what is the fate of notochord in vertebrates
Notochord Notochords are thought to be advantageous (both in an evolutionary and developmental context) because they provide(d) rigid structure for muscle attachment, but were still flexible. In some chordates, it persists throughout life as the main structural support of the body, while in most vertebrates it becomes the nucleus pulposus of the intervertebral disc.[1] The notochord plays a key role in signaling and coordinating development. Embryos of vertebrates still form transient notochord structures today during the gastrulation phase of development. The notochord is found ventral to the neural tube.
Middle ear The middle ear contains three tiny bones known as the ossicles: malleus, incus, and stapes. The ossicles were given their Latin names for their distinctive shapes; they are also referred to as the hammer, anvil, and stirrup, respectively. The ossicles directly couple sound energy from the ear drum to the oval window of the cochlea. While the stapes is present in all tetrapods, the malleus and incus evolved from lower and upper jaw bones present in reptiles.