Fig. 3

Synchrotron x-ray microtomographic images of Ichthyornis dentary. Dentary of Ichthyornis dispar YPM.1775, indicating the implantation of the three teeth in the anterior part of the mandible and an additional, small tooth. a Lingual view. b Occlusal view. c Insert at higher magnification showing a small tooth preserved in the distal part. a, b and c are volumes rendered with a level of transparency, and showing segmented teeth in volume (in grey). The tooth germ shown in c is not segmented and highlighted in a and b. d Horizontal volume section of the mesial part of the specimen, exposing the insertion of teeth in sockets. The alveolar bone is clearly seen in transverse volume section e and in horizontal section f at higher magnification, with woven bone tissue (wb) and lamellar bone forming the septa and the main jaw bone (jb), respectively. Scale bars a, b 0.75 mm, d, e, f 0.25 mm