In: Biology
Vertebrates have added to the original chordate characteristics. One set of vertebrate features protects one of the chordate synapomorphies. What indicates the characters involved?
In chordates, four common features appear at some point during development: a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail.
The characteristic features of the phylum Chordata include the presence of a notochord and paired pharyngeal gill slits. In sub-phylum Vertebrata, the notochord present in embryos gets replaced by a cartilaginous or bony vertebral column in adults. But in cephelochordates, notochord persists throughout life as such and in urochordates, the notochord is present only in larval stages and absent in adults. Thus, it can be said that all vertebrates are chordates .