Inversion of the chordate body axis: are there alternatives?
review · Level V
Where this comes from
- Record sourced from PubMed, PMID 10781041.
- Also identified by PMC identifier 34319.
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Abstract
One major morphological difference between chordates and annelids or arthropods is the opposite orientation of the nerve cord and heart. A long-standing proposal is that the chordate axis evolved by inverting the body of an ancestor with the annelid/arthropod orientation. However, the data can also be explained by a common ancestor with diffuse dorsoventral organization, followed by oppositely directed condensation of the nerve cord and relocation of the heart in the two lines.
Medical subject headings
- Body Patterning
- Chordata, Nonvertebrate
- Phylogeny