[AutumnBison (OP)]

Today, dinosaurs, alligators, crocodiles, gharials and caimen are all that remains of a special group of reptiles called the archosaurs. Recently, it has been accepted by the public that birds did not evolve from dinosaurs but are themselves dinosaurs.

But what if birds evolved from a different group of archosaurs?

Unsurprisingly, as far as reptiles go, Crocodilia is as bird-like in anatomy and even behavior as we're going to get. In the distant past, there were crocodylomorphs of a great slew of varieties imaginable, so it would make sense, in an alternate Earth where pterosaurs definitely never existed and dinosaurs might not exist, for a crocodylomorph to become Aves, the traditional name for the avian dinosaurs, known vernacularly as "birds".

But giving benefit to the presumption that all crocodylomorphs shared at least one anatomical attribute that separated them from dinosaurs, would an avian crocodylomorph have certain and noticeable anatomical differences from avian dinosaurs that I should watch out for? Or would an avian crocodylomorph look exactly like an avian dinosaur?

[jimbobghost]

one might propose that a modern flying creature of a non terrestrial ancestry might primarily live in the water; but have the ability to rise and fly; unlike today's sea birds who do not "live" in the water, but simply float on it.

the creature would have such unique attributes as teeth adapted to catching underwater prey.

[AutumnBison (OP)]

one might propose that a modern flying creature of a non terrestrial ancestry might primarily live in the water; but have the ability to rise and fly; unlike today's sea birds who do not "live" in the water, but simply float on it.

the creature would have such unique attributes as teeth adapted to catching underwater prey.

I said "crocodylomorph", not "crocodilian", which came later.