Why was phylum Elemichordata earlier considered as a sub phylum of Chordata?

Monjur Alahi

Why was phylum Elemichordata earlier considered as a sub phylum of Chordata?


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Salim Ahmed Kawsar

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1. Hemiehordata was earlier considered as sub phylum of Chordata because the buccal diverticulum was considered a notochord. It is now placed as a separate phylum under Non-Chordata. 

2. It possesses certain characteristics of both Chordates and Non-chordates. 

3. Absence of notochord worm-like body, heart located on the dorsal side are the Non-chordate like characteristics seen in Hemiehordata.

4. Presence of nerve chord, pharyngeal gill slits are some of the Chordate-like characters seen in Hemiehordata. Hence, Hemiehordata is considered as a connecting link between Non-chordata and Chordata.

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