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The
dinobirds are feathered dinosaurs. Not feathers for flight like
Archaeopteryx, but feathery coverings for insulation and
decoration. They confirm John Ostrom's theory that birds are the
descendants of predatory dinosaurs – the theropods.
To
understand how scientists reached this conclusion, it helps to sort
theropod dinosaurs into groups, using features that are easy to see.
Features that are shared by all members of the group tend to be
oldest. As members of the group evolved and changed, so new features
appeared. Some features, such as the reduced hands and extremely
short arms shown by Tyrannosaurus rex, were an evolutionary
dead end. Other features, such as very long hands, gave a real
advantage to a whole set of animals whose descendants are modern
birds.
When
the dinobirds were found and their bones examined, scientists faced
two challenges. First, they had to confront a former scientific
'truth' that only birds had feathers – as these dinosaurs definitely
had feathers and certainly were not birds. Secondly, they hadto fit
each dinobird into its theropod dinosaur set.
Table
showing relationships between dinobirds and other
dinosaurs. | 
