The Age of Dinosaur Bones

dinosaurs-the-grand-tour I just finished Dinosaurs: The Grand Tour, by Keiron Pim and Jack Horner, which methodically describes all dinosaur species discovered through about 2012, along with some other interesting creatures and general dino trivia. It was fun to update my dino awareness with a lot of recent discoveries, from new species coming out of China to remains that include skin impressions and stomach contents. It was also interesting to read from a position that is more open about origins, to truly grapple with the implications of the idea that all of these creatures have only been found in specific geological layers.

When learning about dinosaurs – or anything else that relates to prehistory – it is challenging to separate fact from interpretation. The book indicated plenty of places where assumptive interpretations seem to run run far ahead of the evidence. Ozraptor is “known only from an 8cm-long fragment of shinbone.” Other species get speculative drawings, sizes, diets, and more extrapolated from “a few disconnected bones,” “a partial skull,” or “a whole forelimb.” Argentinosaurus is considered the “biggest land animal known for sure to have existed,” despite being “known from only 3 per cent of a skeleton.” My favorite was the description of Equijubus, whose “spiked thumb served for defense or for feeding,” despite the fact that the “only known fossil is a skull and vertebrate.” (I used to think when we overconfidently speculated about the purposes of body parts, it was at least limited to ones we’d actually found!)

In the past, I would have said, “The people making such unwarranted assumptions about what these animals looked like are the same people telling me these animals lived millions of years ago,” finding it easy to dismiss details that contradicted what I considered the one clear interpretation of Scripture. But I now consider such a dismissal unfair – a lazy projection of the weakness of some conclusions to the weakness of others without really considering them. Even if we throw out the most questionable elements of dinosaur knowledge, we are left with the most solid and well-substantiated elements, and that evidence deserves a fair consideration.

There are plenty of fragmented, isolated remains, to be sure. But there are also plenty of “complete fossils.” Some species have been found in large numbers – forty-seven Triceratops skulls were unearthed in the USA’s Hell Creek Formation in the first decade of the 21st century alone. We have “perfectly preserved skeletons retaining skin impressions” of scales. We‘ve matched bone marks to teeth based on their “size, spacing, and serration.” We’ve got a Baryonyx with “remnants of a young Iguanadon in its gut.” We’ve got a Scipionyx specimen with “such detailed features as muscle fibers, the windpipe, the liver and some remains of the intestines.” (woah!) We’ve got eggs, footprints, and poop. We’ve got scientists 3d-scanning skulls to assess inner ear balance and other scientists microscoping fossilized pigment vessels to assess skin colors. (woah!!) We’ve got more and more species revealing impressions of feathers, bristles, quill knobs, wings…. There’s a lot we don’t know, but there’s an increasingly large amount that we do.

There are so many varieties of so many creatures that are unlike anything we know today. Theropods, with their big scary heads and little arms. Sauropods, with their long necks and giant legs and tails. Ceratopsians, with their horns and neck frills. Ankylosaurs, with their full-body armor. And the bird-like dinos, oh the vast quantity of bird-things! I grew up being taught that evolutionists considered Archaeopteryx an intermediate link between reptiles and birds, but that it didn’t count because it was basically just a bird that happened to have some fully-formed definitely-not transitional reptile parts along for the ride. Well, apparently that whole part of the bird-reptile debate is literally outdated by a hundred years. We don’t just have Archaeopteryx now, we have Xiaotingia, and Epidexipteryx, and Caudipteryx, and Shuvuuia, and Unenlagia – a stunning array of bizarre creatures with various assortments of tails and tail feathers and beaks and teeth!

Page after page of extinct species, each with a sidebar graphic unambiguously limiting the evidence of their existence to a specific subsection of the Triassic, Jurassic, or Cretaceous geological layer. If fossil order is truly that consistent, it has strong implications. Not necessarily for evolution specifically – this very pro-evolutionary book has a line that sounds like the repeated refrains in intelligent designist Stephen Meyer’s Darwin’s Doubt: “The patchy evidence we have from ancient rocks shows no confirmed dinosaurs, and then suddenly several kinds in each of these categories.” (I also found interesting the variety in the numbers of sauropod neck vertebrae, given that the common ancestry of mammals is said to be supported by them all having the same number.) But such layer placement – if accurate – at least presents a strong challenge to young-earth creationism and its fossilization by global flood.

