Actually there is abundant evidence of gradual incremental change (fragments)af a result of mutations in DNA, but you are too 'mindless' to make the effort to do any research in the literature to understand it.
Fossil bones are not just bones, but in the fossil bones are DNA still there in the past 50,000 to ~700,000 years. Ancient DNA as old as 50,000 years can be reconstructed and compared to related evolved species showing incremental change in the DNA over time. In older DNA in bones it is more difficult, but yes fragments are found that can be useful to compare extinct animals that are antecedents of evolved living species. The amount and kind of mutations can be calculated in predictable pattern that acts like a 'clock' to measure the rate of evolution over time. The asisstence of modern computers has greatly advance the accuracy of reconstructing ancient DNA.
The ability of related Equus species living today to interbreed is directly related to the amount of mutations in the DNA over time. Closely related species to horses can and so interbreed in the wild in Asia. More distantly related species like the Zebra and Donkey (The domestic version of the African wild ***, E. africanus.) cannot, but can artificially interbreed, but not usually fertile.
Has dinosaur DNA been found? An expert explains what we really know
"By using massive computing resources, DNA from fossils maybe 50,000 years old can be reconstructed from millions of short
fragments. The oldest such samples are 700,000 years old . . . "
Example: First the diverse related Equidae, species living today can be compared to horses. Related species to modern horses that have evolved in recent geologic history can be demonstrated incrementally by comparing the anatomy of the bones and the incremental genetic evolution, back to the time that the antecedents of horses were small dog and cat sized animals that were definitely not horses. Measured genetic change overtime matches the gradual anatomical change in the fossil bone evidence.
Ancient horse DNA reveals gene flow between Eurasian and North American horses
Ancient horse DNA reveals gene flow between Eurasian and North American horses
"A new study of ancient DNA from horse fossils found in North America and Eurasia shows that horse populations on the two continents remained connected through the Bering Land Bridge, moving back and forth and interbreeding multiple times over hundreds of thousands of years.
The new findings demonstrate the genetic continuity between the horses that died out in North America at the end of the last ice age and the horses that were eventually domesticated in Eurasia and later reintroduced to North America by Europeans. The study has been accepted for publication in the journal
Molecular Ecology and is currently available online.
"The results of this paper show that DNA flowed readily between Asia and North America during the ice ages, maintaining physical and evolutionary connectivity between horse populations across the Northern Hemisphere," said corresponding author Beth Shapiro, professor of ecology and evolutionary biology at UC Santa Cruz and a Howard Hughes Medical Institute investigator.
The study highlights the importance of the Bering Land Bridge as an ecological corridor for the movement of large animals between the continents during the Pleistocene, when massive ice sheets formed during glacial periods. Dramatically lower sea levels uncovered a vast land area known as Beringia, extending from the Lena River in Russia to the MacKenzie River in Canada, with extensive grasslands supporting populations of horses, mammoths, bison, and other Pleistocene fauna.
Paleontologists have long known that horses evolved and diversified in North America. One lineage of horses, known as the caballine horses (which includes domestic horses) dispersed into Eurasia over the Bering Land Bridge about 1 million years ago, and the Eurasian population then began to diverge genetically from the horses that remained in North America."
