The dinosaur profiles on this site are classified according to their kinds. The dinosaur family tree encompasses all of the dinosaurs. Around 700 dinosaur species have been named, and recent estimates speculate that there may be double that number of species that simply haven't left behind fossilized remains.
What is it that makes a dinosaur? The name dinosaur, coined by Sir Richard Owen in 1842, means "terrible lizard", referencing their size and majesty. Dinosaurs are distinguished from other reptiles (and from their contemporaries such as ichthyosaurs, plesiosaurs, and pterosaurs) by a number of anatomical differences, but of primary importance upon first glimpse is that they had limbs that are held directly beneath their body. Dinosaurs are a type of archosaur, and as such are relatives of modern-day crocodiles and birds. Dinosaurs came in all shapes and sizes, and the dinosaur family tree (or clade) below highlights these differences.
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| visit this LINK to learn how to read cladograms |
Every dinosaur has a hip bone that resembles either those of birds or those of reptiles; those that have bird-like hips are the Ornithischians, and those with reptile-like hips are the Saurischians. These designations were created in 1887 by the scientists Harry Govier Seeley; by examining dinosaur hip bones, he noted two varieties. Some - such as Allosaurus and Diplodocus - had hips that resembled those of lizards; others, such as Stegosaurus, had hips that resembled those of birds. This was the basis of his 'dividing' of Dinosauria into the lizard-like hipped dinosaurs (the Saurischians) and the bird-like hipped dinosaurs (the Ornithischians). It's ironic, then, that birds came from the lizard-hipped lineage!
The Ornithischians included the ornithopods (bipedal or quadrupedal herbivores), thyreophorans (the armored dinosaurs, such as stegosaurs and ankylosaurs), and the marginocephalians (the dinosaurs with skull armor, such as the pachycephalosaurs and the ceratopsians).
The Saurischians included the sauropodomorphs (the long-necked prosauropods and sauropods) and the theropods (bipedal dinosaurs that were mostly carnivorous - and birds, which chirp outside your window today!).
Read More Below
~ The Ornithischians ~
The Pachycephalosaurs
The Ceratopsians
The Ornithopods
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