Imagine finding a flea that's about an inch-long. You would, if you live in 165 million years ago in the Jurassic period. Well, dinosaurs are big, so it makes sense that their fleas would also be big:
Today, the varied group of parasitic insects known as fleas frequently infests mammals and birds. But little is known about their origins. The flea fossil record consists mainly of modern-looking species from the past 65 million years, and the identity of possible fleas from the Cretaceous period (145 million to 65 million years ago) has been debated by experts. But Michael Engel, a palaeoentomologist at the University of Kansas in Lawrence, and his colleagues have now extended the history of the parasites by at least 60 million years. Their work is published online today in Nature1.
Engel and his co-authors studied nine flea specimens from two sites: the 165-million-year-old Jurassic deposits in Daohugou and the 125-million-year-old Cretaceous strata at Huangbanjigou, both in China. The insects were not quite like fleas as we now know them. Whereas modern fleas range from 1 to 10 millimetres in length, the Jurassic and Cretaceous species were between 8 and 21 millimetres. “These were hefty insects as far as fleas are concerned,” says Engel.