The idea that species can never interbreed and produce fertile offspring has been deprecated.

Canid species can and do crossbreed and produce fertile offspring.

Equids, on the other hand, are well known for typically not doing so (the occasional female mule is fertile), and because the species hybrid we have domesticated and used IS the mule.

When you cross felines, you typically get fertile females and infertile males.

The total disappearance of the Neanderthal Y chromosome in modern populations is potential evidence that human species followed the last pattern.

Many species of bird will also hybridize freely.

We simply can't use "can interbreed and produce fertile offspring" as any kind of standard. Coyotes are clearly not wolves, but...