Stebbins on no transitional forms between phyla
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Quoted person
George Ledyard Stebbins, Jr.
Misquote
And geneticist Stebbins writes: "No transitional forms are known between any of the major phyla of animals or plants." He speaks of "the large gaps which exist between many major categories of organisms."
Source
Anon. (1985). Life--How Did It Get Here? By Evolution or By Creation?. Brooklyn, New York: Watchtower Bible and Tract Society of New York, Inc. p. 65.
Original quote
Thus the fossil record of vertebrates strongly suggests that the characteristics which distinguish the modern higher categories appeared first as distinctive features of certain species or genera. They became characteristics of families, orders, and classes only after descendants of the animals which first possessed them developed them further, radiated into numerous adaptive niches, and became separated from other groups by extinction of intermediate forms. In other groups of organisms such as insects and higher plants, in which the fossil record is far more fragmentary, profound gaps exist between many orders, suborders, and classes. Furthermore, no transitional forms are known between any of the major phyla of animals or plants. In view of the incompleteness and biased nature of the fossil record in all of these groups, and the extremely long time, measured in hundreds of millions of years, since the various phyla of organisms evolved, the large gaps which exist between many major categories of organisms aside from the vertebrates are most reasonably ascribed to known imperfections in the fossil record... (not verified)
Life-- uses a portion of this quote in its attempt to demonstrate that there are no transitional features to be found in the fossil record. The examples it gives of missing transitions are between species and classes. Stebbins, on the other hand, is noting the lack only of fossil evidence of the forms that existed connecting the phyla when they became distinct hundreds of millions of years ago.
Stebbins explicitly attributes the lack of known transitions between phyla to the imperfection of the fossil record and the extreme length of time since the phyla diverged. Note the care taken in separating the misquote from its context in order that this explanation is removed.
Nevertheless, there have been recent discoveries of fossils that may be transitional between phyla:
- Orthrozanclus reburrus shares features with the ancestors of the phyla mollusk, annelid, and brachiopod.
- Vetulicolia may belong to a stem group of deuterostome.
- Anomalocaris canadensis exhibits qualities of both lobopods and arthropods and may have been a transitional form between them.
Original source
Stebbins, G. Ledyard (1966). Processes of Organic Evolution. Englewood Cliffs, N.J.: Prentice-Hall. p. 147. (not verified)
References
- Feuerbacher, Alan. Part 4. The Transformation of Species. Retrieved on 2008-05-01.
- Timmer, John (March 1, 2007). New fossil unites three branches of life in the Cambrian. Nobel Intent. Retrieved on 2008-05-01.
- Fossils of Phylum Vetulicolia. Virtual Fossil Museum. Retrieved on 2008-05-01.
- Kazlev, M. Alan (15 July 2002). Anomalocaris. PALAEOS. Retrieved on 2008-05-01.
External links
- Mark Isaak's page on no transitional fossils.
- Morton, Glenn R. (7/7/01). Phylum Level Evolution.
See also
Acknowledgments
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