Discovery fills a gap in the evolutionary history of monkeys – ScienceDaily

A team of scientists has discovered the oldest fossil of the gibbon, a discovery that helps bridge an elusive evolutionary gap in ape history.

Work, stated in Journal of Human Evolutionand focuses on hylobatids, a family of monkeys that includes 20 species of living gibbons, which are found throughout tropical Asia from northeastern India to Indonesia.

“Fossil remains of Hylobatids are very rare, and most specimens are isolated teeth and segmented jaw bones found at cave sites in southern China and Southeast Asia dating back no more than two million years,” explains Terry Harrison, professor of anthropology in New York. University and one of the authors of the paper. “This new discovery extends the fossil record of hylobatids to 7 to 8 million years ago and, more specifically, advances our understanding of the evolution of this ape family.”

The fossil, discovered in Yuanmou District, Yunnan Province, in southwest China, is from a small monkey called Yuanmoupithecus xiaoyuan. The analysis, which included Xueping Ji of the Kunming Institute of Zoology and lead author of the study, focused on teeth and skull samples from Yuanmobithexincluding the upper jaw of a child who was less than two years old at the time of his death.

Using the molar size as a guide, scientists estimate that Yuanmobithex Its size was similar to today’s gibbons, with a body weight of about 6 kilograms – or about 13 pounds.

“The teeth and the lower face of the Yuanmobithex It is very similar to that of the modern-day gibbon, but in some features the fossil species was more primitive and suggests it was the ancestor of all living species,” notes Harrison, who is part of the New York University Center for the Study of Human Origins.

Ji found the infant’s upper jaw during a field survey and identified it as a helioptide by comparing it with the skulls of modern gibbons at the Kunming Institute of Zoology. In 2018, he invited Harrison and other colleagues to work on specimens stored at the Yunnan Institute of Cultural Relics and Archeology and the Yuanmou Man Museum that had been collected over the past 30 years.

“remains Yuanmobithex Extremely rare, but with diligence, it was possible to recover enough samples to prove that the Yuanmu fossil monkey is indeed a close relative of living hylobatids,” notes Harrison.

The Journal of Human Evolution The study also found that Kapi Ramnagarensiswhich is claimed to be an earlier type of hylobatid, based on a single fossil molar isolated from India, is not a hylobatid after all, but a member of a more primitive group of primates not closely related to modern apes.

“Genetic studies show that the helioptides diverged from the lineage that gave rise to the great apes and humans about 17 to 22 million years ago, so there is still a 10-million-year gap in the fossil record that needs to be filled,” warns Harrison. “With the ongoing exploration of promising fossil sites in China and elsewhere in Asia, it is hoped that additional discoveries will help fill these critical gaps in the evolutionary history of heliopauses.”

The researchers also gained access to skeletal and fossil collections at the American Museum of Natural History in New York and the Smithsonian’s National Museum of Natural History in Washington, D.C., among others, while conducting their study.

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