Study says giant dinosaurs may have evolved from miniature insect-eating animals

Research led by scientists at the American Museum of Natural History suggests that the dinosaur-era giant reptile was a descendant of a very small ancestor, revealing how the characteristics of dinosaurs and flying pterosaurs evolved. About 237 million years ago, during the Mid-Triassic period, a 4-inch-tall (10 cm) insect-eating reptile lived in the original jungles of what is now Madagascar. The animal, known as Kongonaphon Kely, belongs to the evolutionary branch of ornithodira, which includes the nearest common ancestors of dinosaurs and pterosaurs.

Study says giant dinosaurs may have evolved from miniature insect-eating animals

In 1998, a team led by John Flynn, director of the Frick Mammal Fossils at the American Museum, discovered the first Kongonaphon fossils. Until recently, such small reptiles were considered alien, and the ancestors of dinosaurs were similar in size to those of the ancestral group, which later grew into huge sizes as the more familiar dinosaurs evolved. However, as more fossils were discovered and analyzed, Flynn said, another picture emerged.

“This fossil site in southwestern Madagascar, from a little-known time interval around the world, produces some amazing fossils, and this small specimen is in a mess of hundreds of specimens that we have collected over the years from the site,” Flynn said. “It took us a while to focus on the bones before we could focus on them, but once we did, it was clear that we had something unique that deserved closer inspection. This is a good example of why field discoveries — combining modern techniques to analyze recycled fossils — are still so important. “

Study says giant dinosaurs may have evolved from miniature insect-eating animals

Part of the analysis involves a study of the wear of Kongonaphon’s teeth, which suggests it eats insects. This shift in eating habits will miniaturize its ancestors, but it also increases its chances of survival because it fills the ecological niche that carnivorous close relatives have not used. In addition, such small bodies would have a very large surface-to-volume ratio, which meant they would soon become cold, as the late Mesozoic period was a period of extreme climate, suggesting that they developed fuzzy skin coverings found in many dinosaurs and pterosaurs that later evolved into feathers.

“The discovery of small close relatives of dinosaurs and pterosaurs underscores the importance of Madagascar’s fossil record in improving the history of vertebrates from an era that is poorly known elsewhere,” said Lovasoa Ranivohariana, co-director of the project at the University of Antananarivo in Madagascar. “Such discoveries will help people in Madagascar and around the world to better appreciate the special records of ancient life preserved in our rocks.”

The study was published in the Proceedings of the National Academy of Sciences.