tl;dr : What letters do the words in the thread title begin with
An examination of the taxonomic debate regarding the strepsirhine/haplorhine and prosimian/anthropoid styles of classification.
Within the order or primates, it is clear that there are clear distinctions between the two groups of lemurid/lorisids and the Catarrhini/platyrhrhini/homonoid parvorders. That is to say, Lemurs and Lorises are assuredly very different from old world monkeys, new world monkeys, and apes. For this reason, it is the accepted taxonomic practice to divide these groups into two infraorders. Traditionally, these two groups have been distinguished into prosimians (lemurs and lorises) and anthropoids (alternatively, simians; and including apes and monkeys). But here is where things become messy:
These adorable little fellows are tarsiers, so named for their enlarged tarsus bone. Why does this little fellow cause such evolutionary debate, you ask? Well, the answer is, in essence, that he is neither quite a lemur, nor a monkey: It is something that blurs taxonomic barriers like few other creatures. Traditionally, these critters have been pegged as prosimians, but a large body of paleontologists and behavioralists dispute that categorization. A tarsier, they argue, is much more like a monkey than a lemur. But who’s right? It’s tough to say, as tarsiers possess features considered distinctive of each of the two groups. For example,
- Tarsiers are primarily nocturnal, a trait much more common in lemurs and lorisis
- Tarsiers lack eyeshine, and in that regard are like simeans
- Tarsiers have full post-orbital closure of the eye socket, like monkeys, and unlike Lemurs, which have a post-orbital bar
- Tarsiers are generally very small, a characteristic of Lemurs
- Tarsiers lack a tooth comb, and are thus monkey-like in this regard
Thus, there is some degree of taxonomic debate regarding how to categorize Tarsiers. The two approaches are as follows:
1.Simian vs. Prosimian
– This, the more traditional approach, groups tarsiers with “prosimians” (that is, the lemurs and lorises) and pegs new world monkeys, old world monkeys, and apes as “simeans.” Generally, favored by behavioralists.
2. Haplorhines vs. Strepsirhines
– This approach, which has gained momentum as of late, pegs Tarsiers as “haplorhines” along with monkeys and apes, and dub the more morphologically archaic lemurs “Strepsirhines.” Favored by evolutionists.
Which is right? YOU DECIDE.
now everyone behave and maybe they'll let this fly