Amazingly enough, dinosaurs are divided into two orders:  Saurischia and Ornithischia.  Saurischia (lizard-hipped) are characterized as such because of their forward jutting pubic hipbones and their elongated neck bones.  They are divided into two infraorders:  carnivorous (meat-eating) bipedal (walking on two legs) theropods and herbivorous (plant-eating) quadrupedal (walking on four legs) sauropodomorphs.  Ornithischia (bird-hipped) are characterized as such because their pubis (hipbone) is slanted back parallel to another hipbone and they have a predentary bone at the tip of their toothless lower jaw.  They are plant eaters.  There are three infraorders:  the birdlike ornithpods, the armored thyreophorans, and the horned or thick skulled marginocephalians. 

Ornithopoda belong to the Ornithischia order.  Ornithopoda (bird feet) are characterized by their bird-like features.  They have distinctive, bird-like hipbones, a horny beak, and bird feet.  They have bony tendons that stiffen at the tail.  They can be either bipedal or quadrupedal.  They have jaws and cheek teeth designed for eating plant life.  Ornithopoda are divided into eight families.

Lesothosaurus lived in hot, dry environments.  They had small heads and short arms with five fingered hands.  They had long leg bones and were believed to be bipedal.  Their best defense would be to run away from enemies.  They grew to approximately three feet in length.  Fossils were located in Africa.

Heterodontosauridae (different teeth lizard) were approximately four feet in length and weighed up to fifty-one pounds.  They had three types of teeth.  One set was located at the front of its upper jaw and were sharp.  Another set were cheek teeth.  Lastly, they had two pairs of tusks.  Fossils were located in Africa.

Hypsilophodontidae (high-ridge tooth) had small heads, sharp eyes, a strong jaw and cheek pouches for storage.  They had short arms with five fingers and long legs with three sharp toe claws.  They grew to be seven feet in length.  Fossils were found in Europe and North America.

Lambeosauridae (lamb’s lizard) had a large duckbill and a hollow head crest.  They had a large body and long legs.  They grew to be fifty feet in length.  Fossils were found in North America.  One family member is the Corythosaurus (helmet lizard).  They had hollow dome shaped crest on top of their heads.  It is believed the crest kept them cool.  The crests varied in size.  It is believed that mature males had the largest crests.  They grew to be thirty feet long and weighed up to four tons.  Fossil evidence shows that they had a pebbly textured skin.   Fossils were located in North America.

Dryosauridae were a medium size dinosaur.  They were approximately thirteen feet in length.  They had feet with three toes and a stiff, heavy tail used to balance their head and neck.  Fossils were found in Africa and North America.

Camptosauridae are believed to have traveled in herds.  They had short arms and are believed to have been bipedal.  They had a long bony palate at the top of their mouth to allow them to breathe and eat at the same time.  They grew to be twenty-three feet in length and weighed over a ton.  Fossils were found in North America and Europe.

Iguandontidae (iguana tooth) had high-ridged cheek teeth and jaws with a sliding action.  They had five fingered hands that included a thumb, three fingers with claws and a grasping finger.  They grew to be thirty feet in length.  Fossils were found in Europe, Asia, North Africa and North America.  One family member is the Ouranosaurus (brave monitor lizard).  They were twenty-three feet in length.  Their heads were flat on top with a raised bony brow above their eyes. They had a snout and a wide beaklike mouth with high-ridged crown teeth.  For protection they had a spiny ridge that ran along their backs from it shoulders to their tails.  They formed a fan shape that was up to twenty inches high.  They had long hind legs and short arms with hoof like claws on their fingers and toes.  Fossils were located in West Africa.

Hadrosauridae (big lizard) were duckbills.  They had wide toothless beaks and grinding teeth in the back of their mouths.  They were approximately thirty-three feet in length.  Fossils were found in North America.  One family member was the Maiasaura.  Scientists know a lot about more about this dinosaur than any other dinosaurs because nests, eggs and many dinosaurs of varying ages were found.  It is believed that the females built mounded nests from mud and used mud and leaves to cover the eggs to keep them warm and safe from predators.  They grew to be thirty feet long and weighed up to four tons.  They traveled in herds.  Fossils were located in North America.  Another family member is the Edmontosaurus.  They grew to be forty-three feet long and weighed up to four tons.  They had large flat heads.  They had powerful cheek muscles and up to one thousand teeth used to chew food.  Their only defense was to run away from predators.