I had never been much impressed by Bill Nye’s cordial suggestion that upending evolutionary theory was as simple as finding a fossil in the “wrong” layer. Might we simply extend the lifespan of that creature to include that layer? How can you get more “wrong” than finding a living coelacanth 65 million years after its last appearance in the fossil record? Apparently we do find fossils in “wrong” layers but call them “zombie taxons” that washed out of one layer and got redeposited in another, of which a dinosaur tooth appears to be the canonical example! And yet, while such cynicism may work in the abstract, or for an isolated species, it feels like a weaker protest when you consider the sheer volume and consistency of all these dinosaur species within these three major layers (occasional washed up teeth notwithstanding). The probability that such a proportion of such a number of artifacts would be found in these layers all over the world by chance surely must approach the theist’s favorite Boeing-747-from-a-tornado-in-a-junkyard.

Of course, that’s presuming the layer identification of all these fossils is reliably accurate. The date ranges on these layers, as I understand it, are derived from half-life ratios of radioactive decay. Geologists put the dino-zones from 200-something to 65 million years old. We’ve only measured these atomic decays for roughly a century, and even if we’ve found no method of variance, I can be easily skeptical of extrapolating that evidence a million-fold. But suppose the ages are wrong. Forget the interpretation of the particle ratios and just consider the ratios themselves. If all these dinosaur bones are only found in rocks with a relatively narrow range of particle ratios, is there another explanation that makes as much sense as them all living in their own time period?

But I don’t know what percent of fossils are dated that way; I suspect it may be far south of 100%. This book gives paltry few clues at the processes behind the layer classifications it describes. In fact, one of the only references supports my skepticism. Of the genus Jobaria, it says:

The sediment its bones lay in were initially ascribed to the Early Cretaceous but a study in 2009 suggested them to be far older…

Now Jobaria is considered to be Middle to Late Jurassic. Either that specimen was not initially measured by elemental ratios, or was measured by ratios that apparently have enough margin of error to be useless at pinpointing layers. Surely there are others like it. Yet surely all others are not like this.

Still, let’s consider the worst-case scenario. Suppose no fossils are dated this way, but a principle was established on a few weak examples, and now there’s a circular pattern such that many sections of earth aren’t categorized until we find a dinosaur fossil and then decide that it must be a Jurassic or a Cretaceous layer because we already assume that’s when they lived. Even if the layer consistency of dinosaurs is totally a forced tautology, is it true that after a dino-containing layer is named, we frequently find more dinosaurs in the same slab of sediment, but never, say, elephants? Is it true that we find other dinosaurs in their guts, but never humans? That we find teeth marks that match other dinosaurs, but never lions? That we’ve found a Velociraptor locked in battle with a Protoceratops, but never a monkey? What are the odds of all of those things happening by chance?

My thoughts turned to “flood geology,” which assigns the origin of virtually all fossils to Noah’s global flood. In the past I had repeatedly come across arrogant mainstream assertions that the geological evidence clearly disproves such an interpretation, but never with any explanation of why, and I’d read enough hypothetical examples of fossils formed by creatures swept away by “flash floods” to feel comfortable supposing a “global flood” to be similarly plausible. But having considered the weight of the evidence for fossil order in more detail, I wondered, how well-developed was flood geology, anyway? Were there more rigorous details than Ken Ham’s infamous “billions of dead things buried in rock layers laid down by water all over the earth”? Was it all as hand-wavingly speculative as my own lazy musings that, hey, a lot of water could probably do a lot of things, or were there scientific efforts to explain how a short deluge could have produced the specific features we observe today?

I went searching, and I quickly found a lot of really interesting things. But since this post is already long enough, I’ll save that for next week…

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