What Anthropoid Was the Size of a Squirrel?
In 1990, Beard, K. Christopher and colleagues published a paper titled “What Anthropoid Was the Size of a Squirrel?” The paper also includes information on Fayum anthropoids and Gigantopithecus. The two authors also wrote a book called “Saimiri Sciureus: The Origin of Humans.”
Table of Contents
Apidium zuetina
The Apidium zuetina was a small arboreal primate that was the size of a squirrel. It was a diurnal creature, living in what is now Libya, and was closely related to modern-day squirrel monkeys. Although it was much smaller than modern-day squirrel monkeys, Apidium did have a small brain and was capable of jumping from branch to branch. Apidium’s size made it easy for it to cover more distance while searching for food.
These fossil teeth were identified as belonging to a new species, Apidium zuetina. Researchers in Libya accompanied by armed guards collected samples of this ancient mammal in Libya. They studied the fossil teeth to determine its evolutionary relationship to other mammals. Apidium’s teeth evolved rapidly in response to shifting diets, but its skull evolved at a slower rate. Apidium’s teeth are among the hardest parts of a mammal’s body, making them extremely durable and easy to fossilize.
Fayum anthropoids
The fossil record of the Fayum Basin reveals several species of anthropoids, including the first anthropoids. These creatures were about the size of squirrels and ate fruit and leaf material supplemented by meat. Most Fayum anthropoids were diurnal and above-branch quadrupeds. Apidium, for example, was well known for leaping, and hundreds of individuals were found to represent its species. Some species were sexually dimorphic.
In addition to preserving a unique fossil record, the Fayum Depression sediments contain 17 genera of extinct anthropoids. Only four of these early Oligocene anthropoids have been studied quantitatively, based on body mass and development of molar shearing crests. These fossils suggest that Fayum anthropoids were probably frugivorous, but the dietary habits of the late Eocene anthropoids are not known for sure. However, the late Eocene Fayum prosimians have demonstrated remarkable dietary diversity and specialized insectivory.
Gigantopithecus
According to a recent study, Gigantopithecus was a relative of Australopithecus and had a similar diet. The Gigantopithecus fossils were discovered in Vietnam’s Tham Khuyen Cave around eight hundred thousand years ago. These bones were found along with those of the Australopithecus, the larger cousin. The fossils of the two species are considered to have co-existed and possibly co-existed for up to five hundred thousand years.
Gigantopithecus has a skeleton resembling that of orangutans and other great apes. However, the Gigantopithecus skeleton lacks the musculature necessary for bipedal stance. This may have resulted in a gradual extinction, or a sudden and complete demise. Either way, it is believed that this species was as large as a squirrel.
Saimiri sciureus
Despite its small size, the Saimiri sciureus monkey has the characteristics of a true ape: a large head, long tail, and distinctively shaped ears. It belongs to the family Cebidae and weighs between 0.7 and 1 kilogram. Saimiri sciureus is strictly diurnal, with females generally shorter than males. They eat fruits, sprouts, insects, and nestlings. They also are shy, rarely approaching human civilizations, and emit sharp cries. They are most active at dawn and cling to humans in a manner reminiscent of a squirrel.
Although the Saimiri sciureus was once believed to have lived in the forest, it was discovered in the 1950s that some of the earliest human fossils had been found. In fact, the first anthropoid fossils were found in Peru and Chile and were named after the species found in that region. Saimiri sciureus is one of the most studied species in the wild and was known to be as large as a squirrel.
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Jessica Watson is a PHD holder from the University of Washington. She studied behavior and interaction between squirrels and has presented her research in several wildlife conferences including TWS Annual Conference in Winnipeg.