AN ILLUSTRATION OF A HOLLOW-CRESTED DUCK-BILLED DINOSAUR (VELAFRONS COAHUILENSIS) THAT MAY HAVE MADE NOISES WITH ITS HOLLOW CREST. CREDIT: © TODD MARSHALL, 2007

AN ILLUSTRATION OF A HOLLOW-CRESTED DUCK-BILLED DINOSAUR (VELAFRONS COAHUILENSIS) THAT MAY HAVE MADE NOISES WITH ITS HOLLOW CREST.
CREDIT: © TODD MARSHALL, 2007