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| | American Zoologist: Metazoan relationships on the basis of 18S rRNA sequences: A few years later... (Site not responding. Last check: 2007-10-08) |
 | | The third case study concerns the relationships of the mesozoan taxa Orthonectida and Rhombozoa, whose evolutionary origin has been controversial for many years. |
 | | Some consider Mesozoa as very primitive organisms that link protists and animals (e.g., Lapan and Morowitz, 1972; Margulis and Schwartz, 1988), while others believe that the simplicity of Mesozoa is secondary and regard them as degenerate flatworms because of their morphological resemblance with flatworm larvae and their complex life cycle (Stunkard, 1954, 1972). |
 | | Indeed, some consider the morphological similarity between both Orthonectida and Rhombozoa to be purely superficial and the result of convergence due to similar lifestyles (e.g., Brusca and Brusca, 1990). |
| www.findarticles.com /p/articles/mi_qa3746/is_199812/ai_n8824743/pg_2 (1130 words) |
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