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Ankylosaurian phylogeny

From: Ben Creisler

In the new issue of Journal of Systematic Palaeontology:

Richard S. Thompson, Jolyon C. Parish, Susannah C. R. Maidment & Paul
M. Barrett (2012)
Phylogeny of the ankylosaurian dinosaurs (Ornithischia: Thyreophora).
Journal of Systematic Palaeontology 10(2):  301-312

Ankylosauria is a diverse clade of quadrupedal ornithischian dinosaurs
whose remains are known from Middle Jurassic to latest Cretaceous
sediments worldwide. Despite a long history of research, ankylosaur
interrelationships remain poorly resolved and existing cladistic
analyses suffer from limited character and taxon sampling. Here, we
present the most comprehensive phylogenetic analysis of the group
attempted to date. The traditional ankylosaurid–nodosaurid dichotomy
is maintained. Ankylosauridae forms a well-resolved clade, which
includes Zhongyuansaurus, the first ankylosaurid known to lack a tail
club. Nodosauridae includes a number of taxa that were resolved either
as ‘polacanthids’ or basal ankylosaurids in previous analyses. The use
of a broader character sample allows analysis of the
interrelationships of all valid ankylosaur species; this has revealed
several previously unrecognized relationships. Stegosauria is
recovered as the sister taxon to Ankylosauria, while Scelidosaurus is
found to be a basal thyreophoran. Dedicated methods for coding
continuous characters could be used in future to improve the
resolution of ankylosaur phylogeny, particularly in order to explore
the relationships within the poorly resolved nodosaurid clade.