How is the scientific theory of evolution supported by the comparison of the skulls and skeletons of modern humans and extinct hominids?

The evidence supported from the comparison of modern humans and extinct hominids's remains, mostly skeletons an skulls can be easily seen in the gradual changing in the species as they faced different environments. Starting from the earliest hominids, until the modern humans, the basics of the body structure is the same, but as the time was passing, and as the hominid species moved into different environments they show slight modifications. A nice example are the Homo sapiens and the Homo neanderthalensis. Both evolved from the Homo erectus, and both were very similar, but the Homo sapiens lived in an open savanna, while the Homo neanderthalensis in a cold forested region. Because of this, the Homo sapiens became thinner, taller, and also the brain started to develop in a way that was allowing more social interaction, and that gave the shape of the brain in modern day humans, while the Homo neanderthalesis became slightly shorter, bulkier, and the brain developed in way where it was more focused on hunting and performing strategies, and that gave them the more ape-like appearance if their skulls.