This site describes the Troodontidae, a small group (maybe five different species) of very rare and hence poorly known maniraptorans. They are only known from a few incomplete specimens from the Cretaceous period of North America and Mongolia, so their exact affinities to other maniraptorans are uncertain. Their morphology is described in terms of locomotion and other activities and the size of their ... Full description.

This site describes Dromaeosaurs which constitute a small clade of theropod dinosaurs exhibiting some highly derived characteristics that they all share, especially modifications of the forelimb allowing for a flexible seizing function. The site describes their classification, morphology, locomotion, and eating habits with special attention to their "killing claw". This site also includes active links ... Full description.

This site describes the clade Maniraptora (which is defined as containing all dinosaurs closer to birds than to ornithomimids). This is the group of theropod dinosaurs from which many paleontologists believe birds were derived some 150 or so million years ago. The site explains that according to phylogenetic taxonomy, birds are by definition maniraptorans, and the other maniraptorans are their closest ... Full description.

This site describes some of the strangest-looking theropods, known as the oviraptors, a very rare group of maniraptorans represented by excellent fossil finds from the Cretaceous period of Mongolia and North America. Some of the most well-preserved specimens of dinosaurs ever found are oviraptors and fossil evidence is described that indicates bird-like behavior. The site describes their classification, ... Full description.

Coelurosauria is defined as the clade containing all theropods more closely related to birds than to carnosaurs. This site describes classification, which is based on morphology. Links are provided to the three major coelurosaurian groups. Full description.

The Carnosaurs (Greek for "meat-eating lizards") are a group of theropod dinosaurs. The overall morphology of the group is dicussed on this site and further information is included for representative Carnosauria, Allosaurus fragilis, Megalosaurus bucklandii, and Spinosaurus aegypticus. Full description.

The Theropod (meaning "beast-footed") dinosaurs are a diverse group of bipedal saurischians. They include the largest terrestrial carnivores ever to have made the earth tremble. This page provides an explanation of the general characteristics that place dinosaurs in this group, followed by detailed information on the three major groups: Herrerasauridae, Ceratosauria, and Tetanurae. Active links within ... Full description.

This description of the saurischian or "lizard-hipped" dinosaurs discusses the major characteristics that distinguish saurischians from other tetrapods that also have pelves (hips) composed of three elements: the ilium, ischium, and pubis. These are a grasping hand, asymmetrical fingers, a long, mobile neck, and a pubis that points downward and forward at an angle to the ischium. There is also a clarification ... Full description.

Hadrosaurs, the "duckbilled dinosaurs", were common in the Upper Cretaceous of Europe, Asia, and North America. They were members of the Ornithopoda, and close relatives and possibly descendants of the earlier iguanodontid dinosaurs. The morphology of the two subfamilies, Lambeosaurinae and Hadrosaurinae, is discussed, including the purpose of the crest on the head of the former. Two other fossils ... Full description.

Heterodontosaurus ("different-teeth-lizard") was one of the earliest ornithischian dinosaurs. This lightly built, bipedal dinosaur was collected in 1966 from the 200 million year old Lower Jurassic Upper Red Beds, Stronberg series, on the northern slopes of the Krommerspruit Mountain near Voisana, Republic of South Africa. It is in the family Heterodontosauridae. This description of their classification, ... Full description.