CLOSE

How the Club-Tailed Dinosaurs Got Their Clubs

Scientists might now be one step closer to understanding how one of nature’s most formidable weapons evolved.

The ankylosaurs were herbivorous, armor-plated dinosaurs which first appeared around 156 to 152 million years ago and spread out to every continent but Africa. One advanced subgroup known as the ankylosaurids upped the ante with an extra defense mechanism. At the end of their tails, most species had a gigantic club. Weighing up to 45 pounds or more, these bludgeoning tools could have been swung with incredible—perhaps even bone-shattering—force. 

A new paper, published in Journal of Anatomy, argues that the creatures’ firm tails pre-date these powerful clubs. As co-author Victoria Arbour points out, “In order for an ankylosaur to support the weight of a knob and swing it effectively, the tail needs to be stiff, like an axe handle … otherwise, the momentum generated by the knob’s weight could tear muscle or dislocate vertebrae.”

So, which came first, the inflexible tail or the heavy club? Or did they appear simultaneously? To test all three scenarios, Arbour and fellow paleontologist Phillip J. Currie looked over several million years’ worth of ankylosaur evolution, comparing and contrasting such animals as China’s Gobisaurus and the club-less Lianoningosaurus.

They observed that while stiff-tailed ankylosaurids arrived during the early Cretaceous Period (145 to 100 million years ago), clubbed species didn’t make their debut until much later on. So—to re-use Arbour’s “axe” analogy—it looks like the handle predates the blade. “While it’s possible that some of the species could still have developed … [both] in tandem,” she says, “it seems most likely that the tail stiffened prior to the growth of the … knob, in order to maximize the tail’s effectiveness as a weapon.”

Club-less species had other means of protection. Certain species—like North America’s Sauropelta—came with lethal-looking shoulder spikes. Also, stout Gastonia had shark fin-shaped blades running down its tail.

Virtually all ankylosaurs have been described as “tank-like” in appearance. That’s because bony plates called osteoderms covered much of their skin, rendering it all but impenetrable. With predators like T. rex around, such extreme measures were absolutely necessary. 

nextArticle.image_alt|e
iStock
arrow
science
Prehistoric Ticks Once Drank Dinosaur Blood, Fossil Evidence Shows
iStock
iStock

Ticks plagued the dinosaurs, too, as evidenced by a 99-million-year old parasite preserved inside a hunk of ancient amber. Entomologists who examined the Cretaceous period fossil noticed that the tiny arachnid was latched to a dinosaur feather—the first evidence that the bloodsuckers dined on dinos, according to The New York Times. These findings were recently published in the journal Nature Communications.

Ticks are one of the most common blood-feeding parasites. But experts didn’t know what they ate in prehistoric times, as parasites and their hosts are rarely found together in the fossil record. Scientists assumed they chowed down on early amphibians, reptiles, and mammals, according to NPR. They didn’t have hard evidence until study co-author David Grimaldi, an entomologist at the American Museum of History, and his colleagues spotted the tick while perusing a private collection of Myanmar amber.

A 99-million-year-old tick encased in amber, grasping a dinosaur feather.
Cornupalpatum burmanicum hard tick entangled in a feather. a Photograph of the Burmese amber piece (Bu JZC-F18) showing a semicomplete pennaceous feather. Scale bar, 5 mm. b Detail of the nymphal tick in dorsal view and barbs (inset in a). Scale bar, 1 mm. c Detail of the tick’s capitulum (mouthparts), showing palpi and hypostome with teeth (arrow). Scale bar, 0.1 mm. d Detail of a barb. Scale bar, 0.2 mm. e Drawing of the tick in dorsal view indicating the point of entanglement. Scale bar, 0.2 mm. f Detached barbule pennulum showing hooklets on one of its sides (arrow in a indicates its location but in the opposite side of the amber piece). Scale bar, 0.2 mm
Peñalver et al., Nature Communications

The tick is a nymph, meaning it was in the second stage of its short three-stage life cycle when it died. The dinosaur it fed on was a “nanoraptor,” or a tiny dino that was roughly the size of a hummingbird, Grimaldi told The Times. These creatures lived in tree nests, and sometimes met a sticky end after tumbling from their perches into hunks of gooey resin. But just because the nanoraptor lived in a nest didn’t mean it was a bird: Molecular dating pinpointed the specimen as being at least 25 million years older than modern-day avians.

In addition to ticks, dinosaurs likely also had to deal with another nest pest: skin beetles. Grimaldi’s team located several additional preserved ticks, and two were covered in the insect’s fine hairs. Skin beetles—which are still around today—are scavengers that live in aerial bird homes and consume molted feathers.

“These findings shed light on early tick evolution and ecology, and provide insights into the parasitic relationship between ticks and ancient relatives of birds, which persists today for modern birds,” researchers concluded in a news release.

[h/t The New York Times]

nextArticle.image_alt|e
iStock
arrow
science
The Clever Adaptations That Helped Some Animals Become Gigantic
iStock
iStock

Imagine a world in which eagle-sized dragonflies buzzed through the air and millipedes as long as kayaks scuttled across Earth. "Ick"-factor aside for bug haters, these creatures aren't the product of a Michael Crichton fever dream. In fact, they actually existed around 300 million years ago, as MinuteEarth host Kate Yoshida explains.

How did the prehistoric ancestors of today’s itty-bitty insects get so huge? Oxygen, and lots of it. Bugs "breathe by sponging up air through their exoskeletons, and the available oxygen can only diffuse so far before getting used up," Yoshida explains. And when an atmospheric spike in the colorless gas occurred, this allowed the critters' bodies to expand to unprecedented dimensions and weights.

But that's just one of the clever adaptations that allowed some creatures to grow enormous. Learn more about these adaptations—including the ingenious evolutionary development that helped the biggest dinosaurs to haul their cumbersome bodies around, and the pair of features that boosted blue whales to triple their size, becoming the largest animals ever on Earth—by watching MinuteEarth's video below.

SECTIONS

arrow
LIVE SMARTER
More from mental floss studios