tag:blogger.com,1999:blog-7128085831047923286.post4024951406620107888..comments2024-01-02T06:15:13.748-05:00Comments on Pseudoplocephalus: How the ankylosaur got its tail clubVictoriahttp://www.blogger.com/profile/09773365014990396396noreply@blogger.comBlogger14125tag:blogger.com,1999:blog-7128085831047923286.post-48535777916495646552015-09-18T06:05:01.225-04:002015-09-18T06:05:01.225-04:00Getting back to the oldest club--it must be that o...Getting back to the oldest club--it must be that of Dyoplosaurus not E. tutus--or Pinacosaurus. A slight correction in the comment above. Regarding stegosaur caudal weaponry, substitute "distal" for "terminal."starmanhttps://www.blogger.com/profile/09884942748644499035noreply@blogger.comtag:blogger.com,1999:blog-7128085831047923286.post-73875362746186306282015-09-11T15:11:18.151-04:002015-09-11T15:11:18.151-04:00I think the tail isn't quite long or heavy eno...I think the tail isn't quite long or heavy enough compared to the rest of it's massive bulk for that function, especially in early ankylosaurs without tail clubs. In dromaeosaurs, the tail takes up a greater deal of it's length and its total mass, hence its greater suitability to counterbalance the predator during tight turns. And the S-shape and high-held position of the tail makes it all the more efficient, as opposed to the lower, ground-hugging position of ankylosaur tails. Plus there's the feathers on its arms and tail tip to aid in stability during sharp turns.<br /><br />Maybe in ankylosaurs with heavy tail clubs, this might be possible to a lesser degree, swinging it in the opposite direction it wants to turn such as seen in cats, but I doubt it'd be the primary function or as effective as in cats and dromaeosaurs. The stiffened tails would work better in deterring predators from attacking it. With high-speed cornering, I'd think its quadrupedal gait already gives it a good deal of support and stability for such turns. I know cats are also quadrupeds and utilize the tail counterbalance, but they also have a narrower, more flexible speed-built gait that would better benefit from a tail counterbalance as opposed to the wider, more defensive and ground-hugging gait in ankylosaurs (not to say they aren't by any means slow, just more built for defense than speed).<br /><br />I do find your race-car idea pretty interesting, though. I can imagine this as a possibility, especially if coupled with tail swinging in attempt to wear each other down, given that their tails would have strong muscle attachments to the hind legs.Anonymoushttps://www.blogger.com/profile/07099663673798466361noreply@blogger.comtag:blogger.com,1999:blog-7128085831047923286.post-39676417474925335722015-09-03T17:00:57.285-04:002015-09-03T17:00:57.285-04:00Why, this is simply a distraction from the real re...Why, this is simply a distraction from the real reason for the tail-stiffening - clearly, this is the equivalent of the rigid tails sported by dromeosaurs. Obviously, as the ankylosaurs were dashing and leaping about, having a stiffened tail was very helpful in keeping them on the track, what with high-speed cornering and all. I visualize a pack of ankylosaurs competing for mates as a sort of Mesozoic NASCAR form of a lek. Come to think of it, that would also explain the evolution of the tail club!Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-7128085831047923286.post-5929561425847764092015-09-03T13:58:11.784-04:002015-09-03T13:58:11.784-04:00I'd like to add something. There's little ...I'd like to add something. There's little doubt the terminal caudal weaponry of stegosaurs--the thagomizer--was an antipredaor weapon. At least one study identified a stegosaur spike as the cause of injury to an Allosaurus proximal caudal; another attributed the pubic injury of another to this weapon. If stegosaurs needed caudal weapons to repel Allosaurus, wouldn't ankylosaurs have needed something to deal with even deadlier enemies---Daspletosaurus, Tarbosaurus, Tyrannosaurus? IMO it's no accident that clubs appeared and/or became large among ankylosaur contemporaries of such taxa.starmanhttps://www.blogger.com/profile/09884942748644499035noreply@blogger.comtag:blogger.com,1999:blog-7128085831047923286.post-86788530243554257402015-09-03T13:47:40.085-04:002015-09-03T13:47:40.085-04:00Lam Loung, lol, of course predators tried to avoid...Lam Loung, lol, of course predators tried to avoid the club and strike an an anterior area beyond its reach. The problem was, ankylosaurs, like other thyreophorans, could rotate to maintain the right position vis a vis attackers i.e. the tail able to strike them and anterior areas away. (Coombs touched on this in the paper btw.) I suspect some attackers, unable to get around the key defense, attempted to wreck it and disarm the quarry. It wasn't just thyreophorans btw. Remember the SUP Triceratops? :)starmanhttps://www.blogger.com/profile/09884942748644499035noreply@blogger.comtag:blogger.com,1999:blog-7128085831047923286.post-33710330320345659842015-09-03T13:42:12.002-04:002015-09-03T13:42:12.002-04:00See Walter Coombs 1995 Ankylosaurian Tail Clubs of...See Walter Coombs 1995 Ankylosaurian Tail Clubs of middle Campanian to early Maastrichtian age from western North America with description of a tiny club from Alberta and discussion of tail orientation and tail club function. Canadian Journal of Earth Sciences 32 202-212. If you can't access it a quote: "Intraspecific combat using the club seems clumsy and implausible and no modern tetrapod uses its tail for this purpose....Defense against predators is the most reasonable and primary function of the tail club but this does not exclude its use for other purposes." Maybe ankylosaurs did fight one another on occasion--although perhaps rarely if they were solitary--but you see the point.:)starmanhttps://www.blogger.com/profile/09884942748644499035noreply@blogger.comtag:blogger.com,1999:blog-7128085831047923286.post-52897420715536469462015-09-03T09:31:53.680-04:002015-09-03T09:31:53.680-04:00Hmm, starman has some good points. This might cont...Hmm, starman has some good points. This might contradict what I said before, but maybe ankylosaur tails first started off as anti-predator weapons while they competed with each other head-to-head. Then it wasn't until later that some species incorporated their tails into their intraspecific competitions in addition to the primary method of head-to-head shoving. Then perhaps from there, ankylosaurs gradually used their tails against each others' armored hides more frequently, and that was when tail club evolution set into play. Coincidentally, that evolution also made them even more powerful weapons than they already were, and effective predator defense further fueled the evolution of large and sophisticated tail clubs.