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Lectures 19-20

Late Cretaceous - Mongolia, Judith River, Two Medicine, and Hell Creek

Late Cretaceous World

Late Cretaceous of Mongolia

Barrun-Bayan - Late Cretaceous
Djadokhta - Late Cretaceous
Barun-Goyot - Late Cretaceous
Nemegt - Late Cretaceous

Judith River Beds, Alberta

Two Medicine Formation. Montana

Jack Horner collecting at Egg Mountain

Jack Horner collecting dinosaurs at "Egg Mountain" in the Two Medicine Formation [near Choteau] of Montana (photo by L. Psihoyos).

Dinosauria

Theropoda

1. three-toed foot
2. digits IV and V lost on hand
3. long arms
4. semilunate carpal
5. fused pelvis
6. large hole in lacrimal bone in skull
7. ?no unique derived characters?
8. giant, hook-like claw on digit II of pes
9. flight feathers
10. ?no unique derived characters?
11. proximal half of metatarsal of digit III pinched
12. teeth lost in front of mouth and very large claws on manus
Theropod Cladogram

Coelurosauria
Therizinosauria
Therizinosaurus - Mongolia

Arctometarsalia Cladogram 1. proximal half of metatarsal of digit III pinched
2. enlarged brain and eyes and reduced teeth
3. metacarpals of nearly equal length
4. teeth with large denticles
5. highly reduced forelimbs and large size

Arctometatarsalia
Ornithomisauria
Ornithomimus altus - Judith River
Deinocheirus - Mongolia

Troodontidae
Saurornithoides - Mongolia
Stenonychosaurus- Judith River

Tyrannosauridae
Tarbosaurus - Mongolia
Albertosaurus - Judith River

Theropod Cladogram

1. three-toed foot
2. digits IV and V lost on hand
3. long arms
4. semilunate carpal
5. fused pelvis
6. large hole in lacrimal bone in skull
7. ?no unique derived characters?
8. giant, hook-like claw on digit II of pes
9. flight feathers
10. ?no unique derived characters?
11. proximal half of metatarsal of digit III pinched
12. teeth lost in front of mouth and very large claws on manus
13. skull deep, highly fenestrate, lacking teeth

Ovaraptorids
Oviraptor philoceratops

Maniraptora
Deinonychosauria
Velociraptor - Mongolia
Avialae
Mononykus - Mongolia

1. semilunate carpal
2. giant, hook-like claw on digit II of pes
3. flight feathers
4. no shared derived characters?
5. tail becomes pygostyle
6. elongated digit III or hand
7. enlarged keeled sternum
8. no shared derived characters?
9. loss of teeth 10. spike-like manus
Cladogram of the Availae

Ornithischia

Genasauria
Thyreophora
Ankylosauria
Nodosauridae
Edmontonia - Judith River

Ankylosauridae
Euoplocephalus - Judith River

1. cheeks
2. armor
3. armor as plates or spines on back
4. "club" on tail
5. large armor plate on top of center of skull
6. armor as covering or small plates over back
7. armor as spines
8. armor as plates
9. uneven enamel on teeth
10. bony shelf on back of head 11. jaw joint below tooth rows
Stegosauria cladogram

Cerapoda
Marginocephalia
Pachycephalosauria
Homalocephale - Mongolia
Pachycephalosaurus - Judith River
Stegoceras - - Judith River

Ceratopsia
Psittacosauria Psittacosaurus mongoliensis - E. Cret., Mongolia Neoceratopsia
Protoceratops andrewsi - Mongolia
Centrosaurus - Judith River
Monoclonius - Judith River
Styracosaurus - Judith River

Ornithopoda
Hadrosauria
Lambeosaurus
Parasaurolophus
Maiasaura

1. cheeks
2. armor
3. armor as plates covering back
4. armor as spikes or plates
5. uneven enamel
6. back part of skull makes shelf
7. rostral bone
8. frill
9. reduced hands
10. domed head
11. jaw joint below tooth row
12. elongate hands
13. prepubic process well developed
14. ridge on teeth
15. reduction in manus digits I and V (and large nares)
16. digit 1 of hand spike-like
Cladogram of the Genasauria


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