Dinosaurs & Paleontology: Edmontosaurus

Understanding Dinosaurs & Paleontology: Edmontosaurus

Edmontosaurus feeding was more complex than simply biting leaves. Its wide beak likely clipped stems, soft shoots, and other plant material near the ground or from low branches. Inside the mouth, many tightly packed teeth formed a long grinding surface.

As food moved through the mouth, the upper and lower tooth rows worked together to crush it. Worn teeth did not stop the animal from feeding because replacement teeth developed beneath them. This system mattered because plant tissue can be fibrous and difficult to break apart.

Scientists study tooth scratches, worn surfaces, and the shape of the jaws to infer what kinds of food caused that wear. These clues cannot name every plant in its diet, but they can show whether the animal processed tough material regularly.

A large body changes how an animal moves. Edmontosaurus probably spent much of its time walking on four limbs while feeding, since its front limbs could support its weight. Its strong hind limbs could help it move faster when needed.

The long tail acted as a counterbalance, keeping the body steady as the legs moved. Fossil footprints can add evidence that bones alone cannot provide. Track size gives an estimate of foot dimensions, while the spacing between prints suggests stride length.

A trackway does not record an exact speed unless researchers know the time between steps, so scientists use body size and stride patterns to make careful estimates. A single set of tracks may show one animal crossing soft ground. Several similar tracks can suggest repeated travel through the same place, though they do not prove a herd by themselves.

Fossils form only under unusual conditions. A dead animal left on open ground is usually scattered by scavengers, weather, and decay. Better preservation happens when mud or sand covers remains fairly quickly.

Fine sediment can protect delicate features, including skin texture. Waterlogged ground and river deposits can therefore produce more complete specimens than dry uplands. This creates an important limit in paleontology.

The fossil record does not show every animal that lived in an area. It mainly preserves animals that died in places where burial was possible. Paleontologists examine the surrounding rock closely because grain size, layering, plant fragments, and chemical signs help explain the setting in which a body was buried.

Working out when a specimen lived requires more than finding a bone in a layer of rock. Lower layers are generally older than layers above them if the rocks have not been disturbed. Fossils from separate places can then be compared using shared rock layers and known fossil types.

For a numerical age, scientists often date minerals in volcanic ash beds near fossil bearing layers. Some atoms in those minerals change at predictable rates over time. Measuring the remaining atoms and their decay products gives an age estimate.

The bone itself may not be directly dated, so the result depends on how securely the dated layer connects to the fossil layer. Students should pay attention to this difference between ordering events and assigning a number of years. Both methods are useful, but each has uncertainty and limits.