Fossil Proves Ticks Feasted on Dinosaurs 100 Million Years Ago

Hard tick grasping a dinosaur feather preserved in 99 million-year-old Burmese amber. Modified from the open access article published in Nature Communications: ‘Ticks parasitized feathered dinosaurs as revealed by Cretaceous amber assemblages.’ (Photo courtesy paper’s authors)

(CN) – A newly discovered fossilized tick trapped and preserved in amber serves as the first evidence that the blood-sucking creatures lived on feathered dinosaurs as early as 99 million years ago, according to a new study.

The fossil, described Tuesday in the journal Nature Communications, offers rare, direct insight into the relationship between ticks and their hosts. The specimen is the oldest known tick fossil.

While the discovery may conjure images of “Jurassic Park,” the fossil will not yield any dinosaur-building DNA, as all efforts to extract DNA from amber specimens have failed due to the brief life of the complex molecule.

“Ticks are infamous blood-sucking, parasitic organisms, having a tremendous impact on the health of humans, livestock, pets, and even wildlife, but until now clear evidence of their role in deep time has been lacking,” said Enrique Penalver from the Spanish Geological Survey and the lead author of the study.

Cretaceous amber offers a glimpse into the world of feathered dinosaurs, some of which developed into modern-day birds.

“The fossil record tells us that feathers like the one we have studied were already present on a wide range of theropod dinosaurs, a group which included ground-running forms without flying ability as well as bird-like dinosaurs capable of powered flight,” said co-author Ricardo Perez-de la Fuente, a research fellow at Oxford University Museum of Natural History in the United Kingdom.

“So although we can’t be sure what kind of dinosaur the tick was feeding on, the mid-Cretaceous age of the Burmese amber confirms that the feather certainly did not belong to a modern bird, as these appeared much later in theropod evolution according to current fossil and molecular evidence.”

The team also found indirect evidence of dinosaurs hosting Deinocroton draculi, or “Dracula’s terrible tick,” which was a member of a newly described group of the blood-sucking creatures. The new species was also preserved in Burmese amber. One of the specimens was so swollen with blood that it was about eight times the size of its non-engorged companions. Its host animal could not be directly determined.

“Assessing the composition of the blood meal inside the bloated tick is not feasible because, unfortunately, the tick did not become fully immersed in resin and so its contents were altered by mineral deposition,” said Xavier Delclos from the University of Barcelona, a co-author of the study.

Indirect evidence of the likely host of these ticks was found in the form of hair-like structures known as setae, from the larvae of skin beetles, or dermestids. The larvae was found attached to Deinocroton ticks that were preserved together. Modern skin beetles feed in nests, consuming the feathers, hair and skin of the nest’s inhabitants.

As no mammal hairs have been found in Cretaceous amber, the discovery of skin beetle setae on the two specimens of Dracula’s terrible tick suggests that a feathered dinosaur hosted the ticks.

“The simultaneous entrapment of two external parasites – the ticks – is extraordinary, and can be best explained if they had a nest-inhabiting ecology as some modern ticks do, living in the host’s nest or in their own nest nearby,” said David Grimaldi of the American Museum of Natural History, a co-author of the study.

While birds were the only lineage of theropod dinosaurs to survive the mass extinction event at the end of the Cretaceous roughly 66 million years ago, the findings further illustrate that ticks did not just cling on for survival, they thrived.

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