David Tyler on new Cambrian eyes discovery: “Major challenges for advocates of Darwinian gradualism”
|January 6, 2012||Posted by News under Cambrian explosion, News|
Here’s David Tyler on “The remarkable eyes of the Cambrian ocean’s top predator”
Hot on the heels of an arthropod with complex compound eyes from the Emu Bay Shale (in Australia) has come an even more dramatic discovery! The same lagerstatten has yielded some fossil eyes, attributed to Anomalocaris, that show just how much ‘modernity’ can be traced back to the Cambrian fauna.
“The number of ommatidia in the Anomalocaris eyes would almost certainly have greatly exceeded the count based on the exposed surface of the eye alone. [. . .] the total count could be substantially greater than the observed 16,000+ lenses. If this is indeed the case, few living arthropods have as many ommatidia, and these eyes would certainly have functioned with a high degree of acuity. [. . .] Throughout the geological history of Arthropoda, compound eyes have rarely exceeded this size; very large Siluro-Devonian pterygotid eurypterids and some Jurassic thylacocephalans represent some of the rare examples with eyes larger than those of Anomalocaris.”
Discoveries like this create major challenges for advocates of Darwinian gradualism. Again and again, the source of novelty is pushed earlier into the undocumented past. Gradualism as a working concept is sustained, not by data, but by inference – but the gaps available for gradualist change are ever shrinking!
Grad of the gaps, it seems. More.
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