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| © From Frank Ippolito, ©American Museum of Natural History Life restoration of Kongonaphon kely, a newly described reptile near the ancestry of dinosaurs and pterosaurs, shown to scale with human hands. The fossils of Kongonaphon were found in Triassic (~237 million years ago) rocks in southwestern Madagascar and demonstrate the existence of remarkably small animals along the dinosaurian stem. |
A "tiny bug slayer" that only reached 4 inches in height was the ancestor of much larger dinosaurs and flying pterosaurs 237 million years ago, according to a new study.
The diminutive fossil was found in Madagascar, where other intriguing fossils have helped researchers paint a picture of unique animals that lived millions of years ago.
The study published Monday in the journal Proceedings of the National Academy of Sciences.
While dinosaurs were some of the largest creatures to walk the Earth and pterosaurs were the largest to ever fly, their origins may be rooted in creatures on a much smaller scale. This would include the newly discovered fossil Kongonaphon kely, a name comprised of a mix of Malgasy and ancient Greek that means "tiny bug slayer."
The fossil was first discovered in 1998 encased in sandstone at a site in Madagascar. The research team was led by American Museum of Natural History Frick Curator of Fossil Mammals John Flynn and included scientists and students from the University of Antananarivo in Madagascar. They have collected hundreds of fossils from the site over the years, Flynn said, which explains why it took so long for them to investigate this particular fossil.
The researchers were intrigued by its small size and tiny pointed teeth, Flynn said. By studying the teeth, they were able to determine that this creature lived on a diet of hard-shelled insects, which helped them come up with its name.
By studying a small slice of the thigh bone, the researchers were able to determine that the tiny creature was not a baby, but a nearly full-grown adult.
"That's critically important for confidently concluding that the ancestors of dinosaurs and pterosaurs were tiny, in contrast to the later dinosaur giants that roamed the landscape or large pterosaurs flying high above them," Flynn said.
The tiny relatives of giant dinosaurs
The researchers believe that Kongonaphon belonged to the early lineage of Ornithodira, the group of animals that contains dinosaurs (including birds) and their relatives, the flying pterosaurs, according to Christian Kammerer, a research curator in paleontology at the North Carolina Museum of Natural Sciences and a former Gerstner Scholar at the American Museum of Natural History."These are among the most iconic prehistoric animals and are well known from plentiful fossils in the Jurassic and Cretaceous periods," Kammerer said. "However, their origins in the preceding Triassic Period are poorly understood.
The Triassic period lasted from 201 to 251.9 million years ago, while the Jurassic period lasted from 145 to 201 million years ago. The Cretaceous period followed between 65.5 and 145.5 million years ago.
"If you want to know how dinosaurs and pterosaurs first evolved, and how they came to be the dominant vertebrates on land for the next 140 million years, you need to know about their ancestry among the early ornithodirans of the Triassic Period."
But fossils from Triassic ornithodirans are very rare, so the discovery of an early one like Kongonaphon is an important piece of the puzzle, Kammerer said.
"There are other small Triassic reptiles, but this is near the lower limit of body size for the broader dinosaurian lineage -- smaller representatives would not appear until the origin of birds," he said.
And this creature is just one of several small early ornithodirans with long legs and light bodies that suggest a "miniaturization event" before larger dinosaurs roamed the land.
"For most of the Triassic Period, the dominant vertebrates on land were 'protomammals' and ancient relatives of crocodiles," Kammerer said.
"But by the end of the Triassic, we find dinosaur fossils in abundance across the globe, seemingly out of nowhere. If our hypothesis is correct and dinosaurs descended from miniaturized ancestors, however, this helps address this problem on several fronts."
These so-called "protomammals" included rat-to-dog-size and potentially furry animals that could be herbivores or carnivores. Some of Kongonaphon's contemporaries between 235 and 245 million years ago during the Mid-to-Late Triassic period may have included larger beaked reptiles, which are now extinct, Kammerer said.
The bones of tiny animals like Kongonaphon and its contemporaries are delicate, so they don't preserve well in the fossil record. They also couldn't outpace existing animals, but these dinosaur ancestors could fill niches in their ecosystems like munching on insects, while crocodile relatives were interested in meat, Kammerer said.
Finding more fossils, especially skulls and teeth, from reptile contemporaries of Kongonaphon, will help researchers learn more about this period of time when creatures were smaller.
Previously, it was believed that early ornithodirans and the first dinosaurs had a similar body size before they grew to become giants over time. However, by studying their body sizes, the researchers actually noted a decrease early in the dinosaur lineage, indicating the miniaturization event.
Kongonaphon and other early ornithodirans may also explain why dinosaurs and pterosaurs had "fuzz" or feathers on their skin. Smaller dinosaur relatives would have had a hard time regulating their body temperatures and retaining heat. During their time, the days were hot but the nights were cold, according to research about the Triassic climate.
Madagascar's time capsule
The discovery of Kongonaphon and other fossils highlights the unique role of Madagascar."Discovery of this tiny relative of dinosaurs and pterosaurs emphasizes the importance of Madagascar's fossil record for improving knowledge of vertebrate history during times that are poorly known in other places," said Lovasoa Ranivoharimanana, study coauthor and professor and director of the vertebrate paleontology laboratory at the University of Antananarivo in Madagascar, in a statement.
"Over two decades, our collaborative Madagascar-U.S. teams have trained many Malagasy students in paleontological sciences, and discoveries like this helps people in Madagascar and around the world better appreciate the exceptional record of ancient life preserved in the rocks of our country."
Madagascar is one of the few remaining places on Earth that includes fossils from the Early and Mid-to-Late Triassic helping to fill gaps in the record, the researchers said.
Going forward, the researchers still have questions about Kongonaphon and whether it was more closely related to dinosaurs or pterosaurs. The scientists also want to investigate why and how the unexpected miniaturization event occurred and how it changed animals.
"Often, new discoveries like Kongonaphon create unexpected research avenues to pursue," Flynn said.
"We're so glad that our decades-long partnership with colleagues in Madagascar will allow us to both answer important scientific questions while also helping to train the next generation of Malagasy scientists, inform and engage the public in understanding science, and build important bridges and friendships across our communities and cultures."
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