Lythronax vs Diabloceratops

[Deleted]

Lythronax



Lythronax is an extinct genus of tyrannosaurid theropod dinosaur which lived around 80.6 to 79.9 million years ago in what is now southern Utah. The generic name is derived from the Greek words lythron meaning "gore" and anax meaning "king". Lythronax was a large sized, moderately-built, ground-dwelling, bipedal carnivore, that could grow up to an estimated 8 m (26.2 ft) in length and weighed 2.5 tonnes (5,500 lb).


Diabloceratops



Diabloceratops is an extinct genus of centrosaurine ceratopsian dinosaur that lived approximately 79 million years ago during the latter part of the Cretaceous Period in what is now Utah, in the United States. Diabloceratops was a medium sized, moderately-built, ground-dwelling, quadrupedal herbivore, that could grow up to an estimated 5.5 m (18.0 ft) long. Diabloceratops is paleontologically significant because, at the time of its discovery, it was the oldest known ceratopsid, and first centrosaurine known from latitudes south of Montana.

[Dinopithecus]

Thanks.

Now, I think that in a fight to the death, it would probably be an even match assuming similar or equal weights. There is some evidence that theropods could reduce rotational inertia and if that's true, it could potentially outflank the ceratopsian and kill it with a bite to the back of the neck. On the other hand, the ornithischian can obviously gore the theropod to death. I don't see how one has much of an advantage over another.

[Tyrannosauria]

Ceratopsians have very little rotational inertia due to their compact bodies, and they are quick turners due to their wide-gauge front limbs. Theropods, like Lythronax argestes, on the other hand, have too much rotational inertia. They have less compact bodies, and heavy heads, as well as too much weight far from the torso. Lythronax is not outflanking Diabloceratops. This is an even match, and since there is no outflanking, my bet is Lythronax would go for the face, and bite it like Lions do often on Cape Buffalo. That would not be a killer blow, and since it would hurt a lot, it would only enrage the Ceratopsian. I do give this to Lythronax however.

[Dinopithecus]

I think the notion of theropods being horribly unagile is a myth.

jeb.biologists.org/content/204/22/3917.full

The turning agility of theropod dinosaurs may have been severely limited by the large rotational inertia of their horizontal trunks and tails. Bodies with mass distributed far from the axis of rotation have much greater rotational inertia than bodies with the same mass distributed close to the axis of rotation. In this study, we increased the rotational inertia about the vertical axis of human subjects 9.2-fold, to match our estimate for theropods the size of humans, and measured the ability of the subjects to turn. To determine the effect of the increased rotational inertia on maximum turning capability, five subjects jumped vertically while attempting to rotate as far as possible about their vertical axis. This test resulted in a decrease in the average angle turned to 20 % of the control value. We also tested the ability of nine subjects to run as rapidly as possible through a tight slalom course of six 90° turns. When the subjects ran with the 9.2-fold greater rotational inertia, the average velocity through the course decreased to 77 % of the control velocity. When the subjects ran the same course but were constrained as to where they placed their feet, the average velocity through the course decreased to 65 % of the control velocity. These results are consistent with the hypothesis that rotational inertia may have limited the turning performance of theropods. They also indicate that the effect of rotational inertia on turning performance is dependent on the type of turning behavior. Characters such as retroverted pubes, reduced tail length, decreased body size, pneumatic vertebrae and the absence of teeth reduced rotational inertia in derived theropods and probably, therefore, improved their turning agility. To reduce rotational inertia, theropods may have run with an arched back and tail, an S-curved neck and forelimbs held backwards against the body.

www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0025763

" Recent biomechanical analyses of theropod turning performance have commented on the large rotational inertia that the elongate body-plans of most theropods would impart [24]–[25]. Such studies have likely underestimated the turning abilities of most theropods, because they have assumed that the sum total of a theropod's rotational inertia had to be overcome all at once. Theropods were not laterally stiff, and it is likely that most theropods turned with a more serpentine motion – turning first their heads and necks, then torsos, then hips, and finally, in a sinuous motion, their tails."

"Theropod dinosaurs attained the largest body sizes among terrestrial predators, and were also unique in being exclusively bipedal. With only two limbs for propulsion and balance, theropods would have been greatly constrained in their locomotor performance at large body size. Using three–dimensional restorations of the axial bodies and limbs of 12 theropod dinosaurs, and determining their rotational inertias (RIs) about a vertical axis, we show that these animals expressed a pattern of phyletic size increase that minimized the increase in RI associated with increases in body size. By contrast, the RI of six quadrupedal, carnivorous archosaurs exhibited changes in body proportions that were closer to those predicted by isometry. Correlations of low RI with high agility in lizards suggest that large theropods, with low relative RI, could engage in activities requiring higher agility than would be possible with isometric scaling."

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"Unlike extant birds and mammals, most non-avian theropods had large muscular tails, with muscle arrangements similar to those of modern reptiles. Examination of ornithomimid and tyrannosaurid tails revealed sequential diagonal scarring on the lateral faces of four or more hemal spines that consistently correlates with the zone of the tail just anterior to the disappearance of the vertebral transverse processes. This sequential scarring is interpreted as the tapering boundary between the insertions of the M. caudofemoralis and the M. ilioischiocaudalis. Digital muscle reconstructions based on measurements of fossil specimens and dissections of modern reptiles showed that the M. caudofemoralis of many non-avian theropods was exceptionally large. These high caudofemoral mass estimates are consistent with the elevation of the transverse processes of the caudal vertebra above the centrum, which creates an enlarged hypaxial region. Dorsally elevated transverse processes are characteristic of even primitive theropods and suggest that a large M. caudofemoralis is a basal characteristic of the group. In the genus Tyrannosaurus, the mass of the M. caudofemoralis was further increased by dorsoventrally lengthening the hemal arches. The expanded M. caudofemoralis of Tyrannosaurus may have evolved as compensation for the animal's immense size. Because the M. caudofemoralis is the primary hind limb retractor, large M. caudofemoralis masses and the resulting contractile force and torque estimates presented here indicate a sizable investment in locomotive muscle among theropods with a range of body sizes and give new evidence in favor of greater athleticism, in terms of overall cursoriality, balance, and turning agility."

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