The Late Jurassic dinosaur Anchiornis had bird-like arms, legs, tail and footpads, shows a study published in Nature Communications this week. The new body-shape reconstruction is based directly on soft-tissue evidence that has previously been difficult to detect.

Due to the rarity of soft-tissue preservation, the body shape of extinct vertebrates (animals with backbones) usually must be inferred indirectly from skeletal structure and by comparison to living species. However, such reconstructions may not capture the true body shape. To learn more about the body shape of a small, feathered dinosaur called Anchiornis, Xiaoli Wang, Michael Pittman and their colleagues used laser-stimulated fluorescence imaging, a technique that reveals soft tissue details that are invisible under visible light, on nine Anchiornis specimens. The soft-tissue outlines of the specimens revealed that Anchiornis, which was alive around 160 million years ago, already had many of the characteristics of modern birds, including drumstick-shaped legs.

These findings extend previous inferences of Anchiornis body shape, providing a detailed reconstruction of the body. The authors suggest that this work may provide a basis for determining whether Anchiornis was aerodynamic, which may offer insights into the evolution of flight.