The earliest conclusive evidence of the evolution of dinosaurs dates their origins to 230 million years ago. They are believed to have evolved from other reptilian species and developed certain defining characteristics, such as specialized hip and leg bones.Know More
Earlier fossils have been discovered which may predate previously uncovered archaeological evidence. A previously unknown genus of archosaur could push the time period back another 10 million years, while footprints discovered in Europe may place the date back to 250 million years. So little evidence remains from so long ago that it makes it difficult to pinpoint the exact date, year or millennium for a given animal type to have evolved.
What is known, as of 2014, is that the animals referred to as dinosaurs first appeared in the late Triassic period and remained in existence as a group for more than 190 million years. This has been determined based on the depth at which fossils have been found and through the use of radio-carbon dating which allows archaeologists to determine how old an item is based on the constant decay rate of carbon isotopes contained in all matter on Earth. This method is also used in geology when determining the age of rock formations or sedimentary layers.Learn more about Dinosaurs
There are a few well-researched theories about why dinosaurs are extinct; one of the most prominent theories hypothesizes that a massive asteroid impact killed off the dinosaurs. Another states that heavy volcanic eruptions across the Earth may have been responsible.Full Answer >
There is not sufficient proof as to why dinosaurs went extinct, but experts believe it is related to geological events, diseases, climate change and lack of plant life for sustenance. The last known dinosaurs, according to their fossils, existed about 65 million years ago.Full Answer >
Dinosaurs became extinct about 65 million years ago. This extinction event occurred between the Cretaceous and Tertiary periods and wiped out about 50 percent of all other organisms then living on the planet.Full Answer >
The purported mass dinosaur die off known as the K-Pg extinction event took place during the end of the Cretaceous Period (K) during the Mesozoic Era some 65 million years ago. This scientific theory is based on the study of the fossil record, which shows evidence for the existence of dinosaurs during the Mesozoic Era but not during the proceeding Cenozoic Era. There is a clear line of demarcation, an actual line found in sedimentary rock layers known as the K-Pg Boundary, with the majority of the fossilized remains found below this line belonging to the "Age of Dinosaurs" not appearing in the space above the line, which marks the beginning of the Paleogene Period (Pg), the Cenozoic Era and the "Age of Mammals."Full Answer >