Fig. 1

Craniofacial structures at two early life-stages (hatching and first feeding) in Arctic charr (Salvelinus alpinus). Ventral craniofacial bones and cartilages at hatching (a) and first feeding (b) of Arctic charr (Salvelinus alpinus) embryos from lake Vatnshlíðarvatn. EP, ethmoid plate; MC, Meckel’s cartilage; HH, hypohyal; CH, ceratohyal; BSR, branchiostegal rays; PQ, palatoquadrate. We refer to the combination of the HH, CH and BSR as the hyoid arch (HA). For timing and sequence of occurrence of these structures in Arctic charr see Kapralova et al. (2015). The 71 homologous landmarks used to quantify craniofacial shape change at hatching (c) and first feeding (d) can be divided into 17 fixed (larger dots) and 54 semi-landmarks (smaller dots). † BSR themselves were not considered for analyses but their attachment was incorporated as part of the HA