[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Bird extinctions at K-Pg boundary

From: Ben Creisler

I don't recall seeing this paper mentioned yet:

Nicholas R. Longrich, Tim Tokaryk, and Daniel J. Field (2011) 
Mass extinction of birds at the Cretaceous?Paleogene (K?Pg) boundary.
Proceedings of the National Academy of Sciences 108(37): 15253-15257 
doi: 10.1073/pnas.1110395108 

The effect of the Cretaceous-Paleogene (K-Pg) (formerly
Cretaceous?Tertiary, K-T) mass extinction on avian evolution is debated,
primarily because of the poor fossil record of Late Cretaceous birds. In
particular, it remains unclear whether archaic birds became extinct
gradually over the course of the Cretaceous or whether they remained
diverse up to the end of the Cretaceous and perished in the K-Pg mass
extinction. Here, we describe a diverse avifauna from the latest
Maastrichtian of western North America, which provides definitive evidence
for the persistence of a range of archaic birds to within 300,000 y of the
K-Pg boundary. A total of 17 species are identified, including 7 species of
archaic bird, representing Enantiornithes, Ichthyornithes, Hesperornithes,
and an Apsaravis-like bird. None of these groups are known to survive into
the Paleogene, and their persistence into the latest Maastrichtian
therefore provides strong evidence for a mass extinction of archaic birds
coinciding with the Chicxulub asteroid impact. Most of the birds described
here represent advanced ornithurines, showing that a major radiation of
Ornithurae preceded the end of the Cretaceous, but none can be definitively
referred to the Neornithes. This avifauna is the most diverse known from
the Late Cretaceous, and although size disparity is lower than in modern
birds, the assemblage includes both smaller forms and some of the largest
volant birds known from the Mesozoic, emphasizing the degree to which avian
diversification had proceeded by the end of the age of dinosaurs. 

myhosting.com - Premium Microsoft® Windows® and Linux web and application
hosting - http://link.myhosting.com/myhosting