Message #197864

[Ambrosia]

Birds of a Feather

Clues to why dinosaurs underwent such dramatic physical changes may be found in their closest living relatives—birds experts say.

(Related: "New Feathered Dinosaur Found; Adds to Bird-Dino Theory.")

Hornbills, for example, don't sport their distinctive helmet-like head casque (see hornbill picture) until they are about three-quarters grown.

Like deer antlers, the casque helps other animals discern between mature adults and juveniles.

In the same way, dinosaurs' changing appearances might have also promoted visual communication.

For example head knobs or horns, likely paired with color variations, may have created unmistakable visual displays that made sure members of a species recognized one another.

They may also have identified dinosaurs as male or female and marked them as mate-seeking breeders or juveniles in need of protection.