If an Asteroid wiped out the Dinosaurs how did Evolution continue?

[The Grand Nudger]

No, not everything that it could hail from. If you keep tracing the linage of Ica back in time, eventually you will arrive at an bacteria.

But long before reaching the obsurdly distant single cell ancester, the ancesters of Ica would have already lost so many of the derived traits of grass that it is no longer a grass. Before even that other more recent ancetsres of Ica would have lost so many derived traits of Ica that it was no longer an Ica, but was still a grass.

I might just be confused here, but you seem to have reversed the order of a top down system of classification while trying to maintain top down priority. All descendants of the lca are grass, we could call the lca grass itself. It's not necessarily the case that the ancestor of the lca was grass.

Though that could certainly be the case, the lca representing some spur that survived on the otherwise annihilated family tree. Else-wise it would be the only representative of what it is to be grass. The trouble that thinking of it this way runs into is the "what-if" category. What if, despite having no evidence that this is the case, the lca was just a representative of a larger group? Where did all of the other reps of that group go (remember, 90% of all existent grasses trace to an lca...the other ten haven't been studied conclusively)? Why don't we find any evidence of either group? We don't know how long the lca was around, that's true, but we do know that it isn't well represented in the fossil record, and certainly nowhere near as well it's descendants are represented a scant 10-15my later. If I wanted to make the case for multiple reps of grass via lca, or the lcas "length of service" as it were, I'd be looking for the kind of evidence we don't find where we expect we should. I would certainly try to accomplish this before I imagined some sort of buffalo on the plains scenario sans buffalo plus dinosaurs.

When you compare the genomes of Ica, the best you can do is determine when the first Ica ancester that was already itself an Ica first arose. You can not determine when the first Ica ancester that wasn't yet Ica, but is already grass, arose.

As above, there's no reason for the lca's ancestors to have been grass, and we have no evidence that this was so. The lca already encompasses all known finds -including- the one you linked. We don't know how long it was around, but we do know that it wasn't gently waving all over the plains. That type of growth would be immediately recognizable (pollination by air means a hell of alot of opportunity for evidence to be left behind).

It is that second ancester which was the first to have all the traits needed to be grass, but none yet of any of the incremental traits needed to be an Ica, that would mark the origin of grass.

Looking just at Ica it would be hard for you to pin point that.

I disagree, I think the lca offers us the best evidence yet as to where to even -start looking- for evidence of it's ancestors. If they were grass..if they had the defining characteristics - we'd expect evidence that we have not found, again. We simply cant put grass much further back than the lca without any evidence, because it really does offer fantastic potential for being found in the fossil record due to what it means to be a member of the family.

The best you can say is genome study and available fossil evidence does not grossly contradict and falsify each other (for example discovery of what is very much an Ica like grass fossil 100 mya). I am not sure if they really support each other.

Well, they establish that up to 5my before kt there was an lca for said grasses doing it's thing (for an indeterminate period before), that very near kt reps of a few of it's descendants found their way into a dinos stomach. That 10my -after- kt all existent grasses had likely diverged from that lca, and that a few short my after the world was covered with the shit. No other "horizontal relative" of that lca is found in the genomes of any existent species (nor are we sitting on a mound of fossilized grasses -more accurately fossilized evidence of reproduction- which do not appear to be representative of that lineage). I'd say that paints a hell of a picture. It's not a polaroid, granted, but before the genome and this recent find we had bupkiss...lol.

(Mind you, I'm not an advocate of colonizer grass speeding across a desolate impact cratered landscape. There's a 10my gap between kt and the "grass explosion" leading into the cenozoic. I doubt that the flora hadn't rebounded by the time 10my had passed. Neverthless, both the genome and the what we have of the fossil record tell us that grass was at one point, not all that important or widely distributed - and then, post kt...it become a veritable force of nature. Could we chalk that down to the kt event? Sure, but not in the way you'd likely object to, a way I;d object to as well.)