Fig. 4 in Unique bone histology in partial large bone shafts from Upper Triassic of Aust Cliff, England: An early independent experiment in gigantism

Fig. 4. Flow diagram explaining the peculiar patterns of remodelling seen in the Aust Cliff bones BRSMG Cb3869 and Cb3870. In a simple vascular canal, lamellar bone is deposited centripetally forming a primary osteon. In the Aust Cliff shafts, the inner lamellae of this primary osteon are later resorbed from the inside. When erosion stops before the entire primary osteon is resorbed, leaving a resorption line within the primary osteon, new lamellae can be deposited and a secondary osteon forms within the primary one. With ongoing resorption, an erosion cavity forms, the size of which exceeds the one of the former primary osteon. When resorption stops, deposition of lamellar bone can resume.