<br /><br />Or at least that's my thought. Starman, if I may be so bold to say that I would think that predators would try to get around and avoid such a dangerous weapon and target a more vulnerable region rather than take it on directly and risk greater injury. I do find your idea very interesting, though.<br /><br />In any case, you've definitely got me interested in those papers you mentioned earlier. Can you tell me where I can find them? Anonymoushttps://www.blogger.com/profile/07099663673798466361noreply@blogger.comtag:blogger.com,1999:blog-7128085831047923286.post-48831159016581217832015-09-03T06:53:11.120-04:002015-09-03T06:53:11.120-04:00Also, if the club were essential to protect the ta...Also, if the club were essential to protect the tail tip from injury while striking the armor of another ankylosaur, why did it take so long to evolve? As we now know, armor long predated clubs.starmanhttps://www.blogger.com/profile/09884942748644499035noreply@blogger.comtag:blogger.com,1999:blog-7128085831047923286.post-8832461127365923812015-09-03T06:47:56.989-04:002015-09-03T06:47:56.989-04:00In one of his papers, Coombs concluded clubs proba...In one of his papers, Coombs concluded clubs probably weren't used for intraspecific fighting. Carpenter suggested head to head shoving like in tortoises. It may say something that clubs appeared in the Campano-Maastrichtian period, coinciding with predators potentially most dangerous to ankylosaurs, whereas intraspecific fighting had presumably occurred long before that.starmanhttps://www.blogger.com/profile/09884942748644499035noreply@blogger.comtag:blogger.com,1999:blog-7128085831047923286.post-44453520918253743032015-09-02T22:55:29.402-04:002015-09-02T22:55:29.402-04:00I think there's a good chance that ankylosaur ...I think there's a good chance that ankylosaur tail clubs were being used for intraspecific fighting, for sure! Some research along those lines is currently on my to-do list!Victoriahttp://pseudoplocephalus.blogspot.canoreply@blogger.comtag:blogger.com,1999:blog-7128085831047923286.post-26426769179377648872015-09-02T22:53:27.717-04:002015-09-02T22:53:27.717-04:00Thanks! For the science behind the phylogenetic tr...Thanks! For the science behind the phylogenetic trees, I use Mesquite to assemble my character matrix and TNT to analyze the data (both are free to download). I then take the results files and make nicer looking diagrams in Adobe Illustrator (sadly, not a free download by a long shot).Victoriahttp://pseudoplocephalus.blogspot.canoreply@blogger.comtag:blogger.com,1999:blog-7128085831047923286.post-59358450647371589152015-09-02T12:04:53.591-04:002015-09-02T12:04:53.591-04:00I recall that a stiff tail with interlocking verte...I recall that a stiff tail with interlocking vertebrae could absorb and transmit impact force better than a flexible one, so there's that. And then perhaps the tail club evolved to protect the tail's tip, since the force being greatest at a pendulum's distal end could backfire and the animal would also injure itself. Although if it were pitted against the fleshy legs of a tyrannosaur or other predator, I imagine the problem wouldn't be as severe. Up against armor, however, and the tail would need protection to keep from self-injury, hence the tail club. I guess this goes back to what you've suggested before about ankylosaur tails possibly being used primarily for intraspecific combat over predator defense, I believe you mentioned. Thoughts?<br /><br />(Also, I posted a related question on one of your earlier blogs and am really interested in your feedback)<br />http://pseudoplocephalus.blogspot.com/2011/05/ankylosaur-tail-pathologies.html?showComment=1435782717215#c5399598550848633062Anonymoushttps://www.blogger.com/profile/07099663673798466361noreply@blogger.comtag:blogger.com,1999:blog-7128085831047923286.post-16770594547378721812015-09-01T10:36:34.088-04:002015-09-01T10:36:34.088-04:00Pinacosaurus is the earliest ankylosaurid known to...Pinacosaurus is the earliest ankylosaurid known to have had a caudal bludgeon? I dunno--the more recent dates for what I presume to be Alaagteegian beds are younger than 75 Ma, whereas Euoplocephalus was about that age. <br />Lol, no way a stiff tail was as good a weapon as one with a knob. I suspect part of the reason for the evolution, first of stiff distal caudals and then a club, was the need to avoid being disarmed in combat. If the ankylosaur (or any thereophoran) could initially keep a theropod at bay with its swinging tail, the attacker might try to overcome it by wrecking its defense. An infected thagomizer, broken spikes, and chewed nodosaur caudals are known, besides possible bite marks in knobs. A stiff distal tail was harder to chew off than a flexible one, and a knob harder still. Tyrannosaur evolution, by Campano-Maastrichtian time, may have made the need for resistance especially acute given the enhanced penetrating ability of tyrant jaws (whereas earlier theropods had slashing jaws).starmanhttps://www.blogger.com/profile/09884942748644499035noreply@blogger.comtag:blogger.com,1999:blog-7128085831047923286.post-47999855702664290772015-08-31T12:33:52.531-04:002015-08-31T12:33:52.531-04:00Interesting, Good diagrams.
What software do you ...Interesting, Good diagrams.<br /><br />What software do you use to create them?Stephen Mnoreply@blogger.com