 |
 |
     |
  |
    |
|||
| 1. What is a dinosaur? | |
|
A dinosaur can be defined as "The most recent common
ancestor of Iguanodon and Megalosaurus, and all
of its descendants". A dinosaur can be diagnosed as a reptile with the following suite of characters: Jaw muscles that reach up onto the top of the skull, plus a big ridge on the upper arm bone (humerus), plus bony processes at the hip, knee, and ankle to help them stand with their limbs straight under the body. Most dinosaurs can be identified because they have an erect limb posture, plus the three bones of the pelvis (ilium, ischium, pubis) are joined to form an open hip socket for reception of the thigh bone (femur), plus the longest finger is the second finger. You might find some of these features in other reptiles, but not all together. There are two major groups of dinosaurs that can be divided into the more famous seven groups of dinosaurs: Saurischia ("lizard-hipped", not really lizard-like but close enough) * Theropods (two-legged meat-eaters, and birds) * Sauropodomorphs (Two and four-legged plant-eaters with long necks) Ornithischia ("bird-hipped", not really bird-like but close enough) * Ornithopods (two-legged plant-eaters) * Stegosaurs (plated dinosaurs) * Ankylosaurs (armored dinosaurs) * Pachycephalosaurs (dome-headed dinosaurs) * Ceratopsians (horned dinosaurs) To Learn more about Dinosaurs and their relatives, please visit our Tree of Life Interactive |
|
 |
About This Site | - | Contact | - | - | Privacy / Copyright | |