tag:blogger.com,1999:blog-38902250.post9210492669101189822..comments2023-10-25T04:04:15.348-07:00Comments on When Pigs Fly Returns: Horns & Spikes, Part 1: Postorbital HornsZachhttp://www.blogger.com/profile/08692080707969333711noreply@blogger.comBlogger7125tag:blogger.com,1999:blog-38902250.post-17415092240138711502009-05-25T21:03:26.790-07:002009-05-25T21:03:26.790-07:00Lol! For lack of a better word, Horner's theories...Lol! For lack of a better word, Horner's theories are a total GAS.<br /><br />Horner predicted, among other things:<br /><br />* T.rex was a scavenger at heart (disproven by partially healed T.rex bite marks on Triceratops skulls)<br /><br />* Nanotyrannus was just a juvenile Albertosaur (disproven when Bakker chiseled through the false plaster preorbital horns)<br /><br />* Dracorex and Stygimoloch and all the other small boneheads were all juveniles of Pachycephalosaurus (disproved by complete fusion of skull bones in the smaller genera, and by simple morphology - plus such a radical metamorphosis is not seen in anything more advanced than an Ocean Sunfish)<br /><br />* AND NOW... "Triceratops horridus and T. prorsus are the same...." and he fiercely defends these baseless hypotheses against far more rock-solid ones. When will these inane lumper ego trips end?<br /><br />The only reason he's such a celebrity is his work on Maiasaura - which he wasn't even interested in to begin with. I think Triceratops actually had THREE species (I count ?T.elatus? because of its more flattened head and lack of upward frill curvature, and large size).<br /><br />Ironically, Horner's bid for less maastrichtian diversity is an attempt to fit into his rival Bakker's theory of disease wiping out the dinosaurs (lack of diversity is a possible sign of a pandemic) - but even so, three Triceratops species is STILL not a lot of diversity. So Horner is, in my mind, trying FAR too hard.Paleo Kinghttps://www.blogger.com/profile/15938850679516021616noreply@blogger.comtag:blogger.com,1999:blog-38902250.post-48594493972624208652009-05-22T03:31:00.337-07:002009-05-22T03:31:00.337-07:00metalraptor said: Not to mention that some researc...<I>metalraptor said: Not to mention that some research suggests that Triceratops did use its horns for some kind of combat. Thought I am not sure how good this research is, since I read an article once (was it in Carpenter's books I think?) that suggests the disputed "horn holes" were either pathological from some disease, or unique individual marking (sort of like a birthmark).</I>Both papers involve the same authors (I'm senior author on one, and junior author on the other), talking about different phenomena. The "horn hole" paper (in the "Horns and Beaks" volume) is talking about the rather common occurrence of fenestrae in the squamosal bone of the frill in various ceratopsids. We (Darren Tanke and I) think that most occurrences of squamosal fenestrae are not pathologic, because 1) they are reasonably regular in shape, size, and position (nicely rounded, relatively small, and always in the middle of the squamosal); and 2) the fenestrae almost never show any sign of trauma (healing fractures, osteomyelitis, etc.). It is difficult to imagine a wound (short of a laser beam from those extraterrestrials that were the <I>true</I> cause of the K/T extinction) that would leave such a clean piercing through the frill. Instead, we think these holes are probably just the result of random bone resorption processes - you see similar things going on in thin bones of other animals (e.g., scapulae).<br /><br />The <A HREF="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0004252" REL="nofollow">other paper</A> to which you refer, on "combat" in <I>Triceratops</I>, does not necessarily conflict. In that paper, we (me, Darren, and Ewan Wolff) didn't deal with these extra fenestrae at all, but instead dealt with things we felt more likely to be true trauma (from whatever source) - fractures and periosteal reactive bone (often resulting from "scrapes"). Here, we do suggest that the pattern is consistent with some form of combat behavior (unlike what is seen with the fenestrae).<br /><br />So in summary, most of the extra holes in the frill probably aren't the result of trauma, but fractures and scrapes probably are.