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no for real, those lil spurs that some snakes have? those are leggies.

those itty bitty bits of bone in the ribs, right at the base of the tail? that’s actually all what remains of the pelvis an leggies. li’l bits of femur, that be the spurs. 

whale leggy

say hello to very good fine whale Orcinus orca. 

now look at friend orca’s skeleton. see any bones what don’t make sense?

look close. most of them nice bones you can see have purpose. they support, they fins, they teefers, et centera. but look real close. see ‘em there? hanging low after the ribs? what those? 

those be leggy.

this picture here is of very fine whale grandpa name Rhodocetus. you can see that whale grandpa is clearly lots like a whale! look at him teefers. look at him skull. compare to fine whale orca skull up top. see similars? similar shape, similar teefers, lotsa similars.

now look at him LEGS.

that right there is whale grandpa’s LEG. and his pelvis. see dark round place where femur goes? this whale had leg. but grandpa whale not so great at walking; grandpa whale good at swim! now this grandpa whale livin’ aboot 48-48 million years back, give or take. 

then later, we get this grandma whale. she mighty fine grandma whale name Dorudon.  

gramma whale Dorudon lived later, ‘bout 40-34 million years ago. her leggies were itty bitty! but they stil stuck out and could still move. 

after Dorudon, whale leggies get smaller n smaller until they just itty bitty remnants. n before grampa whale Rhodocetus? other grampa n gramma whales leggies were bigger. so we can see over time that whale leggies get smaller n smaller because they weren’t useful under the water. we have loads n loads of whale skellies from all over the planet an’ through time. we can see whale friend go from having the useful leggies to having no leggies and i think that is very good evidence of the evolutions.

I’ll start with the no. No, they’re definitely vestigial limbs. That bony area’s a similar structure in all cetaceans and it’s really made up of two parts: the pelvic remnant and the femoral remnant. So in orcas they’re really reduced and streamlined, but you can see in baleen whales that there’s a lot of the pelvis/femur structure still in place. I used an orca because it was easy to find pics of their skeleton at 4 AM, but if you look at other whales, there’s clearly defined ischium/pubis/femur construction. Like, here’s an outline of a right whale skeleton with the leggy bits labeled.

Their femur remnant actually slots into the acetabulum like on a tetrapod that walks!

But the yes is that the pelvic bones actually aren’t vestigial meaning “useless.” Rather, they’re vestigial meaning “reduced.” They’re certainly smaller than they were, but much like our appendix, they actually do serve a purpose! 

Then something really big happens, something that catches the attention of all the cats, and suddenly instead of a twitching flat lump, you’re facing an fully grown, fully coordinated, VERY angry moose.