Loss? But we've seen gains. Consider the development by early humans of new species of wheat.
quote: Varieties of wheat that have forty-two chromosomes are the most recently evolved and most used types of wheat. All of these varieties have been cultivated by humans (as opposed to growing wild). They are hybrids of twenty-eight-chromosome wheats and wild fourteen-chromosome wheats or grasses. Early bread wheat was the result of the crossing of goat grass (Aegilops tauschii ) with Triticum turgidum. Modern bread wheat varieties have forty-two chromosomes and evolved from crosses between emmer and goat grass, which is the source of the unique glutenin genes that give bread dough the ability to form gluten. Goat grass grows abundantly in the region stretching from Greece to Afghanistan. Descriptions of the fourteen species of wheat that yield the thousands of wheat varieties grown today are provided here.
But clearly much has been gained, and not just by "hybridization"! The wheat that is cultivated nowadays is substantially different than the types of grain that grew before humans began farming.
I was expecting you to say that since this is all a result of interference by an intelligent agency (humans) that doesn't prove that evolution happens naturally, without interference by an intelligent agency.
But of course new species have been observed to evolve, so ...
But since the living organisms on the earth nowadays are different from those on the earth millions of years ago and the only way for mammals to produce more mammals is to give birth to them (similar arguments apply to creatures that hatch, spawn, etc.), some significant changes must have occurred during that lineal descent.
Unless you think lots and lots of miraculous creations happened instead of ordinary births...
But an earth only a few thousand years old has so many logical inconsistencies (How long did it take the Colorado River to carve out the Grand Canyon? How long did it take for coral reefs to form? How can we see galaxies that are millions of light years away? etc.) that it's not a falsifiable concept.
And the Flood? How did the koalas get to Australia from Mount Ararat after the Flood?
Wait a minute . . . how did the koalas get from Australia to board Noah's Ark in the first place?
But if all those geological strata with all those fossils were laid down by the Flood, how can you also claim those same waters cut through those carefully laid strata to form the Grand Canyon at the same time?
And if those swirling waters were sufficient to cut away all that rock, why wouldn't they scour the coral reefs bare?
And if they didn't scour the coral reefs bare, weren't the flood waters supposed to deposit (carefully, in perfect order) all those millions of years of sedimentary layers on top of that coral?
But how could the same waters that laid down the strata, supposedly uniformly, then wash away specific areas of the canyon so non-uniformly?
As for the coral, the flood waters either scoured them away (a much easier task than carving out the Grand Canyon) or the flood waters buried the coral deep under sediment, killing it (or both). Remember Gen 7:4 "every living substance that I have made will I destroy from off the face of the earth."
The idea of the Flood laying down geological strata was debunked long ago. To take just one example, fossils are sorted by time period: earlier organisms at lower levels. A flood would have jumbled everything up, humans with trilobites and dinosaurs with dogs, etc.
The idea of the Grand Canyon being carved by a massive flood was debunked long ago: it is, for instance a deep, meandering riverbed, not a wide, shallow, direct path.
As for the corals, how could they have survived being buried under all that sediment? Since they didn't survive, we wouldn't see any reefs nowadays. Even if Noah had brought along some coral larvae and released them after the flood, how could they have grown to the depth and worldwide extent that we see today?
You say, "somehow they got sorted by the Flood." But that's not what happens in a flood, is it? On the other hand, accretion over millennia does lay down layers "sorted" in historical order. That's not even mentioning the lava flows that appear in between sedimentary layers. Hard for a flood to lay down lava.
And no, rushing flood waters would not have worn out a riverbed like that. "Upstream of the Grand Canyon, the San Juan River (around Gooseneck State Park, southeast Utah) has some of the most extreme meandering imaginable. The canyon is 1,000 feet high, with the river flowing five miles while progressing one mile as the crow flies (American Southwest n.d.). There is no way a single massive flood could carve this." - http://talkorigins.org/indexcc/CH/CH581.html