How did the modern giraffe evolve from the Canthumeryx?

Answer 1

It evolved to fit the environment. The modern giraffe got its long neck due to reaching into high trees. At least that's how I remember it from Anthropology classes.

Answer 2

It evolved over millions of years through a series of small changes.

1) First the ancestral canthumeryx would be reaching for leaves from high trees. As a result, it would stretch its neck little by little.

2) As it stretched to reach the leaves from high trees its neck would get a little bit longer. It would pass this longer neck on to its offspring.

3) The canthumeryx offspring would have a longer neck as a result. It would then reach for the leaves from high trees, causing its neck to stretch out a little bit. It would then pass this modification on to its offspring.

4) These small changes, over very long periods of time (millions of years), caused the canthumeryx neck to get longer and longer. Eventually speciation occurred and the species we recognize as the modern giraffe was born.