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“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.”

Alan Feduccia (World authority on birds), Science, “Archaeopteryx: Early Bird Catches a Can of Worms”, 1993.

Palaeontology: Inside the oldest bird brain, by Lawrence M. Witmer

Did Archaeopteryx, the most primitive known bird, have 'the right stuff'? Looking into its skull with advanced technology provides insight into the dinosaurian transition to birds, and the evolution of flight.
Archaeopteryx may not be a global star of the calibre of, say, Tyrannosaurus rex, but it undoubtedly has iconic status. Combining the feathered wings and wishbone of birds with the toothed jaws and long bony tail of reptiles... [subscription required to read more]

Nature 430, 619-620 (5 August 2004) | doi:10.1038/430619a; Published online 4 August 2004

Summary (Source): Study of Archaeopteryx brain and inner ear confirm they are transitional between dinosaurs and modern birds.

In Nature 430, 666 - 669, (2004), Alonso et al) study the brain and inner ear of Archaeopteryx. They find that the brain and ear lie midway between that of dinosaurs and birds. They report that : 'birds with the same body mass as Archaeopteryx have from one third to five times bigger brains. However, the brain of Archaeopteryx is about three times the volume of those of non-avian reptiles of equivalent size.'

Also data is presented in graphic form that shows that Archaeopteryx semicircular canals have a form that is midway between dinosaurs and birds.