TIMELINE	Middle Jurassic
Period	Subdivision	Timespan
Middle Jurassic	Callovian	164,700,000 to 161,200,000 year ago
	Bathonian	167,700,000  to 164,700,000 years ago
	Bajocian	171,600,000  to 167,700,000 years ago
	Aalenian	175,600,000 to 171,600,000 years ago