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Tyrannosauridae and Carnotaurinae (Theropoda) forelimb evolution and malformations in teratology



Ben Creisler
bcreisler@gmail.com


A recent online paper:

Geoffrey Guinard (2014)
Introduction to Evolutionary Teratology, with an Application to the
Forelimbs of Tyrannosauridae and Carnotaurinae (Dinosauria:
Theropoda).
Evolutionary Biology (advance online publication)
DOI: 10.1007/s11692-014-9296-1
http://link.springer.com/article/10.1007/s11692-014-9296-1

Conceptualisation of evolution requires new inclusions, as evidenced
by contributions brought by evolutionary developmental biology—the
evo-devo connection. Integration of teratology in an evolutionary
framework fits in this continuity. It highlights the production of
developmental anomalies (more or less drastic) over evolutionary
times, which become integral parts of groups and taxa. Originating in
Étienne Geoffroy Saint-Hilaire’s work, the contemporary independent
formulation of evolutionary teratology allows a better understanding
of some anatomical structures. The limbs of tetrapods are a promising
field of study as some changes in their shapes, proportions and
compositions are close to malformations observed in teratology. The
forelimbs condition of Tyrannosauridae and Carnotaurinae is a good
example. They are theropod dinosaurs characterised by different
anterior micromelias, codified following an anatomical nomenclature.
An association with the knowledge from developmental biology helps to
discern possible productive mechanisms of such micromelias, including
the influence of developmental rates, Hox genes, growth factors and
developmental pathways conserved in evolution. What is more, the case
of Tyrannosauridae and Carnotaurinae imposes to use the 'adaptive'
reasoning in a more balanced framework. Indeed, the viability and
evolutionary success of an organism is the result of the equilibrium
of aptitudes between its various anatomical parts interacting with the
circumstances.