What is the proof, if any, that invertebrates evolved into vertebrates?

Question

First life must of been soft like a sponge if Evolution is true. What is the evidence that may prove that sponge-like life evolved a backbone? And, has this alleged change ever been observed?

Answer 1

I actual dont know the answer if u take time to read these sites they cna help u get a better understanding, hope this helps u with ur homework.

Answer 2

Invertebrates and vertebrates is not a perfect dichotomy.  Look up amphioxus and primitive fish

http://www.ucmp.berkeley.edu/chordata/ce...

http://en.wikipedia.org/wiki/Prehistoric...

Answer 3

The classic example supported by molecular genetics, anatomy and paleontology is the evolution of the vertebrates from sessile filter feeders in the ocean.  The filter feeders have no vertebrae, but when they reproduce, they give off small swimming offspring that have a small rod down their backs.  This rod, known as the notochord, is found in all embryonic vertebrates.  In the vertebrate chordates, this rod becomes incorporated into the vertebrae.  

That is, the juvenile offspring of the invertebrates evolved into the vertebrates.  Evolutionary biologists call this process neoteny.  See the reference below.

I am a biologist.