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Juvenile birds as models for theropod evolutionary changes

From: Ben Creisler

A new online paper:

Ashley M. Heers & Kenneth P. Dial (2012)
>From extant to extinct: locomotor ontogeny and the evolution of avian flight.
Trends in Ecology and Evolution (advance online publication)

Evolutionary transformations are recorded by fossils with transitional
morphologies, and are key to understanding the history of life.
Reconstructing these transformations requires interpreting functional
attributes of extinct forms by exploring how similar features function
in extant organisms. However, extinct–extant comparisons are often
difficult, because extant adult forms frequently differ substantially
from fossil material. Here, we illustrate how postnatal developmental
transitions in extant birds can provide rich and novel insights into
evolutionary transformations in theropod dinosaurs. Although juveniles
have not been a focus of extinct–extant comparisons, developing
juveniles in many groups transition through intermediate
morphological, functional and behavioral stages that anatomically and
conceptually parallel evolutionary transformations. Exploring
developmental transitions may thus disclose observable, ecologically
relevant answers to long puzzling evolutionary questions.