Early ossification and development of the cranium and paired girdles of Chanos chanos (Teleostei, Gonorynchiformes)

Abstract

In this chapter, we provide new data on the timing of ossification of cranial and paired girdle elements, and compare our results, when it is possible, with previous work on early ossification development of Chanos chanos. This is particularly important because of the basal phylogenetic position of Chanos among living ostariophysans and among extant gonorynchiforms as well (see Fig. 3.1). We describe the normal cranial and girdle patterns of ossification in Chanos chanos and evaluate to what extent the cranial development is consistent, or whether some intraspecific differences occur in comparison to previous results by Taki et al. (1987) and Kohno et al. (1996a) based on ontogenetic series grown in the same Aquaculture Department as the specimens used in this study. We assess previously published developmental work in a few ostariophysans and test some previous hypotheses on heretochrony and patterns of diversification. [A study of chondrification versus ossification processes in Chanos chanos is outside the scope of this paper, but it is the subject of a separate paper (Arratia and Grande, in preparation).]