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Post by Infinity Blade on Jan 29, 2015 8:09:29 GMT 5
It looks to me as if the canines of Harpagolestes were broken off and/or worn down to a very substantial extent (it at least looks more like it to me in the lower canines). And I don't know about you guys, but it looks like the mesonychid would have had some pretty large canines. Would I be wrong in assuming/expecting that? I've seen skull reconstructions of Harpagolestes and they aren't really quite that big.
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Post by Infinity Blade on Mar 17, 2015 6:43:53 GMT 5
www.nature.com/srep/2012/121220/srep01009/full/srep01009.html^The ~10kg Megapiranha paranensis apparently bites with a force of ~1240-4749N which is pretty monstrous for such a size. Likewise, the teeth are described as being labiolingually compressed with serrated carinae (while "the mid tooth expands into a broad lingual shelf that is anchored to the jaw with a robust circular base"). So...then these piranhas had a powerful bite for their size and lethal teeth too...I'm really baffled.
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Post by theropod on Mar 17, 2015 10:57:49 GMT 5
www.nature.com/srep/2012/121220/srep01009/full/srep01009.html^The ~10kg Megapiranha paranensis apparently bites with a force of ~1240-4749N which is pretty monstrous for such a size. Likewise, the teeth are described as being labiolingually compressed with serrated carinae (while "the mid tooth expands into a broad lingual shelf that is anchored to the jaw with a robust circular base"). So...then these piranhas had a powerful bite for their size and lethal teeth too...I'm really baffled. The abstract specifically refers to its " novel dentition" adapted to these bite forces, so the dentition was obviously optimised to withstand them. Anyway, teeth alone are never lethal…
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Post by Infinity Blade on Mar 17, 2015 23:51:47 GMT 5
www.nature.com/srep/2012/121220/srep01009/full/srep01009.html^The ~10kg Megapiranha paranensis apparently bites with a force of ~1240-4749N which is pretty monstrous for such a size. Likewise, the teeth are described as being labiolingually compressed with serrated carinae (while "the mid tooth expands into a broad lingual shelf that is anchored to the jaw with a robust circular base"). So...then these piranhas had a powerful bite for their size and lethal teeth too...I'm really baffled. The abstract specifically refers to its " novel dentition" adapted to these bite forces, so the dentition was obviously optimised to withstand them. Anyway, teeth alone are never lethal… I know, but I still find it amazing considering their morphology. And you know I meant teeth (that are well-compromised for soft tissue damage) that are in a set of jaws.
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Post by theropod on May 31, 2015 23:50:37 GMT 5
It was merely a test, hence the lack of labeling, but I thought I’d share it anyway. Theropod maxillary tooth morphometrics.Green: Carnosaurs, +’s are Allosaurus, rest are Acrocanthosaurus and Carcharodontosaurus (and CPT-1980) Red: Ceratosauria , triangles are Majungasaurus, rest is C. dentisulcatus) Blue: *’s are T. rex, rest Gorgosaurus and DaspletosaurusYellow: DilophosaurusI’ve only used confirmed maxillary teeth, except for the riodeva specimen (of which I’m reasonably certain it is a maxillary tooth due to its sheer size and proportions). ––– Reference:Smith, Joshua B.; Vann, David R.; Dodson, Peter (2005): Dental Morphology and Variation in Theropod Dinosaurs: Implications for the Taxonomic Identification of Isolated Teeth. The Anatomical Record, Vol. 285 (A) pp. 699-736
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Post by Infinity Blade on Jun 6, 2015 19:02:45 GMT 5
Wear biomechanics in the slicing dentition of the giant horned dinosaur TriceratopsGregory M. Erickson, Mark A. Sidebottom, David I. Kay, Kevin T. Turner, Nathan Ip, Mark A. Norell, W. Gregory Sawyer, Brandon A. Krick Abstract" Herbivorous reptiles rarely evolve occluding dentitions that allow for the mastication (chewing) of plant matter. Conversely, most herbivorous mammals have occluding teeth with complex tissue architectures that self-wear to complex morphologies for orally processing plants. Dinosaurs stand out among reptiles in that several lineages acquired the capacity to masticate. In particular, the horned ceratopsian dinosaurs, among the most successful Late Cretaceous dinosaurian lineages, evolved slicing dentitions for the exploitation of tough, bulky plant matter. We show how Triceratops , a 9-m-long ceratopsian, and its relatives evolved teeth that wore during feeding to create fullers (recessed central regions on cutting blades) on the chewing surfaces. This unique morphology served to reduce friction during feeding. It was achieved through the evolution of a complex suite of osseous dental tissues rivaling the complexity of mammalian dentitions. Tribological (wear) properties of the tissues are preserved in ~66-million-year-old teeth, allowing the creation of a sophisticated three-dimensional biomechanical wear model that reveals how the complexes synergistically wore to create these implements. These findings, along with similar discoveries in hadrosaurids (duck-billed dinosaurs), suggest that tissue-mediated changes in dental morphology may have played a major role in the remarkable ecological diversification of these clades and perhaps other dinosaurian clades capable of mastication." advances.sciencemag.org/content/1/5/e1500055
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Deathadder
Junior Member
aspiring paleontologist. theropod enthusiast.
