A singing Archaeopteryx

During the 19th century most discussions of the earliest known bird, Archaeopteryx, focused on its relationship to other fossil reptiles, whether or not it could fly, and what it indicated about the origins of flight. A bird would not be a bird without song, though, and at least two authors attempted to imagine what sounds the early bird might have made had it tried to sing. The first was Eden Phillpotts in the fictional book Fancy Free. In one particular chapter an Archdeacon describes a fantastic Mesozoic safari (with a tomcat named Peter by his side), describing that and as he relaxed by the side of a felled Triceratops he heard a very strange noise;

Then followed perhaps my most remarkable experience. I was resting awhile after lunch,finishing the whisky and smoking a cigar, while the black cat coursed about of his free
will, when suddenly the weirdest sound that ever fell on mortal ear saluted mine. I never heard anything distantly approaching it before ; I know not how to describe it. The sound was something between the hiss of a serpent and the coo of a dove. The primeval beast responsible for it evidently combined the vocal qualities of bird and reptile. Naturally I marvelled, for birds were still strangers to the world. And yet an element of music in the sound led me to suspect that a creature at least of semi-ornithological nature was making it. "

'Peter, ' I said, for he was very excited at the noise, ' we must be in the presence of an Archaeopteryx! No other Jurassic concern could make that unutterable burlesque of melody.' And I was right. A moment later I came across an Archaeopteryx sitting on a fallen tree stump and singing, or, at least, under the impression that he was doing so. I stood and listened to the first dawnings of bird music ; I, who knew what the lark, and the thrush, and the nightingale could produce at their best, gave ear to that cock Archaeopteryx warbling according to his limited lights. It was pathetic to see how he enjoyed it himself, and how his hen enjoyed it. He was the very first thing of his kind that Nature had managed ; naturally he could conceive of nothing finer than his primitive self and preposterous voice. He gurgled and hissed, and squeaked, and even tried to trill. Then Peter, who recognised in him a true bird, despite the fact that he had claws on his wings and teeth in his mouth, captured that unfortunate Archaeopteryx after a tough struggle, and dragged him to me in some joy. "

The Bird Its Form and Function By William Beebe

Fancy, indeed. Yet in this case art preceded a bit of scientific speculation. In his general-audience book The Bird: Its Form and Function the ornithologist William Beebe also considered what Archaeopteryx must have sounded like if it tried to sing;

Our fancy may add an archaic attempt at song -- a lizard's croak touched with the first harmony, which was to echo through all the ages to follow; we may also imagine, if we will, leathery eggs deposited in a rotten knot-hole of a Jurassic conifer.

Whether or not Archaeopteryx made an such attempt cannot be known. I do not see any reason to doubt that Archaeopteryx was capable of making noises, although whether we would consider such vocalizations song (if we could hear them!) would probably depend on our definition of it. Speculation aside, passages such as those quoted above are informative in that they reveal the conception of Archaeopteryx as a "good bird." Even if it could not fly very well, it must have been at least somewhat birdlike in its habits; it was the earliest known bird, after all. Such was the supposition, anyway.