NEW JERSEY — The field of archaeology requires uncommon patience. Is that specimen so painstakingly coaxed from the hard earth animal or early human? Is it historically, significantly old or just old enough to be mildly interesting? The answers come slowly, sometimes in months, often in years.

So it was that New Jersey archaeologist David Braun tempered his excitement after he and other researchers, among them a Rutgers University professor and a group of Rutgers students, found what looked to be very unusual footprints in the ancient sediment of a riverbed in Kenya.

“We knew we might have something special, but we also kept thinking, ‘OK, these could be from a baboon,’” Braun said.

Turns out all that caution was unnecessary. Over three summers, Braun and his colleagues unearthed a bit of archaeological gold: what’s believed to be the first known footprints of Homo erectus, an ancestor to modern humans. The finding was reported Friday in the journal Science.

The researchers, who included Rutgers professor John W.K. Harris and a team of international experts, determined the feet that left those prints 1.5 million years ago were almost exactly like ours, with nearly identical heels, insteps and toes. Significantly, the big toe ran parallel with the other toes, suggesting a modern upright gait.

The footprints also indicated that those who left them took long strides like modern humans, allowing them to run and travel long distances. That squares with the fossil record, which shows that Homo erectus began migrating out of Africa about 1.8 million years ago.

Only one cluster of older pre-human footprints has ever been found. They were discovered in 1978 in Laetoli, Tanzania, and had been left 3.7 million years ago by Australopithecus afarensis, the small, apelike species to which the famous skeleton “Lucy” belonged.

Hunting for history is Braun’s life work. The 32-year-old Elizabeth native has spent every summer since 1996 digging in Kenya’s Turkana Basin, a treasure trove of fossils. A graduate of Haverford College in Pennsylvania, he obtained masters and doctoral degrees at Rutgers, where he studied under Harris.

Both men are now co-directors of a field school, run jointly by Rutgers and the National Museum of Kenya, that trains young archaeologists. Braun also teaches at the University of Cape Town in South Africa. He lives in New Jersey about four months of each year.

It was in the summer of 2005 that the researchers made their discovery a few miles east of Lake Turkana, though they didn’t know initially how big it would be. The group was cutting into the wall of a bluff to examine the geology of the area when they noticed deformations in the sediment.

“It was odd-looking,” said Braun, the son of a Star-Ledger columnist, Bob Braun. “We were looking at it from the side, and it wasn’t until we excavated from the top that we realized these were footprints.”

They were mostly animal prints, he said. Zebra, antelope, water birds. But there were also tantalizing prints that looked a lot like human prints.

A fuller excavation began in the summer of 2006, followed by two more in 2007 and 2008. Their excitement growing, Harris and Braun turned to other experts for help.

Matthew R. Bennett, a professor from Bournemouth University in England, used a digital laser scanner to create three-dimensional images of the footprints in 2007, showing them in detail.

Braun said more than 50 people crowded around Bennett’s laptop when the images were first created, clamoring for a look.

“When we saw that, we realized that what we had was really spectacular,” he said.

Never before had ancient footprints come to life so thoroughly. Such prints are almost always destroyed over time. In this case, Braun said, the river appeared to change course, washing sand into them without extensively damaging them.

In all, the group found more than a dozen prints on two layers of sediment separated by about 10,000 years. In one layer, they found two trails of two footprints each and one that included seven prints. Three prints were found on the lower layer.

More than 30 Rutgers undergraduate students rotated in during the three summers, along with about 15 graduate students.

Rutgers graduate Robert Abrunzo, 23, of North Haledon, returned to Kenya three times to participate in the field school and the dig. He said he remains awed by the experience.

“Getting to see these footprints come out was amazing,” Abrunzo said. “To look at something and say, ‘A million and a half years ago our ancestors were walking here, there’s no words to express it.”

By Mark Mueller | The New Jersey Star Ledger