tag:blogger.com,1999:blog-140938929136406282.post8112735484095023738..comments2023-11-18T15:42:20.251-05:00Comments on DinoGoss: Tyrannosaur Tooth CountMatt Martyniukhttp://www.blogger.com/profile/04220900229537564466noreply@blogger.comBlogger5125tag:blogger.com,1999:blog-140938929136406282.post-27362733938174020332011-05-22T05:30:47.653-04:002011-05-22T05:30:47.653-04:00Matt, what I am saying is that here you have two s...Matt, what I am saying is that here you have two studies, one which purports that these Asian Maas tyrannosaurids likely all represent one taxon, and another study that purports that all NA Maas tyrannosaurids represent one taxon, and they both differ on several particular details. Both may be correct, but when one insists the other study should conform to its own particulars on ontogeny, then I start having conniptions. There is no third study that supports the conclusions of either, save the ontogenetic studies of Carr et al., which was used to support the late-juvenility of <i>Raptorex</i> but which, surprisingly enough, shows it still presents unique features at a stage older than MPC-D 107/7 when in other taxa (we only have albertosaurins and <i>bataar</i> to go with) these features are lost. I am not taking sides here, although I must respect that Carr has, so far, the better-based of the two. This also isn't about Horner-bashing; I just think he's wrong to assume his complex is whole <i>a priori</i>.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-140938929136406282.post-58636201693797874442011-05-18T08:03:25.284-04:002011-05-18T08:03:25.284-04:00@Reprobus Whoops! you're right, I meant to say...@Reprobus Whoops! you're right, I meant to say overSPLIT there. Revised that sentence.<br /><br />@qilong So you're saying it's more parsimonious to assume the "Samson" specimen and possibly MOR 1125 represent N. lancensis, rather than admit that the N. lancensis holotype falls within or close to the range of variation for T. rex? Essentially that there really are two similarly sized tyrannosaur taxa in the Hell Creek and that they're differentiated by tooth count alone. How would one disprove such a hypothesis? Horner's lumper hypothesis could be disproved by, as chemolithoautotrophic pointed out, discovery or identification of a juvenile tyrannosaur morph that is closer to T. rex than to N. lancensis. The splitter hypothesis is untestable as far as I can see, short of an adult, rex morph sitting on a nest containing eggs with lancensis morph juveniles. Dismissal of any potential intermediates between the two morphs as "well, we don't know which one that is" doesn't address either hypothesis. How can we ever know which species these intermediate morphs are if we ignore parsimony and assume diversity a priori?Matt Martyniukhttps://www.blogger.com/profile/04220900229537564466noreply@blogger.comtag:blogger.com,1999:blog-140938929136406282.post-20351793420548226912011-05-18T00:58:48.494-04:002011-05-18T00:58:48.494-04:00Not long ago I've watched a recent video from ...Not long ago I've watched a recent video from "Dinosaur George" where he said something along the lines of someone doing research that involved a close exam of a new (I guess) juvenile T. rex specmimen and a comparison with Nanotyrannus, and that the authors could already tell that they were definitely different species.chemolithoautotrophichttps://www.blogger.com/profile/16095852342098869989noreply@blogger.comtag:blogger.com,1999:blog-140938929136406282.post-56174007429382779112011-05-17T20:57:04.806-04:002011-05-17T20:57:04.806-04:00I don't think the slide indicates what Horner ...I don't think the slide indicates what Horner thinks it does. At least, that's the slide. It doesn't contradict Tsuihiji et al., for example, in arguing there is a taxonomic split in allometry (both positive and negative) of the dentary along with decreasing tooth count in taxa <i>other</i> than <i>Tarbosaurus bataar</i>, while the massive jump from 17 to 12 is not shown relative to size. I can give it that Horner is showing a non-sclaed series of dentaries which vary in alveolar count, and the demonstration is very good ... but only for his sample size, which he assumes to be only <i>Tyrannosaurus rex</i>. When you have an artificial bin like this being used to form a metric for other taxa, I think you start failing to prove your point in the general, even if you're right in the specific.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-140938929136406282.post-53483011180691658972011-05-17T16:56:14.808-04:002011-05-17T16:56:14.808-04:00Did we watch the same video...? You came to the ex...Did we watch the same video...? You came to the exact opposite conclusion i.e. should have said: Here Horner gives the basics of his theory that dinosaurs are overSPLIT... specimens that WERE THOUGHT to belong to the DIFFERENT species actually represent juveniles of THE SAME species.<br /><br />Other than that, nice pics of the jaw.Reprobushttps://www.blogger.com/profile/10650084661969561056noreply@blogger.com