99-million-year-old ticks sucked the blood of dinosaurs

Ticks may be a disease-carrying menace for hikers and pets, but they’re also masters of survival: The parasites were sucking the blood of dinosaurs 99 million years ago, according to a set of amber fossils from Myanmar. One of the samples, in which a tick is hanging onto a dino feather, provides the oldest direct evidence of what these ancient parasites ate.

The find is a “paleontologist’s dream,” says Ricardo Pérez-de la Fuente, a paleontologist at the Oxford University Museum of Natural History in the United Kingdom who helped lead the work.

The amber samples—hardened tree resin that can preserve animals trapped within in exquisite detail—held several clues showing that ticks fed on dinosaurs. The most direct evidence comes from the tick grasping a feather that belonged to a theropod dinosaur, a member of the group that ultimately gave rise to modern birds. Another includes two ticks together, both of which have hairs stuck to them from a type of beetle larvae thought to live in dinosaur nests.

It’s unusual to find a parasite and remains of its host preserved together, and this is the first direct evidence we have that ancient ticks sucked dinosaur blood, says Pérez-de la Fuente. “It shows that the relationship between ticks and birds is an ancient one: It was present in the ancestors of both lineages.” (Many modern ticks feed on birds.)

The samples—reported today in Nature Communications —come from a famous amber deposit in Myanmar thought to be 99 million years old. They were originally purchased from amber dealers by private collectors, who later donated the samples to museums. Scott Anderson, an amber collector in Pennsylvania, described one of the specimens, a blood-filled tick about half a centimeter long, at a paleontology meeting a few years ago. He was originally hoping that the blood might contain recoverable DNA, but it did not. He then teamed up with Pérez-de la Fuente and other colleagues to better characterize several of his samples. The researchers determined the specimens were a previously undescribed species of tick, which they named Deinocroton draculi, or “Dracula’s terrible tick.”

The hairs stuck to the two D. draculi closely resemble those found on a certain type of beetle larvae. Today, these beetle larvae live in bird and mammal nests, feeding on sloughed-off skin and feathers. They use the sticky hairs to fend off predators, and the hairs can end up collecting to form thick mats in nests where the beetle larvae reside, says Pérez-de la Fuente. “The most likely scenario is that the two ticks got entangled with the hairs when visiting the nest of a feathered dinosaur.”

That’s plausible, says Ryan McKellar, a paleontologist at the Royal Saskatchewan Museum in Regina, Canada, who was not involved with the work. For the beetle hairs to be preserved alongside a pair of ticks suggests they were trapped in the resin fairly close to wherever they encountered the beetle larvae. That was likely a nest, he says, although it’s not clear what animal might have built the nest. “The authors have done a fantastic job of extracting every possible clue from these ancient snapshots.”