Possible Clues:

• Stegosaurus remnant
• Bit of an old dinosaur!
• Stony impression of one stuck in the past?
• You can dig it
• Petrified remains preserved within a rock
• Dinosaur held up by pterodactyl is so fierce
• Item dug up in a dig
• Back part of medal is soft, unlike this old relic
• Graceful female, not male, standing up for oldie?
• Ammonite, say