The lizard men, or simply lizards, were an otherwise unnamed species of reptilian humanoids who were enslaved by a species of humanoid rodents called "rats".
They were used as food by the rats, and, since the lizard men were a very strange and peculiar race, they didn't seem to mind much, and they even admitted that they were delicious, although they still preferred basking over getting eaten.
Mariner frees the lizard men from oppression
In late 2380, in violation of the Prime Directive; as well as her captain and mother's orders, Ensign Beckett Mariner attempted to stage an uprising against the rat people, and used a vehicle to topple a rat statue.
Her mother, Carol Freeman, later arrived on the planet, and was angered that she was going to have to explain to Starfleet Command why there was an interspecies war on a previously peaceful world.
After sending Mariner back to the USS Cerritos, Freeman asked one of the rats if they would stop eating the lizard men if they gave them food replicators. The rat then asked if the replicators could make nutrient pellets, to which Freeman said "Yes!" (LD: "Crisis Point")