Of course its myth.

Have you NO sense of humor?

The actual evolution of species that evolved billions of years ago is no easy thing to trace as the following description of Gastropod evolution will attest:

Unambiguous Gastropods first appear in the second half of the late Cambrian (Dolgellian Age), probably evolving from bellerophontiform "tergyma" ("monoplacophora") like Cyrtolites. Earlier spiral shells attributed to the class, and dating to the early and middle Cambrian, are now considered to be non-molluscan (e.g. Aldanella) or non-gastropod (either Helcionellid, tergmyan, or Paragastropod) mollusk.

Like the Cephalopods that also appeared at this time, Gastropods radiated very quickly, but unlike the Cephalopods made it through the end Cambrian mass extinction event with few casualties. These very early forms can in a variety of shell types, including bellerophontiform, discoidal (planispiral), low-spired anistrophical (conventional helically coiled spiral) and hyperstrophic ("upside down" spiral - Macluritina) coiled forms, loosely coiled, and high spired types.

Working out the evolutionary relationships of creatures long-gone is not easy. All these very early forms used to be included under the now redundant taxon "Archaeogastropoda". Also, Dr Wagner's cladistic analysis [Wagner 1999] has shown that many forms previously considered Vetigastropod (Pleurotomarid) are actually members of either the Euomphalida (probably Eogastropoda) or the Murchisoniida (probably Orthogastropoda). The bellerophontiform gastropods he considers to be bi-phyletic, with one group perhaps ancestral to, and another an off-shoot of, a very early paraphyletic assemblage called the Sinuopeidae (latest Cambrian to middle of the Early Ordovician). Of course, it is also possible that the Sinuopeids evolved from torted bellerophontiforms, which in turn developed from untorted bellerophontiforms.

However, while looking for an example of evolution for you I did find this:

Snails Caught in Act of Evolution
By William J. Cromie

Gazette Staff

An elegant and direct example of evolution in action has been found by Harvard paleontologist Stephen Jay Gould while exploring a beach in the Bahamas.

Walking along the south shore of Great Inagua Island, the Agassiz Professor of Zoology noticed a telltale change in the shells of land snails scattered on a mud flat. He saw large, finger-shaped

shells of Cerion excelsior, an extinct snail once widespread in the Bahamas. Nearby were smaller, rounder, vertically striped shells with prominent whorls, belonging to a species called Cerion rubicundum, a well-known resident of the island.

"Scattered between them were thousands of highly variable shells spanning the full range of form from pure C. excelsior through intermediates of all degrees to C. rubicundum," Gould recalled. "It was difficult to escape the idea that the former had evolved into the later."

The history of life on Earth is written in shells, bones, footprints, and imprints found in mountains, canyons, and at the bottom of the seas. Over millions of years, movements of air, water, and continents destroy these silent signs, creating gaps in the natural record, or the fossils are scattered and compressed in different layers of sedimentary rocks. Gould, who is also curator of invertebrate paleontology at the Museum of Comparative Zoology, was looking down at a complete story of one species evolving into another in less than 20,000 years.

See:

http://www.news.harvard.edu/gazette/1997/0...sCaughtinA.html

for the complete text.

Arthur