Paleontologists' study of the physiognomy of the saber-toothed cat illustrates how scientists extrapolate function from form. Holophoneus, a cat that appeared in North America in the early Oligocene epoch in the Tertiary period of the Cenozoic era, about 38 million years ago, had large upper canines ("saber-teeth") and a downward extension, or flange, formed by the front of the lower mandible. When the mouth was closed, the canines rested just outside the flange, which acted as a guard for these down-pointing teeth; the lower jaw could be opened extremely wide to free the canines for use. Unable to bite like a modern cat, the saber-toothed cat is thought to have used its canines to stab its victims.

The evolutionary line of the saber tooth culminated about 2.5 million years ago with the appearance of Smilodon and Megantereon. Smilodon, the larger, was at least as big as the modern African lion (Felis leo) and had upper canines that were sometimes as long as eight inches. Because of its heavily-muscled neck and forequarters, the saber tooth was probably a slow animal that fed on large, slow-moving prey. If that was the case, the extinction of the mammals that constituted the saber tooth's prey probably led to its extinction about 10,000 years ago.

1. The passage Is primarily concerned with

A. correcting an error of paleontological classification
B. examining the evolution of one species of saber-toothed cat
C. theorizing about the decline of prehistoric mammals
D. discussing the evolutionary significance of certain features of the saber-toothed cat
E. analyzing the Oligocene period and its legacy


2. It can be inferred from the passage that the evolutionary adaptations of the saber tooth

A. took place around 38 million years ago
B. were dependent on the evolution of the saber tooth's prey
C. led to its extinction approximately 10,000 years ago
D. were insufficient to compensate for the disappearance of primary food sources
E. resulted in the emergence of the modern African lion


3. According to the passage, the flange referred to in line 8 (Highlighted) was used to

A. guard against attack by other large cats
B. protect the saber tooth's oversized canines
C. ensure that the cat would not be injured by its own oversized teeth
D. hinge the upper and lower jaws
E. stab the saber tooth's victims


4. All of the following are true of the Smilodon EXCEPT:

A. Smilodon appeared roughly 2.5 million years ago.
B. Smilodon could grow larger than the modern African lion.
C. Smilodon was smaller than Megantereon.
D. Smilodon's neck was heavily muscled.
E. Smilodon's canines could grow to a length of more than seven inches.


5. Which of the following, if true, would most undermine the argument posed by the author of the passage in lines 23-29 (Text in Red)

A. Other mammals were known to have hunted Holophoneus throughout the Cenozoic era.
B. Archaeologists discovered a 12,000-year-old Smilodon skeleton that possessed five-inch canines.
C. A recent archaeological dig uncovered a 9,000- year-old Megantereon skeleton.
D. The mammals that formed the basis of Smilodon's diet exist to this day.
E. Other slow-moving mammal species have been discovered to have survived the last 10,000 years.


6. It can be inferred from the passage that modern cats

A. do not use their teeth to stab their victims
B. are direct descendants of Holophoneus
C. first appeared on the evolutionary scene about 2.5 million years ago
D. possess flanges much smaller than those of saber-toothed cats
E. bite differently than Smilodon did


7. Which of the following is an assumption underlying the author's description of Similodon's evolution?

A. Megantereon did not use its teeth to stab its victims.
B. Holophoneus was the first saber-toothed cat to have a dental flange.
C. Holophoneus was extinct by the time Smilodon appeared on the evolutionary scene.
D. The slow-moving prey of saber-toothed cats could only be killed by stabbing.
E. A heavily-muscled neck is characteristic of a slow-moving animal