When people find dinosaur bones today, they aren’t really finding unchanged bones. They’re finding fossils (FAH-sulz).
Fossils are any traces of life from a long-ago age.
Sometimes a dinosaur died near a stream or river. If the stream or river overflowed, the dinosaur’s body would be covered by mud and sand. Over millions of years, the mud and sand turned into solid rock. And the dinosaur’s skeleton was still inside!
Museum of the Rockies/Bruce Selyum
At the same time, water in the earth seeped into the dinosaur’s bones. Miner-als in the water turned the bones to stone, too.
So a dinosaur fossil is really a rock that used to be a bone buried inside another rock that used to be some mud and sand!
The Natural History Museum, London
Fossils can tell us a lot about dinosaurs.
People used to call anything that was dug out of the ground a fossil. (Even potatoes!)
Fossil teeth can tell us the kind of food a dinosaur might have eaten. Flat teeth are good for chopping up plants. Sharp, pointed teeth are good for ripping flesh.
Fossil leg bones can tell us how a dinosaur might have walked. Long leg bones are good for fast running. Short, thick leg bones mean the dinosaur prob-ably moved slowly.
Footprint fossils can help us guess how much a dinosaur weighed. Deep footprints mean the dinosaur who made them must have been very heavy. Shal-low footprints mean the dinosaur must have been a lightweight.
Footprint fossils can even tell us how dinosaurs traveled. Many footprints going the same way mean the dinosaurs were probably moving in packs or herds. Big footprints beside little footprints mean the dinosaurs may have been traveling with their families.
Almost everything that we know about dinosaurs we know from fossils. But fossils can only give us clues about dinosaurs and the Age of Reptiles. We have to use our imaginations to picture how these amazing creatures really looked, how they lived, and how they died.
The Department of Library Services, American Museum of Natural History: Neg. No. 324393 Photo. Roland T. Bird
Fossils can even tell us about dinosaur eggs, dinosaur nests, and dinosaur babies.
The Department of Libary Servies, American Museum of Natural History: Neg, No. 4107655 Photo. Shackelford
Dinosaur eggs are usually found in nests. But dinosaur nests are not like the ones birds build in trees. Most dinosaur nests were dug in sand or mud.
Scientists say that some dinosaurs returned to the same nesting grounds year after year.
The biggest dinosaur egg fossils ever found are about the size of a football. But the mother dinosaur that laid them was over 40 feet long!
Why did huge dinosaurs lay small eggs? Scientists think that if dinosaur eggs had been bigger, the shells would have been too thick for baby dinosaurs to break out of.
