A long-standing mystery surrounding dozens of unusually small dinosaur fossils has finally been solved.
A specimen once thought to be a small type of armored dinosaur is now confirmed to be a young ankylosaurid. The discovery gives researchers a clearer picture of how these heavily armored dinosaurs grew and developed.
Liaoningosaurus fossils confused scientists for decades
The fossil belongs to a species called Liaoningosaurus paradoxusa name that reflects the confusion it caused. Since it was first described in 2001, it has been classified as ankylosaurid, known for its strong armored body.
However, all known fossils of this species are surprisingly small, measuring less than 40 centimeters in length. This size is much smaller than what scientists expect for adult ankylosaurids, which often grow to over 3 meters.
No larger specimens have ever been discovered, so some researchers have suggested that this may be a rare case of a small ceratopsian. Some even suggested that this animal may have lived partially in water.
New findings published in the Journal of Vertebrate PaleontologyOpens in new window cast doubt on these ideas. These fossils likely represent juvenile dinosaurs, rather than small adults. One specimen even shows signs of being a hatchling, making it the youngest ankylosaurus ever discovered.
Professor Paul Barrett, one of our dinosaur experts and co-author of the study, said:Liaoningosaurus Much is unknown about this species, and adults have not been identified, causing much debate. ”
“However, our research confirms that these dinosaurs were baby dinosaurs, rather than small adults. Young ankylosaurus fossils are rare, so these fossils have a lot they can tell us about the early development of armored dinosaurs.”
Bone growth analysis reveals young age
Because everything is known Liaoningosaurus The fossils were similar in size, and it was not possible to determine whether they were adults or juveniles based on body length alone. To answer that question, scientists looked at the microstructure of bone.
Similar to tree rings, bone tissue contains growth lines that mark each year of an animal’s life. The number and spacing of these lines tells us both age and growth rate.
The researchers took bone from two specimens. One is the largest ever discovered and the other is the smallest.
Neither fossil shows growth lines, indicating that both individuals are less than a year old. The smaller specimen also had bone features typical of very early developmental stages.
“This small fossil showed features found in other newborn dinosaurs, such as the presence of hatching lines,” Paul said.
“This is a small ring-like feature on the bones of animals when they hatch from eggs. So we can say that this individual hatched very recently when it died, making this the first hatched ankylosaurus we’ve ever found.”
Fossil ruins in China preserve details of ancient life
all known Liaoningosaurus The fossils come from northeastern China’s Liaoning province, which is famous for its highly preserved fossils from the Cretaceous period, which dates from 145 to 66 million years ago. The area also produces feathered dinosaurs, including: microraptor and Sinornithosaurus.
Fossils were formed when dead animals sank to the bottom of shallow lakes. Frequent volcanic activity covered the lake bed with ash, helping preserve details and providing a vivid snapshot of life at the time.
What baby ankylosaurus reveals about dinosaur growth
Even though I’m an adult Liaoningosaurus Although no specimens have yet been found, these young fossils still provide valuable clues about the development of ankylosaurs.
Fossil evidence of juvenile ankylosaurs is rare, and most known examples lack the characteristic armor seen in adults. This has led some scientists to believe that armor was developed later in life.
but, Liaoningosaurus Fossils show that at least some armor was already present at a very early stage.
“We have found very few baby fossils, so Liaoningosaurus “This is the only valid way to know what ankylosaurs look like right after they hatch,” says Paul.
” Liaoningosaurus The fossil had already developed some armor. Now that we know that they are babies and not adult miniatures, we can say that this type of trait was acquired fairly early in their development. ”
“But even greater insight would come if we could find adults as well. Then we could see the differences between adults and babies of the same species and learn how those traits develop.”
