What killed the dinosaurs?By Riley

What did kill the dinosaurs?

• Until recently most scientists thought they knew what killed off the dinosaurs. A 10km-wide meteorite had smashed into the Yucatan peninsula in Mexico, causing worldwide forest fires, tsunamis several kilometres high, and an 'impact winter' - in which dust blocked out the sun for months or years. It was thought that the dinosaurs were blasted, roasted and frozen to death, in that order.

• But now a small but vociferous group of scientists believes there is increasing evidence that this 'impact' theory could be wrong. That suggestion has generated one of the bitterest scientific rows of recent times.

How old were the dinosaurs?

• A new dinosaur relative found in Tanzania is the oldest known creature of its kind—a discovery that pushes back the origin of dinosaurs by at least ten million years, paleontologists say.

• Dubbed Asilisaurus kongwe, the Labrador retriever-size creature was a silesaur, the closest relatives to true dinosaurs. The newfound animal lived 243 million years ago, during the middle Triassic period.

• Since silesaurs and true dinosaurs diverged from a common ancestor, the two groups should have existed during the same time frame. But the oldest known true dinosaurs date back to just 230 million years ago.

What did the dinosaurs eat?

• Some dinosaurs ate lizards, turtles, eggs, or early mammals. Some hunted other dinosaurs or scavenged dead animals. Most, however, ate plants (but not grass, which hadn't evolved yet). Rocks that contains dinosaur bones also contain fossil pollen and spores that indicate hundreds to thousands of types of plants existed during the Mesozoic Era. Many of these plants had edible leaves, including evergreen conifers (pine trees, redwoods, and their relatives), ferns, mosses, horsetail rushes, cycads, ginkos, and in the latter part of the dinosaur age flowering (fruiting) plants. Although the exact time of origin for flowering plants is still uncertain, the last of the dinosaurs certainly had fruit available to eat.

What made the dinosaurs?

• When earth had only water dinosaurs were fish. They then evolved into giant frogs and then into dinosaurs. When earth got more land, swampy lizards evolved into dinosaurs.