The first record of fossilized soft parts in ossified tendons and implications for the understanding of tendon mineralization Author Surmik, Dawid Author Słowiak-Morkovina, Justyna Author Szczygielski, Tomasz Author Wojtyniak, Marcin Author Środek, Dorota Author Dulski, Mateusz Author Balin, Katarzyna Author Krzykawski, Tomasz Author Pawlicki, Roman text Zoological Journal of the Linnean Society 2023 2023-07-01 198 3 747 766 https://academic.oup.com/zoolinnean/article/198/3/747/7076280 journal article 10.1093/zoolinnean/zlad001 0024-4082 8141891 Edmontosaurus regalis (UAMES 52615) Both cross-sectioned tendons show a highly porous structure built of fibrous primary matrix ( Fig. 1A–C ). The general structure of the sectioned tendons is homogenous. The matrix is composed of coarse collagenous fibre bundles containing numerous bone cell lacunae ( Fig. 1A, C ). The vascular canals forming the porous structure of the tendons are young Haversian canals ( Fig. 1A–C ). The cross-sectioned larger tendon shows few scattered secondary osteons in the centre of the tendon surrounded by collagen-fibre bundles ( Fig. 1D ). The tendon of a slightly smaller cross-section ( 3.5 mm diameter; Fig. 1A, B ) is more porous than the larger one ( 6 mm ; Fig. 1C, D ). The different structure between the sampled tendons may result from a different location in the body.