The dura mater has two layers, or lamellae: The superficial layer (also called the periosteal layer), which serves as the skull's inner periosteum, called the endocranium; and a deep layer called the meningeal layer; the actual dura mater.
The term thagomizer was coined by Gary Larson in humor, in a 1982 Far Side comic strip, in which a group of cavemen in a faux-modern lecture hall are taught by their caveman professor that the spikes on a Stegosaur's tail are so named after the late Thag Simmons.
Larsonâs cartoons are as popular as they are bizarre. Less than six years after it first appeared in print, The Far Side has become a regular feature of more than 200 newspapers. There are successful lines of Far Side greeting cards, posters and T-shirts, and Larsonâs four books have all become hits.