Temporal patterns of barren intervals in the Phanerozoic

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 correlates well 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

Are global Phanerozoic marine diversity curves truly global? A study of the relationship between regional rock records and global Phanerozoic marine diversity

The consensus view that the amount of rock available for sampling does not significantly and systematically bias Phanerozoic marine diversity patterns has broken down. How changes in rock availability and sampling intensity affect our estimates of past biodiversity has been investigated with a variety of new approaches. A number of proxies for the amount of rock available for sampling have been used, but most of these proxies do not rely directly on evidence from large-scale geological maps (maps that cover small areas) and accompanying memoirs. Most previous map-based studies focused on single regions or relied on small-scale synoptic maps. We collected data from published geological maps and memoirs from western Europe, Australia, and Chile, which we combined with COSUNA data from the United States to generate the first multiregional data set for investigating whether the global Phanerozoic marine diversity record is a true global record, or is instead biased toward North America and Western Europe as has long been suspected. Both short and long-term trends in variation in the amount of outcrop display limited correlation among the regions studied. A series of diversification models obtained better matches to observed fossil diversity from the European and U.S. records than for the Chilean and Australian records, further supporting suspicions that the global Phanerozoic diversity curve is disproportionately influenced by European and U.S. fossil data. These results indicate that future research into Phanerozoic marine diversity patterns should not continue to apply global eustatic curves as a proxy for rock at outcrop, but should use regional data on rock occurrence

Faunal diversity, heterogeneity and body size in the early triassic: testing post-extinction paradigms in the Virgin Limestone of Utah, USA

The recovery intervals after mass extinction events are portrayed as times of ecological stress, with effects including reduced body size (Lilliput Effect), reduced taxonomic diversity and lowered ecological complexity. As the end-Permian mass extinction is the largest of the 'Big Five' events, with a prolonged recovery interval postulated during the Early Triassic, we expect these effects to be most pronounced in Early Triassic faunas. We have used new data and analytical techniques on the fauna of the Spathian Virgin Limestone to test whether the Lilliput Effect can be observed, whether the fauna is vertically and laterally homogeneous, and whether taxonomic diversity is significantly lower than that of comparable nearshore marine deposits transgressive over redbed sequences from other deposits not regarded as falling into post-extinction recovery intervals. The Lilliput Effect can be observed in some cases, but no uniform trend in body size reduction emerged. When the distributions of the body size across a range of marine invertebrate taxa was compared between the Virgin Limestone and the latest Triassic Penarth Group of Britain there was no support for a significant reduction in body size among the Virgin Limestone fauna. Evidence for faunal homogeneity was also limited. The alpha diversity of individual sites in the Middle Triassic Muschelkalk of central Europe was generally higher than Virgin Limestone sites, after accounting for differences in sample size using rarefaction, but there was some overlap. Although the beta diversity of the Muschelkalk is also apparently higher, a number of biases may be elevating Muschelkalk diversity. Future comparisons between recovery and 'normal' faunas need to ensure that as many confounding factors as possible are controlled for and that multiple samples are tested

Extent and economic effect of heat loads on dairy cattle production in Australia

Objective: To investigate the extent of heat load problems, caused by the combination of excessive temperature and humidity, in Holstein-Friesian cows in Australia. Also, to outline how milk production losses and consequent costs from this can be estimated and minimised. Procedures: Long-term meteorological data for Australia were analysed to determine the distribution of hot conditions over space and time. Fifteen dairy production regions were identified for higher-resolution data analysis. Both the raw meteorological data and their integration into a temperature-humidity thermal index were compiled onto a computer program. This mapping software displays the distribution of climatic patterns, both Australia-wide and within the selected dairying regions. Graphical displays of the variation in historical records for 200 locations in the 15 dairying regions are also available. As a separate study, production data from research stations, on-farm trials and milk factory records were statistically analysed and correlated with the climatic indices, to estimate production losses due to hot conditions. Results: Both milk yields and milk constituents declined with increases in the temperature-humidity index. The onset and rate of this decline are dependent on a number of factors, including location, level of production, adaptation, and management regime. These results have been integrated into a farm-level economic analysis for managers of dairy properties. Conclusion: By considering the historical patterns of hot conditions over time and space, along with expected production losses, managers of dairy farms can now conduct an economic evaluation of investment strategies to alleviate heat loads. These strategies include the provision of sprinklers, shade structures, or combinations of these

Broadening the scope of recurrent copy number variation and other congenital anomalies associated with mullerian disorders

No abstract available