NSF Postdoctoral Research Fellow at Stony Brook University.

I study how bone tissue, growth, and metabolism evolve at macroevolutionary time scales.

The Wheeler Formation has been previously dated to approximately 507 million year old, so we know the trilobite is also about 507 million years old.

Other rocks were so transformed by heat and pressure during the heaving and buckling of the Earth's crust in periods of mountain building that their original features were obliterated.

From the results of studies on the origins of the various kinds of rocks (petrology), coupled with studies of rock layering (stratigraphy) and the evolution of life (paleontology), today geologists reconstruct the sequence of events that has shaped the Earth's surface.

At the close of the 18th century, the haze of fantasy and mysticism that tended to obscure the true nature of the Earth was being swept away.

Careful studies by scientists showed that rocks had diverse origins.

There are two main methods determining a fossils age, relative dating and absolute dating.

Relative dating is used to determine a fossils approximate age by comparing it to similar rocks and fossils of known ages.

Certain layers are in the form of sand bars and gravel banks - rock debris spread over the land by streams.

Some rocks were once lava flows or beds of cinders and ash thrown out of ancient volcanoes; others are portions of large masses of once-molten rock that cooled very slowly far beneath the Earth's surface.

Absolute dating is necessary for knowing specific time e.g.