Written by Harold B. White 9/93, Revised most recently April 2013

Otopteryx volitans, aka the Earwing, uses its large ears to fly backwards.

Page 3: Molecular Evolution in the Spirit of Snouters

Most evolutionists and paleontologists now agree that a large asteroid hit the earth near the Yucatan Peninsula about 65 million years ago (33-35). The impact created a huge crater and the resulting blast initiated a world-wide atmospheric crisis that apparently doomed the dinosaurs and many other taxa to extinction. [Please view the 33 min on-line video, The Day the Mesozoic Died] A few insignificant mammals survived. They evolved and speciated to occupy the ecological niches vacated during the mass extinction. A tremendous diversity of forms arose from this radiation. Dinosaurs might still rule the world and likely humans never would have evolved without this astronomical disaster. This scenario has led fanciful biologists with minds like Dr. Seuss to contemplate the evolutionary consequences of another similar asteroid encounter. In this genre, although not following an asterioid impact, the German zoologist Harald Stumpke created an imaginary island populated with organisms known as snouters (36, a French translation) that evolved and diverged from an single founding species.

Assignment: By now in this course, you have studied a variety of examples of biochemical evolution and appreciate major aspects of evolution at the molecular level. The following assignment asks you to use your imagination to create a plausible senario in adaptive molecular evolution.

Based on what we know about the relationships among dinosaurs, crocodillians, and birds, it is quite likely that dinosaurs posessed a lactate dehydrogenase B that served double duty as an epsilon-crystallin in the dinosaur crystalline lens. Assume that the asteroid impact of 65 million years ago did not occur and that dinosaurs survived to the present day. Also assume that early on in this mythical lineage of dinosaurs there was duplication in the gene for LDH-B/epsilon-crystallin. Using reasonable patterns in molecular evolution and what you have learned about lactate dehydrogenase and crystallins, imagine the long-term evolutionary effects of selection on paralogous LDH-B and epsilon-crystallin. Describe the changes in both genes and protein products you would expect as the result of the selective forces that would be present.

Return to Page 1- Visualizing Lactate Dehydrogenase

Return to Page 2 - Corrective Lenses


33. Alvarez, L. W., Alvaerez, W., Asaro, F, and Michel, H. V. (1980) Extraterrestrial Cause for the Cretaceous-Tertiary Extinction. Science 208, 1095-1108.
34. Kerr, R. (1992) Huge Impact Tied to Mass Extinction. Science 257, 878-880.
35. Sheehan, P. M., Fastovsky, D. E., Hoffmann, R. G., Berghaus, C. B. and Gabreil, D. L. (1991) Sudden Extinction of the Dinosaurs: Latest Cretaceous, Upper Great Plains, U. S. A. Science 254, 835-839.
36. Harald Stumpke "Bau und Leben der Rhinogradentia", THE SNOUTERS Form and Life of the Rhinogrades. Translated 1967 by Leigh Chadwick with an Epilogue by Gerolf Steiner. University of Chicago Press.
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Created  1 November 2000. Last updated 6 April 2013 by Hal White
Copyright 2013, Harold B. White, Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716