The headless rider would quickly make friends with an Asian ankylosaurus; where the former mostly misses its head, these dinosaurs are often found without their body. In fact, the lack of bodies of ankylosaurs has dissatisfied paleontologists, who are eager to learn more about how the sturdy herbivores became tanks with a heavily armored tail.
Now an international team of researchers has described the remains of an ankylosaurus from the Gobi Desert in Mongolia, which has expanded the understanding of paleontologists about the diversity and evolution of this family. The team suggests that ankylosaurs used digging for defensive or strategic purposes. Their research on a Cretaceous ankylosaurus – which should not yet be linked to a specific species, as ankylosaurs are described on the basis of their skulls, and this skeleton was found without one – was published today in Scientific reports.
These ankylosaurus fossils are embedded in a mold of a chicken lump. It died about 70 million years ago, and even though it was discovered 50 years ago, it took until 2008 before an excavation team had enough resources and time to analyze the fossil. It was transported to a South Korean laboratory in 2012 to be prepared and returned to Mongolia four years later.
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“Past body skeletons of armored dinosaurs are quite rare,” Yuong-Nam Lee, a paleontologist at Seoul National University in South Korea and co-author of the article, said in an email. ‘The almost complete skeleton we’ve been studying lately provides valuable information about their evolution and behavior. By comparing our specimen with other related dinosaurs, we now know that the armored dinosaurs in Asia developed rigid bodies and reduced the number of pedal phalanges. [toes] through time. ”
You may think that an ankylosaurus with a sturdy body is not news. But Lee’s team found that this Mongolian dinosaur has even less flexibility than its ankylosaurid cousins from North America, perhaps to support their longer tails or because of their molten vertebrae. The authors wrote that the reduced count of the toes is probably an adjustment to support their heavier weight. It would also have reduced the motility of animals, which would have made Asian ankylosaurs even more imaginative than previously thought.
Most importantly, the paleontological team argues that ankylosaurs may have been built to dig. That skeletal stiffness would have stabilized the animal when he dug with his front legs, they write, and the slight curve to his toes would give his front legs a trowel-like shape. The authors do not suggest that ankylosaurs were animals in themselves – more that, while looking out with a ferocious teropod, they could have dug trench-like depressions and been exposed to the surface with their bony skin. Lee compares this behavior to modern horned lizards.
“We’re curious if young ankylosaurs are digging too,” Lee said. ‘Baby ankylosaurs do not have extensive body armor attached to their bodies, and this should have made them vulnerable to predators. If the babies could dig, it would seem possible to live in underground spaces, as armadillos do today. ‘
This is speculative, but if you have a well-articulated skeleton, future paleontologists will give you something more to look at than a thick skull. The authors of the study found perforated holes on the skeleton, evidence of intestinal beetles, known for their appetite for rotting meat. This indicates that the animal has been on post-mortem for at least a while.
“Digging like modern-day elephants like for minerals, food or water, I could see, because this behavior was also suggested for sauropods,” said ReBecca Hunt-Foster, the paleontologist at the Dinosaur National Monument in Utah, who is not connected . with the new paper. ‘They may also have used their diggers to dig nests. However, it can be difficult to deduce behavior from body fossils alone. ”
The researchers also found that five theropod phalanges were embedded in the ribs of the ankylosaurus – it was clear that this dinosaur had good reason to wear so much protection.