How Dinosaurs Are Named

Most of the time, paleontology is an anonymous and not terribly exciting occupation--the typical PhD candidate spends most of her day laboriously removing encrusted dirt from newly discovered fossils. The one chance a researcher really gets to shine is when he or she discovers--and gets to name--a new type of dinosaur.

There are all sorts of ways to name a dinosaur. Some of the most famous dinos are named after prominent anatomical features (e.g., Triceratops, which means "three-horned head") while other are named according to their supposed behavior (the most famous example is Oviraptor, which means "egg thief"). A bit less imaginatively, some dinosaurs are named after the places their fossils were unearthed--witness the Canadian Edmontosaurus.
Generally, dinosaurs are referred to by their genus--the next step up the taxonomic tree from an individual species. For example, the dinosaur commonly known as Ceratosaurus comes in four different flavors: nasicornus, dentisulcatus, ingens and roechlingi. Most people can get by with just saying "Ceratosaurus," but scientists refer more precisely to the spcies Ceratosaurus ingens (the whole name is italicized, with only the genus name capitalized).
"Deprecated" Dinosaurs
According to the arcane (but eminently fair) rules of paleontology, a dinosaur's first official name is the one that counts. That is, if a paleontologist digs up a unique dinosaur in South America, his name is the one that sticks, even if an identical species is found and named a week later (before the first researcher had a chance to publicize his discovery).

Occasionally, this strict rule can lead to some confusion. The most famous example is Apatosaurus, which is now the "correct" name for the sauropod once known as Brontosaurus. It turns out that the same famous paleontologist who discovered (and named) the bones of Apatosaurus later discovered (and named) the bones of what he thought was an entirely different dinosaur. When it turned out that Brontosaurus was the same animal as Apatosaurus, official rights reverted back to the original name, leaving Brontosaurus as what paleontologists call a "deprecated" genus.
"People"-saurs

Surprisingly, fairly few dinosaurs are named after people, perhaps because paleontology tends to be a group effort. Some legendary practitioners, though, have been honored in dinosaur form: for example, Othnielia is named after the famous paleontologist Othniel C. Marsh (the same scientist who caused the whole Apatosaurus/Brontosaurus blowup), while the dino dubbed Drinker wasn't a primitive alcoholic, but named after the 19th-century fossil hunter Edward Drinker Cope.

Perhaps the most widely publicized people-saur of modern times is Leaellynosaura, which was discovered by a married pair of paleontologists in Australia in 1989. They decided to name this small, gentle herbivore after their young daughter, the first time a child has ever been honored in dinosaur form!