Posts: 240
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Post by Deathadder on Jun 6, 2015 19:59:17 GMT 5
Nice finds to everyone.
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Post by Infinity Blade on Jul 29, 2015 8:55:36 GMT 5
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Post by theropod on Nov 4, 2015 17:51:00 GMT 5
Lautenschlager, S., 2015. Estimating cranial musculoskeletal constraints in theropod dinosaurs. Royal Society Open Science 2, 150495. doi:10.1098/rsos.150495 " Many inferences on the biology, behaviour and ecology of extinct vertebrates are based on the reconstruction of the musculature and rely considerably on its accuracy. Although the advent of digital reconstruction techniques has facilitated the creation and testing of musculoskeletal hypotheses in recent years, muscle strain capabilities have rarely been considered. Here, a digital modelling approach using the freely available visualization and animation software Blender is applied to estimate cranial muscle length changes and optimal and maximal possible gape in different theropod dinosaurs. Models of living archosaur taxa (Alligator mississippiensis, Buteo buteo) were used in an extant phylogenetically bracketed framework to validate the method. Results of this study demonstrate that Tyrannosaurus rex, Allosaurus fragilis and Erlikosaurus andrewsi show distinct differences in the recruitment of the jaw adductor musculature and resulting gape, confirming previous dietary and ecological assumptions. While the carnivorous taxa T. rex and Allo. fragilis were capable of a wide gape and sustained muscle force, the herbivorous therizinosaurian E. andrewsi was constrained to small gape angles." rsos.royalsocietypublishing.org/content/royopensci/2/11/150495.full.pdf
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Post by theropod on Nov 5, 2015 1:00:59 GMT 5
A new paper about theropod gapes just turned up: rsos.royalsocietypublishing.org/content/2/11/150495It turns out that while Tyrannosaurus' gape is outmatched by that of a carnosaur, it could still open it's mouth wider than an alligator, a therizinosaur, or a buzzard. Also, Tyrannosaurus used sustained force to crush bone, not that "one bite crush kill" that many still believe lol "In T. rex, however, the muscle strain curves for the majority of the different muscles lie on a narrow trajectory (figure 6c,d). This suggests that these muscles had a homogenous muscle performance and provided a sustained bite force, as necessary to crush bone and dismember prey."The findings are fairly consistent with Bakker 1998’s figures and his finding that the specialized joint morphology in Allosaurus allowed gapes in excess of 90° without dislocation. This had me wondering though, if Allosaurus (79-92° gape angle based on muscle constraints) requires these specializations (antarticular, backwards-bent quadrate, spiral grove and enlarged quadrate condyles) to prevent dislocation, may the joint morphology generally be the more limiting factor? And yes, crushing takes time. Crocodiles vs turtles is a great example. I still don't really understand what sustained bite force is. Either that or I forgot. Sustained bite force is bite force that is excerted constantly over a longer period of time, as opposed to bite force peaks, which are the highest forces measured at any point during the biting process.
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Post by Infinity Blade on Nov 5, 2015 1:02:31 GMT 5
So would it be something like multiple bites?
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Post by theropod on Nov 5, 2015 1:03:50 GMT 5
No, but a bite and holding on for a longer period of time. You can’t crush a large bone structure by taking a short, forceful nip at it.
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Post by Infinity Blade on Nov 12, 2015 9:15:41 GMT 5
antediluviansalad.blogspot.com/2015/09/terror-birds-cometh-new-theory.html^I found this above blog post by Duane Nash that gives a different interpretation of phorusrhacid killing/feeding methods. Basically, Nash isn't really convinced by the "battle axe" attack method, but rather believes that the birds utilized a biting adaptation akin to those of extant carcass-dismembering birds and Mesozoic theropods with the hooked beak, a serrated tongue, and choanal papillae. Very interesting IMO.
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Post by theropod on Nov 13, 2015 1:32:21 GMT 5
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Post by Infinity Blade on Nov 13, 2015 1:44:40 GMT 5
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