THEREPODA

            Characters:

                        *1. Bipedal

                        *2. Serrated teeth

                        *3. Hollowing of vertebrae and long bones

                        *4. Enlarged hand with vestigial fourth and fifth digits

                        5. Lacrimal bones well exposed dorsally (extends onto top of skull)

                        6. Another hole in front of antorbital opening

                        *7. Sacrum with at least five vertebrae

                        8. Ilium somewhat elongate particularly forward portion

                        9. Foot that is compact, narrow and long with 5^th metatarsal reduced to splint

*10.manus digits capable of extreme extension owing to large pits on the upper surfaces of the ends of the metacarpals.

   Ceratosauria

            Characters:

                        *1.Fusion of sacral ribs with ilium

*2. Neck vertebrae with two pairs of pleurocoels and transverse processes strongly turned back.

                        3. Modification of knee joint

                        4. Ventral and lateral flare of crest above acetabulum

                        5. Fusion between upper ankle bones

            Genera: Dilophosaurus, Coelophysis, Ceratosaurus

   Tetanurae

            Characters:

*1. Back half of tail stiffened by interlocking zygopophyses and fore-and-aft projections of neural arches

                        2. Tooth row does not extend behind antorbital opening

                        3. Pronounced groove across front aspect of astragalus

                        4. Pleurocoelous dorsal vertebrae (cavities on sides)

                        5. Shortening of vertebral column in front of pelvis

                        6. Modification of the antorbital region

                        7. Prominent muscular ridge on the scapula

                        8. Changes in the hand skeleton

            Genera: Megalosaurus,, Spinosaurus

        Avetheropoda (All ancestors of birds)

                        *1. Addition of fenestra in the maxilla

                        *2. Modification of back of the skull and palate

                        3. Forward stiffening of the tail skeleton

            Carnosauria Genera: Allosaurus,Monolophosaurus, Sinraptor

-external nares enlarged, sinuses in the facial skeleton elborated, back of skull, brain case and vertebral column modified.

            Coelurosauria Genera: Composognathus

                        1. Enlargement of antorbital fossa

2. Rear extent of the jaw joint in front of the most posterior extent of the occipital condyle

                        3. Metacarpal III shorter than metacarpal II

                        4. Very narrow contact between pubis and ischium

                        Tyrannosauridae

Characters:

                                    *1. Front teeth are D-shaped

                                    *2. Very reduced forelimbs

                                    *3. Very large “boot” on end of pubis

                                    Genera: Albertosaurus, Tyrannosaurus 

                        Ornithomimosauria (Reduction of teeth-absence upper jaw and reduction lower)

                                                            Genera: Struthiomimus

Maniraptoriformes

Characters:

                                    1. Greater neck flexure

                                    2. Semi-lunate wrist bone

                                    3. Lengthening of forelimb

                                    4. Bowed ulna

                                    5. Elongation of middle digit (metacarpal 3) of manus

                                    6. Modified palate

                                    Oviraptorosauria Genera: Oviraptor

                                                -no upper teeth and few lower, large orbit

`                                  Therizinosauridae

                                    Eumaniraptora

                                                Deinonychosauria

                                                Characters:

                                                *1. Pelvis in which pubis is rotated downward or down and back

                                                *2. Loss of fourth trochanter on femur

                                                *3. Modifications to stiffen tail by lengthening zygopophyses

                                                *4. Development of sickle-shaped claw on second toe 

                                                            Troodontidae Genera: Troodon

                                                            Dromaeosauridae Genera: Velociraptor, Deinonychus

                                                            Avialae