Extended Data Fig. 4: Evidence for both subadult and adult individuals of Filikomys primaevus at Egg Mountain.

MOR 10908E and 10908B exhibit features characteristic of skeletally immature, subadult mammals³¹: (i) unfused cranial sutures, (ii) MOR 10908E is the smallest (based on dentary length) of all the individuals preserved in MOR 10908, (iii) both have open lower incisor roots (orange arrows), indicating that the tooth was still erupting, (iv) MOR 10908E has unworn cheek teeth and MOR 10908B has only very minor cheek-tooth wear, and (v) the long bones are missing their epiphyses, indicating that they were unfused at the time of death. MOR 10908D, 10908C, and 10908A exhibit features characteristic of skeletally mature, adult mammals³¹: (i) fused cranial sutures, (ii) MOR 10908A is the largest (based on dentary length) of all the individuals preserved in MOR 10908, (iii) all have closed lower incisor roots (blue arrows), indicating that the tooth was fully erupted, (iv) the cheek teeth of MOR 10908C and 10908A are heavily worn, and (v) the long bones have fused epiphyses. See Supplementary Discussion for more information. Scale bars = 5 mm.