Fossils of the soft tissues of dinosaur tendons have been discovered

Tendons are elements connecting muscles and bones. In most vertebrates, they are flexible and elastic but in dinosaurs (including birds) some of them ossify. The excellent state of preservation of ossified tendons of three dinosaurs allowed discovery of fossilized soft tissues. Structures resembling fibril bundles, blood vessels, and bone cells were identified, resembling those present in ossified turkey tendons. The research indicates that dinosaur tendons ossified through metaplasia, i.e., mineralization of already differentiated soft tissues.