evolution of vartebrate?

Answer 1

Here's the evolution of multicellular lifeforms in a nutshell:

Initially, all multicellular organisms evolved from a prototype unicellular ancestor (something similar to protists, bacteria, etc).... then, thousands of years/generations later, one or several mutations occurred that caused the single cells to begin living in colonies, ie: groups of cells functioning together as one. (sea sponges represent the most primitive multicellular organism and are likely a direct descendant of this multicellular prototype ancestor)... Upon successive genetic changes, some generations of multicellular organisms grew more and more complex.... There was a developmental transition from radially symmetric organisms to bilaterally symmetric organisms (like a hydra or jellyfish). If you look at an evolutionary tree (or "cladogram"), more complex organisms stem from branches out of groups of more primitive organisms. Thus, we have a gradual change over many, many generations.... Some branches die out (the result of an environmental selection pressure), while others (with more favorable adaptations) thrive and go on to give rise to even more diverse/complex descendents.... There is molecular, embryological and fossil evidence that this is the way life evolved on earth.

Now that we've established the overall picture, I can address the topic of where the first vertebrates showed up:

The first animal with a true, bony backbone originated from the chordates (all animals with a backbone or spinal column) and, with the chordates, makes up phylum Chordata. The big difference between vertebrates and the other chordates is that vertebrates have 'cephalization' (ie: the eyes and all sensory organs are borne on the head). Vertebrates can have a cartilageonous skelenton or a bony one. Examples are sharks (which are cartilagenous fish; ie: their skeletons are made of cartilage, no bony) versus goldfish (which have a true bony skeleton). With the advent of the backbone came the ability to bear limbs.... From wikipedia (because I'm short on time and cutting and pasting is faster than explaining it myself): "The skeleton of most vertebrates, that is excluding the most primitive ones, consists of a skull, the vertebral column and two pairs of limbs. In some forms of vertebrates, one or both of these pairs of limbs may be absent, such as in snakes or whales. These limbs have been lost in the course of evolution. The skeleton of most vertebrates, that is excluding the most primitive ones, consists of a skull, the vertebral column and two pairs of limbs. In some forms of vertebrates, one or both of these pairs of limbs may be absent, such as in snakes or whales. These limbs have been lost in the course of evolution."

This is essentially a complete overview of how the first vertebrates/chordates evolved from invertebrate ancestors, and all of it can be verified through the fossil record. There is also molecular evidence that can link more evolved descendents with organims representative of their primitive ancestral conditions.

(Regarding a few of the posts before mine: I really don't understand how anyone can still disbelieve in evolution! Obviously, many people have not had sufficient scientific education to know that this can all be proven!! Scientists didn't just make all of this up one day because they were bored!)

Answer 2

The main reason for a vertebrae is to create a new way for organisms to move and to better seek out food. This started with the hydrostatic skeleton of hydras and sea anemones, evolved to the flexible but fused notochord of some simpler fishes, and then finally to the solid segmented endoskeletons of amphibians, lizards, and mammals.

The interesting thing is that if you look at the development of a human embryo to a full grown baby, you'll also see the evolution of the vertebrae. At early points in development, all human fetuses have notochords and gills, just like simpler fishes and they eventually develop into the chubby, cute poop dispensers that we all love.

Answer 3

What exactly do you want to know?

The oldest vertebrate fossils found are 550million years old.

It started in marine animals and as they evolved they moved on to land and diverged into all kinds of shapes and sizes.

Answer 4

evolution is very limited and can't transfere one genus to another, but this is the formation theory by nonbeleivers

Answer 5

They didn't. God already made them with a backbone.