Digging Deep Into Ankylosaurid Behavior

Best known for their heavily fortified exterior, ankylosaurids may have also defended themselves against large land predators through digging.

AsianScientist (Mar. 22, 2021) – Scientists have unearthed fossilized remains of an ankylosaurid in Mongolia’s Gobi Desert, revealing that these armored dinosaurs may have been able to dig. Their findings were published in Scientific Reports.

Though they may resemble a Pokemon’s fully evolved form thanks to their body armor, ankylosaurids were real-life dinosaurs that lived sometime between 84 to 72 million years ago during the Cretaceous Period. Wide and bulky with short, powerful limbs, these dinosaurs are best known for the spiky bony protrusions studding their skin as well as their large tail club capable of crushing bone.

Despite their formidable exterior, ankylosaurids were mostly herbivorous. Accordingly, their heavy armor offered the dinosaurs protection from large land predators—including the famed Tyrannosaurus rex. Such predators would have had to flip over the armored dinosaur to reach its Achilles’ heel—or rather, underbelly.

However, the armor may not have been the ankylosaurids’ only defense. After examining a specimen excavated from Mongolia’s Gobi Desert in 2008, Professor Lee Yuong-Nam and his colleagues from Seoul National University observed several anatomical features that indicate that the dinosaurs may have also been adapted to digging.

For instance, the bones in the specimen’s front feet were arranged in a shallow arc, which could have allowed ankylosaurids to dig soft earth. In contrast, the decreased number of bones in its hindfeet, compared to other dinosaurs, may have acted as an anchor to stabilize the ankylosaurids as they dug into the ground. Likewise, the specimen’s unique, squat body shape—wider in the middle and narrower at the front and rear—may have helped its body remain straight while digging.

Though hunkering down has long been assumed to be the go-to defense of ankylosaurids, crouching down into the shallow pits they had dug may have made it more difficult for predators to turn them over—helping the dinosaurs protect their limbs and vulnerable underbelly.

“Anatomical features discussed in this paper could be good supporting evidence for the surface digging ability of ankylosaurids,” concluded the authors. “Taking advantage of digging, ankylosaurids may have [also] been able to dig out roots for food, dig wells to reach subsurface water, or dig into the sediments so they could find supplementary minerals to consume as modern African elephants do today.”

The article can be found at: Park et al. (2021) A new ankylosaurid skeleton from the Upper Cretaceous Baruungoyot Formation of Mongolia: its implications for ankylosaurid postcranial evolution.


Source: Scientific Reports; Photo: Yusik Choi.
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