Was Glorfindel's horse one of the Mearas?

[Galin]

I agree that the passage from the late Glorfindel text I cited (different from the description in Appendix A) implies that it was Glorfindel's influence which helped his horse. That said, while it was noted of the Mearas: "Men said of them that Béma (whom the Eldar call Oromë) must have brought their sire from West over Sea.'"

... it's also described (the constructed Silmarillion), that the Elves had horses whose sires came from Valinor (I broke up the paragraph below for emphasis here, or for some reason anyway):

Fingolfin and Fingon his son held Hithlum, and the most part of Fingolfin's folk dwelt in Mithrim about the shores of the great lake; to Fingon was assigned Dor-lómin, that lay to the west of the Mountains of Mithrim. But their chief fortress was at Eithel Sirion in the east of Ered Wethrin, whence they kept watch upon Ard-galen; and their cavalry rode upon that plain even to the shadow of Thangorodrim, for from few their horses had increased swiftly, and the grass of Ard-galen was rich and green.

Of those horses many of the sires came from Valinor, and they were given to Fingolfin by Maedhros in atonement of his losses, for they had been carried by ship to Losgar.

In any case

[blantyr]

Originally Posted by Galin

I agree that the passage from the late Glorfindel text I cited (different from the description in Appendix A) implies that it was Glorfindel's influence which helped his horse. That said, while it was noted of the Mearas: "Men said of them that Béma (whom the Eldar call Oromë) must have brought their sire from West over Sea.'"

... it's also described (the constructed Silmarillion), that the Elves had horses whose sires came from Valinor (I broke up the paragraph below for emphasis here, or for some reason anyway):

I have always assumed the elf-horses and the Mearas were distantly kin, very likely descended from those that came from Valinor. I'd assumed that some such had always been with the elves, but at some point enough of them to breed had joined the humans that later moved to Rohan.

I also see Shadowfax as exceptional even by the standards of the Mearas. Tolkien's world has a feeling of devolution, of the pure and the best being old, and the further and longer one is distanced from the Two Trees, the more degraded and lesser one becomes. In the old days fea abounded, greatness was common, strength was abundant. As the ages passed, most became lesser, weaker. Only in certain special lines such as the Mearas or the Dúnadan did the old purity remain sufficient to echo the old times. For the most part, the fea dispersed, each generation had less than the generation before, until at the start of the Fourth Age and the passing of the rings, little was left.

But I always thought Shadowfax an exception. Perhaps the Valar thought the White Rider would need a companion and blessed him somehow.

But I can't point at references to support the above conjecture.