One of the fossilized bugs, discovered by researchers Capital Normal University in Beijing, was found to be full of iron, suggesting the insect perished just after sucking animal blood. It's the earliest example of a blood-feeding insect.
The specimen was found by researcher Dong Ren in China's fossil-rich Yixian Formation. The species and family of insects these specimens belong to has yet to be determined, but are some the earliest ancestors of true bugs.
True bugs, insects of the Hemiptera order, are so called because they have have specialized mouth parts used to suck plant juices and animal fluids. All true bugs are insects, but not all insects are true bugs. Modern true bugs include insects like cicadas, bed bugs and aphids. Bees, for example, which use a retractable mouth part, are not true bugs but Hymenoptera -- a separate order. Mosquitos aren't true bugs either, as they are part of the Diptera order, which also includes flies.
There's no way to prove whether the bugs dined on dino blood or not. But given the specimens were dated to the Cretaceous period, the height of the dinosaurs' reign, it's hard to imagine the bloodsuckers didn't stop over for lunch on the back of a Tyrannosaurus rex or Triceratops.
Ren's study was published in the journal Current Biology.