Fossil finds put gibbons in Asia as early as 8 million years ago
Small-bodied, long-armed apes known as gibbons swing quickly via the bushes, far outpacing scientists’ makes an attempt to decipher these creatures’ evolutionary story.
Now, a partial higher jaw and 7 remoted tooth discovered close to a southwestern Chinese language village have added chew to a suggestion that the earliest identified gibbons hung on the market about 7 million to eight million years in the past, researchers report within the October Journal of Human Evolution..
These fossils, in addition to 14 tooth beforehand discovered on the identical web site and a close-by web site, belong to an historic hylobatid species known as Yuanmoupithecus xiaoyuan, say paleoanthropologist Xueping Ji of the Kunming Pure Historical past Museum of Zoology in China and colleagues. Hylobatids, a household of apes that features about 20 species of residing gibbons and a black-furred gibbon known as the siamang, inhabit tropical forests from northeastern India to Indonesia.
Ji’s group has presumed that Y. xiaoyuan was an historic gibbon since introducing the species in a 2006 Chinese language publication. However extra fossils have been wanted to examine that suspicion.
The newly found higher jaw piece — discovered by an area villager and given to Ji throughout fieldwork round a decade in the past — comprises 4 tooth, together with a partly erupted molar that helped researchers establish it because the stays of an toddler that died earlier than reaching age 2.
Comparisons with trendy apes and fossils of historic primates peg Y. xiaoyuan because the oldest identified gibbon and solid doubt on a two-year-old report {that a} roughly 13-million-year-old molar tooth present in northern India got here from a hylobatid, the staff says (SN: 9/8/20). The fossil present in India, assigned to a species dubbed Kapi ragnagarensis, represents an extinct group of South Asian primates that weren’t intently associated to present-day apes, the scientists say.
Prior DNA analyses of residing primates prompt that hylobatids diverged from different apes in Africa between 22 million and 17 million years in the past. Nevertheless it’s a thriller when gibbon ancestors arrived in Eurasia, says paleoanthropologist and examine coauthor Terry Harrison of New York College. A niche within the fossil file of about 10 million years exists between the estimated time when hylobatids emerged in or close to Africa and proof of Y. xiaoyuan in Asia.
Genetic proof additionally signifies that gibbon species in the present day shared a standard ancestor round 8 million years in the past, when Y. xiaoyuan was alive. “It may very well be that [Y. xiaoyuan] is the ancestor of all later gibbons,” Harrison says. If not, Y. xiaoyuan was intently associated to a contemporary gibbon ancestor, he suspects.
Bumps and depressions on chewing surfaces and different tooth and jaw options of Y. xiaoyuan look very similar to these of residing gibbons, Ji’s staff says. Some traits of the fossil species have been precursors of barely completely different traits in trendy gibbons, the researchers counsel.
Primarily based on molar sizes, they estimate that Y. xiaoyuan weighed about six kilograms, much like gibbons in the present day. Molar construction signifies that Y. xiaoyuan targeted on consuming fruits, like most gibbon species in the present day, Harrison says.
Ji’s group “makes an excellent case that [Y. xiaoyuan] is a hylobatid,” says paleoanthropologist David Alba of Institut Català de Paleontologia Miquel Crusafont in Barcelona.
However the evolutionary standing of Okay. ragnagarensis stays unsettled as a result of solely a single tooth from that species has been discovered, says Alba, who didn’t take part within the new examine.
