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Jurassic Forum » JURASSIC references & paper reviews » Non-Jurassic references » Smith, McGowan (2007, 2008) (Two papers about palaeodiversity & barren intervals)
Smith, McGowan (2007, 2008)
mhornДата: Monday, 25.01.2010, 23:13 | Сообщение # 1
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Smith A.B., McGowan A. (2007) The shape of the Phanerozoic marine paleodiversity curve: how much can be predicted from the sedimentary rock record of Western Europe? // Palaeontology. Vol. 50. Pt.4. P.1–10.
Palaeodiversity curves are constructed from counts of fossils collected at outcrop and thus potentially biased by variation in the rock record, specifically by the amount of sedimentary rock representative of different time intervals that has been preserved at outcrop. To investigate how much of a problem this poses we have compiled a highresolution record of marine rock outcrop area in Western Europe for the Phanerozoic and use this to generate a model that predicts the sampled diversity curve. We find that we can predict with high accuracy the variance of the marine genus diversity curve (itself dominated by European taxa) from rock outcrop data and a three-step model of diversity that tracks supercontinent fragmentation, coalescence and fragmentation. The size and position of two of the five major mass extinction spikes are largely predicted by rock outcrop data. We conclude that the long-term trends in taxonomic diversity and the end Cretaceous extinction are not the result of rock area bias, but cannot rule out that rock outcrop area bias explains many of the short-term rises and falls in sampled diversity that palaeontologists have previously sought to explain biologically.

Smith A.B., McGowan A. (2008) Temporal patterns of barren intervals in the Phanerozoic // Paleobiology, 34(1), pp. 155–161.
It has recently been argued that barren intervals of marine sedimentary rock are less common in the Cenozoic than in the Paleozoic, and that this arises as a direct consequence of widespread epeiric seas and the prevalence of dysaerobic conditions at such times. We show, using an independent and more direct measure of rock outcrop through time in western Europe, that barren marine sedimentary rocks do become less frequent toward the present, but that this is not linked
to any epeiric-seas effect. The proportion of barren to fossiliferous rock outcrop correlateswell with the inferred Phanerozoic marine diversity curve (although more so in the Paleozoic than in the post-Paleozoic), and shows no correlation or only a weak negative correlation with area over which the sediments have been deposited. We therefore concluded that the Phanerozoic trend in fossiliferousness most likely records the degree to which space is occupied in the shallow marine realm.

Middle Jurassic - Lower Cretaceous ammonites & aptychi
Jurassic Forum » JURASSIC references & paper reviews » Non-Jurassic references » Smith, McGowan (2007, 2008) (Two papers about palaeodiversity & barren intervals)
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