Carnosaurs contain 1 family:
Family Allosauridae
Early Jurassic to Early Cretaceous
Evolutionary Novelties:
a) evenly rounded rostrum
b) upper tooth sockets that extend all the way to the back of the rostrum
c) medially flattened tip of lower jaw
Example: Allosaurus
Other Carnosaurs of uncertain affinity
Megalosaurus
Lower and Middle Jurassic
-similar to Allosaurus, but very fragmentary remains
Spinosaurus
Lower Cretaceous of Egypt
- lacks serrated teeth
- fin on back with neural spines up to 1.8 meters long
Coelurosaurs
Evolutionary Novelties:
1) extra fenestra in palate
2) elongate forelimbs more than 50% as long as hind limbs
3) long, slender hand with long 2nd and 3rd digits
4) arctometatarsal hindfoot structure
Main Families:
a) Family Tyrannosauridae
Upper Cretaceous
Evolutionary Novelties:
a) "D"-shaped cross sections to teeth in pre-maxillary
b) opening in jugal bone of skull
c) very small forelimbs with only 2 digits
Examples: Tyrannosaurus, Albertosaurus, Daspletosaurus, Tarbosaurus, Nanotyrannus
b) Ornithominosauridae - "bird-mimic lizards"
Known only from Upper Cretaceous of Asia and Western North America
Evolutionary novelties:
1) lightly built skull
2) very large orbits
3) shallow snout
4) long neck
5) lack teeth
Examples: Struthiomimus, Gallimimus (seen in Jurassic Park)
c) Dromaeosauridae
known from Lower and Upper Cretaceous of western North America and Upper Cretaceous of Asia
Evolutionary Novelties:
1) relatively large head
2) large teeth serrated on both edges
3) relatively long forelimbs with 3 fingered hands
4) pelvis with a posteriorly directed pubis
5) tail with ossified tendons
6) hind feet with enormous claw on
digit 2
Examples: Deinonychus "terrible claw", Velociraptor, Utahraptor
Other (rare) Coelurosaurs
1) Oviraptorosaurs "egg stealer"
- probably close relatives of Ornithomimosaurs
Evolutionary novelties:
a) toothless jaws
b) very large fenestrae in mandible
c) short snouts
d) very deep and strong lower jaws
e) crest of sponge-like bone on tip of snout
f) fused clavicles
2) Troodontiids
- probably closely related to Dromaeosaurids
Evolutionary Novelties:
a) long skull and narrow snout
b) large brain case
c) inflated bony casing for the middle ear
d) small and numerous teeth serrated along posterior edges
e) ankle bones fused to each other and to tibia
f) small claws on 2nd digit of hind feet
g) very large eyes
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