Monday, May 30, 2016

[Paleontology • 2016] Macrofossil Evidence for A Rapid and Severe Cretaceous–Paleogene Mass Extinction in Antarctica

 Typical Cretaceous marine environment in Antarctica, including the paperclip-shaped 'heteromorph' ammonite Diplomoceras
Painted reconstruction: James McKay DOI:  10.1038/ncomms11738 

Debate continues about the nature of the Cretaceous–Paleogene (K–Pg) mass extinction event. An abrupt crisis triggered by a bolide impact contrasts with ideas of a more gradual extinction involving flood volcanism or climatic changes. Evidence from high latitudes has also been used to suggest that the severity of the extinction decreased from low latitudes towards the poles. Here we present a record of the K–Pg extinction based on extensive assemblages of marine macrofossils (primarily new data from benthic molluscs) from a highly expanded Cretaceous–Paleogene succession: the López de Bertodano Formation of Seymour Island, Antarctica. We show that the extinction was rapid and severe in Antarctica, with no significant biotic decline during the latest Cretaceous, contrary to previous studies. These data are consistent with a catastrophic driver for the extinction, such as bolide impact, rather than a significant contribution from Deccan Traps volcanism during the late Maastrichtian.

James D. Witts, Rowan J. Whittle, Paul B. Wignall, J. Alistair Crame, Jane E. Francis, Robert J. Newton and Vanessa C. Bowman. 2016. Macrofossil Evidence for A Rapid and Severe Cretaceous–Paleogene Mass Extinction in Antarctica. Nature Communications. 7, Article number: 11738. DOI:  10.1038/ncomms11738 

Antarctic fossils reveal creatures weren’t safer in the south during dinosaur extinction via  @Scienmag

Painted reconstruction of typical Cretaceous marine environment in Antarctica, ....:
Images from Seymour Island in the Antarctic Peninsula:
Photographs of fossils:  Credit: Richard Cruise, University of Leeds

1 comment:

  1. There are three types of rocks: metamorphic, igneous, and sedimentary. Metamorphic rocks are formed through high pressure nad heat, igneous rocks are made from the cooling of magma, and sedimentary rocks are made from particles of other rocks which were transported and compacted by wind and water. Fossils are mostly found in sedimentary rocks because fossilization is a truly delicate process. Usually only the hard parts of an organism make it through, but sometimes soft part can leave impressions into sediment. Even the hard parts have a difficult time of being fossilized, for the remains could be eliminated by scavengers, bacteria, water, and wind can all contribute to the fossils’ demise. Paleontologists usually only find fragments at a time. It is rarely them finding a whole complete skeleton lying there waiting to be discovered.