When a bird in flight is not in transition

WITH reference to Richard Collins’ article (‘Sturgeons are the missing link,’ Irish Examiner, February 6), experts such as Dr Alan Feduccia (author of ‘The Origin and Evolution of Birds’) have long acknowledged that Archaeopteryx is fully bird, and not part-reptile: “Paleontologists have tried to turn Archaeopteryx into an earth-bound, feathered dinosaur."

"But it's not. It is a bird, a perching bird. And no amount of 'paleobabble' is going to change that."

Creatures like the sturgeon, Archaeopteryx and, most famously, the platypus are mosaic creatures containing features typical of different classes of creature but not usually found together in the one organism.

Note that these features Archaeopteryx's tail, the sturgeon's cartilaginous skeleton and the platypus's bill are all fully functional.

But to qualify as a transitional form, a creature would need emergent structures not yet fully developed.

Darwin predicted thousands would be found, but to date there is not one example that is not hotly disputed.

Ken Ryan

Raheny Park

Raheny

Dublin 5.