The effects of redox conditions on arsenic re-release from excavated marine sedimentary rock with naturally suppressed arsenic release

The validity of biological explanations of patterns of palaeodiversity has been called into question owing to an apparent correlation of diversity with the amount of sedimentary rock preserved. However, this claim has largely been based on comprehensive estimates of global marine Phanerozoic diversity, thus raising the question of whether a similar bias applies to the records of smaller, well-defined taxonomic groups. Here, new data on European Caenozoic marine sedimentary rock outcrop area are presented and compared with European occurrences of three groups of marine mammals (cetaceans, pinnipedimorphs and sirenians). Limited evidence was found for a correlation of outcrop area with marine mammal palaeodiversity. In addition, similar patterns were identified in the cetacean and pinnipedimorph diversity data. This may point to the preservation of a genuine biological signal not overwhelmed by geological biases in the marine mammal diversity data, and opens the door to further analyses of both marine mammal evolution and geological bias in other small and well-defined groups of taxa.

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Temporal patterns of barren intervals in the Phanerozoic

Paleobiology ◽

10.1666/07042.1 ◽

2008 ◽

Vol 34 (1) ◽

pp. 155-161 ◽

Cited By ~ 21

Author(s):

Andrew B. Smith ◽

A. J. McGowan

Keyword(s):

Sedimentary Rock ◽

Western Europe ◽

Sedimentary Rocks ◽

Direct Consequence ◽

Rock Outcrop ◽

Shallow Marine ◽

Marine Diversity ◽

Marine Realm ◽

Weak Negative Correlation ◽

Marine Sedimentary Rock

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.

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