Fossil Record and Mass Extinctions

One of the observations Darwin used as support for life on Earth changing over time was the fossil record. Animals and plants appear and disappear from the fossil record. One of the most famous examples of this phenomenon is presence and extinction of the dinosaurs. Most people are familiar with the mass extinction 65 million years ago that marked the end of the dinosaurs’ time on Earth. However there have been 4 other mass extinction events that we know of from the fossil record at 443, 354, 248, and 206 million years ago. It is thought that these were triggered by an increase in volcanic activity. The mass extinction of the dinosaurs coincided with an increase in volcanic activity and the impact of an asteroid in the gulf of Mexico.

Theropods

Theropods are a group of dinosaurs that include Velociraptors and Tyrannosauruses. There were therapods that had feathers and some scientist group modern birds with these dinosaurs because they are their closest relatives. I had the kids look at pictures of modern birds, especially big flightless birds like ostriches and cassowaries, and compare them to dinosaurs. Scientists have learned that ostriches use their feathers to help them turn when running and to come to a quicker stop. This could be a reason that dinosaurs who were too big and heavy to fly may have had feathers. Another reason could have been to keep them warm.

Activity

What did dinosaur’s skin look like? I asked the kids to imagine what dinosaurs looked like on the outside. I let the kids choose a dinosaur coloring sheet. We had already discussed feathers, but plant eaters may have camouflaged into their environment. Could carnivores had stripes like tigers? Some kids used neon colors and I asked if that could mean it was warning coloration because the dinosaurs had venom.