Physical Origins.Cyndaquil is the first Pokémon starter design to be inspired purely from a mammal. It's appearance seems to be based off of combination of echidna and shrew physical traits, such as the rounder body shape of the echidna and the snout shape of a shrew. It's closed eyes may be in reference to a baby honey badger, as it's evolved form is heavily based off of an adult version of the same mammal.
While a Cyndaquil's back is usually smooth, it has four spots through which it can spout fire. When this fire is burning, it resembles the spikes or quills of a porcupine or hedgehog. All of these traits are from mammals that all look relatively similar. The end result of all of these design features is the absolutely adorable Pokémon Cyndaquil.
Name origins.Originally created in Japan, Cyndaquil actually has a different name than the one the English versions of the games use. It's original Japanese name is Hinoarashi, which is one of many Japanese Pokémon names that are a play on words. It is likely a combination of the words "hi" and "yama-arashi" which translate to "fire" and "porcupine" respectively. Literally translated though, "hi no arashi" would translate to mean "storm of fire."
The English name of Cyndaquil is also a combination of words, though it doesn't have a particular double meaning like the Japanese version does. It is most likely a combination of the words "cinders," or ash, and "quill," based off of Cyndaquil's porcupine/hedgehog appearance.