More than a decade ago, a research team traveled to Campo Azul on the hunt for sauropod fossils, long-necked dinosaurs, paleontologist Daniel Martins dos Santos told McClatchy News in a Feb.

In contrast, the ornithischian fossil record in Laurasia during this time is less varied and mainly includes armoured dinosaurs," they note. It was found in the so-called Ziliujing Formation ...

Only the bony spikes remained on other fossils from armored dinosaurs. This is because keratin — the dead cells that make up structures like hair and fingernails — doesn't fossilize well.