Help Me Understand

[TheRocketSurgeon]

So... on to the second category - the fossil record.

The fossil record shows the appearance and for many the disappearance of creatures and plants throughout geological time.  This begs the question of how these creatures came to be.  The fossil record is still incomplete, and by it's very nature shows us snapshots in time.  I always like when a creature which is believed to be extinct for millennia suddenly shows up. 

Charles Darwin said

Geology assuredly does not reveal any such finely-graduated organic chain; and this, perhaps, is the most obvious and serious objection which can be urged against the theory. (The Origin of Species)

And despite a largely expanded fossil record this is still true.  We do see some similarities, in which we can imagine a common lineage, but I am not persuaded by the evidence I have seen.  It is still not a finely graduated chain which is described.  I have also become leery of drawings presented as evidence.  I have found at times, where claims and similarities are greatly exaggerated based on scant fossil evidence.  I do want to know what they are basing their conclusion on what are the similarities and differences, and what fossil they have. This is often lacking at least in the popular articles.

Also, I do believe that the fossil record does show a punctuated equilibrium.  Where creatures suddenly appear fully formed, and remain largely unchanged for their time in the fossil record.  Similarly in events such as the Cambrian explosion we see major changes in a relatively short period of time.

Also just to be up front - I do question some of the assumptions in dating.  We are assuming that the daughter isotope is completely removed during formation of the rock.  Also the dating is not done on the fossils themselves, nor the rock in which they are found (you cannot date sedimentary rock in which most fossils remain).

Well, I'll start with your Darwin quote. The fact that you listed that tells me you have not read his book. Creationists are fond of quoting Darwin's "this is a problem for my theory" statements, found in On the Origin of Species  and elsewhere in his writings, but it's just the way he wrote. He would start with the objections he expected to hear, from those to whom he was showing his radical new idea, and then continue on to explain why it was not a valid objection. For some reason, there are entire organizations that delight in quoting his opening line, and then ignoring everything he says after it. Secondly, there are lots of things which were not known to Charles Darwin in the mid-1800s, when he was writing his ideas down, compared to our knowledge today. Not one scientist on earth uses Darwin as the basis for his understanding of biology, except for the law of Natural Selection, one of the four major mechanisms by which the percentages of genes expressed in a population are altered from generation to generation (the other "reducing" element being genetic drift, while mutation and recombination increase the variety of genotypes/phenotypes available for NS to operate upon).

I'm not really sure what you mean by "how they came to be". We know how species come to be; it's not a really complex question... though defining a "bright line" of what exactly constitutes speciation and/or a distinctive species can be problematic, depending on how one defines several factors in considering it so. Populations expand and fragment, and if behavioral changes or territorial separation cause two groups of the same population to cease exchanging genes within the gene pool of that species, then Group A and Group B will begin to diverge from one another with each generation, until at some point they are no longer able to interbreed and produce fertile offspring. As we know with mules and ligers, there can be quite a distinct difference between recently-related species before they cease to at least have the ability to produce viable offspring. Perhaps the easiest analogy for understanding species "creation" is to think of a family tree, and with isolated species groups as sharing a grandparent. "Cousin" species are distinct from one another, yet share a common ancestral population (the grandfather, in this analogy). Go back far enough, and every species on earth is a distant cousin.

The objection that species once thought extinct sometimes show back up isn't really an objection against evolution, but against zoology.

Seriously, though, it's a common misconception that things are trying to "evolve upward", or "toward" something. Older types which experienced insufficient selection pressure (being already well-adapted to their environments to the point that very few things caused them to lose members due to fitness problems), like sharks or alligators or turtles, stick around just fine as they were, as long as their environment does not change radically enough to place them under pressure, while other species may be under such selection pressure that they change fairly radically through each generation (though still by incremental degrees; even punctuated equilibria is slow, only appearing fast on a geological timescale). Humans are not any "more evolved" than a worm, or a monkey. 

Think of a sperical-shaped tree full of branches, ever expanding outward and branching new offshoots, but only having leaves (existing species) on the very tips. Some branches are thick and some are thin, depending on how populous that species is, but all are "expressed" only at the tip. Some branches dwindle and die out, no longer reaching the surface. Some split off in directions so radical it takes an expert to find the branch from which they originated, especially if the central vein of that old branch no longer reaches the surface. Pick any leaf on that tree to look at, and another from the far side of the tree, and you find two "equally-evolved" species. The old view of climbing a great ladder toward compexity, as described by Aristotle, is almost entirely mistaken, yet continues to inform our common view of how species evolve.

I'm curious to know exactly what your questions are about the fossil record, because I'm unfamiliar with any major problems with it. Sure, there are gaps, but one of the biggest finds in evolutionary biology's history, Tiktaalik roseae, was found as a direct result of our understanding of the fossil record and its geological stratification, because of another (descendant) species that was found that suggested it should have an ancestor like Tiktaalik.