<br /><br />Re: Zach's question on geographic disparity, etc., this is a point of some discussion right now. I would definitely refer you to the NAPC abstract volume (<A HREF="http://napc2009.org/wp-content/uploads/2009/05/napc-2009-abstracts.pdf" REL="nofollow">available as a PDF</A>), to have a look at Scanella and Fowler's work.Andyhttps://www.blogger.com/profile/16171447306687358664noreply@blogger.comtag:blogger.com,1999:blog-38902250.post-86109494458291705662009-05-20T13:19:34.013-07:002009-05-20T13:19:34.013-07:00I mean like pulling a Paul and lumping all members...I mean like pulling a Paul and lumping all members of Centrosaurinae in Centrosaurus, and all members of Chasmosaurinae in Triceratops (or whichever genera came first in these cases).Metalraptorhttps://www.blogger.com/profile/17053007518293924808noreply@blogger.comtag:blogger.com,1999:blog-38902250.post-48389909191299931982009-05-20T09:47:26.434-07:002009-05-20T09:47:26.434-07:00Thanks for the comments, guys. Andy, I didn't know...Thanks for the comments, guys. Andy, I didn't know they were both old adults! The skull Forster uses in her "two-species" paper (YPM 1922) looks like it confirms nicely to Horner's young adult stage, what with the slightly upturned postorbitals and more obvious epoccipitals. <br /><br />Are the two species geographically disparate? Could this be a case of sexual dimorphism? Hell, I'm a lumper too. :-)<br /><br />Metalraptor: As far as I know, nobody's tried synonymizing entire groups--I assume you mean at the generic level. <I>Centrosaurus</I> used to include like three different genera. Otherwise its taxonomy has remained pretty stable. <I>Agujaceratops</I> used to be a species of <I>Chasmosaurus</I>, though.Zachhttps://www.blogger.com/profile/08692080707969333711noreply@blogger.comtag:blogger.com,1999:blog-38902250.post-26366671429462642192009-05-20T06:58:54.208-07:002009-05-20T06:58:54.208-07:00You may want to watch out for the idea that T. pro...You may want to watch out for the idea that T. prorsus and T. horridus are the same species. The idea has been proposed by Horner, who is a notorious lumper, especially when it comes to Maastrictian taxa (partially since he wants to have as little dinosaur diversity as possible in the Maastrictian to go along with his theories). But I agree, the evidence for T. prorsus and T. horridus seems rather strong here. But if both are old adults, this may complicate things.<br /><br />Anyway, it also does seem more likely that chasmosaurines used their horns for defense or intra-specific combat as much as display. Centrosaurine's horns came in a wide variety of forms, twisting this way and that. Compared to them, chasmosaurines are unmistakably vanilla. They all have pretty much the same two postorbital horns, one nasal horn combo, and they mostly point the same way. This probably indicates that that position was useful for something. Combat seems the most likely reason. Not to mention that Triceratops has a solid frill amongst ceratopsians. Not saying that the frill was for defense, but one would expect a stronger frill on an animal that used its horns for defense, to keep the frill from breaking like a puny centrosaurine frill when it bashed heads.<br /><br />Not to mention that some research suggests that Triceratops did use its horns for some kind of combat. Thought I am not sure how good this research is, since I read an article once (was it in Carpenter's books I think?) that suggests the disputed "horn holes" were either pathological from some disease, or unique individual marking (sort of like a birthmark).<br /><br />Speaking of lumping and the Maastrictian, I just thought of some odd things. First, people oftentimes claim that there was something wrong with the Maastrictian biota, since Triceratops was the most common animal. But ceratopsians skulls are notorious for fossilizing well, especially Triceratops of all species. Maybe the Maastrictian biota wasn't that biased, it was just a preservational bias towards ceratopsians. Second of all, I cannot believe that someone has not tried to synonymize all of the chasmosaurines and all of the centrosaurines yet. I know that this would be horribly wrong, but I talked with Dr. Michael Ryan of Paleoblog about this once, and he said that postcranially ceratopsians are pretty much indistinguishable from each other. So I could see someone actually trying to lump them together, even though this would never be accepted in the paleontological community.Metalraptorhttps://www.blogger.com/profile/17053007518293924808noreply@blogger.comtag:blogger.com,1999:blog-38902250.post-57322034751652600342009-05-20T03:44:58.854-07:002009-05-20T03:44:58.854-07:00Great write-up.
In your post, you make it seem as...Great write-up.<br /><br />In your post, you make it seem as if <I>Avaceratops</I> is a chasmosaurine though.Ivanhttps://www.blogger.com/profile/11637204084596462318noreply@blogger.comtag:blogger.com,1999:blog-38902250.post-69816960235877190242009-05-19T21:20:12.729-07:002009-05-19T21:20:12.729-07:00Awesome post (on a topic near and dear to my heart...Awesome post (on a topic near and dear to my heart)! Re: the <I>T. prorsus</I> vs. <I>T. horridus</I> thing, the holotypes for both species are old adults. . .I'm quite skeptical of claims synonymizing them as ontogenetic stages, to say the least. Judging by the NAPC abstract volume, we should have some interesting contributions on <I>Triceratops</I> coming out of MOR in the near future, though!Andyhttps://www.blogger.com/profile/16171447306687358664noreply@blogger.com