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Species-level phylogeny of Cretaceous Hesperornithiformes

Ben Creisler

A new online paper:

Alyssa Bell & Luis M. Chiappe (2015)
A species-level phylogeny of the Cretaceous Hesperornithiformes (Aves:
Ornithuromorpha): implications for body size evolution amongst the
earliest diving birds.
Journal of Systematic Palaeontology (advance online publication)
DOI: 10.1080/14772019.2015.1036141

Despite extensive discoveries across the globe over the past two
centuries, little phylogenetic work has been done on the
Hesperornithiformes. Spanning the late Early to Late Cretaceous,
hesperornithiforms are one of the most diverse groups of Mesozoic
birds in terms of both their geographical distribution and the wide
differences in body size and diving specializations. This study
presents the first phylogenetic analysis of the Hesperornithiformes
that includes a majority of the described taxa, enabling the first
detailed look at evolutionary relationships within the clade. The
results of this study support the monophyly of the
Hesperornithiformes, which is recovered as the sister clade to the
avian crown group, Neornithes. Within the Hesperornithiformes, the
Brodavidae and Hesperornithidae are monophyletic while the
Baptornithidae are polyphyletic. Little evidence of species-level
taxonomic differentiation is found within Hesperornis, with many
species indistinguishable from Hesperornis regalis. Evolution within
the Hesperornithiformes provides a fascinating example of progressive
development of specialized diving adaptations in birds. The
acquisition of these diving specializations appears to be uncorrelated
to the independent evolution of multiple large increases in body size.