Paleontologists’ study of the
physiognomy of the saber-toothed cat
illustrates how scientists extrapolate
function from form. Holophoneus, a cat
5 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
10 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
15 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.
20 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
25 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
30 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.
It can be inferred from the passage that the evolutionary adaptations of the saber tooth
took place around 38 million years ago
were dependent on the evolution of the saber tooth’s prey
led to its extinction approximately 10,000 years ago
were insufficient to compensate for the disappearance of primary food sources
resulted in the emergence of the modern African lion
physiognomy of the saber-toothed cat
illustrates how scientists extrapolate
function from form. Holophoneus, a cat
5 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
10 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
15 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.
20 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
25 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
30 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.
It can be inferred from the passage that the evolutionary adaptations of the saber tooth
took place around 38 million years ago
were dependent on the evolution of the saber tooth’s prey
led to its extinction approximately 10,000 years ago
were insufficient to compensate for the disappearance of primary food sources
resulted in the emergence of the modern African lion
