Jurassic Giant Fleas Likely Preyed Upon Hairy or Feathered Hosts

Writing in the journal Nature this week, KU entomologist Michael Engel and an international research team have described the oldest definitive fleas to date: giant fleas from the Middle Jurassic and Early Cretaceous of China.

The findings by Engel, André Nel and colleagues show that these ancient fleas were wingless and distinctly larger than recent fleas with body lengths of 14–20.6 mm (.5 to almost an inch) in females and 8–14.7 mm (about .25-.5 inch) in males. They also had many defining features of fleas while they retained primitive traits, such as non-jumping hind legs.

Their most impressive feature, however, was their long and serrated suctorial siphon, which was used for piercing the hides of their hosts. These were longer in females than in males. The authors note that an apparent difference between these and modern fleas is the size of the mouthpart, which are relatively shorter in today’s examples. However, they are proportionally about the same length relative to overall body size in both the ancient and modern flea.

The discovery also provides a clue as to the development of chosen hosts for fleas. The fleas’ special morphology suggests that they had hairy or feathered ‘reptilian’ hosts before moving on to mammals and birds later on.