Ailuros are derived from a pliosaur line, which due to extreme predation by the line that would eventually produce the Deep Kings, were forced into a smaller form more suited to hiding in rocks and coral. Intelligence is still unsure of how exactly it evolved, but the most common theory is they needed  it to avoid the intelligence forming in the Deep King's line. So it became an arms race of intelligence, and the Ailuros barely won.
Physically the Ailuros resemble depictions of sailor's mermaid tales; the upper torso is somewhat humanoid, with two arms and a head, but they look nothing like any Human or Elf. Large inky eyes and a gaping hole of a mouth lined with teeth the size of a forearm give a horrifying visage. The Ailuros can't physically close their mouth entirely, due to their large teeth, so they can't chew, which has led to great curiosity on their behalf on the different types of eating on land. Their lower torso resembles a long tail, like that of the pliosaur, long and well muscled. Two small fins where legs would be on a biped allow better steering and small movement on land. The Ailuros primarily hunt with their hands, three fingered graspers, but can swallow a large amount of things entirely whole. The largest known is reports of an adult human, but no confirmed reports. Their speech is a mixture of small clicks and vocalizations, but with time they can learn to speak the language of the land-dwellers. Ailuros reproduction resembles Human or Elven reproduction, but through a more r-type reproduction.