The rise of bilaterians

@article{Freeman2009TheRO,
  title={The rise of bilaterians},
  author={Gary P. Freeman},
  journal={Historical Biology},
  year={2009},
  volume={21},
  pages={114 - 99}
}
Recently Shen et al. have argued that the Ediacaran faunas from Avalon-Charnwood [580–560 million years ago (MA)], the White Sea-Flinders Range (560–550 MA) and Namibia (550–543 MA) occupied the same morphospace even though these faunas differed in species composition, ecology, biogeography and age. The traits they used to characterise these faunas could not distinguish between important promorphological features such as radial vs. bilaterian and unitary vs. colonial animals. Their… Expand
The rise of bilaterians: a few closing comments
TLDR
Although Vernanimalcula is a fossil, the purported germ layers of Vern animalcula are of diagenetic origin and there is no morphological evidence in support of its bilaterian affinity, so it is inappropriate to analyse Ediacara fossils using “promorphologies” of extant animals. Expand
The rise of bilaterians: a reply
In the March–June 2009 issue of Historical Biology, Freeman (2009) published a critique of our morphological and phylogenetic analyses of Ediacara fossils (Shen et al. 2008; Xiao and Laflamme 2009).Expand
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TLDR
All the available information is strongly in favor of multiple evolution of non-planktotrophic development, and only the terminal addition theory is in accordance with the Darwinian theory by explaining the evolution through continuous series of adaptational changes. Expand
Comment on Xiao et al. (2009), response to: the rise of bilaterians
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