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Opponents of evolution theory are desperately circling their wagons again trying to maintain their belief that all species of living organisms arrived on Earth at the same time in essentially their present form. Most have finally accepted mutation and natural selection as fact but insist they only explain small differences in the organisms within species and there is no evidence that new species evolve from old ones. WRONG!
Where have they been? New methods of studying the DNA genomes of different life forms allow molecular geneticists not only to determine what species came from what, but approximately when the split began.
For 3.5 billion years all species of organisms on Earth have had to compete with other species for the available resources they needed and for a place to live in order to survive long enough to reproduce and pass on their genes to a new generation. Over time, they have acquired a set of genes that produce the most efficient traits for their particular environment. Each population of a species has a large majority of its members with these genes, but a small minority of members have genes that produce less efficient traits. These less efficient genes only allow a few members to survive long enough to pass on their genes to a new generation. The resulting population of any species will maintain this ratio of efficient to less efficient genes until the environment in which they live changes. This could be a change of climate, in the number and type of predators, in the number and type of competitors for available resources, in how food or water has to be acquired, or in modifications of the landscape.
Significant change in a species’ environment is the trigger for the formation of “new” species. Natural selection is very efficient in producing the trait that is most fit for an organism in a large population having multiple trait alternatives. However, if a group of organisms get isolated from the larger population by migration, or by an unusual event such as a hurricane, forest fire, earthquake, volcano, or any other reason, and the isolated group has a majority of its members with a trait that is less than fit, it might get fixed into the group by inbreeding. In other words, more offspring would have this trait because the most efficient trait in the larger population is no longer available to be inherited. The inbreeding would produce less than fit traits in the isolated group and threaten the group’s survival. However, if enough members of the group survived, ongoing mutations over a long period of time would allow natural selection to again determine the most fit traits, and the organism would again reach the height of maximum fitness for its new environment. The new group might become so different from the original population that it would not, or could not, mate with them when they come into contact again. At this point the new group has become a new species. This is the primary way new species, and eventually new life forms, arise.
When a new species of organisms evolve from a larger group, it does not necessarily mean the larger group will become extinct. They, like all life, will only become extinct when they can no longer compete. The new species may have acquired traits that make them more successful, at the old group's expense, resulting in the old group's demise. However, both groups might have traits that allow them to cope with their environment, in which case they will coexist until conditions change favoring one or the other. This is why some species that evolved billions of years ago, like some bacteria and archaea, are still with us. Some species of reptiles evolved millions of years ago and still survive, along with new species that evolved from some of its members.
There are no species of organisms that are more perfect than others. Every species that has ever existed was perfect for its environment at the time. Each and every organism and each and every species has evolved from a pre-existing one!
Read Settled Science and visit a museum of natural history to learn about some of the many plants and animals that thrived on Earth for millions of years that were replaced by “new” ones.
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Evolution Blog 
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