Millions of years ago, during the mid-Mesozoic Era, the dinosaurs were, too, plagued by pests – jumbo-sized flea-like insects that were sneaky enough to suck their blood. These fleas were able to live and tell the tale, as evident by the fossils discovered earlier this year by a group of Chinese researchers in Inner Mongolia.

“These are really well-preserved fossils that give us another glimpse of life into the really distant past,” Oregon State University zoologist George Poinar, Jr states in the university’s press release. Poinar, who researches insect pathology and studies insects (including “‘younger fleas from 40-50 million years”) fossilized in amber, wrote a commentary on the Chinese researchers’ paper, both of which were published in the April 24 issue of the online journal Current Biology.

Two types of species were found: Pseudopulex jurassicus and Pseudopulex magnus, both of which are now the oldest known parasites. The former is smaller and from the middle Jurassic Epoch (approx. 170-160 million years ago). The latter – the larger of the two – lived during the Early Cretaceous Period (approx. 140-100 million years ago), and is the one that sucked blood from dinosaurs.

Although this ancient flea shares many of the anatomical features of the modern flea, they differ in certain aspects. Built to maneuver through fur and hair of smaller mammals, modern fleas are miniscule and compressed and have short antennae.

The Pseudopulex magnus, on the other hand, had a much bigger (and flatter) body, which was around the size of an inch. Its size hints that the flea may have fed on larger animals, including medium-sized mammals and dinosaurs. Because it did not have any extended hind legs, it had not been able to jump.

The Pseudopulex magnus bore long claws that helped them climb on and latch onto the dinosaur’s large scales. It fed itself with a rather large proboscis – one that looks like a hypodermic needle – that would have been able to pierce the soft areas of flesh between the tough scales.

Its bite would be excruciating for mammals and humans alike if this humongous flea were alive today. “We can be thankful our modern fleas are not nearly this big,” says Poinar. Either the dinosaurs did not feel the needle-like proboscis, or the Pseudopulex magnus was quick enough to make a dine and dash.

Poinar states in his commentary that modern fleas may be related to this ancient insect, though they may not be descendants from a direct lineage, and have mostly likely descended from a branch of another species, which is now extinct.

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About the author

Sarah Hansen
Sarah is currently earning her M.F.A. in Creative Nonfiction at Sarah Lawrence College. She has an avid interest in the sciences, particularly astronomy, and hopes to one day publish works of fiction, poetry, and creative nonfiction.