http://www.newsweek.com/t-rex-was-fearsome-predator-it-couldnt-stick-out-its-tongue-986536

Depictions of dinosaurs often show the animals baring their teeth with their tongues outstretched like lizards. However, a study published in the journal PLOS ONE indicates that this image may be inaccurate because dinosaur tongues were probably stuck to the bottom of their mouths, much like those of crocodiles and alligators today.

To make their discovery, an international team of researchers from The University of Texas at Austin (UT) and the Chinese Academy of Sciences compared the hyoid bones—bones which support the tongue—of extinct dinosaurs, pterosaurs and crocodilians to those of modern birds and crocodilians.