Striking Features : Fins , eyes and vertebrates One important part to distinguish Ichthyosaur 's is their distinctive characteristics . Ryosuke pointed out in his article the relative feature of these creatures and how it has helped them adapt to the environment they are in . The first important feature is the fore fin of such creatures . Ryosuke argued that such fins underwent a process of evolution which helped them swim better and deeper . The relative features can be seen in the process : ``...