How did dinosaurs sleep?

ROWENA BROSNAN, MANCHESTER

As strange as it might be to imagine, dinosaurs would have slept. Would they lie down, or sleep standing up? Would they take quick rests or long slumbers? We don’t really know the answers. But there is one dinosaur whose sleep habits are well understood: the tiny puppy-sized troodontid theropod Mei long, a close relative of birds. Two skeletons of this 125-million-year-old dinosaur have been found fossilised in a sleeping position (pictured). It seems as if a volcanic eruption suffocated and buried these dinosaurs while they were napping, similar to how some humans were caught unaware at Pompeii by the eruption of Mount Vesuvius. The skeletons are in the same ‘tuck in’ sleeping posture of today’s birds: the body sits on folded limbs and the head is tucked in between the arm and torso. Birds sleep this way to conserve heat in their heads – a necessity for warmblooded animals. Perhaps this is a sign that some dinosaurs were warm-blooded too. SB

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