The 5th Limb? (Tails)

Hi Nuggin,I found this website which claims that some human beings are born without a coccyx.It also has some other cool facts about useless body parts:

quote:

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NECK RIB
A set of cervical ribs”possibly leftovers from the age of reptiles”still appear in less than 1 percent of the population....

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SUBCLAVIUS MUSCLE
This small muscle stretching under the shoulder from the first rib to the collarbone would be useful if humans still walked on all fours. Some people have one, some have none, and a few have two...

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PLANTARIS MUSCLE
Often mistaken for a nerve by freshman medical students, the muscle was useful to other primates for grasping with their feet. It has disappeared altogether in 9 percent of the population.

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THIRTEENTH RIB
Our closest cousins, chimpanzees and gorillas, have an extra set of ribs. Most of us have 12, but 8 percent of adults have the extras....

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Creationist websites appear to claim that the coccyx fufils a useful function, as an anchor for nerve and muscle development in the embryo and adult. Quite why they think this is an argument against evolution is beyond me...Brennakimi is correct to say that you can't be a chordate without having a tail; but when one bears in mind that snakes have over 400 vertebrae and humans only 33, it seems reasonable to suppose that at least some parts of the tail have been lost and gained over evolutionary time. If the picture of the dolphin above is correct, then it DOESN'T have a coccyx because it lacks fused sacral bones (are they fused in the cat?). Given that dolphins evolved from terrestrial mammals with fused sacral bones(?), they must either have "un-fused" or been lost and evolved new sacral bones from the lumbar region. I don't know which. Probably one of the fossil-people can elucidate.apologies for editing this post repeatedly.This message has been edited by mick, 12-04-2005 07:58 PMThis message has been edited by mick, 12-04-2005 08:05 PMThis message has been edited by mick, 12-04-2005 08:09 PM

Okay, I did a bit more reading and found that the sacrum did indeed unfuse itself during the evolution of cetacea.The sacrum is the set of bones (often fused together in terrestrial mammals) which support the pelvic girdle.The sacrum, however, is not the coccyx: So, basically, Brennakimi is correct, unless somebody can come up with an animal with no backbone lower than its pelvis.Nevertheless, the loss of the fused sacrum in whales is pretty remarkable.MickThis message has been edited by mick, 12-04-2005 08:35 PM

Okay, there's a couple of breeds of manx cat called "rumpy riser" and "rumpy" which have no caudal vertebrae (no backbone below the pelvic girdle) and therefore are completely tailless in every sense of the word. linkMick

It also seems that some families of megachiroptera (a suborder including the vampire bats) have no caudal vertebrae, i.e. no tail beneath the pelvic girdle.

I think that the "tail-less" dogs are generally the product of the tail being snipped off by the owner. As far as I know, and a dog fan here might correct me, it's a middle-ages idea that it was supposed to help the dogs run through thick undergrowth in search of prey. It kind of makes you wince when you read Brennakimi's view that the tail is part of our spine... There's no way I'd dock the tail of one of my dogs.MickThis message has been edited by mick, 12-04-2005 09:24 PM