Always. The evidence they were ever anything but horses is non-existent.
Tall horses? Dappled horses? Big muzzle, short tail? Feral? Domestic? It's still a horse. There are plenty of genetic strains of the horse. There is enormous variation in genetic makeup and a huge spectrum of epigenetic expression that the horse can produce according to environment, climate, diet, predators, ground cover, vegetation, habits. Some species are night-blind. Others have extra ribs.
But it is still a horse. Not a different species.
One big paradigm shift I have had mentally recently, maybe my biggest readjustment in quite a while, is the epiphany I have had about taxonomies. They are artificial constructs created by experts in narrow fields to assist them in making up impressive looking charts they can hang in their classrooms. Taxonomies may not exist in fact at all, throughout the universe, anywhere.
This is critical in my profession, where slavish obsession to the mental framework of the taxonomy has possessed the industry for nigh ten years because of their usefulness in designing GUIs with the "OBJECT-ORIENTED" paradigm. The OOP ideology is best distilled to IS-A relationships. It works great for GUIs. Everything else ... I just don't know anymore.
I am starting to believe that IS-A is all wrong. It is more like HAS-A in the real world. There is no PARENTED-TO when what matters more is GROUPED-BY. You have to be a programmer to appreciate what I am talking about. TABLES are BETTER THAN OBJECTS. Horrific blasphemy, I know. But true. This is part of my coming to understand the Lua scripting language and why it kicks amazing ass in 65K of compiled code.
The horse is not a family of species. Wrong. That is incorrect. The "horse" is a creature whose defining classification rests on the fact it falls into the HORSE-GROUP. Having a fluffy mane doesn't make it not a horse or even a different species. It's a HORSE with a fluffy mane.
We have no skeletons of horse-sloths, horse-shrews, horse-monkeys, horse-sheep, horse-goats.
There are no intermediary stages.
Perhaps this is because Robert Felix is correct. So-called "evolution" is in fact a brief, punctuated equilibrium in which a mad scientist's lab of freakish creation amidst magnetic storms produces wild variety and complexity from the existing gene pool. Followed by eons of steady state biology. I believe this is the case. I think Robert Felix is better than Darwin and closer to the truth of the situation.
Whatever is the truth, the only thing I can tell you with certainty is absolutely not accurate is traditional Neo-Darwinism. The facts say that is not how this works at all.
P.S. I inquired some more in this vein. Do you know the reason scientists prefer taxonomies over extraordinary coincidences? The fact is, taxonomy is artificial, invented and easy enough anybody can do it without fear of being proven wrong. On the other hand, recognizing HAS-A relationships can be a lot more demanding and requires good mental discipline, whereas IS-A can be pretty much whatever you want to say it is as an arbitrary assignment. You can pretend IS-A represents a cascade of accidents, like for example putting some deer at the top of a tree of horse relationships and just announcing "all horses must be descended from the deer." It may be a complete fabrication and made up on the spot, but the chart looks cool ... giving the impression the scientist really knows what the hell they are talking about. By the time they are proven wrong and people know horses did not descend from deer, they will be safely ensconced in retirement. To see HAS-A groups is to concede that somehow, as incredible as it may seem, there appears to be a metaphysical category of things called "HORSES" to which something belongs, even as it exhibits great differentiation in its own way. When we talk and think in terms of HAS-A, we are showing recognition that there may not be a tree of relationships all multiplied from some original form at all. Taxonomies appeal to gnostics. HAS-A says we admit ... all we know about it for sure is that it is some kind of horse. It may have not come from anything. It may have always been a horse, for all eternity.