The new feathers of the Archaeopteryx

To date, 14 Archaeopteryx fossils have been unearthed in quarries in Bavaria, Germany, since the first specimen was discovered in 1861. This dinosaur, which lived 150 million years ago, is generally considered the oldest known bird. But this iconic Jurassic animal, studied from every angle, still has some surprises in store: published in Nature on May 14 , a study of the fourteenth Archaeopteryx—on display at the Field Museum of Natural History in Chicago since 2024—clarifies anatomical details and reveals the existence of feathers that had not yet been described.

It took more than a year for the team of Jingmai O'Connor, associate head of the Chicago Museum's reptile fossil collection, to partially excavate (FMNH) PA 830, its code name, from the slab of hard rock where it is trapped. The paleontologists relied on X-ray scan data to determine precisely where the bones were located beneath the surface, in order to avoid damaging them with their milling machines. And to spare the soft parts—skin, scales, feathers—they used ultraviolet light, which has the particularity of making them stand out visually, through fluorescence.

This painstaking work paid off: several characteristics of the animal that could not be brought to light in other fossils are discussed in the study. First of all, the architecture of the skull, at the level of the palate, appears less rigid than in so-called "non-avian" carnivorous dinosaurs - incapable of flight. The excavation of the spine then revealed two additional vertebrae in the tail, which appears more elongated than previously thought. Furthermore, the lack of fusion between certain bones suggests that the animal had not reached maturity, which could explain its small size compared to its peers - it has the stature of a pigeon, while the largest are closer to that of a crow.

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