First appearing in the Triassic period roughly 230 million years ago, dinosaurs were the dominant vertebrate for over 135 million years, finally going extinct in the late Cretaceous period, roughly 65 million years ago. This extinction signalled the end of the Mesozoic era and ushered in the rise of mammals. During the Jurassic period birds evolved from terrestrial dinosaurs and now constitute the closest link to them. Discovery of dinosaur remains have been recorded as far back as the Western Jin Dynasty in China, but significant discoveries did not become widespread until the 19th century. Today scientists have identified nearly 1,000 distinct species of dinosaurs. The following resource will outline various integral aspects of the study of dinosaurs.
The Triassic Period
The beginning of the mesozoic era was the Triassic period, which was the result of a massive extinction event called the Permian-Triassic extinction event. It was during the middle of the Triassic that dinosaurs began to emerge, however they were not a dominant species until the Jurassic.
The Jurassic Period
At the end of the Triassic another global extinction event occurred called the Triassic-Jurassic extinction event. Nearly 20% of marine families disappeared and on land almost all large amphibians and reptiles besides dinosaurs and crocodiles died off. This resulted in dinosaurs becoming the most dominant land creature alive for the next 135 million years.
The Cretaceous Period
The final period of dinosaur evolution occurred in the Cretaceous period, which was the final period of the Mesozoic era of Earth history. The period was relatively warm and much of the Earth was covered in shallow inland seas which were home to many creatures. This was also the period where mammals became more present, but dinosaurs still ruled the land until a massive extinction event occurred at the end of the period.
Dinosaurs evolved greatly over the course of the existence, beginning as small Archosaurs in the Triassic moving through the Jurassic when dinosaurs became the dominant land species as well as evolved into birds, and into the Cretaceous period.
Dinosaurs were a diverse group of animals. There were omnivores, carnivores and herbivores. Some were large and others small, while some lived on land, others in the sea as well as in the sky.
- Paleobiology at the Smithsonian Institute
- Library of Paleogeography
- Palaeogeography, Palaeoclimatology, Palaeoecology
- Journal of Paleontology