Re: Proto-penguins lived with dinosaurs: official article PDF

["bh480@scn.org" <bh480@scn.org>]

From: Ben Creisler bh480@scn.org


OK. There seems to be some tongue-in-cheek confusion about ancient penguin
DNA. Here's the official citation that the stories were based on. Note that
the PDF can be downloaded for free!

http://mbe.oxfordjournals.org/cgi/content/abstract/msj124v1

Molecular Biology and Evolution advance publication
Early Penguin Fossils, plus Mitochondrial Genomes, Calibrate Avian
Evolution 
Kerryn E. Slack , Craig M. Jones , Tatsuro Ando , G. L. (Abby) Harrison ,
R. Ewan Fordyce, Ulfur Arnason, and David Penny  
David Penny, E-mail: d.penny@massey.ac.nz <mailto:d.penny@massey.ac.nz>

        Abstract        
Testing models of macroevolution, and especially the sufficiency of
microevolutionary processes, requires good collaboration between molecular
biologists and paleontologists. We report such a test for events around the
Late Cretaceous by describing the earliest penguin fossils, analyzing
complete mitochondrial genomes from an albatross, a petrel and a loon, and
describe the gradual decline of pterosaur at the same time modern birds
radiate. The penguin fossils comprise four naturally associated skeletons
from the New Zealand Waipara Greensand, a Paleocene (early Tertiary)
formation just above a well-known Cretaceous/Tertiary boundary site. The
fossils, a new genus (Waimanu), provide a lower estimate of 61-62 Ma for
the divergence between penguins and other birds and thus establish a
reliable calibration point for avian evolution. Combining fossil
calibration points, DNA sequences, maximum likelihood and Bayesian
analysis, the penguin calibrations imply a radiation of modern
(crown-group) birds in the Late Cretaceous. This includes a conservative
estimate that modern sea and shorebird lineages diverged at least by the
Late Cretaceous about 74 ± 3 Ma (Campanian). It is clear that modern birds
from at least the latest Cretaceous lived at the same time as archaic birds
including Hesperornis, Ichthyornis and the diverse Enantiornithiformes.
Pterosaurs, which also coexisted with early crown-birds, show notable
changes through the Late Cretaceous. There was a decrease in taxonomic
diversity, and small- to medium-sized species disappeared well before the
end of the Cretaceous. A simple reading of the fossil record might suggest
competitive interactions with birds, but much more needs to be understood
about pterosaur life histories. Additional fossils and molecular data are
still required to help understand the role of biotic interactions in the
evolution of Late Cretaceous birds and thus to test that the mechanisms of
microevolution are sufficient to explain macroevolution.



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