Yellow-spotted lizards are actually a real animal, though they are not as lethal as portrayed in this book.
They are dark in colour with yellow spots running down their length. They have black teeth and a white tongue, a snake-like head, a rough body, and a pale yellowish underbelly. They are very aggressive and will bite a human who comes too close, but their bite is not venomous. They eat insects, scorpions, spiders and centipedes, and they actually tend to live on damp ground in rainforests or wet areas, not the desert. They like to hide under rocks or logs, and they are nocturnal. The lizards described in the story, though very like the real yellow-spotted lizards in appearance, are much more dangerous.