FIGURE 7.

Dissected myosepta of Chauliodus sloani (USNM 200984, 145 mm SL) photographed under polarized light. (a) Myoseptum of V11 at 0,31L. Simple epineural (ENTB) present. In hypaxial part of the myoseptum, the ossification represents an LTB, pointing to neural arch. Epicentral (ECT) present. (b) Myoseptum of V14 at 0,36L. Simple epineural (ENTB) present. The intermuscular in ventral part of myoseptum is proximally forked, with an EPTB as anteromedial branch and an LTB as anterolateral branch. (c) Myoseptum of V27 at 0,55L. Anterior cones present. Ventral LTB projects into VAC. (d) Myoseptum of V41 at 0,79L. Simple intermuscular ossification represents LTB epaxially and hypaxially extending from anterior (DAC/VAC) into posterior cones (DPC/VPC). Dorsally there is an epineural tendon (ENT) present. Ventrally, the MT turns posteriad and forms a ventral secondary anterior cone (VSAC). (e) Myoseptum of V47 at 0,88L Abbreviations: DAC, dorsal anterior cone; DPC, dorsal posterior cone; ECT, epicentral tendon; ENT, epineural tendon; ENTB, epineural tendon bone; EPTB epipleural tendon bone; F.NL, foramen for the nervus lateralis; HM, horizontal midline; LT, lateral tendon; LTB, lateral tendon bone; MT, myorhabdoid tendon; R, rib; RMA, attachment site of red musculature; RMTs, tendons within red muscle bundles; VAC, ventral anterior cone; VPC, ventral posterior cone; VSAC, ventral secondary anterior cone