A family of harvestmen that inhabits tropical forests on both sides of the Pacific Ocean originated in Mesoamerica roughly 82 million years ago. The arachnids' migration is a rare example of a trans-Pacific dispersal.
Prashant Sharma and Gonzalo Giribet at Harvard University in Cambridge, Massachusetts, sequenced and analysed DNA from 147 specimens from the sister superfamilies of Zalmoxoidea (a member pictured) and Samooidea. The authors conclude that the species spread from the Amazon Basin across the Pacific and settled on islands of the Indo-Pacific.
The creatures probably did not disperse through the break-up of the supercontinent Gondwana, so the authors speculate that they made their way across the Pacific on floating vegetation carried by ocean currents.
Proc. R. Soc. B http://dx.doi.org/10.1098/rspb.2012.0675 (2012)
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Arachnids crossed the Pacific. Nature 485, 550 (2012). https://doi.org/10.1038/485550a