Four-Winged Microraptor *Jian changmaensis* Illuminates Cretaceous Predator-Prey Dynamics

A three-dimensional specimen of a new dromaeosaurid, *Jian changmaensis*, was recovered from the Lower Cretaceous Xiagou Formation of the Changma Basin, Gansu Province, northwestern China. The site, previously known for over 100 bird fossils, yielded only this single non-avian dinosaur.

Four-winged dinosaur: Scientists just found a four-winged dinosaur in northwestern China, and it may be the predator that left behind piles of crushed bird bonesScience Daily

The preserved upper arm bone is ~4 inches long, implying a wingspan of roughly four feet—comparable to a barn owl. Feathered fore- and hindlimbs formed four wing surfaces. Researchers infer that, like other microraptors, *Jian* could not sustain powered flapping but was capable of controlled gliding, akin to a flying squirrel.

Four-winged dinosaur: Scientists just found a four-winged dinosaur in northwestern China, and it may be the predator that left behind piles of crushed bird bones

The specimen confirms that non-avian theropods coexisted with early birds in the Changma ecosystem. Its carnivorous size makes it the most plausible source of the pellet-like bone clusters that have long puzzled paleontologists, providing a view of Cretaceous predator-prey interactions. The find also pushes microraptor distribution beyond northeastern China and may represent the youngest record of the clade.

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Lead authors Jingmai O'Connor (Field Museum) and Matt Lamanna (Carnegie Museum) say *Jian* offers critical insight into the Changma region’s biological history and the evolutionary context of avian ancestors. They highlight that the discovery expands microraptor biogeography and underscores ecological dynamics preceding the end-Cretaceous extinction.

Four-winged dinosaur: Scientists just found a four-winged dinosaur in northwestern China, and it may be the predator that left behind piles of crushed bird bones

The authors caution that the predator hypothesis is provisional; the fossil consists of a fragmentary arm and lacks direct evidence such as stomach contents or bite marks on bird bones, leaving alternative explanations for the pellet accumulations viable.

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Authors note the absence of unequivocal feeding traces linking *Jian* to the crushed bird remains; further specimens are needed to confirm its role as the pellet-producing predator.

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• “Scientists have found these weird, broken-up clusters of bird bones at this site, and we didn't know what made them. This new microraptor dinosaur, Jian changmaensis, is our best guess,” — Jingmai O'Connor, Associate Curator of Fossil Reptiles, Field Museum

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• “The piece of its upper arm bone that we have is about 4 inches long, so the entire dinosaur probably had something like a four-foot wingspan, around the size of a barn owl.” — Jingmai O'Connor

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• “Jian and the other microraptors probably weren't capable of true, powered flight, but they could probably glide like a flying squirrel,” — Jingmai O'Connor

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• “Jian changmaensis reveals that non-avian dinosaurs lived in what is now the Changma Basin, an area famous for its fossil birds,” — Matt Lamanna, Curator of Vertebrate Paleontology, Carnegie Museum of Natural History

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Planned fieldwork will target additional specimens and search for direct predation evidence, such as tooth marks on bird fossils. Aerodynamic modeling of microraptor gliding will test *Jian*’s locomotor capabilities.

Four-winged dinosaur: Scientists just found a four-winged dinosaur in northwestern China, and it may be the predator that left behind piles of crushed bird bones