Pachycephalosaurs and Ceratopsians

1. Pachycephalosaurs and ceratopsians are united in a group called _____.

a. Thyreophora

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b. Marginocephalia

c. Ornithopoda

d. Ornithischia


2. Ceratopsians comprise two groups, _____.

a. Psittacosauridae and Neoceratopsia

b. Protoceratopsidae and Ceratopsidae

c. Homalocephalidae and Pachycephalosauridae

d. Neoceratopsia and Pachycephalosauria


3. _____ well represents the primitive, ancestral structure of the Ceratopsia.

a. Protoceratops

b. Triceratops

c. Leptoceratops

d. Psittacosaurus


4. Neoceratopsians are divided into two families, the _____.

a. protoceratopsids and ceratopsids

b. psittacosaurids and ceratopsids

c. homalocephalids and pachycephalosaurids

d. none of the above


5. There are two kinds of ceratopsids, _____.

a. ceratopsines and chasmosaurines

b. ceratopsines and leptoceratines

c. ceratopsines and pachyrhinosaurines

d. ceratopsines and protoceratopsines


6. Unlike other ceratopsines, Triceratops had _____.

a. a long, low snout

b. large postorbital horns

c. a short frill that lacked fenestrae

d. all of the above


7. There are two groups of pachycephalosaurs, the _____.

a. primitive pachycephalosaurs and Pachycephalosauridae

b. Ceratopsidae and Pachyrhinosauridae

c. Homalocephalidae and Protoceratopsidae

d. none of the above


8. The features of the pachycephalosaurid skull and skeleton designed to resist impacts include the _____.

a. reinforced upper lip of the hip socket

b. shortened base of the skull

c. greatly thickened dome of the skull

d. all of the above


9.True or False– Marginocephalians were plant-eating ornithischians closely related to ankylosaurs.

10.True or False– Pachycephalosaurids butted heads against other dinosaurs and each other.



Key Terms:

define the following key terms.


11. Frill

12. head-butt

13. Ontogomorph

14. Steoceras

15. Triceratops



Short Answer Questions:


16. What evolutionary novelties are shared by ceratopsians and pachycephalosaurs to unite them as marginocephalians?


17. What features distinguish Psittacosaurus from neoceratopsians?


18. Describe the lifestyle of Protoceratops.


19. What features of Triceratops identify it as a typical ceratopsine? How is it different from a pachyrhinosaurine?


20. Discuss the possible functions of the horns and frills of ceratopsians.


21. How are primitive pachycephalosaurs distinguished from derived pachycephalosaurids?


22. Why do some paleontologists think pachycephalosaurs butted heads? Why might pachycephalosaurs have done this?


23. What are the similarities and differences in the evolution of ceratopsians and pachycephalosaurs?