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Reference article Parazoa

The following is included in this article.

The Ctenophora, originally part of Eumetazoa, appear to be the basalmost animals.

Based on the latest information as of 2017 it is just plain wrong. Ctenophores are part of Eumetazoa and are not the basal animals. Sponges (Porifera) are based on the geologic record as well as phylogenetic analysis.

It has been shown the original phylogenic analysis placing Ctenophores was using an incomplete dataset to place ctenophora at the base of the metazoan. When the dataset was expanded it was found they were much higher up and a part of the bilataria. In addition when the data was re-analyzed, it was found to produce different results with Porifera at the base and Ctenophora farther up the line.

In addition, the fossil record has revealed sponge-like animals that date back approximately 760 million years ago. The farthest back they can push ctenophores is about 560 - 500 mya ago.

Another factor is the makeup of Porifera and sponges. Porifera do not have tissues -- no neural net, no gut -- while ctenophores do. Porifera also only have two cell layers with a mesohyl gel-like layer in between while ctenophores have three cellular tissue layers. The consensus is porifera would have to have lost a lot of genetic makeup to cause the loss of these structures.

I recommend the following be changed and the cladistic figure be adjusted accordingly:

The Ctenophora, originally part of Eumetazoa, appear to be the basalmost animals.

Most experts include Ctenophora in the Eumetazoa based on phylogenetics and the use of large datasets.

In addition, current theory is the Parazoa consist solely of Porifera and refers to the fact it only has two cell layers, not three, like the other metazoan,

When Placazoa are looked at phylogenetically they are placed above Porifera but below Ctenophora and considered part of bilateral clade and not included in Parazoa.

It helps if people who write these articles actually read the latest research before writing and then return to review it in light of new information. You can't get any more current than the middle of 2017 if it is the beginning of the fourth quarter 2017. Allowing information that is inconsistent with current theory to remain posted makes Wikipedia suspect as to veracity in other areas.

Marc Yergin, BS, MS Pittsburgh, PA marc.yergin@gmail.com

12. Pisani, D., et al. December 15, 2015. Genomic data do not support comb jellies as the sister group to all other animals. PNAS 112(50): 15402-15407

13. Dohrmann, M. and Worheide, G. 2017. Dating early animal evolution using phylogenic data. Scientific Reports. 7(1): 3599

14. Brain, C.K., et al. 2012. The first animals: ca 760-million-year-old sponge-like fossils from Nambia. South African Journal of Science. 108(1/2): Art #658, 8 pages

15. Simon, P., et al., April 3, 2017. A Large and Consisten Phylogenomic Dataset Supports Sponges as the Sister Group to All Other Animals. Current Biology 27:958-967