A 90-million-year-old tick recently found in the heart of New Jersey has left entomologists scratching their heads.
The tick is the oldest representative of the order Parasitiformes, increasing the order’s age by 50 million years, said Hans Klompen, an assistant professor of entomology at Ohio State University.
Tick experts currently believe that these insects evolved in South America.
“The idea that ticks originated in South America has not been helped by this find,” Klompen said. “The specimen is old enough that it should not have been found in New Jersey.”
Klompen describes the New Jersey tick, formally called Carios jerseyi, in the current issue of the journal Annals of the Entomological Society of America. He co-authored the paper with David Grimaldi of the American Museum of Natural History in New York City. In the mid-1990s, workers from the museum discovered the tick – along with several other species of plants and animals – in an 80-pound amber outcrop excavated from a vacant lot in central New Jersey. The museum asked Klompen to describe and categorize the tick.
What puzzles him just as much as the climatic conundrum are the three dozen or so tiny bristle-like hairs aligned in two rows on the back of the tick. It’s unlike anything that Klompen says he’s seen on ticks.
“It was very surprising,” he said. “Soft ticks normally have far fewer hairs over their entire body. But this tick is much closer to what I anticipate as the evolutionary starting point of all ticks.”
Carios jerseyi is an argasid, or soft tick. The tick, estimated to be anywhere from 90 to 94 million years old, was fossilized in its larval stage. Entomologists know more about hard ticks (or ixodids) because of a more extensive fossil record. Still, the age of the oldest hard tick on record is a mere 35 to 40 million years.
The tick measures 520 by 445 micrometers (or 0.02 by 0.01 inches.) It’s not easy to fit C. jerseyi in with a specific group of ticks, Klompen said, not because of its size, but because of its physical characteristics. He’s not sure what purpose the neatly aligned hairs across the tick’s backside serve.
“Most of the hairs on the body of a mite or a tick are probably contact receptors,” he said. “If something gets too close, the tick notices it’s there. Other argasids have hairs, but they’re typically much longer and arranged chaotically.”
Carios jerseyi did live at the same time as the dinosaurs, and Klompen admits that it’s possible that the tick and its kin could have fed on the animals. “Ticks will feed on anything that has blood,” he said. But what C. jerseyi fed on will remain a mystery for the present time, since scientists want to preserve the specimen – the only one of its kind – in its current form. Besides, fossilized ticks are a rarity.
“Would ticks feed on dinosaurs if dinosaurs were still around today? You bet,” Klompen said. “Nearly all soft ticks will feed on a wide range of hosts. If it has blood, a soft tick will go for it.”
Rather than feasting on dinosaurs, Klompen says, it’s more likely that C. jerseyi fed on sea-faring birds. At least that’s one theory on how the tick got to New Jersey.
Carios jerseyi shows similarities to a group of ticks known for feasting on birds. And a small feather (7.5 mm, or 0.3 inches) from an unidentified bird was also found preserved in the same outcrop of amber. “Finding this feather suggests that the tick might have traveled to North America on a seabird,” Klompen said.
“And with what we currently know about the ancestral stomping grounds of ticks, this tick would had to have a host to get to New Jersey,” he said. “And it almost had to be a host that flew.”
Finally, Klompen tells those musing about the possibilities of creating a dinosaur from blood consumed by a tick not to hold their collective breaths. The tick did live during what’s known as the upper Cretaceous period, when dinosaurs roamed the earth. But, Klompen says, “You won’t reconstruct a dinosaur from the blood of a blood-feeding arthropod.”