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Dinosaur and pterosaur head crest evolution by sexual selection
From: Ben Creisler
bscreisler@yahoo.com
A new online paper:
DAVID W.E. HONE, DARREN NAISH & INNES C. CUTHILL (2011 [2012])
Does mutual sexual selection explain the evolution of head crests in pterosaurs
and dinosaurs?
Lethaia (advance online publication)
DOI: 10.1111/j.1502-3931.2011.00300.x
http://onlinelibrary.wiley.com/doi/10.1111/j.1502-3931.2011.00300.x/abstract
Cranial ornamentation is widespread throughout the extinct non-avialian
Ornithodira, being present throughout Pterosauria, Ornithischia and Saurischia.
Ornaments take many forms, and can be composed of at least a dozen different
skull bones, indicating multiple origins. Many of these crests serve no clear
survival function and it has been suggested that their primary use was for
species recognition or sexual display. The distribution within Ornithodira and
the form and position of these crests suggest sexual selection as a key factor,
although the role of the latter has often been rejected on the grounds of an
apparent lack of sexual dimorphism in many species. Surprisingly, the
phenomenon of mutual sexual selection -- where both males and females are
ornamented and both select mates -- has been ignored in research on fossil
ornithodirans, despite a rich history of research and frequent expression in
modern birds. Here, we review the available evidence
for the functions of ornithodiran cranial crests and conclude that mutual
sexual selection presents a valid hypothesis for their presence and
distribution. The integration of mutual sexual selection into future studies is
critical to our understanding of ornithodiran ecology, evolution and
particularly questions regarding sexual dimorphism.