Whales and other aquatic mammals withdraw them into folds in the body when not in use (male genitals also are concealed this way) when they are not in use. Male snakes also conceal their copulatory organs inside the body when they are not mating. So this is not an insurmountable problem.
They the same as those referenced in post #6?
Just to throw in another angle here…
Because snakes and many other reptiles have such a different metabolism from mammals, there are many ambush type hunters in the reptile world, including snakes and crocodilians. These kinds of animals can afford to sit around for weeks until a proper meal wanders by. While this doesn’t explain why snakes lost their limbs, it does perhaps explain why a mammal needs to keep the limbs. A mammal has to eat regularly - only a few can go more than a few days and those few have some pretty extreme adaptations to do it (hibernation, camel humps, etc.) A snake I rescued from bad owners went 11 months between meals.
Snakes rely on ambush hunting to such an extent because they’re slow. People often report being chased by snakes, but even the fastest snakes are the equivalent of a slow jog and many snakes never get faster than a human’s walking pace. Presumably, a legless mammal would be about the same speed and would have to count on either slow-moving prey or ambush hunting.
So it may very well be that a limbless body form on land just can’t find food regularly enough to support the needs of a mammal.
Three-toed sloths seem to be reasonably chilled and don’t break any speed records when they move around - I’m not sure speed over land is a pre-requisite for mammalian survival.
All snakes are carnivores. Sloths don’t have to move fast because they are herbivores, and their food doesn’t move at all. Herbivores need large guts to process large amounts of low-quality food by fermentation. This kind of bulky gut may not be compatible with legless locomotion.
And I recognize that constrictors eat their prey whole and spend a long time digesting it. However, they get a much higher energy return from digesting a stomach full of meat than a herbivore would from plants. I don’t think a herbivore would get enough energy return to be able to make a living in this fashion.
Ugh. Yes, the post which I somehow completely missed, and even links more or less to the same article; I linked to the picture, CalMeacham to the main article.