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North Carolina Museum of Natural Sciences, Flickr // CC BY-NC-ND 2.0
North Carolina Museum of Natural Sciences, Flickr // CC BY-NC-ND 2.0

10 Ridged Facts About Acrocanthosaurus

North Carolina Museum of Natural Sciences, Flickr // CC BY-NC-ND 2.0
North Carolina Museum of Natural Sciences, Flickr // CC BY-NC-ND 2.0

This intimidating predator would look great on the big screen. Ahem, Steven Spielberg...

1. Acrocanthosaurus is the Official State Dinosaur of Oklahoma.

Acrocanthosaurus was discovered in Oklahoma’s Atoka County in the 1940s, and in 2006, it was declared the state’s official dinosaur—even though it already had a state fossil (another big carnivore named Saurophaganax). 

2. It Wasn’t Much Smaller than T. Rex.


While there aren't any complete specimens, most paleontologists estimate that a fully-grown Acrocanthosaurus would have been around 35 to 38 feet long. By comparison, Tyrannosaurus rex could reach about 40 feet. Both rank among the biggest meat-eating dinosaurs ever found.

3. Those Arms Might Have Helped it Ensnare Prey.

According to one 2006 studyAcrocanthosaurus’ forelimbs had a very limited range of motion. Still, despite that shortcoming, analysis revealed that the arms would have been quite adept at pulling things toward the animal's torso. Perhaps Acrocanthosaurus came up to victims from behind, sank its claws into them, and held on tight while chomping like mad.

4. Acrocanthosaurus Didn’t Keep its Chin Up.  

A 2005 computer simulation found that, given the shape of its inner ear (which helps creatures keep balanced), Acrocanthosaurus habitually let the tip of its snout point 25 degrees downward rather than straight ahead. 

5. The Dinosaur Might Have Stalked Maryland.

Though far better remains are known from Oklahoma and Texas, Acrocanthosaurus-like teeth have been found in the Old Line State.

6. A Similar-Looking Dinosaur Lived in England.

Becklespinax was 16 feet long and lived in the UK from 142 to 132 million years ago. Its name references some long spines that protruded from its vertebrae—much like the ones we see on Acrocanthosaurus. The two are widely thought to be relatives.

7. Many Footprints Have Been Attributed to Acrocanthosaurus.


Dinosaur Valley State Park in Glen Rose, Texas is loaded with 112-million-year-old fossilized track ways, most of which were probably made by passing Acrocanthosaurus. Some especially cool prints even hint at a prehistoric battle: While exploring the area in the ‘40s, explorer Roland T. Bird noticed a set of theropod tracks running parallel to some that were left by a sauropod. At one point, the predator appears to have broken stride and taken two consecutive right steps.

Why would it do this? Maybe the carnivorous theropod had latched on to the much bigger, long-necked herbivore. But the sauropod’s tracks show no change in spacing or direction—so if this particular animal was indeed under attack, it was weirdly relaxed about it.

8. The Animal Has Proven Very Difficult to Classify.

Acrocanthosaurus has been viewed as a close cousin of Allosaurusa North American predator that died out long before the ridge-backed dino came along. It’s also been lumped closer to a humongous carnivore from Africa known as Carcharodontosaurus. Thankfully, the water got slightly less murky in 2011. By comparing and contrasting several anatomical features, including the brain cavity, paleontologists Drew R. Eddy and Julia A. Clarke found that while Acrocanthosaurus definitely shared a common ancestor with Allosaurus, the dinosaur really belongs to Carcharodontosaurus’ family.

9. Acrocanthosaurus Had Plenty of Dietary Options.

One hundred and twenty-five million years ago, this massive carnivore shared its range with such sauropods as Astrodon and the 60-foot-tall Sauroposideon. A beaked, long-tailed plant-eater called Tenontosaurus was also available.

10. The North Carolina State Museum of Natural Science Once Paid $3 Million for One.

North Carolina Museum of Natural Sciences, Flickr// CC BY-NC-ND 2.0

Over the past 25 years, dinosaur skeletons have gotten absurdly expensive. In 1997, the Chicago Field Museum—backed by corporate sponsors—bought Sue, a T. rex skeleton that's 90 percent complete, for $8.36 million at auction. Shortly thereafter, the North Carolina State Museum of Natural Science found itself shelling out $3 million to secure a handsome Acrocanthosaurus from southern Oklahoma


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Prehistoric Ticks Once Drank Dinosaur Blood, Fossil Evidence Shows
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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]

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The Clever Adaptations That Helped Some Animals Become Gigantic
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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.

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