Living In the deep swamps of Westeros, lizard-lions are formidable predators that resemble partially submerged logs floating in water and have teeth like daggers. The sigil of house Reed depicts a lizard-lion.
Went with a different direction rather than a normal alligator. So think, rauisuchian with branch-like growths and lots of moss hanging from it might and alright choice. Its Westeros after all, everything wants to kill.