I believe the answer you're looking for is Evolution.
The option which is not a characteristic of chordates is chloroplasts in their cells.
Chordates do have a dorsal supporting rod (vertebrates are types of chordates - they have a spine), a dorsal hollow nerve cord (within the spine), and pharyngeal pouches. However, they do not have chloroplasts, because that is a characteristic of photoautothropic eukaryotes, which chordates certainly are not.
Answer:
Organisms decompose more quickly when they are in contact with oxygen. ... When an organism is buried quickly, there is less decay and the better the chance for it to be preserved. The hard parts of organisms, such as bones, shells, and teeth have a better chance of becoming fossils than do softer parts.
Explanation: