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Avian extinction at end of Cretaceous



From: Ben Creisler
bcreisler@gmail.com

A new paper:



Alan Feduccia (2014)
Avian extinction at the end of the Cretaceous: Assessing the magnitude
and subsequent explosive radiation.
Cretaceous Research 50: 1-15
http://dx.doi.org/10.1016/j.cretres.2014.03.009
http://www.sciencedirect.com/science/article/pii/S0195667114000494

Debate on the magnitude of Cretaceous extinctions and timing of modern
bird origins has sharply coalesced over the past two decades into
contested models, gradualistic or explosive. Molecular clocks,
bolstered by phylogenetic, biogeographic, and vicariance models,
support an Early Cretaceous origin for birds and mammals over 100
million years ago. Yet, although numerous new Chinese fossils of
archaic ornithurine birds have been discovered in the Jehol Biota of
the Early Cretaceous of China, none shows close affinity to modern
neornithines; it is not until the latest Cretaceous when some fossils
show more advanced ornithurine morphology, and are possibly
Neornithes. In contrast to mass survival scenarios, most
paleontological evidence appears to support an explosive radiation
following the Cretaceous-Paleogene (K-Pg) mass extinction event,
closely paralleling the geometry of mammal evolution. Gradualistic
models ignore recent evidence of cataclysmic worldwide events
following the impact event. How could mass survival of the
environmentally sensitive birds have occurred following cosmopolitan
environmental destruction, when other terrestrial vertebrates,
particularly ectotherms, suffered dramatic loss? Given the paucity and
scrappy nature of avian fossils immediately prior to and after the
K-Pg boundary, it is prudent to use mammalian and other biotic
evolution in the Paleogene as a guidepost for avian evolution. Our
continued inability to produce a veracious phylogeny of higher avian
taxa is likely related to a Paleogene explosive burst or ‘big bang’
evolution of bird and mammal evolution, resulting in short ordinal
internodes.

Highlights:

Recent evidence indicates the end-Cretaceous bolide strike has been
underestimated.

Evidence shows major extinctions of vertebrates, as well as plants and insects.

There is no evidence that birds passed unscathed through the extinction event.

Scrappy fossils near the K–Pg boundary present major identification problems.

Birds suffered major extinctions at the K–Pg boundary, then radiated
explosively.