Instant dinosaurs: just add mountains. Does this and other fossil news make sense?
Mountains into dinosaurs: Here’s the headline on PhysOrg: “Mountains, seaway triggered North American dinosaur surge.” The idea is not that mountains made dinosaurs make more babies, but that North American mountain uplifts made dinosaurs evolve into more species. “We hypothesize that such isolation facilitated rapid speciation and increased diversity in these animals,” one of the authors of a paper on PLoS ONE stated. The paper’s title makes it clear: they believe “Mountain Building Triggered Late Cretaceous North American Megaherbivore Dinosaur Radiation.” They explicitly pointed to geological “triggers” like mountain uplift and seaways as a “causal mechanism” to explain the diversity of late Cretaceous dinosaurs. Their study of the timing of geological events was performed “to identify correlative factors that may have driven lineage diversification at more inclusive levels.”
There’s a well-known maxim in science, “correlation is not causation.” Did they explain how the presence of a mountain or sea barrier “triggered” beneficial mutations to be selected for the formation of new species of dinosaurs? Did they evaluate other animal groups with their hypothesis that mountains trigger speciation? No; they didn’t even compare other dinosaur groups. “Application of these results to other dinosaur groups contemporaneously living in Laramidia is an interesting prospect. The major hurdle to such comparative studies is insufficient fossil records of other clades, although based on limited data theropods may exhibit similar trends.”
Volcanoes into teeth: Another use of the phrase “evolutionary trigger” can be found in an article by National Geographic about fossil rodents with “supertough teeth.” According to reporter Brian Handwerk, two new fossil rodent species from South America “arose during a rodent evolutionary explosion, which occurred after their ancestors had likely rafted to the continent from Africa on floating debris about 3.5 million years ago.” While visions of exploding rodents may not be a pretty picture, Handwek was excited. He claims that South America was an “evolutionary hot spot” 40 million years ago. What was the trigger for the “rodent evolutionary explosion”? One paleontologist explained, “frequent volcanism, which can make soils rougher, could be an evolutionary trigger for hypsodonty” (heavily enameled crowns). It could be, sure. Anything could be. It could also be an evolutionary trigger to wear the teeth down and make them go extinct. There are volcanoes all over the world; where is the corroborating evidence that animals living near volcanoes evolve supertough teeth?…
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