Vertebrate extinctions and reorganizations during the Late Silurian Lau Event
Mats E. Eriksson et al., Dept. of Geology, GeoBiosphere Science Centre, Lund University, Solvegatan 12, SE-223 62 Lund, Sweden. Pages 739-742.
During the Silurian Period (about 443-416 million years ago) fish faunas were struck hard by extinctions caused by the so-called Lau Event. This globally recognized event had significant effects on marine life, oceanic chemistry, and the sea-floor sediments deposited. Eriksson et al. show that the Lau Event had a profound impact on the early evolutionary history of vertebrates, wiping out almost two-thirds of the fish species and causing major ecological reorganizations over an estimated time span of 200,000 years. Immediately prior to the event, the jawed acanthodians dominated the fish faunas, whereas the event led to a diverse fauna and a brief but marked dominance of the jawless thelodonts. Both these groups of fish are now extinct but were common inhabitants in the Silurian seas. The stepwise changes observed among the fish faunas resemble those of conodonts, another extinct group of vertebrates, suggesting a similar mode of life and response to the Lau Event.
Super-heavy pyrite (34Spyr > 34SCAS) in the terminal Proterozoic Nama Group, southern Namibia: A consequence of low seawater sulfate at the dawn of animal life
Justin B. Ries et al., Dept. of Marine Sciences, 333 Chapman Hall, CB# 3300, Univ
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