Ticks, as we know them today, are pesky parasites that feed on the blood of mammals and birds. They’re also a resilient insect that existed long before the appearance of mammals, leading scientists to ask the question: Whose blood did they feed on before mammals?

Amber, hardened tree resin, from a well-known deposit in Myanmar is providing new clues. Scientists, including Ricardo Pérez-de la Fuente, from Oxford University Museum of Natural History, and David Grimaldi, from the American Museum of Natural History, examined the amber samples and found a tick grasping onto a feathered dinosaur.

“Here, we report direct and indirect evidence in 99 million-year-old Cretaceous amber showing that hard ticks and ticks of the extinct new family Deinocrotonidae fed on blood from feathered dinosaurs,” according to the study’s abstract.

In another piece of amber, two ticks are attached to microscopic hairs that are similar to hairs found on a type of a beetle larvae, which today are found in birds nests.

“The most likely scenario is that the two ticks got entangled with the hairs when visiting the nest of a feathered dinosaur,” Pérez-de la Fuente, one of the study’s lead authors, told Science.

Another piece of amber included a tick after feeding, however the blood in the tick could not be analyzed because it was contaminated, according to NPR.

Prior to this study, scientists thought that ticks may have fed on early amphibians, reptiles, or ancestors of mammals, according to paleontologist Ben Mans, who was not part of the study. Mans told NPR, “The paper is a pleasant surprise.”