As early as 252 million years ago, some plants may have curled up their leaves at night for a cozy “sleep.”
Fossilized leaves of two now-extinct Gigantonoclea species bear signs of nyctinasty, or circadian rhythmic folding at night, researchers report February 15 in Current Biology. That would make these specimens the first known fossilized examples of this curious plant behavior, the team says.
The two leaf fossils were discovered in a rock layer in southwestern China that dates to between 259 million and 252 million years ago. In both species, the leaves were broad, with serrated edges. But most curiously, they bear oddly symmetrical holes.
Symmetrical leaf damage
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