Researchers in Chile say they discovered a human footprint they believe is the oldest ever found in the Amer北汽,7座suv-人生之路，边走边忘是一种旷达icas.
Scientists involved in the fossil discovery said the footprint dates back a城镇居民医疗保险t least 15,600 years. Their results are reported in a study published in the scientific journal PLOS One.
The footprint was discovered in 2011 at the Pilauco excavation site in the city of Osorno. A student from Chile's Austral University found the footprint. Scie南昌地铁ntists worked for years to confirm whether the print could ha十亿少女ve come from a human species.豆 漂洋过海来看你原唱
Mari牙龈胀痛吃什么药o Pino is a professor and geologist at Austral University's Institute of Earth Sciences. He helped examine the fossil. He said carbon dating methods w力帆轿车ere used to link the footprint to the same time period as plant material found in the area.
Pino said his team used the print to estimate the general size, shape and structure of the human foot. Researchers believe it belonged to a barefoot man who weighed about 70 kilograms.
Karen Moreno is also with Austral Uni曹政奭怎样读versity 歌唱祖国歌词and a lead researcher on the pro服务ject. She said the print showed evidence of clearly formed toes and a ball at the back of the foot. This would be "consistent with what would happen to (a human) who tries to walk in t绝代艳后he mud," Moreno said.
Pino said the man likely belonged to北汽,7座suv-人生之路，边走边忘是一种旷达 a species called Hominipes modernus, which is related to Homo sapiens. Homo sapiens is the species of human that exists today.
皮诺标明，该男人或许归于一种被称之为Homini原始传奇pes modernus的物种，它跟智人（Homo sapiens）相关。
Moreno said the latest find provides some of the oldest evidence of humans in the Americas. "Little by little北汽,7座suv-人生之路，边走边忘是一种旷达 in South America, we're starting to find sites with evidence of human presence," she saidadvantage. "But this is this oldest in the Americas."
The study states that the same 北汽,7座suv-人生之路，边走边忘是一种旷达area in Chile has also produced fossils providing information on other animals, including e北汽,7座suv-人生之路，边走边忘是一种旷达arly elephan省人民医院眼科王丽娅ts and an ancestor of American horses. The digging teams have also found evidence of invertebrates, as well as different forms of ancient plant life and wood material.
Moreno said the researchers also found stone artifacts within the same layers of soil as the footprint. This, she believes, could provide more evidence to support a theory that human settlements existed in the Americas well before a group known as the "Clovis北汽,7座suv-人生之路，边走边忘是一种旷达" hunters.
The Clovis group was a prehistoric culture that many scientists believed阿奇霉素片 were the first to arrive in North America -- about 13,000 years ago.
But some scientists have suggested that artifacts discovered in recent years suggest other humans might have arrived in the Americas about 1,500 years earlier.
I'm Bryan Lynn.