Crocodile x Avatar By Me! What do you guys think?
They evolved from ikrans, smaller ones that became adapt to life in swamps, hugging onto mangrove trees and catching fish. As they spent some more time in and around water. Some of these ikran diverged into this crocodilelike creature in the artwork. They lost their wings in a process of regressive evolution (evolution/change where a feature is lost usually in exchange for another trait, ie dodo birds and other large flightless birds). The first and largest red skin membrane/sail aligned with the animal's spine are the first two larger wings of the ikran that fused into one organ. The second to sail membranes on opposite pairs on the tail are the two smaller wings. Both wing pairs realigned themselves to enhance maneuvering in water and gathering heat to be more active than their prey.
These sail membranes, along with their eye crests can change color. Males can change these sail and crest (and their dulap below their throat) colors from dull blue to bright, almost neon red to attract mates.