Balto-Slavic glottal stop

And of course the biggest paraphyletic grouping of all, "animals", at least in common speech.

Estonian is closer to Finnish genetically than it is to Võro (south Estonian), Norwegian closer to Icelandic than to Danish, Catalan closer to French than to Spanish... the list goes on.

Wait, how is "animals" used in common speech?

To include all of animalia except for humans.

Ah, okay. I was confused because I thought you were referring to the use of the word which only includes zoo animals, farm animals, etc. while excluding some animals like insects and arachnids. (If you've ever heard a child make a distinction between "animals" and "bugs")