Development of the chondrocranium of the shallow-water Cape hake Merluccius capensis (Cast.). Part 1: Neurocranium

Abstract

The development of the neurocranium of Merluccius capensis, from the earliest identifiable stage, is described. The anterior mesenchyme gives rise to the rostral cartilage, the lamina orb ito nasalis and probably also to the planum ethmoidale. There is no true ethmopalatine articulation, only a rostropalatine articulation. The ethmopalatine articulation is represented by the preorbital ligaments. A cartilago supraentethmoidalis develops, but no processus ethmoideus. A preoptic root is absent and only a foramen olfactorium advehens is delimited. A lateral commissure and prootic process, and consequently a trigeminofacialis chamber, are absent. Both the auditory capsules and the occipital arches take part in the development of the tectum synoticum. The tectum posterius does not develop separately, but as a posterior extension of the tectum synoticum.