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Dinosaur limb evolution rates in bird radiation

From: Ben Creisler

A new online paper:

Roger B. J. Benson and Jonah N. Choiniere (2013)
Rates of dinosaur limb evolution provide evidence for exceptional
radiation in Mesozoic birds.
Proceedings of the Royal Society B  280 no. 1768 20131780
doi: 10.1098/rspb.2013.1780

Birds are the most diverse living tetrapod group and are a model of
large-scale adaptive radiation. Neontological studies suggest a
radiation within the avian crown group, long after the origin of
flight. However, deep time patterns of bird evolution remain obscure
because only limited fossil data have been considered. We analyse
cladogenesis and limb evolution on the entire tree of Mesozoic
theropods, documenting the dinosaur–bird transition and immediate
origins of powered flight. Mesozoic birds inherited constraints on
forelimb evolution from non-flying ancestors, and species
diversification rates did not accelerate in the earliest flying taxa.
However, Early Cretaceous short-tailed birds exhibit both phenotypic
release of the hindlimb and increased diversification rates,
unparalleled in magnitude at any other time in the first 155 Myr of
theropod evolution. Thus, a Cretaceous adaptive radiation of
stem-group birds was enabled by restructuring of the terrestrial
locomotor module, which represents a key innovation. Our results
suggest two phases of radiation in Avialae: with the Cretaceous
diversification overwritten by extinctions of stem-group birds at the
Cretaceous–Palaeogene boundary, and subsequent diversification of the
crown group. Our findings illustrate the importance of fossil data for
understanding the macroevolutionary processes generating modern