Medullary bone in fossils: function, evolution and significance in growth curve reconstructions of extinct vertebrates

Medullary bone (MB) is a special endosteal tissue forming in the bones of female birds during egg laying to serve as a labile calcium reservoir for building the hard eggshell. Therefore, the presence of MB reported in multiple nonavian dinosaurs is currently considered as evidence that those specimens were sexually mature females in their reproductive period. This interpretation has led to further inferences on species‐specific growth strategies...