Is a Basset Hound a "transitional life form" between a Tea Cup Poodle and a St. Barnard? (I'd hope (and expect) you'd say "no" to that. LOL)
They are both the same species, hence merely variations.
Who's to say that what you have here; and what they label as a "transitional life form" is not just another variant within a string of species of a particular phyla or even a variant of a particular species?
A transitional form has apomorphic characters of two distinct taxa. For example Archaeopteryx has mostly dinosaur characteristics. But it also has a number of features found only in birds. It's not quite a bird, but it's very close to the line that gave rise to birds.
By drastically changing the environment (artificially, in the case of dogs) you can get some extreme results. Eventually, there can be reproductive isolation and speciation. But you don't see that in dogs.
Now obviously we know of genes that are mutated. The vast majority of them are the cause of disease, deformations or disabilities.
No. The vast majority of them do nothing. A few are harmful, and a very few are useful. Natural selection sorts them out.
Many of these mutations are spontaneous
What are non-spontaneous mutations?
because the parent organisms don't have them and aren't carriers.
You have dozens of mutations in your genome that weren't present in either parent. But they all were present in either the egg or the sperm of your parents. That's how it works. Somatic mutations, such as tumors, aren't in your genome,and aren't passed on. Is that what you mean?
We also see environmental insults create mutations in fully developed organisms that affect whole populations of offspring.
There are mutagens. Generally, this is bad for a species, because for most populations, the general mutation rate is optimal for them.
For example, a high percentage of kids with spina bifida are born to Vietnam veterans because of Agent Orange. We have a pocket of kids born in the 1950's who are deformed because of Thalidomide. Would you conclude based in their deformed limbs that these kids were "transitional life forms" between humans and seals?
See above. Do those kids have apomorphic characters of primates and pinnipeds? No, they just have a malformation caused by a teratogen; they don't have genes for very short limbs.
Just because you see something in the fossil record that looks like a cross between A and B does not mean that it is.
It comes down to evidence. You look for homologous organs, not analogous ones. Hence, birds and bats may look very similar, but when you examine them closely, bats show mammalian homologues, and birds show archosaurian ones. Would you like to talk about those?
No, an organism that has a fully functioning body. (Or as far as we can tell by possibly only just a skeleton.)
Then every transitional form, such as archaeopteryx, is a fully formed organism. It's one of Darwin's secondary points; evolution can't do everything, because you have to have fully-functional transitional forms to get from A to B.
We don't see examples of organisms that have half developed flipper feet,
[ quote]fishes tales[/quote]
You'd have to cite the article of the find for me to assess what you mean by "desert fossil".
Fossils of organisms that lived in deserts, such as Protoceratops.
The Paleoenvironments of Tugrikin-Shireh (Gobi Desert, Mongolia) and Aspects of the Taphonomy and Paleoecology of Protoceratops (Dinosauria: Ornithishichia)
David E. Fastovsky, Demchig Badamgarav, Hideki Ishimoto, Mahito Watabe and David B. Weishampel
PALAIOS
Vol. 12, No. 1 (Feb., 1997), pp. 59-70
The article you cite here has a picture of animal tracks that were obviously made when the sand / or dirt was mud. (You would not have been able to see the animal's tracks if it wasn't walking through mud.
Yes, it does rain in the desert, and there are places in deserts where there is water. This is why the tracks of those animals are so rare; they lived in arid conditions.
In order to preserve those tracks as you see them; they had to be covered by another layer of sentiment very quickly.
Or just dry out and slowly get covered by wind-blown deposits.
If you were to take a deceased sparrow and bury it at the beach; what would happen? Would you get a fossil, or would it just decompose?
Almost all organisms buried anywhere, decay. Only rarely do they get preserved as fossils. But once covered in dry sand, bones of organisms persist for a very long time, occasionally becoming fossils.