On a tree of what is now Myanmar, roughly 99 million years ago, a cousin of the current long-legged spiders lived the best and the worst day of his life (cited Michael Greshko).

Precisely on the most beautiful, perhaps in the prelude to the sexual act, the poor specimen of Halitherses grimaldii remained trapped in a drop of resin suddenly fallen, with a penis as long as half of his body in full erection. A real waste for the animal (not a spider but an arachnid of the order of Opilionidi), a fortune for the researchers who described it as one of the best preserved examples of animal penises set in amber.

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dead alone. Of the partner, in the fossil, there is no trace: the two lovers were separated by a tragic accident or perhaps the erection was only the fruit of the last spasms of death of the spider, which - unlike other males of arachnids and scorpions, which transfer the sperm into the female with modified limbs - boasted a real penis, erected by blood pressure.

Family jewel. But the poor man's sexual habits are not the only interesting fact that emerges from the fossil. These "super-endowed" arachnids, whose body size generally does not exceed 7 mm, have existed for at least 400 million years, and their study may reveal important details on the spread of animal species during the separation of terrestrial plates. But to differentiate them is very difficult, and here the penis comes into play.

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On display. With a certain irony, evolution has hidden the main differences between one species and the other precisely in the male extremity, which never before had shown itself so evidently. "In these animals, the penis is often more important than the shape of the limbs and the body, " confirms Jason Dunlop, first author of the study.

New family. That of the Halitherses grimaldii has a thin trunk, a glans in the shape of a heart and an extremity that seems to twist around itself: characteristics very different from those of the known Opilionidi: the arachnid died during the preliminaries would therefore belong to a new, distinguished family of great amateurs.