Which Extant Chordates are Postulated to Be Most Like the Earliest

Question

Which extant chordates are postulated to be most like the earliest chordates in appearance?
A)lancelets
B)adult tunicates
C)amphibians
D)reptiles
E)chondrichthyans

Accepted Answer

Lancelets, also known as amphioxus, are considered to be the most basal extant chordates and share many similarities with the earliest known fossil chordates. They have a simple, elongated body with a notochord and pharyngeal slits for filter feeding, similar to the structures found in early chordate fossils. Adult tunicates, while also chordates, have a more derived morphology and lack many of the features found in early chordate fossils. Amphibians, reptiles, and chondrichthyans are all vertebrates, but they have more complex bodies and are not as similar in appearance to the oldest known chordate fossils.