Dinosaur Evolution Is Relative
The science news media are all reporting that the “oldest known dinosaur relative” has been found. The artist reconstructions of Asilisaurus kongwe, found in middle Triassic layers in Tanzania, make the creature look quite dinosaurian; at least it was dog-sized and walked on thick legs under its body like its famous brethren did. Its early date (230 million years, by evolutionary reckoning) creates a conundrum for evolution. It pushes the common ancestor of dinosaurs and pterosaurs (if there was one) farther back in time, to 245 million years ago.
The fossil presents another problem for evolution. “Until now, paleontologists have generally believed that the closest relatives of dinosaurs possibly looked a little smaller in size, walked on two legs and were carnivorous,” PhysOrg said. “However, a research team including Randall Irmis, curator of paleontology at the Utah Museum of Natural History and assistant professor in the Department of Geology and Geophysics at the University of Utah has made a recent discovery to dispel this hypothesis.” That discovery was a herbivorous, four-legged silesaur – a sister group of contemporaries to the dinosaurs – that looked very different from what was expected. One of the authors of a paper in Nature said, “The crazy thing about this new dinosaur discovery is that it is so very different from what we all were expecting, especially the fact that it is herbivorous and walked on four legs.” Science Daily also echoed the press release from the University of Utah. National Geographic announced, “Dinosaurs Ten Million Years Older Than Thought.”
The evolutionary story that was expected was that herbivory evolved late in the silesaur lineage. Finding a herbivorous silesaur 10-15 million years earlier means that its carnivorous ancestor had to be earlier, too. But even that story is murky. Are vegetarians better adapted? “Although difficult to prove, it’s possible that this shift conferred an evolutionary advantage.” But then, herbivory arose in three groups: silesaurs, and both major groups of dinosaurs. “The researchers conclude that the ability to shift diets may have lead [sic] to the evolutionary success of these groups.” Why do paleontologists think so? “These shifts all occurred in less than 10 million years, a relatively short time by geological standards, so we think that the lineage leading to silesaurs and dinosaurs might have had a greater flexibility in diet, and that this could be a reason for their success.” It sounds like he just said that fast evolution is evidence for evolution. Live Science put it this way: “The analysis provides a window into dinosaur evolution, particularly how the animals acquired plant-eating abilities.” Somehow, evidence that the animal ate plants told them how they got the ability to eat plants, even though National Geographic admitted, “What emerged looked nothing like what paleontologists had imagined.”
Evolution was not very evident in the fossil bed where Asilisaurus kongwe was found, however. Also found were crocodiles. So much for dinosaur-like body plans evolving from crocs. “The presence of these animals together at the same time and place suggests that the diversification of the relatives of crocodilians and dinosaurs was rapid, and happened earlier than previously suggested.” Somehow, we are told, this “sheds light on a group of animals that later came to dominate terrestrial ecosystems” for 185 million years. Irmis was apparently not shamed by this blow to expectations. Quite the contrary: he said, “It’s very exciting because the more we learn about the Triassic Period, the more we learn about the origin of the dinosaurs and other groups.” Christian Sidor, a co-author of the paper, was less sanguine: “It’s making the picture a little bit murkier, because we have a possible herbivore and quadruped very close to the dinosaur lineage.” Christopher Brochou made hey out of both sides of the truck: Hey, “it’s part of a larger, growing realization that the earliest archosaurs were far more diverse than we ever thought,” he said, but hey: it’s also “an elegant fulfillment of a prediction” that dinosaur ancestors would include members that were both crocodile-like and bird-like. Picturing the common ancestor of those is left as an exercise.
Live Science noted that the research was funded by the National Geographic Society, Evolving Earth Foundation, Grainger Foundation, and the National Science Foundation.
To be a good evolutionary paleontologist these days, you have to mold your brain contrary to its natural tendencies. You have to get rid of shame, reproach and despair. You have to think positive: no matter what happens, no matter what turns up, it glorifies Darwin and sheds light on evolution. It must. It may look like abrupt appearance. It may look like a falsification of common ancestry. But if you have trained your mind to think Darwinly long enough, you learn to say that looks are deceiving. What it really means is that evolution is very flexible. It can happen in the blink of an eye, leaving no trace. Then, animals that burst onto the evolutionary tableau can persist with little change for hundreds of millions of years. See?
Imagination is the caulk that holds these disparate bits of fact together, so they can be force-fitted into a mosaic of King Charles that the public can worship. Shedding light on evolution does not mean shedding light on the facts as facts, but onto the mosaic into which they have been placed. That’s why nothing in biology makes sense except in the light of evolution. King Charles makes sense. Creationism is nonsense – by definition. Practice this long enough and you get used to it. Floodlights on the mosaic; ain’t it grand?