FLINT, Michigan — Scientist Kristian J. Carlson spent a year studying skeletons from an ancient South African cave — and possibly has helped discover a new species of prehistoric man.

The Flint native’s work with a team of scientists in Johannesburg, South Africa, is gleaning international fame after the group’s discovery of 2 million-year-old fossils that have been called the “Rosetta Stone” of humanity.

Carlson, 39, who grew up near Mott Park, is leading the analysis of the unearthed partial bones of “apemen” who apparently lived during one of the world’s most mysterious periods and who may have been the direct ancestors of humans.

“To have this level of involvement with this kind of work, it’s a dream come true,” said Carlson, who has lived in South Africa for nearly two years. He is a senior researcher at the Institute for Human Evolution, University of the Witwatersrand, in Johannesburg.

He has traveled around the world to study the bones of the newly announced species, found in 2008 near the Cradle of Humankind World Heritage Site at the Malapa excavation area, about 170 miles from Johannesburg.

Findings on the new species, Australopithecus sediba, were published in April. They offer key clues to theories on the ape-to-man transition — from living in trees to full life on land — and could write a new chapter in evolutionary history.

“It’s really getting at the question of where we come from,” said Carlson, who attended St. Paul Lutheran Elementary school in Flint and still considers himself religious. “(Humans) like to know the order of things. We’re very inquisitive and want to know how we got here. At what point did our brains become similar to what they are?”

The group is not calling the sediba a missing link, but members believe the rare find will fill a critical gap.

And the discovery is making waves in the science community after being announced in the journal Science last month and also airing on a CBS “60 Minutes” segment.

“People can go their whole careers without finding one specimen,” Carlson said. “Having this good of material to work with ... it’s sort of like an unfilled crossword puzzle with so many opportunities and places to start. There’s a clean slate.

“We’ve announced it, so the scientific community knows about it, and now we’ll spend our lifetime studying it.”

Carlson is among a team of six scientists led by principal investigator Lee Berger, a paleoanthropologist at the University of the Witwatersrand. On a hunt, Berger’s now 11-year-old son spotted one of the fossils — that of a young male.

There are some records of species before and after the sediba, but scientists have yet to determine when hominids made the transition from dependency on life in trees to life on the ground.

“We do feel that possibly sediba might be a Rosetta Stone for defining for the first time just what the genus Homo is,” Berger said in April.

The sediba was comfortable in two worlds, walking on two legs but still swinging from trees.

The apemen had short powerful hands and fingers like humans but long tree-climbing arms like apes. They had an advanced pelvis and long legs that could have allowed them to run in a stride similar to humans.

Their smaller brains, more delicate facial features and smaller teeth also gave them features that are closer to humans than those from the next closest ancestor, scientists say.

The well-preserved fossils, which are of an adult female about 30 years old and an adolescent boy with a complete skull, were apparently buried in shallow water underground between 1.78 million and 1.95 million years ago.

Findings on two other partial skeletons of an adult female and an infant haven’t been published yet.

They were found among skeletons of a saber-toothed cat, an antelope, mice and rabbits.

“The completeness of these two skeletons is extremely rare,” said Carlson, also a senior researcher and research associate in Indiana University Bloomington’s Department of Anthropology. “The time this comes from, around 2 million years ago, is also a big mystery for all of us in the field. We have a good idea of what was earlier and what was later, but there’s this gap.

“For us, it’s the combination of all these things that makes this a unique find.”

Carlson, who said he believes in God, expects some fundamentalists to dismiss the findings’ implications because they indicate humans evolved from something apelike.

The fossils also are being hailed as marking a new link between the traits of the Australopithecus africanus species, which was present 1 million years earlier, and the later taxon Homo habilis, which eventually evolved into the Homo erectus, scientists say.

IU anthropology professor Kevin Hunt, who advised Carlson when the Flint native was earning his doctoral degree at IU, said he is most interested in the regional characteristics shown in the fossils.

Their features are unlike the usually rugged fossils from South Africa identified by heavy faces and huge molars.

He said South African species always have been viewed as a side branch that was isolated from other evolving species — but that the discovery indicates interbreeding and a link between East Africa and South Africa.

“This shows that this species was evolving all over Africa,” he said. “That suggests all of the fossils in South Africa have to be taken seriously as ancestors of modern humans. It must be part of the regular puzzle of human evolution.”

Hunt said he was not surprised by Carlson’s significant role in the study.

“He’s been a world traveler ever since he left Flint and is becoming an international name,” Hunt said. “Wherever he goes, he seems to make himself invaluable. It’s wonderful to see him be a part of this team.”

Carlson, who lived in Flint before moving to Pennsylvania for high school, is giving his family back home some bragging rights.

“They’re working with this treasure trove. One of his remarks was he wakes up and every day is Dec. 25,” said father Jim Carlson of Flint Township. “He’s had so many life experiences up to this point, but now he’s into some really new findings that are historic in proportion to the whole field of science and evolution, and we thank God for that. This is huge.”