Diving Ichthyosaur

temnodontosaurus had largest eyes of known vertebrate, indicating diving capacity

many extant lung-breathing marine vertebrates capable of deep diving. there indications diving capacity of ichthyosaurs. ascending greater depth can cause decompression sickness. resulting bone necrosis has been documented jurassic , cretaceous ichthyosaurs, present in 15% , 18% of specimens respectively, rare in triassic species. sign basal forms did not dive deeply, might explained greater predation pressure during later epochs, more necessitating fast flight surface. however, last possibility contradicted fact that, modern animals, damage not caused limited number of rapid ascension incidents, gradual accumulation of non-invalidating degeneration during normal diving behaviour.

additional evidence provided eyes of ichthyosaurs among vertebrates both relatively , absolutely largest known. modern leopard seals can dive 1 kilometre hunting on sight. motani suggested ichthyosaurs, relatively larger eye sockets, should have been able reach greater depths. temnodontosaurus, eyes had diameter of twenty-five centimetres, still see @ depth of 1600 meters. @ these depths, such eyes have been useful see large objects. later species, such ophthalmosaurus, had relatively larger eyes, again indication diving capacity better in late jurassic , cretaceous forms.