Ambopteryx longibrachium was a small dinosaur, unearthed from Jurassic-era sediments. It was a tree-dwelling creature, estimated to be around 32 centimeters (12.6 inches) in length and weighing about 306 grams (10.8 ounces). Its existence highlights the varied adaptations that allowed dinosaurs to thrive in different ecological niches during the Mesozoic Era.
Discovery and Initial Insights
The fossilized remains of Ambopteryx longibrachium were discovered in 2017 near Wubaiding Village in China’s Liaoning Province. This region is well-known for its exceptionally preserved fossils from the Late Jurassic period, approximately 163 million years ago. Initial examinations broadly classified Ambopteryx longibrachium as a scansoriopterygid dinosaur, a group of small, non-avian theropods. This classification immediately generated scientific interest, as scansoriopterygids are recognized for their unusual body proportions, particularly in their forelimbs. The discovery provided further context for understanding this unique group of dinosaurs.
Unusual Wing Structure
The most striking feature of Ambopteryx longibrachium is its membranous, bat-like wings, which set it apart from feathered dinosaurs. These wings were supported by unique skeletal adaptations. The third finger of its hand was significantly elongated, and a rod-like bone, called a styliform element, extended from the wrist (ulna).
This styliform element, which is also found in pterosaurs and flying squirrels but not in other dinosaurs, provided additional support for the wing membrane, or patagium. The wing membrane itself was preserved as a brownish layer surrounding the forelimb and abdomen, indicating its continuous structure. While some feathers were present on its head, neck, and shoulders, the primary flight surfaces were membranous. This distinct wing structure suggests that Ambopteryx likely glided rather than engaged in powered flight, representing an alternative evolutionary pathway to aerial locomotion among dinosaurs.
Evolutionary Connections
Ambopteryx longibrachium contributes to the discussion surrounding the evolution of flight in dinosaurs and birds. Its membranous wings provide evidence of evolutionary experimentation with diverse flight strategies among dinosaurs closely related to birds. This discovery, along with that of Yi qi, another scansoriopterygid with similar wing structures, challenges the idea of a single, linear progression of bird evolution solely from feathered dinosaurs.
The presence of membranous wings in Ambopteryx and Yi qi demonstrates convergent evolution, where different lineages independently develop similar traits to adapt to similar environmental pressures. While feathered wings ultimately became the dominant form of flight in birds, the scansoriopterygids pursued a different aerial solution. This group’s unique anatomy suggests a short-lived evolutionary attempt at flight, highlighting the varied paths taken by ancient life forms in their exploration of aerial capabilities.
Life and Environment
Scientists have inferred details about the lifestyle and habitat of Ambopteryx longibrachium from its fossilized remains. Its long forelimbs and clawed fingers indicate an arboreal, or tree-dwelling, existence. These features would have aided it in climbing and navigating through ancient forests. Examination of the abdominal region of the Ambopteryx specimen revealed gastroliths, which are stomach stones, and fragments of what appear to be bone. This evidence suggests an omnivorous diet, likely consisting of insects and small plants. The Jurassic ecosystem of Liaoning Province, where Ambopteryx lived, was a diverse environment with a variety of flora and fauna that could have supported such a diet.