An international team says that these flea-like animals -- Pseudopulex jurassicus and Pseudopulex magnus -- similar but not identical to modern fleas, were probably 10 times the size of a flea often seen crawling on the family dog -- with an extra-painful bite to match.
"These were insects much larger than modern fleas and from the size of their proboscis we can tell they would have been mean," Prof George Poinar at Oregon State University, who led the team, wrote in the 'Current Biology' journal.
The palaeontologists claim that these giant fleas crawled onto a huge dinosaur's soft underbelly and give it a bite that might have felt like a needle going in.
Prof Poinar said: "It would have felt about like a hypodermic needle going in -- a flea shot, if not a flu shot. We can be thankful our modern fleas are not nearly this big."
He said it's possible that the soft-bodied, flea-like insects found in these fossils from Inner Mongolia are the evolutionary ancestors of modern fleas, but most likely they belong to a separate and now extinct lineage. (MORE) PTI MOT MOT