Exactly when the mermaid was added to Warsaw's coat of arms is not known but it was already in place in 1390 with a shape very different from today's.
It presented the animal with a bird's legs and a torso covered with dragon scales.
On the seal of 1459, it already had feminine characteristics, the torso of a bird, human hands, the tail of a fish and bird legs with claws.
The first presentation of the traditional mermaid dates from 1622.

http://www.wikiwand.com/en/Mermaid_of_Warsaw