"What conceivable substantiation can you have for this? "
This is exactly the issue at hand here. What is the measured rate of change? You mention a couple centuries isn't enough, my question to you is, in a couple centuries how many DISTINCT animal types have we observed go extinct?
List of extinct bird species since 1500 - WikipediaList of recently extinct mammals - Wikipedia
Now, here's some science for you, whether you want to disqualify me because I'm not an expert or because I can't link to any scientific studies, I think what I'm about to say makes a point at least worth listening to:
If you look at the creatures that have become extinct in recent history you will notice some of them have very distinctive features that makes them unique. In the same time frame how many new creatures have appeared as visually unique as some of the ones listed above? Yout must admit there is a large discrepancy.
So when the original poster poses the question of whether all those fossils were, in fact, transitional, or not, I think a perfectly valid point is raised. Further still, if we count "improvements" in creatures that have taken place in 200 years there really aren't many as significant as the ones extinguished.
Another interesting thing to note about that chart is that none of those fossils are placed as transitional. So before you take everything you read or hear in that field as gospel or absolute truth, try to think for yourself a bit and see if the data really makes sense.
So again, going back to the original poster's question, based on the limited evidence that we have a large number of fossils must have become extinct without transitioning. Regardless of what anyone may claim, current technology doesn't allow us to be certain which fossils were in the chain and which fossils were loose ends.
Your chart, if anything, shows EXACTLY that. Loose ends!
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