We have known for many years that the eyes of trilobites, going back to the Early Cambrian, have highly sophisticated optics. Although vision has been invoked as a probable characteristic of many other types of animal, there have been few examples of preserved eyes in the fossil record, even in the Burgess Shale and Chengjiang lagerstatte. However, the Emu Bay Shale, which provides exquisite preservation of Early Cambrian animals, has now supplied us with the earliest example of an non-trilobite arthropod eye. Of the seven specimens recovered to date, three are spectacular for the detail revealed and stunning because they document eyes that "are as advanced as those of many living forms". One of the authors of the research paper, Dr Jim Jago, is quoted in the press release:
"These are by far the most complicated eyes known from this period of earth's history. Each eye is seven to nine millimetres across and comprises over 3000 tiny lenses. As yet, the animal to which these eyes belonged is unknown, but they may have belonged to a large shrimp like animal. However, the rock layers in which the eyes are preserved include a dazzling array of fossil marine animals, many being new to science. They include primitive trilobite-like creatures, bizarre armoured worms and large swimming predators."
One of the newly reported complex eyes from the Emu Bay Shale (source here)
The abrupt appearance of complexity in the fossil record has often been documented in this blog, primarily to raise questions about the relevance of Darwinism for understanding the origins of complexity. Time and time again, Darwinists fill the gaps in knowledge with their theoretical models, but sooner or later, the next generation of scholars will realise that Darwinists have constructed a virtual world that does not match the real world revealed by research. The features that appear abruptly are as follows:
1. Compound eyes with lenses that are larger than any others previously documented in the Cambrian Period. The largest have an elevational diameter of 150 micrometres and the smallest are about half this size.
2. The arrangement of the lenses shows a regional specialisation otherwise unknown in the Early Cambrian. The larger lenses create a "bright zone" and in living animals this generates binocular vision whilst retaining wide peripheral fields. These features are very useful to fast-moving predators.
Here is Jim Jago again:
"The fossil compound eyes have over 3000 lenses, giving them much sharper vision than anything previously found from rocks this old. The eyes are much more complex than anything found previously in rocks of similar age. The newly discovered eyes are as advanced as the eyes in many living insects such as robberflies. The arrangement and size of the lenses indicates that these eyes belonged to an active predator that was capable of seeing in low light."
The significance of the find is that there are no earlier intermediate forms from which to construct an evolutionary scenario, and that the structure of these eyes is essentially modern. The authors of the research paper anticipate this problem for evolutionary theory in their first sentence: "theory suggests that complex eyes can evolve very rapidly" and they cite the well-known 1994 paper by Nilsson and Pelger. They are right to say "theory suggests" because the Nilsson and Pelger paper has no links with empirical data. It is a conceptual model of morphological change - it completely by-passes issues of how light is sensed, transmitted to the brain and decoded. Parameters are introduced that are guesstimates; there is no link to Darwinian mechanisms of mutation and natural selection; assumptions are introduced throughout, with the minimum of justification. The weight that is put on this paper is justifiably called "A Scientific Scandal" by David Berlinski (for his essay, go here). The paper is really a dressed-up "just-so" story - with no link to the real world. Theory is fine as long as it is tested and validated - the problem with Nilsson and Pelger's theory is that it is an exercise in vivid imagination, has not been tested and cannot be regarded in any sense as authoritative.
There is no doubt that the Cambrian Explosion is a puzzle to Darwinists (for the reason why, see here). Many of them still refuse to concede that there was an non-Darwinian explosion of animal forms and they keep looking for ways of stretching out the timescales. However, others look for some strong selection pressures that could drive rapid evolution. The authors of the research paper align themselves with the latter group: "[The eyes] provide further evidence that the Cambrian explosion involved rapid innovation in fine-scale anatomy as well as gross morphology, and are consistent with the concept that the development of advanced vision helped to drive this great evolutionary event." Their reference for this points to Andrew Parker, who has championed this interpretation. The problem is that there are no transitional eyes to give this argument a connection to evidence. In fact, numerous "explanations" have been proposed, but none of them are compelling. It is far better to admit we do not know, as Shu did in 2008:
"Although we remain as blind men interpreting elephants when we search for the origin of metazoans, more and more accumulating data and hypotheses certainly help us with a better understanding the classic can of worms in both biology and geology."
The hypothesis to which I return repeatedly in these blogs is that the fossil record is not so much a record of evolutionary transformation, as a record of ecological transformation. Whilst I cannot claim the new fossil eyes are a proof of the hypothesis, they can certainly be understood in this way. As the Cambrian seas became richer ecosystems, the fauna became more diverse and the food webs more complex. As part of this picture, the arthropods with "modern" eyes do not look out of place at all.
Modern optics in exceptionally preserved eyes of Early Cambrian arthropods from Australia
Michael S. Y. Lee, James B. Jago, Diego C. Garcia-Bellido, Gregory D. Edgecombe, James G. Gehling & John R. Paterson
Nature, 474, (30 June 2011), 631-634 | doi:10.1038/nature10097
Despite the status of the eye as an "organ of extreme perfection", theory suggests that complex eyes can evolve very rapidly. The fossil record has, until now, been inadequate in providing insight into the early evolution of eyes during the initial radiation of many animal groups known as the Cambrian explosion. This is surprising because Cambrian Burgess-Shale-type deposits are replete with exquisitely preserved animals, especially arthropods, that possess eyes. However, with the exception of biomineralized trilobite eyes, virtually nothing is known about the details of their optical design. Here we report exceptionally preserved fossil eyes from the Early Cambrian (~515 million years ago) Emu Bay Shale of South Australia, revealing that some of the earliest arthropods possessed highly advanced compound eyes, each with over 3,000 large ommatidial lenses and a specialized 'bright zone'. These are the oldest non-biomineralized eyes known in such detail, with preservation quality exceeding that found in the Burgess Shale and Chengjiang deposits. Non-biomineralized eyes of similar complexity are otherwise unknown until about 85 million years later. The arrangement and size of the lenses indicate that these eyes belonged to an active predator that was capable of seeing in low light. The eyes are more complex than those known from contemporaneous trilobites and are as advanced as those of many living forms. They provide further evidence that the Cambrian explosion involved rapid innovation in fine-scale anatomy as well as gross morphology, and are consistent with the concept that the development of advanced vision helped to drive this great evolutionary event.
Primitive creatures had powerful eyes, University of South Australia, Press Release (30 June 2011).
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