Dinosaur skin cells found inside hollow spikes reveal a mosaic of skin in a 125-million-year-old iguanodontian
A juvenile iguanodontian Haolong dongi from China's Jehol Biota preserves hollow spike–like skin structures that house epidermal cells at cellular resolution, showing a thick outer cornified layer and layered epidermis around a porous dermal core. The spikes are a skin organ rather than mere scales or bone, illustrating mosaic skin in dinosaurs and suggesting defensive or other functions, while noting that conclusions come from a single specimen and may not generalize.
