The 1.5 million acre Lake Mead National Recreation Area covers “mountains, canyons, valleys and two vast lakes,” the National ...

The recent shells retain the organic material that give the shells ... the original is a function of the chemistry of the groundwater. The ammonoid (the round, snail-ish fossil) has been replaced by ...

Based on the fossil record, ammonites came in a wide range of sizes and shapes, from smaller than an inch to as large as nine feet wide. Some ammonites had long, straight shells, while others had ...

Land animals and plants usually decomposed or were eaten, and mainly the hard parts -- teeth, bones, shells, or wood -- were preserved. Fossils can be formed in several ways. Buried bone and shell ...