Ceratopsians Didn't Use Their Horns For Defense

[goodlife18]

Which studies say any of the frills were strong enough to protect against a bite or a puncture? I don't know of any that have ever been done. Except apparently this new one which says they couldn't (in Triceratops at least). Science isn't about just going with whatever seems to make sense, its about trying to prove things wrong. If somebody proves wrong the idea that frills are strong enough for defense then we have to throw that idea in the garbage.

Most ceratopsian frills are thin struts of bone covered in skin and muscle. Using them for defense would be like using a paper shield. Not even a paper shield... like using your own chest as a shield for yourself! It never made any sense and I'm not sure why anybody ever thought it, other than it makes for cool pictures If frills were used for defense, we would expect to observe armor or osteoderms and lack of blood vessels, but we don't. They were covered in skin and full of blood, like stegosaur plates. Obviously, Triceratops frills were different as they were solid. So we need to study them to see what the reason for being solid was. Were they solid enough for defense? Maybe, gotta test it. If Horner did, gotta read his methods and see if they check out before judging.

Most ceratopsian frills are thin struts of bone covered in skin and muscle. Using them for defense would be like using a paper shield. Not even a paper shield... like using your own chest as a shield for yourself!

The frills of most ceratopsians were not heavy duty but I would hardly compare them to paper. Nor would I say using your chest as a shield.

A better analogy would be like using your arms to shield your neck from an attacking animal. Human arms are not armour plated and will obviously suffer a lot of damage, perhaps you would even lose the use of your arms if used as a 'shield'.

I do acknowledge that ceratopsian frills were  not meant to function like the armour of ankylosaurs.  I'm not saying that Ceratopsians actively used their frills as shields but the frill was indeed covering the neck area so it would have unexpectedly got in the way of a good bite to the neck.

The  point is about offering the  attacker an obstacle in the way, something else to bite on rather than fully expose your  neck or chest, which will buy you that few crucial seconds to shake off the attack and position yourself to fight back.
 

Which dinosaurs didn't have good eyesight?

What about Ankylosaurs? They are known to have good sense of smell but not so much for eyesight.

[HD-man]

The Forster/Farke quote is a good summary of the matter. Forster/Farke specifically refer to Farke 2004 ( http://palaeo-electronica.org/2004_1/horn/horn.pdf ). There's also Farke et al. 2009 ( http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0004252 ). For some reason, Horner is making excuses to ignore this evidence ( http://news.sciencemag.org/2009/01/triceratops-horns-arent-just-show ). The pachycephalosaur situation is similar ( http://phenomena.nationalgeographic.com/2013/07/19/butting-heads-over-skull-injuries-and-dinosaur-head-butts/ ).

Quoting Forster/Farke (See pages 48-49 of NH114n04.pdf: http://digitallibrary.amnh.org/handle/2246/6511 ):

When fossil ceratopsians, or horned dinosaurs, were first discovered in the American West in the 1870s, the enormous spikes, horns, and neck shields that sprouted from the creatures' humongous skulls instantly captivated the public and paleontologists alike.  Speculation about the purpose of these bizarre cranial appendages quickly followed.  Paleontologists suggested that the long horns were used defensively, to "impale the enemy."  Even today this idea makes perfect intuitive sense.  Any animal fairly bristling with long, pointed horns and spikes simply looks ready to fend off any and all would-be predators.  More recently, paleontologists have suggested that other dinosaurs, notably the dome-headed pachycephalosaurs, also used their cranial appendages defensively.
Pointy headgear certainly plays a role in the defensive strategies of many modern animals.  For example, the horned lizard Phynosoma mcalli apparently uses the horns on its head to deter the shrike, a bird fond of impaling lizards on thorns or barbed wire for later consumption.  Longer horns make a lizard less likely to end up as a shrike's meal.  Much larger animals adopt a similar defensive strategy: some unfortunate visitors to Yellowstone National Park have experience the use of horns by bison firsthand.
But paleontologists early on recognized that defense may not have been the sole function of cranial "weaponry." In 1907 J.B. Hatcher and colleagues charmingly informed their readers that "Triceratops was extremely deficient mentally" and likely quite docile, except during the breeding season, when "combats between rival males ... must have been prompted and carried out by blind, unreasoning instinct."
The "mate competition" hypothesis is borne out by research showing that the cranial headgear of most modern animals evolved not only for defense against predators, but also for ritualized jousting or just plain "showing off" among members of their own species.  Male bighorn sheep with the largest horns, for instance, have the highest social rank and are more likely to mate.  Similar patterns hold for many horned or antlered mammals, including African antelope, deer, and pronghorn.  Among reptiles, the male Jackson's chameleon (which looks like a miniature Triceratops with three horns and a bony frill, or ruff, over its neck), also engages in horn-to-horn combat with other males of its kind.
Actual evidence of horn use in ceratopsians is circumstantial.  On some Triceratops fossils, both on the face and on the frill (the only plate extending back over its neck), there are healed puncture wounds as evidence of combat with members of the same species.  Other skulls show that ceratopsians underwent rapid evolutionary change and that, in particular, the size and shape of their horns and frills responded to shifting circumstances with great plasticity.  Those findings suggest that natural selection focused on diversifying the cranial appendages for use in relations with other members of the same species.  Beyond that, comparison to modern animals is all paleontologists have to go on to infer ceratopsian behavior.   
Ultimately, dinosaurs probably used their cranial appendages in whatever way they were needed.  The pattern is well demonstrated in deer: even though antlers function primarily for display and for combat with rivals, they can also be used with deadly efficiency against predators.  Triceratops likely used its horns to impress mates, shoo off rivals, or argue for territorial ownership.  But it's hard to imagine that such deadly weaponry wasn't aimed at a menacing Tyranosaurus when the need arose.  If you've got it, use it.

