[metmom]

That is like asking why you don't see failed auto designs on the road. For an animal to be fossilized is a one in a million shot.

Are you telling us then that only the successful designs somehow were the only ones to get fossilized by some chance?

“Failed” body plans don't get to grow into the million population group, they die young if they are even born at all.

What ever happened to the changes being gradual? Evos constantly mock non-evos for their comments about one species giving birth to another significantly different progeny, but that is exactly what you are implying needs to happen. The gradual changes didn't make it. They would have had to be more dramatic to survive birth and reach age of reproduction.

Those gradual changes would be considered *failed* if they weren't enough to allow stunning success but not all those *failed* plans need be fatal, as in the case of limbs developing to flippers. A limb going to flipper is not a serious enough failure in change that the individual would not not make it to birth. That is not a fatal birth defect.

But what good would a partially formed limb that is transitioning from leg to flipper be? It would be a liability to a land creature, leaving it more susceptible to injury and death as the land creature could not use a hybrid leg/flipper for locomotion very easily, nor could it use a hybrid arm/flipper to gather food.

The hybrid limb/flipper would not be a great advantage in the water as it would not be as useful as a fully developed flipper to escape being preyed on by those creatures such as sharks which have fully functioning flippers.

An animal in process of going from land to water or water to land is not well suited to survive either on land nor in water in the transition stage.

So how did it manage to do that?

[allmendream]

Does a flying squirrel need a working wing? Has it lost the use of its arm? Bats are pretty dexterous with the ‘thumbs’ on their wings as well. The change from a glider to a flier would be a gradual process if the flier experienced an advantage.

Similarly a river living mammal could easily develop a multipurpose leg that also had function as a flipper, like a seal. A seal has not lost function of its front legs, they are now better flippers than legs.

And I am not implying ‘hopeful monsters’, I am saying that any gradual deviation from a successful body plan will be weeded out by natural selection. Obviously what is “successful” will change as circumstances change, from needing to be streamlined, to being a tetra-pod, back to needing to be streamlined, as all evidence suggests marine mammals went through.

These gradual changes can be observed in short periods of time that make large changes over large periods of time no problem at all. And none of the fossil intermediates will be ‘monsters’ or some sort of half formed creature, they will be a fully formed species that was just gradually more marine than its predecessors.