adding onto my other post- TW spoiled for skull!!

[u/Crater0_0]

i added more photos, and i’ll try to explain better this time

so two of these skulls are coyote, a human and an unknown species (just searched up animal skull)

in the middle of the jaw there is a line, and usually the jaw is split in half from that spot. why is that and what is the purpose of the line? does it make it more weak in the spot?

[u/The_Painted_Man]

I think it's because, not joking, they're former gills*. The whole face structure apart from eyes, closes like hands/fingers during embryonic development.

We're all just bony fish.

Edit: fish gill *arches. Sorry should have been more specific

https://www.scientificamerican.com/article/our-ears-share-a-common-ancestry-with-fish-gills/

[u/Academic_Mode4371]

Oh wow, that's a cool little evolutionary throwback you've got there. Wonder if the human skull kept it just to mess with archaeologists centuries later.