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Fourteen specimens, including five counterpart specimens, represent a new taxon, Megalomatia minima gen. This discovery allows us to discuss the adaptations and evolution of basal actinopterygians in more detail than before.
The otoliths in situ of Megalomatia support the previous interpretation that basal actinopterygians have a sagitta as the largest otolith. The trunk lateral line canal, which runs under the scales instead of passing through them, represents a plesiomorphic gnathostome trait. Notably, the large protruded eyes suggest that Megalomatia probably has binocular vision, which would have played a significant role in targeting and catching prey with the primitive jaw structure.
In addition, the firstly formed skeletal elements such as the jaws, pectoral girdle, and opercular series, and the posteroanterior pattern of squamation development are likely linked to the adaptation of young individuals to increase their viability for feeding, respiration, and swimming. The study of fish ontogenies provides comprehensive knowledge of their developmental patterns, functional development tendencies, and environmental preferences according to different developmental stages 1 , 2 , 3.
In addition, the characteristics observed in fish throughout their developmental stages reflect possible adaptations in response to functional demands, probably correlating with individual survival success.
