As big as it is, California has been home to only a modest number of dinosaurs and prehistoric animals over the past 250 million years, as listed below. (See an interactive map of dinosaurs and prehistoric animals in the United States.)
Better known by its informal name, the Saber-Tooth Tiger, Smilodon is far and away the most famous (and most common) prehistoric mammal of California, thanks to the recovery of thousands of skeletons from the famous La Brea Tar Pits of Los Angeles. This predator was smart, but not smart enough to avoid getting trapped in the muck itself! More about Smilodon
Californosaurus is one of the most primitive ichthyosaurs ("fish lizards") yet identified, as betrayed by its relatively unhydrodynamic shape (a short head perched on a bulbous body) and short flippers. Confusingly, this marine reptile is often referred to as Shastasaurus or Delphinosaurus, but paleontologists prefer Californosaurus, probably because it's more fun.
The prehistoric whale Cetotherium--one species of which prowled the shores of California--can be considered a smaller, sleeker version of the modern gray whale. Like its modern descendant, Cetotherium filtered plankton from seawater using baleen plates, and it was probably preyed on by the giant prehistoric sharks of the Miocene epoch.
As big as California is, this state has yielded only one indisputable dinosaur fossil, the tough, compact, heavily spiked ankylosaur Nodosaurus. If paleontologists ever get around to analyzing the scattered hadrosaur (duck-billed dinosaur) bones scattered around the Eureka state, Nodosaurus may finally get some competition!
5. Assorted Megafauna Mammals
Although Smilodon (above) is the most famous megafauna mammal to be recovered from the La Brea Tar Pits, it was far from the only furry beast of Cenozoic California. Also prowling the state were (to name a few) the American Mastodon, the Giant Ground Sloth, the Giant Short-Faced Bear and the Dire Wolf, which competed directly against Smilodon for prey.