Self-study
Paleontologist: Plesiosauromorphs were gigantic, long-necked marine reptiles that ruled the oceans during the age of the dinosaurs. ████ ███████ ███████ ████ █████████████████ ██████ ███ ███████ ████████ █████ █████ ████████ █████████████████ ████████ ██████ ██ ███████ █████ ████ ████ ████ ██████████ ████████████████ ████ ████ █████ ████ ███ █████ ████ ███ █████ ██ █████ ███████████ ███ █████████████ ███████
Summary
The paleontologist concludes that plesiosauromorphs did not ambush their prey, but instead likely chased it over long distances. She supports this claim by pointing out a similarity between plesiosauromorph fins and the wings of birds that engage in long-distance flight.
Notable Assumptions
The paleontologist assumes that a physical similarity between fins and bird wings indicates they were used for the same purpose. This is quite the assumption to make, given the many differences between aquatic fins and wings.
12.
Which one of the following ██ ██ ██████████ ██ █████ ███ ████████████████ ████████ ████████
a
Birds and reptiles █████ ████ ████████ ████████ ███████ ████ ███████ ████ ██████ ████████████ ██████████
The premises tell us that plesiosauromorphs and certain birds share a physical similarity, but we don’t care why they share that similarity. It could be from a common ancestor, random luck, or magic, with no difference to the argument.
b
During the age ██ ██████████ █████████████████ ████ ███ ████ ██████ ████████ ████ ███ █████ ████ █████
The paleontologist is only concerned with plesiosauromorphs, so information about other species is not necessary. As such, the existence of other marine reptiles with similar fins wouldn’t affect our argument.
c
A gigantic marine ██████ █████ ███ ██ ████ ██ ████ ██████ ████ ██ ████ ███ ███████ ████████████ ████████ ██ ███ ████ ████ ██ ██ ███ ███ ████ ██ ███████ ████ ████ ████ ██████████
(C) would strengthen our argument, but it is too strong and therefore not necessary. Negating it yields, “gigantic marine mammals didn't need to chase prey over long distances to survive,” which still leaves open the possibility that plesiosauromorphs hunted in that manner.
d
Most marine animals ████ █████ ████ ████ ████ █████████ ███ ███████████ ███ █████████████ █████████
This answer choice is far too strong to be necessary. We only need some marine mammals that chase prey over long distances to be specialized for long-distance swimming, not most.
e
The shape of █ ██████ ████████ ███ ███████ ███ ███ ███ ██████ █████ ██ ███ ████ ███ ██ ███ █████ ██ █ ██████ ████ ███████ ███ ███ ███ ████ ██████
If we negate (E) to say that fin shape doesn’t affect swimming in the same way that a bird’s wing affects flying, then long, thin fins would no longer be an indication of long-distance swimming. The argument would fail to make sense, so (E) is necessary.