1.Tarsiers are Prosimians. So, how has the tarsier’s classification changed over time? Why? Assign a letter (A, B, C on the image below) to the following evolutionarily significant traits: Loss of a tail: Prehensile tail: Opposable thumbs:

- Prosimians include monkeys, apes, and humans (simians), however tarsiers are more closely linked to simians than other prosimians. All primates other than simians are considered prosimians, which includes all current and extinct strepsirrhines (lemurs, lorisoids, and adapiforms), as well as haplorhine tarsiers and their extinct cousins, the omomyiforms. In comparison to simians, they are said to possess traits that are more "primitive" (ancestor or plesiomorphic) (monkeys, apes, and humans). In the ape radiation, tarsiers exhibit an unexpected path of evolution. Early researchers were perplexed by the tarsier's unusual body and tiny stature, and so they classified them as prosimian primates—below monkeys (simian) level—along with lorises, galagos, and lemurs. The molecular evidence has since overturned that categorization, designating them as an early surviving branch of the anthropoid radiation (Ross and Kay, 2004). Early anthropoids were diurnal and adapted for daytime vision, and the tarsier line began off as such, having lost its nocturnal vision specialisations, but later returned to nocturnal existence by re-specializing for dim light. This makes the development of tarsiers uncommon. This mostly included developing very wide eyes in relation to the skull. The dorsal lateral geniculate lamination pattern of tarsiers is obviously of the anthropoid type as opposed to the strepsirrhine type, supporting their categorization (Wong et al., 2010). It's interesting to note that the main visual cortex, or V1, of tarsiers makes about 20% or more of entire visual cortex, which is proportionally more than virtually any other primate. Tarsiers are highly visual hunters of insects and other tiny prey, and they rely on a big V1 to provide the precise representation required for this task. Because of their tiny size and small brains, tarsiers may have lost certain cortical regions as a result of their need on a big V1. They have a V2 and MT, maybe additional visual regions, but not much prefrontal or posterior parietal brain.