To describe a new specie, it has to be carefully examined in order to determinate that it doesn´t belong to an another specie already described.
Once it has been determinate the novelty of the specie, the researchers write a formal description of it, takes pictures and name it with the new scientific name. Then, the researchers refer it to a scientific magazine. The editor of the publication will comunicate the new discovery to an experts in that gender. If the experts agreed, and the publication accept the study, the specimen converts to a new specie. The process is long and could take years betwen the inicial discovery and the formal acceptation of the new specie
The earliest animals would have been invertebrates. Meaning they had no bones to fossilized in the first place and would have been mostly soft tissue supported by internal pressure or surrounding water pressure in the ocean.
