Mammals evolving to lay eggs would, in fact, be a progression in the fickle realm of biology. Not having your child born until it is outside of you might make reproduction more appealing, leading to a rise in the population. Not that humans need that. But it might be good for various fox species.
An egg cracked into two halves, from within a hyperrealistic fox, lush night forests and sparkling fireflies spill out like a verdant summer dream creating a pool of magic around the eggshell. Hyperealistic masterpiece digital art 32k black background