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closeReptiles are still quite successful
Posted by keesey on 31 Aug 2012 at 00:03 GMT
if reptiles were previously so successful, why did they not reclaim the earth to launch a second reptilian age
http://plospathogens.org/article/info:doi/10.1371/journal.ppat.1002808#article1.body1.sec3.p3
Even using "Reptilia" as a paraphyletic wastebasket, there are more living reptilian species than mammalian species. Phylogenetically speaking, the reptilian clade, Sauropsida, also includes birds, which boosts the number even higher.
When people think of the Mesozoic as the "Age of Reptiles" they are often thinking of amniotes that are more closely related to birds than to other living amniotes (pterosaurs, non-avian dinosaurs). Arguably this dominion has not changed, since there are twice as many living species of birds as living species of mammal.
The idea that the success of therian mammals is due to fungal resistance is intriguing, but the treatment of faunal turnover here is really simplistic, and seems to be based more on pop-sci storytelling than actual data.
RE: Reptiles are still quite successful
ACasadevall replied to keesey on 31 Aug 2012 at 19:18 GMT
Dear Mike,
Thank you for your posting. I agree that the reptiles are still quite successful. However, my goal was not to provide a treatise on ‘faunal turnover’, which would not have been possible given the word limit, but rather to propose a hypothesis that could serve as a cognitive tool to understand the effects of ecological change on evolutionary selection and the emergence of infectious diseases (the article’s last sentence). I am the first one to admit that this hypothesis is thought-based, having emerged from different lines of evidence concerning the frequency of fungal diseases in mammals, fungal thermal tolerances and the geological record. As for the term ‘age of reptiles’, it was used in the popular sense, although I agree that this might involve a misconception. As to the comment that the essay is more ‘pop-sci storytelling than actual data’, perhaps it is, with the caveat that many ultimately validated scientific theories, such as plate tectonics, evolution, and even general relativity, began as thoughts with very little data. Although I do not wish to imply that my essay is in the league of these august theories, the fact of the matter is that they too could have been fallen into the ‘pop-sci storytelling’ category when first proposed. As with any theory, over time, evidence will accrue that will either support or refute the hypothesis and that is the way science does business.
Arturo Casadevall
RE: Reptiles are still quite successful
ACasadevall replied to keesey on 31 Aug 2012 at 19:19 GMT
Dear Mike,
Thank you for your posting. I agree that the reptiles are still quite successful. However, my goal was not to provide a treatise on ‘faunal turnover’, which would not have been possible given the word limit, but rather to propose a hypothesis that could serve as a cognitive tool to understand the effects of ecological change on evolutionary selection and the emergence of infectious diseases (the article’s last sentence). I am the first one to admit that this hypothesis is thought-based, having emerged from different lines of evidence concerning the frequency of fungal diseases in mammals, fungal thermal tolerances and the geological record. As for the term ‘age of reptiles’, it was used in the popular sense, although I agree that this might involve a misconception. As to the comment that the essay is more ‘pop-sci storytelling than actual data’, perhaps it is, with the caveat that many ultimately validated scientific theories, such as plate tectonics, evolution, and even general relativity, began as thoughts with very little data. Although I do not wish to imply that my essay is in the league of these august theories, the fact of the matter is that they too could have been fallen into the ‘pop-sci storytelling’ category when first proposed. As with any theory, over time, evidence will accrue that will either support or refute the hypothesis and that is the way science does business.
Arturo Casadevall