia, and New Guinea invertebrate faunas are much better known (Grant-Mackie et al., 2000; Haig et al., 2007; Hikuroa and Grant-Mackie, 2008). From Jurassic deposits in eastern Australia 4 freshwater/estuarine species of bivalve have been recorded during a recent revision (Hocknull, 2000). Significant biostratigraphic or biogeographical value have not yet been revealed by these 4 isolated records (see Grant-Mackie et al., 2000).
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Jurassic Australia |
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Author: M.H.Monroe Email: admin@austhrutime.com Sources & Further reading |