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.Continue Reading
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
Tyrannosaurus rex dinosaurs lived during the late Cretaceous period, which was about 65 million years ago, on a continent named Laramidia. Laramidia is now part of North America. The name Tyrannosaurus rex means "tyrant lizard king."Full Answer >
There is evidence that dinosaurs did not have a single, uniform and universal diet but rather a wide variety of dietary habits, with evidence supporting the idea that carnivorous, herbivorous and omnivorous species all existed. Different feeding styles were also likely, with some carnivorous species hunting prey such as mammals and small reptiles, while other carnivores may have been opportunistic carrion scavengers. There was likely even a good range of dietary variety amongst the herbivorous dinosaurs, which may have made up the majority of all dinosaur species.Full Answer >
Fossils are important evidence of evolution because they clearly show the incremental development of modern species from long-extinct primitive organisms. Many modern species, such as the horse, have a clear fossil record showing how they came to exist in their current forms.Full Answer >
There are some animals on earth that can be traced back to the Mesozoic Era when dinosaurs walked the earth; these animals include monotremes such as the duckbill platypus, reptiles such as the crocodilians and sea creatures such as the sea urchin. For the most part, the animals that are alive today have made evolutionary changes from the forms they had when dinosaurs were alive. For example, though the event that caused dinosaurs to die out also killed many other reptile species, several surviving reptile species have direct ancestors from that era, including the crocodilians, which are smaller than their Mesozoic ancestors.Full Answer >