Bactrosaurus (Greek for "staff lizard"); pronounced BACK-tro-SORE-us
Habitat: Woodlands of Asia
Historical Period: Late Cretaceous (95-85 million years ago)
Size and Weight: About 20 feet long and 2 tons
Diet: Plants
Distinguishing Characteristics: Thick trunk; club-shaped spines on backbone
Among the earliest of all the hadrosaurs, or duck-billed dinosaurs--roaming the woodlands of Asia at least 10 million years before more famous descendants like Charonosaurus--Bactrosaurus is important because it possessed certain characteristics (such as a thick, squat body) more often seen in iguanodont dinosaurs. (Paleontologists believe that hadrosaurs and iguanodonts, which are both technically classified as ornithopods, evolved from a common ancestor). Unlike most hadrosaurs, Bactrosaurus seems to have lacked a crest on its head, and it also had a row of short spines growing out of its vertebrae that formed a prominent, skin-covered ridge along its back.
http://dinosaurs.about.com/od/herbivorousdinosaurs/p/bactrosaurus.htm