BACK TO DINOSAURS 1997 HOME PAGE

Lectures 16-18

Early Cretaceous - Cloverly Formation, North China, and Mongolia

Early Cretaceous World

Cloverly Formation

The Cloverly formation outcrops in Wyoming and Montana and consists of variegated mudstones and sandstones deposited by streams and rivers and in shallow lakes. A reasonably rich assemblage of dinosaurs has been produced from the Cloverly, notably Deinonychus, Tenontosaurus, and Sauropelta (all below).

Mongolia

northern Liaoning Province

Jehol Group

Saurischia

Theropoda
	Tetanurae
		Arctometatarsalia
			Troodontia
				Sinornithoides youngi - Mongolia



			Ornithomimosauria
				Gallimimus bullatus - Mongolia










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














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





		
		Therizinosauria
				Erlikosaurus - Mongolia
				Segnosaurus - Mongolia
				Alxasaurus - China  





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







		?
			Compsognathus prima (Sinosauropteryx) - Liaoning Province

			Protarchaeopteryx robusta - Liaoning Province


		Maniraptora
			Deinonychosauria
				Deinonychus antirrhopus -Cloverly







		Ornithurae
				Confuciusornis sanctus - Liaoning Province

		Carinatae
				Chaoyangia - Liaoning Province






Confuciusornis sanctus, modified from Hou et al. (1996)


Chaoyangia, modified from Hou et al. (1996)











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






Thyreophora
	Ankylosauria
		Sauropelta - Cloverly

Ornithopoda
	Iguanodontia
		Tenontosaurus - Cloverly
		Iguanodon - Wealden and Mongolia?

Marginocephalia
		Yaverlandia Wealden

Ceratopsia
	Psittacosauridae
		Psittacosaurus mongoliensis - Mongolia 
		Psittacosaurus meileyinggensis - Liaoning Province





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. manus digit 1 spike-like

REFERENCES

Ji, Q. and Ji, S., 1996. On discovery of the earliest bird fossil in China and the origin of birds. Chinese Geology 10 (233): 30-33.

Sereno, P. C., Rao C., 1992, Early evolution of avian flight and perching; new evidence from the Lower Cretaceous of China. Science, v. 255, n. 5046, p. 845-848.

BACK TO THE DINOSAUR AND THE HISTORY OF LIFE HOME PAGE