All organisms on Earth are related. The study of these relationships is called phylogeny. To help you understand how some of the vertebrates mentioned on other pages of this site are related this page has a 'map' of their relationships. The name for this type of 'map' is a cladogram. What it shows is how recently two groups ('clades') shared a common ancestor. It is a bit like a family tree, but the rules are more complex. Each group at the tip of a branch shares unique features. So for example birds and some theropod dinosaurs are more closely related to each other than to anything else. This makes birds dinosaurs! So 'Something has survived', but without any help from Hollywood.To find out more visit Byron's Dinosaur Homepage Some of the names on the diagram may be unfamiliar, so they are explained below the diagram. The cladogram has been simplified, so there are some groups missed out that aren't featured on this site. To find out more visit. These relationships are often under dispute and can change. Scientists usually don't know the 'right' answer. They come up with theories that best fit the data and then wait to see if anybody finds anything that their idea cannot explain. At that point it is back to the drawing board!