Increase of body size in sixgill sharks with change in diet as a possible background of their evolution

摘要: Body size variation of a predator is simple way to follow the main changes in its food source during life history or along evolution ecology and paleoecology, respectively. Here, we present possible first evidence such predator-prey co-evolution through study body among sixgill sharks (genus Hexanchus) inferred from their fossil record by comparison two recent species. As for observed ontogenic diet change living bluntnose shark (H. griseus), ancestors appear have developed similar penchant dining on marine mammals at end Paleogene with remarkably well-correlated timing.