Since I periodically mention fossils, I’m borrowing from the National Parks Service list of FAQs and adding/abridging a little, complete set here: https://www.nps.gov/subjects/fossilday/faq.htm
What is a fossil?
Fossils are traces or remains of things that were once alive. Most of us immediately picture giant dinosaurs, but there are also microfossils-fossils that can’t be seen without the aid of a microscope. Bacteria and pollen can fossilize too! Fossils that are physical remains of an organism are called body fossils. Fossils from actions, like footprints, are called trace fossils.
How do fossils form?
Most of life dies and decays without a trace, but very rarely something can become fossilized. It helps to be buried quickly, before decay can set in. Once buried, groundwater seeps in, and minerals in the water can replace the body of bone or shell. Eventually the entire bone or shell could become stone. Mammoths and mastodons are recent fossils-frozen solid but still their original tissues.
How do we know the age of fossils?
There are two types of dating fossils-relative tells us what fossils are newer or older depending on where they’re found in layered deposits. Unless there’s been geologic upheaval, the lower down they are the older they are.
Absolute dating uses radioactive isotopes of elements to get an approximate age of a fossil or its surrounding rock. (For the dating of the earth itself, check out Clair Patterson’s investigations.)
What is paleontology?
Paleontology is the branch of science that studies the history of life on earth.
Can I find a dinosaur bone in my backyard?
Maybe! It depends where you live-you need to live somewhere where the top layer of rock dates from the right age and were the right type of rock to fossilize. If you’re in the Rocky Mountains you’ll have better luck than southern New England, which is better for trace fossils.
Why study fossils?
Studying fossils helps us understand the evolution of life on earth and how species are related and have adapted to survive a dynamic planet. Fossils can act as ancient thermometers, giving us more information on ancient climates (Did you know 50 million years ago Wyoming had lakes with crocodiles and palm?), changing climates, and climate change’s effect on life