Equidae (sometimes known as the horse family) is the taxonomic family of horses and related animals, including the extant horses, donkeys, and zebras, and many other species known only from fossils. All extant species are in the genus Equus.
This is another example of micro evolution because the evolution is always limited to the same family of species.
Okay, so now the distinction between micro and macro has moved from differences within species to differences within members of the same family. Fine. So, did God specially create the three of them by three separate acts of creation, or were they once the same species, and then only later became three distinct species that cannot produce fertile offspring cross-species?
You are pointing out an important clarification. Creation scientists more precisely use the word "kind" as a dividing line between micro and macro evolution but sometimes that has been confused with species (which has happened on this thread by using species very generically). The idea of "kind" is a family group of related species. As you well know the whole species groupings undergoes reconstruction from time as more information is obtained. The "kinds" are viewed as the original boundaries or groupings set from creation from which the multiplication of species would take place. How scientists group the extinct animals known only by the study of the fossil record is something that has fluctuated based on the data available and how it is interpreted. This difficulty is there for all scientists--whether atheistic or theistic. I cannot answer your question for sure, but as noted above, DNA studies are showing there are more extinct species that should be grouped into one family than previously thought. In fact the growing trend of DNA studies is bringing more species into one family rather than creating more divergence. Based on this it is far more likely that there was variation within the kind which led to species within the same family not being able to interbreed due to genetic changes over time. At any rate I do not think there is any conclusive evidence that suggests macro evolution. The fossils of allegedly different lines of evolution in vastly different time frames are sometimes found within the same sedimentary layer of time. This to me would point to more parallel developments and less linear developments.
