A
A number of animal species that inhabit the islands are not found in the Americas.
B
Genetic analysis indicates that the iguana species on the islands are different in several respects from those found in the Americas.
C
Documented cases of iguanas rafting long distances between land masses are uncommon.
D
Fossils of iguana species closely related to those that inhabit the islands have been found in Australia.
E
The lineages of numerous plant and animal species found in Australia or in South America date back to a period prior to the fragmentation of Gondwana.
Extracurricular
This is not what the question is talking about but it's very cool:
Scientists once believed that the oversized head, long hind legs, and tiny forelimbs that characterized Tyrannosaurus rex developed in order to accommodate the great size and weight of this prehistoric predator. However, this belief must now be abandoned. The nearly complete skeleton of an earlier dinosaur has recently been discovered. This specimen had the characteristic T. rex features but was one-fifth the size and one-hundredth the weight.
Summarize Argument: Phenomenon-Hypothesis
The author hypothesizes that the belief T. rex developed certain features to accommodate its great size must be abandoned. This is because an earlier dinosaur skeleton has been discovered with the same features but of a far smaller size and weight.
Notable Assumptions
The author assumes that the skeleton in question is that of an adult dinosaur. The author also assumes that the dinosaur in question didn’t develop a large head, long hind legs, and tiny forelimbs for some other reason than to accommodate its size. The author therefore believes such adaptations can only arise in response to size.
A
Was the ratio of the head size of the recently discovered dinosaur to its body size the same as that for T. rex?
Even if the skeleton in question had a smaller or larger head relative to its body than T. rex, the skeleton still exhibits T. rex features. Such features were thought to be adaptations to great size, but the skeleton is far smaller than T. rex.
B
At what stage in its life did the recently discovered dinosaur die?
If the skeleton is a dinosaur who died in its infancy, then perhaps that dinosaur was simply a young precursor to T. rex who could’ve grown to a great size. This would undermine the author’s argument that certain T. rex features couldn’t have been size adaptations.
C
Was T. rex the largest and heaviest prehistoric predator?
We don’t care if T. rex was the absolute biggest prehistoric predator, which has nothing to do with whether certain features were size adaptations. There could’ve been larger predators with different adaptations.
D
Was the species to which the recently discovered dinosaur belonged related to T. rex?
Even if that species was indeed related to T. rex, the skeleton is a much smaller dinosaur. For all we know, T. rex relatives could be small dinosaurs while nonetheless being relatives.
E
Did the recently discovered dinosaur prey on species as large as those that T. rex preyed on?
Irrelevant. The features in question weren’t, according to traditional theory, adaptations for predation. They were adaptations for size.