Hamish Tyson, of Pt Chalmers School, asks :-

What was the first dinosaur in the world?

Ewan Fordyce, a paleontologist at Otago University, responded.

Paleontologists cannot say exactly which was the first dinosaur, but we do know that varied dinosaur `ancestors' were present in the middle of the Triassic Period, about 235-240 million years ago. These fossils represent small species of 'archosaurs,' or 'ruling reptiles' - the group of advanced reptiles to which dinosaurs belong. One example is Lagerpeton, a small dinosaur- like reptile which probably walked bipedally (on its two back legs), with its forelimbs free to handle food. Lagerpeton has a small and lightly-built skeleton. It was probably a carnivore (meat-eater). Fossils of Lagerpeton and other dinosaur 'ancestors' occur in Argentina (South America), which was part of the supercontinent of Gondwana during Triassic times.

True dinosaurs appeared later in the Triassic, by about 220-230 million years ago. These early dinosaurs are known from many sites in North and South America, Africa, Europe, India and China, but we do not have any yet from New Zealand. One famous example is Coelophysis, a lightly-built, sharp-toothed, bipedal carnivore from North America. Coelophysis is about 3m long. It was probably a fast runner.

Dinosaurs became more common and varied worldwide during the Jurassic Period (about 145-210 million years ago), and many groups survived well until the end of the Cretaceous Period at about 65 million years ago.