It’s hard not to be awed by nature’s big predators, but learning more about megalodons – giant sharks that prowled the oceans millions of years ago and were three times the size of today’s great whites – can take that fascination to the next level. Three researchers who analyze the chemistry of fossils – in this case, hand-size megalodon teeth – explain how they have gotten clues about this creature’s diet and perhaps how it died out. Also, don’t miss the story on how hammerhead sharks evolved to have their crazy-shaped heads.

One of our most-read stories from the past week examined food expiration dates and the lack of any science behind most of them. University of South Florida public health researcher and microbiologist Jill Roberts explains how various labels can be generated, describes how science-based approaches differ and offers some advice: “In the absence of a uniform food dating system, consumers could rely on their eyes and noses, deciding to discard the fuzzy bread, green cheese or off-smelling bag of salad.”

University of Michigan biomedical scientist Ashu Tripathi offers a compelling case for focusing more research on natural compounds that can be used in drugs, including much-needed antibiotics. He notes that roughly 75% of antibiotics are derived from nature, but finding naturally occurring compounds that fight microbes comes with some challenges, which have contributed to this practice’s falling out of favor since the 1980s. “I believe that undiscovered treatments for a wide range of diseases are lying right under our noses in natural products,” he writes.

Also in this week’s science news:

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Megalodon would have dwarfed today’s great white sharks. Christina Spence Morgan

Megalodon sharks ruled the oceans millions of years ago – new analyses of giant fossilized teeth are helping scientists unravel the mystery of their extinction

Emma Kast, University of Cambridge; Jeremy McCormack, Goethe University Frankfurt am Main; Sora Kim, University of California, Merced

Megalodon, the world’s largest known shark species, swam the oceans long before humans existed. Its teeth are all that’s left, and they tell a story of an apex predator that vanished.

Without obvious signs of contamination like the mold in this jam, consumers use expiration dates to decide whether to keep or throw away food. Ralf Geithe via iStock/Getty Images

Food expiration dates don’t have much science behind them – a food safety researcher explains another way to know what’s too old to eat

Jill Roberts, University of South Florida

Current expiration date system leads to confused consumers and wasted food.

Around 75% of antibiotics, including penicillin and amphotericin B, are derived from natural products. Aphiwat Chuangchoem/EyeEm via Getty Images

Nature is the world’s original pharmacy – returning to medicine’s roots could help fill drug discovery gaps

Ashu Tripathi, University of Michigan

With the dual threats of antibiotic resistance and emerging pandemics, finding new drugs becomes even more urgent. A trove of medicines may be lying under our nose.