Complete question: The image shows the skulls of three different organisms. The foramen magnum position is the hole in the skull where the spinal nerve cord passes through. Based on the structure of the skulls, which two statements can you infer?
a) All three organisms share a common evolutionary lineage
b) Wolves do not share any common ancestors with humans and chimpanzees.
c) Humans likely share more common ancestors with chimpanzees than they do with wolves.
d) Chimpanzees share more common ancestors with wolves than they do with humans.
Note: The skull figures are shown in the attached file
a) All three organisms share a common evolutionary lineage
c) Humans likely share more common ancestors with chimpanzees than they do with wolves.
Explanation:
Although controversial, there is a theory that states that the foramen magnum is associated with bipedalism and human beings´ evolution. According to different studies, the foramen magnum moved from the posterior part of the skull to a central and ventral position. This displacement occurred as mammals began to move in two legs - bipedalism-.
When comparing different mammals skulls it seems evident that bipedalism and foramen magnum position and orientation are highly related. Although all mammals have a common ancestor, the foramen magnum of bipeds mammal organisms is located more anteriorly and ventral than the foramen magnum of the quadrupeds mammals.
In the exposed example, when comparing these three skulls, the two statements that might be inferred are:
a) All three organisms share a common evolutionary lineage. This is true because they are all mammals, and as a group, they share a common ancestor in evolution.
c) Humans likely share more common ancestors with chimpanzees than they do with wolves. This is true because by analyzing the foramen position, we can see that both the chimpanzee and the human´s foramen is located on the ventral side of the skull. Chimpanzees´ hole is more posteriorly and humans´ hole is more anteriorly or centrally located, but in both cases, they are in ventral position. Wolves´ hole, on the other hand, is located posteriorly. As we said before, Although all mammals have a common ancestor, the foramen magnum of bipeds mammal organisms is located more anteriorly and ventral than the foramen magnum of the quadrupeds mammals. And groups closer to human beings (in this case is chimpanzee) show their foramen magnum in a similar place than those mammal groups that are further in evolution (wolves).
