Dinosaurs first appeared nearly 230 million years ago during what is now known as the Triassic Period. For the next 135 million years, these creatures ruled the earth as the dominate vertebrates, or animals possessing a spine or backbone, through the Jurassic Period until the Cretaceous–Paleogene extinction event took place at the end of the Mesozoic Era. Through research of fossilized remains, it is believed that most species of today's birds have evolved from certain theropod families of dinosaurs and are still considered the present day descendants of the dinosaur ancestry.
The term "dinosaur" can apply to an enormously wide range of animals. To date, there are over 9,000 different species of bird identified on the planet earth, all of which are considered to be descendants of dinosaurs from millennia past. On every continent on the globe, archeologists, scientists and other researchers have uncovered over 500 additional unique families of dinosaur that include more than 1000 further distinct species. Some were carnivores, or meat-eating, while others were herbivores, or plant-eating. Some walked on two legs, others on four, and still others seemed to evolve into a species that could switch between the two methods of mobility at will. Some of these magnificent beasts had beautiful adornments of crests and horns, while others seemed to morph their skeletal structure into spines of armor.
Comparatively speaking, birds are the dominant biological classification of flying vertebrate since the time of the pterosaurs. Further data unearthed in the fossilized habitats of ancient animals shows that many species of dinosaur were egg laying, nest building creatures, another factor which offers credence to the theory that birds are the progeny of dinosaurs. Furthermore, since the first skeletal remains were discovered in the early 19th century, it has been determined that these beasts were of all shapes and sizes. Not all dinosaurs were the enormous beings that we are used to seeing in museums, books and movies, such as Jurassic Park. Many extinct varieties were of a similar size to that of our birds today.
Although the early Greeks coined the name "dinosaur", meaning "terrible lizard", these creatures weren't really lizards at all. These were a very distinct grouping of animals which possessed an upright posture unlike those of their reptilian counterparts. In the early part of the 1900's, most scientists believed dinosaurs to be cold-blooded animals, sluggish in nature. But more recent research from the decades beyond the 1970's seems to indicate that many of the carnivorous variety were especially active, socially interactive within their ecosystems, with decidedly elevated metabolisms.
Due to the perpetual zeal and excitement that all human beings seem to possess regarding our ancient ancestors, public funding in the field of dinosaur research is only increasing more and more every year, contributing to new and exciting discoveries that help us to learn more about our evolving human race through the ever diligent exploration of the dinosaur.