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plz answer 1, 2, 3 based on the slide provided

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Station 1. Cranial Traits
A. Postorbital bar and postorbital closure
A postorbital bar is a bony ring that forms the outside border of the eye orbit. This structure encircles
the eye orbit but does not form a wall behind the orbit. This structure is found in all primates.
Primates that have a postorbital bar as well as a complete bony wall behind the orbit (i.e., a fully
enclosed orbit) have postorbital closure. Strepsirrhines have a postorbital bar, but not postorbital
closure. Haplorhines (except tarsiers) have postorbital closure. Tarsiers have partial
postorbital closure. If you do not have a postorbital bar, you are not a primate.
1. Looking at Slide #1 (Lab PDF), list which skull(s) (A, B, C, D) have only a postorbital bar.
Which have a postorbital closure? Which have neither? (4 points)
Postorbital bar ONLY
Postorbital closure
B. Orbital convergence
Primates' eyes are located closer toward the midline of the face than those of other mammals.
Thus, the fields of visions of the two eyes overlap and the eyes are said to converge. Non-primate
mammals often have eyes placed on the sides of their heads, or divergent orbits. Orbital convergence
is more pronounced in haplorhines than in strepsirrhines, making the strepsirrhines more
2. Using the same slides consider which skulls (A, B, C, D) have convergent eye orbits? Divergent?
Transitional? (4 points)
3. Based on this, which are strepsirrhines?

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