Pterodactyloidea Pterodactyloidea Pterodactyloidea (derived from the Greek words "πτερόν" ("pterón", for usual "ptéryx") "wing", and "δάκτυλος" ("dáctylos") "finger" meaning "winged finger", "wing-finger" or "finger-wing") is one of the two traditional suborders of pterosaurs ("wing lizards"), and contains the most derived members of this group of flying reptiles. They appeared during the middle Jurassic Period, and differ from the basal (though paraphyletic) rhamphorhynchoids by their short tails and long wing metacarpals (hand bones). The most advanced forms also lack teeth, and by the late Cretaceous, all known pterodactyloids were toothless. Many species had well developed crests on the skull, a form of
Therizinosaurus Therizinosaurus Therizinosaurus (; 'scythe lizard', from the Greek "therizo" meaning 'rake' or 'to cut off' and "sauros" meaning 'lizard') is a genus of very large theropod dinosaurs. "Therizinosaurus" comprises the single species T. cheloniformis, which lived in the late Cretaceous Period (early Maastrichtian stage, around 70 million years ago), and was one of the last and largest representatives of its unique group, the Therizinosauria. Fossils of this species were first discovered in Mongolia and were originally thought to belong to a turtle-like reptile (hence the species name, "T. cheloniformis" – "turtle-formed"). It is known only from a few bones, including