Evolution of Orangutans Essay
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Orangutans are apes with reddish-brown hair that originated 2 million-100,000 years ago. Orangutans are categorized the Hominidae family, which is commonly known as the Great Apes. Orangutans live in Asia, only found on the islands of Sumatra and Borneo. They are known for their long arms which can reach to a length of 7m, fingertip to fingertip (See Appendix A, Fig.
1). There is no real evidence of who the orangutan’s ancestors were. The primate lineage was thought to start 65 million years ago; this began as the Euarchonta which lead to the primates present today(See Appendix A, Fig. ).
Primates were divided into two groups called Strepsirrhines, which included lemurs and lories, and Haplorhines, which included tarsiers, monkeys, and apes. After 35 million years, the Haplorhines split into another two groups called Platyrrhini, which included the New World monkeys of South and Central America, and the Catharinni, the Old World monkeys of Africa and Asia, and apes. About 10-15 million years after that, the group split into two superfamillies called Cercopithecoidea which includes Old World monkeys, and Hominoidea, which includes apes.
Some researchers say that the orangutan originated from Lufengpithecus, while others say that they originated from Sivapithecus. Lufengpithecus has four species; Lufengpithecus lufengensis, Lufengpithecus hudienensis, Lufengpithecus keiyuanensis and Lufengpithecus chiangmuanensis. Lufengpithecus lufengenis fossil was found in lignite beds at the Shihuiba Locality in Lufeng County, Yunnan, China. It was thought to represent Sivapithecus because of the similarities between the species. The Lufengpithecus chiangmuanensis fossil, that dates back 10-13. million years ago, was discovered not long ago in Thailand.
Researchers think that the Lufengpithecus chiangmuanensis is the closest to the orangutan because of the shape of its jaw, and because it was found in Thailand near where the orangutans live today. But there is no true evidence that the Lufengpithecus is the ancestor of the orangutan by just looking at their face structure and where it was found (See Appendix A, Fig. 3). Sivapithecus lived in the woodlands of Central Asia 8-12. million years ago. It was about 5 feet long, weighing about 50-75 pounds. It had feet like a chimpanzee and it had a diet of plants with large canines. The large canines were used to eat tough tubers and stems rather than fruits. This species was when early primates came down from trees and started to explore the grasslands. Other than it’s chimpanzee like feet, its face resembled an orangutan (See Appendix A, Fig. 4). Sivapithecus mainly lived on the ground because of the size of their body.
One of the things that a Sivapithecus could do is walk standing upright like a human. Standing upright for a Sivapithecus wasn’t so easy as they didn’t always have balance when using their hind limbs so they used their forearms to help. Walking vertically helped the Sivapithecus by walking on the ground rather than climbing trees, so they didn’t need to use the trees to move around.. Walking on the ground might not have been an option because there were some areas that didn’t have a lot of vegetation.
As the continents were drifting apart, there was a decrease in vegetation. This was an environmental pressure for the Sivapithecus because it made them rely on their hind limbs to move around the area. Sivapithecus was so flexible that it made it easier to swing and climb trees. The extension and stable joints in their body gave them a huge advantage and helped them in the ability of hanging and swinging around in trees. There isn’t a lot of information about the ancestors of the orangutan and how it evolved because there isn’t enough evidence.
Some researchers say the Lufengpithecus is the ancestor and some say the Sivapithecus is, but no one is absolutely sure if either of those two species are the actual ancestors of the orangutan. Just like the species Lufengpithecus chiangmuanensis, which was discovered about 8 or 9 years ago, there may be a species not yet discovered and it might be the orangutan’s ancestor. From what researchers found, they don’t fully know how the orangutan evolved.