Fossilized footprints discovered in New Mexico indicate that early humans were walking across North America around 23,000 years ago, researchers reported Thursday. The first footprints were found in a dry lake bed in White Sands National Park in 2009. Scientists at the U.S. Geological Survey recently analyzed seeds stuck in the footprints to determine their approximate age, ranging from around 22,800 and 21,130 years ago. The findings may shed light on a mystery that has long intrigued scientists: When did people first arrive in the Americas, after dispersing from Africa and Asia? Also read: Egypt team identifies fossil of land-roaming whale species Most scientists believe ancient migration came by way of a now-submerged land bridge that connected Asia to Alaska. Based on various evidence — including stone tools, fossil bones and genetic analysis — other researchers have offered a range of possible dates for human arrival in the Americas, from 13,000 to 26,000 years ago or more. The current study provides a more solid baseline for when humans definitely were in North America, although they could have arrived even earlier, the authors say. Fossil footprints are more indisputable and direct evidence than “cultural artifacts, modified bones, or other more conventional fossils,” they wrote in the journal Science, which published the study Thursday. “What we present here is evidence of a firm time and location,” they said. Based on the size of the footprints, researchers believe that at least some were made by children and teenagers who lived during the last ice age. David Bustos, the park's resource program manager, spotted the first footprints in ancient wetlands in 2009. He and others found more in the park over the years. Also read: Fossil leaves may reveal climate in last era of dinosaurs “We knew they were old, but we had no way to date the prints before we discovered some with (seeds) on top,” he said Thursday. Made of fine silt and clay, the footprints are fragile, so the researchers had to work quickly to gather samples, Bustos said. “The only way we can save them is to record them — to take a lot of photos and make 3D models,” he said. Earlier excavations in White Sands National Park have uncovered fossilized tracks left by a saber-toothed cat, dire wolf, Columbian mammoth and other ice age animals.

Bones found in an Israeli quarry are from a branch of the human evolutionary tree and are 120,000 to 140,000 years old, scientists reported Thursday. A team of anthropologists spent years analyzing the fragments of a skull, lower jaw bone and tooth that were uncovered in Nesher Ramla in 2010, comparing them to hundreds of fossils around the world from different eras. The researchers determined that the fossils likely came from a hominin group closely related to Neanderthals and sharing many of their features, such as the shape of the lower jaw. The scientists also believe that there are enough similarities to link this group to other populations found in prior cave excavations in Israel dating to around 400,000 years ago. Also read: Weird ‘living fossil’ fish lives 100 years, pregnant for 5 “The teeth have some unique features that enable us to draw a line between these populations,” said Tel Aviv University dental anthropologist Rachel Sarig, a co-author of the paper published Thursday in the journal Science. This group probably inhabited the region from around 400,000 to 100,000 years ago, said Tel Aviv University physical anthropologist Israel Hershkovitz, another co-author. He said the remains found at Nesher Ramla are likely from “some of the last survivors of a once very dominant group in the Middle East.” Prior research has shown that homo sapiens – modern humans – also lived in the region at the same time. Many scientists believe that the arrival of homo sapiens in Europe presaged the decline of Neanderthals there, but the story may have been different in the Levant region — the crossroads between North Africa and Eurasia. Also read: Researchers discover fossils of new species in Arizona The new findings add to research showing that homo sapiens and Neanderthal-like groups overlapped in the Middle East over a significant amount of time, probably tens of thousands of years. There were likely cultural and genetic exchanges between the groups, the paper authors suggest. “The Neanderthal story can no longer be told as a European story only. It’s a much more complicated story,” said Hershkovitz. Sheela Athreya, a Texas A&M University paleoanthropologist who was not involved in the study, said the new research “gives us a lot to think about in terms of the history of population groups in this region, and how they may have interacted with populations in other regions, in Europe and North Africa.” Also read: Scientists find possible evidence of chromosomes, DNA preserved in dinosaur fossils The Nesher Ramla fossils “look like something on a lineage heading toward Neanderthal,” said Eric Delson, a paleoanthropologist at Lehman College in New York who was not involved in the study. He characterized the findings as “fossils of what appears to be an intermediate variety — this group may be predecessors to Neanderthals in this area.”

The coelacanth — a giant weird fish still around from dinosaur times — can live for 100 years, a new study found. These slow-moving, people-sized fish of the deep, nicknamed a “living fossil,” are the opposite of the live fast, die young mantra. These nocturnal fish grow at an achingly slow pace. Females don’t hit sexual maturity until their late 50s, the study said, while male coelacanths are sexually mature at 40 to 69 years. And maybe strangest of all, researchers figure pregnancy in the fish lasts about five years. Also read: Researchers discover fossils of new species in Arizona Coelacanths, which have been around for 400 million years, were thought extinct until they were found alive in 1938 off South Africa. Scientists long believed coelacanths live about 20 years. But by applying a standard technique for dating commercial fish, French scientists calculated they actually live close to a century, according to a study in Thursday’s Current Biology. Coelacanths are so endangered that scientists can only study specimens already caught and dead. In the past, scientists calculated fish ages by counting big lines on a specific coelacanth scale. But the French scientists found they were missing smaller lines that could only be seen using polarized light — the technique used to figure out the age of commercial fish. Study co-author Bruno Ernande, a marine evolutionary ecologist at France’s marine research institute, said polarized light revealed five smaller lines for every big one. The researchers concluded the smaller lines better correlated to a year of coelacanth age — and that indicated their oldest specimen was 84 years old. Using the technique, the scientists studied two embryos and calculated the largest was five years old and the youngest was nine years old. So, Ernande said, they figured pregnancy lasts at least five years in coelacanths, which have live births. Also read: Rare fishing cat captured in Chattogram village That five-year gestation is “very strange” for fish or any animal, said Scripps Institution of Oceanography’s Harold Walker, who wasn’t part of the research. Even though coelacanths are unrelated genetically and show wide evolutionary differences, they age slowly like other dwellers of the deep, sharks and rays, Ernande said. “They might have evolved similar life histories because they are sharing similar type habitats,” he said.