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Course: American Museum of Natural History > Unit 1
Lesson 1: What is a dinosaur?- What makes a dinosaur a dinosaur?
- What is and is not a dinosaur?
- What is and is not a dinosaur?
- How do dinosaurs get their names?
- How do dinosaurs get their names?
- Linking birds and dinosaurs
- How do we know which kinds of dinosaurs were most closely related?
- How do we know which kinds of dinosaurs were most closely related?
- Quiz: What is a dinosaur?
- Exploration Questions: What is a dinosaur?
- Answers to Exploration Questions: What is a dinosaur?
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How do we know which kinds of dinosaurs were most closely related?
Although most of the news stories one reads about dinosaurs involve spectacular, if not speculative, aspects of dinosaur history, such as new theories about their behavior, extinction, or ecology, less attention is paid to studies analyzing their evolutionary relationships. This is unfortunate because understanding questions of dinosaur behavior and biology depends on a firm understanding of their evolutionary relationships.
Cladogram
To reconstruct the evolutionary relationships between different groups of dinosaurs, one must carefully study and analyze the anatomy, essentially searching for characteristics that are shared among different kinds of dinosaurs, which are then interpreted to have been present in the common ancestor, or first member of a group, and inherited by its descendants. This analysis produces a branching diagram, called a cladogram, on which different kinds of dinosaurs are shown at the endpoints of the branches. The branching points connecting the different branches represent the common ancestor for the group whose branches come out of that branching point, and based on the characteristics shared by dinosaurs on those branches, we can infer that those shared characteristics were present in the common ancestor.
The result is a pattern of smaller groups of dinosaurs contained within larger groups of dinosaurs. For example, T. rex is a member of a small group (Tyrannosauridae) that also contains Albertosaurus. Both those are members of a larger group, which contains other meat-eating dinosaurs such as Allosaurus, Velociraptor and birds, called Theropoda. Then, all theropods belong to a larger group that also contains the giant sauropods, called Saurischia. A good way to think about this is to compare it to your evolutionary relationships as a human. Humans, along with apes, belong to a larger group of mammals called hominoids, and hominoids along with monkeys, lemurs and tarsiers all belong to the larger group called primates. By following the sequence of characteristics inherited from more distant common ancestors to more recent ones, one can trace the anatomical evolution of a particular kind of animal.
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- How can you research dinosaur behavior?(6 votes)
- based on a dinosaurs characteristics or injuries or other fossil evidence. For example, A triceratops skull with gash marks from other triceratops horns probably tells you that they are aggressive or are competing for mating supremacy(6 votes)
- where dinosaur came from?(5 votes)
- scientists believe all dinosaurs had one, distant, common, ancestor. The fossil record is incomplete, so they don't know exactly what it looks like, but they can make a rough reconstruction from what we know of dinosaurs.(0 votes)
- the dinosaurs are display all over the world .but the dinosaurs still are related to us but why?(2 votes)
- Jurassic Park isn't that accurate, you know... You can't really know Dinosaur behavior. It would take time travel to know that.(1 vote)
- the dinosaurs are on display closely related(1 vote)
- on display where? I dunno about that. Stegosaurus and Tyrannosaurus were not that closely related(1 vote)
- what is the bigest dinosawer(2 votes)
- It is Argentinosaurus, it weighed 200 tons.(1 vote)
- Are megalodons still existent today?(1 vote)
- no, they died 1.5 mya. they probably starved when their prey the ancestors of modern whales swam to colder waters where they couldn't follow. plus, the baby megalodons probably faced competition from early great white sharks.(1 vote)
- How do you know if the t-rex was a scavenger or a hunting predator?(1 vote)
- why arent the animls avlive(0 votes)
- climate change, meteors, and other scientific explanations... so no one knows(3 votes)
- How do far different animals/dinosaurs relate if has nothing in common(1 vote)
- They still are evolved from the origin of life, and they are billions and billions of years of evolution apart, but they still have a common ancestor.(1 vote)
- all the birds are kinds of dinosaurs or only some of them?(0 votes)