Haolong dongi Preserves 125-Million-Year-Old Skin Cells in Hollow Spikes

1 articles · Updated · spacedaily.com · Jul 29

A nearly complete 2.45-meter juvenile Haolong dongi from China’s Yixian Formation preserves hollow neck-and-back spikes with skin architecture visible down to individual keratinocytes and possible nuclei.
Tomography, laser-stimulated fluorescence and histology showed the cells were mineralized within the spike walls—not loose in empty tubes—with an outer cornified layer, multilayered epidermis and a porous dermal core.
Most spikes measured just 2 to 7 millimeters, with a few possibly exceeding 4 centimeters, and the team argues they were a distinct skin appendage rather than feathers, osteoderms or pointed scales.
The rear-pointing projections may have helped defend a juvenile herbivore, though thermoregulation or sensory roles remain possible and the single specimen cannot show how the structures changed in adults.
The find from the exceptionally preserved Jehol Biota broadens the known range of dinosaur skin anatomy and underscores how ordinary bone-heavy fossils can miss soft-tissue features entirely.