, a rock due in the main to the accumulated débris of plants and animals, especially to the shells of marine animals.

Lithosphere

, the rocky crust of the earth.

Mesozoic

, the era of reptile dominance, in which occurred the rise of dinosaurs, birds and flying reptiles, flowers and higher insects, and primitive mammals.

Metamorphic

, recrystallized by heat (i.e., a rock), or changed by pressure.