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Finding a fossil in a coal mine is no big deal. Coal deposits, after all, are petrified peat swamps, and peat is made from decaying plants, which leave their imprints in mud and clay as it hardens into shale stone. But it was a different thing entirely when John Nelson and Scott Elrick, geologists with the Illinois State Geological Survey, examined the Riola and Vermilion Grove coal mines in eastern Illinois. Etched into ceilings of the mine shafts is the largest intact fossil forest ever seen—at least four square miles of tropical wilderness preserved 307 million years ago. That's when an...

Bird wings clearly share ancestry with dinosaur "hands" or forelimbs. A school kid can see it in the bones. But paleontologists have long struggled to explain the so-called digit dilemma. Here's the problem: The most primitive dinosaurs in the famous theropod group (that later included Tyrannosaurus rex) had five "fingers." Later theropods had three, just like the birds that evolved from them. But which digits? The theropod and bird digits failed to match up if you number the digits from 1 to 5 starting with the thumb. Theropods looked like they had digits 1, 2 and 3, while birds have...

A 250-million-year shutdown of volcanic activity which is thought to have occurred early in Earth's history may be what turned the planet into a glacier-covered snowball. It could also have helped give rise to our oxygen-rich atmosphere. Previous studies have noted that very little volcanic material has been dated to between 2.45 and 2.2 billion years ago, but it was widely assumed the gap would vanish as more samples were dated. Now an analysis of thousands of zircon minerals collected from all seven continents indicates that the gap may be real after all. Zircons provide a record of past volcanic...

The oldest known human hair belonged to a 9,000-year-old mummy disinterred from an ancient Chilean cemetery. Until now: a recent discovery pushes the record back some 200,000 years. (And the newly discovered strands received a rather less dignified burial.) While excavating in Gladysvale Cave, near Johannesburg, South Africa, a team of researchers from the University of the Witwatersrand discovered an ancient brown-hyena latrine. Upon inspection, hyena coprolites - fossilized dung - appeared to contain uncannily hair-like structures.