[Simon]

http://scienceblogs.com/notrocketscience/2009/01/27/old-wounds-show-that-triceratops-used-its-horns-for-combat/

Old wounds show that Triceratops used its horns for combat
Posted by Ed Yong on January 27, 2009

Thanks to its trinity of horns, Triceratops has become of the most recognisable of dinosaurs. The sight of two bulls charging at each other and jousting with their horns must have been an incredible one – geeky palaeontologists might get a small thrill just thinking about it. But did it ever really happen? Did Triceratops ever use its unmistakeable horns in combat, or were they simply for show?

Both theories have been put forward, but Andrew Farke from the Raymond M. Alf Museum of Palaeontology (who blogs at the Open Source Palaeontologist) thinks that both were probably right. By looking at the pattern of injuries on the skulls Triceratops specimens, his team has found evidence that the dinosaur really did use its horns for duelling, and its giant neck frill for protection. Triceratops was effectively a reptilian knight that carried two lances and a shield on top of its enormous head.

Farke compared the skull of Triceratops with a related but very different ceratopsian (horned dinosaur) called Centrosaurus. While Triceratops had two large horns over its eyes and a short one on its snout, Centrosaurus had the opposite arrangement – its eyebrow-horns were tiny and its nose one was huge.

Farke reasoned that if these animals fought with one another, their horn arrangements would have led to very different fighting styles. And over time, that would mean that the two animals would build up injuries in different hotspots. If, on the other hand, their horns and frills were only used to display to mates and rivals, they ought to have picked up injuries in more or less the same places.



To test his theory, Farke searched the skulls of several Triceratops and Centrosaurus specimens for signs of damage, be they actual fractures or "periosteal reactions" – ridges of bone that grow as a result of injury.

The results were clear – most of the skull bones in both animals had similar frequencies of injury, with a single exception. Compared to Centrosaurus, Triceratops had ten times as many lesions on its squamosal bone, which starts from behind its eye and covers the lower part of its frill. If you imagine two bulls lowering their heads and jousting with their horns, the squamosal bone is the one that would take the brunt of the impact.



There are, of course, other possible explanations, but Farke has ruled them out. Predators like Tyrannosaurus probably hunted both horned dinosaurs so there's no reason to think that their attacks would have led to more injuries in one than the other. Indeed, 14% of the Triceratops specimens had injuries of some sort, while just 3% of the Centrosaurus ones did. Infections can also create lesions on bone, but there's no reason o believe that a Triceratops-specific infection would have targeted the squamosal bone over and above any other parts of the skull.

All in all, Farke believes that most of Triceratops's squamosal injuries were inflicted by the horns of battling rivals. Unlike many previous studies, his team haven't tried to come up with back-stories to explain individual wounds and indeed, many of the injuries they found were probably not inflicted during duels. But the overall pattern supports the use of horns in fights.

Of course, that doesn't rule out their role in display as well. Indeed, the horns and particularly the frills of ceratopsians probably initially evolved for that purpose, or for recognising members of their own species. As the group developed ever-larger brow horns and combat became more intense, their frills would have also become more important for defence, as well as display.

So what of Centrosaurus? It's relative lack of skull injuries suggests that, unlike Triceratops, it wasn't one for head-on confrontations. Farke suggests that this animal may have clashed by aiming its blows at an opponent's flanks rather than its head. Indeed, specimens of Centrosaurus, as well as related species like Chasmosaurus and Pachyrhinosaurus have often been found with fractured ribs. It will be interesting to see if the frequency of these injuries were higher in this group than in Triceratops.

Reference: PLos ONE DOI: 10.1371/journal.pone.0004252

[stargatedalek]

That article is talking specifically about Triceratops and Centrosaurus, no one was ever denying that some ceratopsians used their horns and frill to fight (what exactly they fought is still up in the air).  We were discussing evolutionary origins to ceratopsian frills and horns.

And I for one am not particularly convinced by that study, and I think its rather silly to presume that because there is evidence Triceratops used its horns to fight that other ceratopsians with no (or minimal) evidence of this must also have done so just in different ways.

[Dinoguy2]

That article is talking specifically about Triceratops and Centrosaurus, no one was ever denying that some ceratopsians used their horns and frill to fight (what exactly they fought is still up in the air).  We were discussing evolutionary origins to ceratopsian frills and horns.

And I for one am not particularly convinced by that study, and I think its rather silly to presume that because there is evidence Triceratops used its horns to fight that other ceratopsians with no (or minimal) evidence of this must also have done so just in different ways.

To be fair, I also brought up the origin of Triceratops' weird, solid frill, and said we'd need to test the idea that it became solid for defense. This paper is exactly what I was looking for, because it suggests it may have become more solid for infraspecific combat. That implied this type of combat was unique to Triceratops among ceratopsids. That might also help explain it's forward-pointing horns that become more forward-facing as it ages. Many chasmosaurines have upward eye horns or short eye horns as adults, or eye horns that vanish as they age (like Chasmosaurus itself).

[stargatedalek]

Aah alright, my mistake.