Suppose dinosaurs dressed like people and cavorted in dances like the waltz or the hula, to the sound of disco or hard rock. Wordsmith Yolen out 17 witty poems on this theme, playing expertly with both sound ("When the allosaurus/Does a rumba/Does she lumber?/Is she limber") and sense ("Dress Code: A Sedimental Journey": ". . .A fad is a fad. . .And that's why no clothes are imprinted on stones:/Only the remnants of dinosaur bones"). Dinosaurs are sure-fire popular; the fun of Degen's lively rendition of them frolicking in fancy dress outshines Yolen's rather quietly satirical comparison with their human cousins. It's too bad that editors still don't excise casual mention of the never-existent brontosaurus; still, sprightly, clever good fun.