Triceratops spp. vs. American Mastodon

[Infinity Blade]

Not seeing anything that would help the Triceratops "invalidate" a stab from the mastodon's tusk, especially in the facial region (which mastodons attacked when fighting each other). Also, note that the specimen I'm referring to has tusks that point upward, not curving inward like the tusks depicted in Larramendi's skeletal.

[dinosauria101]

You may want to recheck my post. It was just edited with a better size comp to show my point.

[Infinity Blade]

I can't discern much of a difference (especially since I don't have the previous one for reference) and I'm still not seeing your point. I can still see the mastodon being capable of stabbing the ceratopsid somewhere in the face.

[dinosauria101]

Also theropod's post isn't the ONLY estimate; I was able to get 14 tonnes with GAT's skeletal. 11-14 tonnes is a good range for the biggest Trikes. Average is indeed iffy, but theropod got, using a rough estimate, 6.4 tonnes based on GSP's skeletal*, which I would still back over the average sized, 7.8 tonne American mastodon. Other skeletals, such as Hartman's and GAT's get higher averages, all of which I'd for sure back over the average mastodon.

Anyhow, let me rephrase what I said.
MOST mastodons don't have much of a realistic way to kill the Trike. Some, like the one you posted, MIGHT be able to kill the Triceratops if it just stood there and did nothing, but it probably wouldn't be enough in a fight to the death before it lost. And if Trike decides to attack from the flank, even better. Not saying it would do so every time but it's probably not unreasonable to think it could or would sometimes.

*The thing about GSP is that those Trike skeletals are not the best. They're usually arbitrary composites of multiple specimens as well as often no cross-scaling. I would in general avoid them unless GSP has a Trike skeletal made of 1 specimen only using others to fill in gaps and doing proper cross scaling. As for GAT, it is rough, but going by GAT's skeletal and theropod's methods, I got ~9 tonnes average for Trike.

[denis]

Dec 9, 2019 17:15:06 GMT 5 dinosauria101 said:

I meant head on wrestling as is commonly depicted among mastodons; it might work on a MASTODON which the shape of the skull actually allows it to gore, but the head of Triceratops is differently structured therefore invalidating that. Could be incorrect but what I'm seeing is a disparity in skull morphology as a goring blockade - maybe this size comparison can help to illustrate what I mean (largest mastodon vs USNM 4276, as well as a top view of 2 mastodons to show the disparity; skeletals are by GetAwayTrike and Larramendi while Trike top view is GSP):

Alternatively, maybe it would be better to say the mastodon can kill other mastodons but the strategy won't really work on a Triceratops.
So rephrased: The mastodon's weapons, while they may work on other mastodons, won't work too well here

Average for Trike AFAIK is uncertain (I'd back the ceratopsian even at some size disadvantage), but at max it might have a decent mass advantage at up to 14 tonnes vs just 11 tonnes. 

Yeah. This is the same thing for all elephants too.

[spartan]

I also don't see what you mean. The Mastodon's tusks appear to be in a good position to gore the dinosaur.

[dinosauria101]

True. I'd back Trike over most, if not all, elephant species depending on estimates

[dinosauria101]

Dec 9, 2019 17:44:47 GMT 5 spartan said:

I also don't see what you mean. The Mastodon's tusks appear to be in a good position to gore the dinosaur.

Some specimens would certainly be capable of goring, some less so due to varying degrees of tusk curvature. What I mean is their curvature/angle would make good, clean stabs hard if not impossible for some, and others would probably be THEORETICALLY capable of killing the dinosaur if it just stood there, but it wouldn't be enough in a fight to the death

[6f5e4d]

Triceratops wins, as it may be heavier and its horns are more suited for stabbing compared to the mastodon.

[dinosauria101]

^Basically this.
Here's a size chart I put together of 595BS71 (11 tonnes) and UCMP 128561 (14 tonnes using this skeletal and accounting for bulk increase). Skeletals by Larramendi and GetAwayTrike.

Take note of how much burlier the Trike is; they look similar in size or Trike a bit smaller from side view but it has a 3 tonne weight advantage.

[spartan]

Could you stop using 14t Triceratops like it's some kind of established maximum size?

[dinosauria101]

I'm not. It's just one estimate, and I even said that using the skeletal would get 14 tonnes.
The max Triceratops could be anywhere from 11 to 14 tonnes, like I said earlier. But we already had an 11 vs 11 tonne comparison, so I made an 11 vs 14 tonne one

[shadi]

Dec 30, 2016 18:41:03 GMT 5 Infinity Blade said:

Note that ceratopsians like Triceratops were about as anatomically adapted for speed as rhinos, which in turn are more cursorial than proboscideans. Considering that the mastodon's limbs are seemingly more muscular and stockier than a modern elephant's, I don't know if it would, if anything, be faster or slower than an elephant (when it comes to fast running, muscle power helps, but stockier limb proportions hurt). At any rate though, I kind of doubt it would match the ceratopsid in speed.

There are indications that ceratopsians were slow moving. Carrano(1999) found that ceratopsians plotted firmly as graviportal, defined as "a complementary set of features(more robust individual limb elements, shorter distal limb segments, and more distally placed muscle insertions)..in the limbs of animals designed to move with lower speeds."

Barret(2017)points out:

"In all groups, the humeral head is restricted to the posterior surface of the humerus, so that the humerus was habitually retracted and could not have been protracted past the vertical (Maidment and Barrett 2012; Fig. 1). Stride length in quadrupedal ornithischians was probably strongly dictated by this constraint and, presumably, would have limited these animals to relatively slow locomotion"

And Maidment(2012):

"Quadrupedal ornithischians had habitually bent elbows and probably could not have protracted their humerus beyond vertical (Maidment and Barrett, unpublished data). The scapulae of mammals are mobile, contributing to effective forelimb length [38], while those of quadrupedal ornithischians were rigid and probably did not move significantly during the step cycle. The forelimbs are significantly shorter than the hind limbs in all quadrupedal ornithischians because they evolved from bipedal ancestors, which is not the case in mammals. These factors all indicate that ornithischians probably had shorter strides (being limited by forelimb length) than those of mammalian quadrupeds, and could not have moved as quickly"

5.) The Triceratops clearly has much more room for thigh musculature (compare the length of its ilium to the mastodon's), and I'd imagine stronger shank muscles (the cnemial crest is well-developed in Triceratops, while it's not in proboscideans).
.

The pelvic musculature of Chasmosaurus was computer modelled by Maidment(2013) and it was found that their muscles had poor leverage, which suggested poor locomotory ability:

The fact that most muscles have very low leverage for all functions in Chasmosaurus is perhaps suggestive of relatively poor locomotor performance in this taxon and, potentially, ceratopsids in general. given the association of low moment arms with a lack of ‘cursorial features’ ( Chasmosaurus lacks elongate and slender forelimb epipodials and has a high humerus/radius ratio; ), we suggest it is more likely that Chasmosaurus possessed poor locomotor performance."

[Infinity Blade]

Jan 25, 2023 0:37:59 GMT 5 shadi said:

Dec 30, 2016 18:41:03 GMT 5 Infinity Blade said:

Note that ceratopsians like Triceratops were about as anatomically adapted for speed as rhinos, which in turn are more cursorial than proboscideans. Considering that the mastodon's limbs are seemingly more muscular and stockier than a modern elephant's, I don't know if it would, if anything, be faster or slower than an elephant (when it comes to fast running, muscle power helps, but stockier limb proportions hurt). At any rate though, I kind of doubt it would match the ceratopsid in speed.

There are indications that ceratopsians were slow moving. Carrano(1999) found that ceratopsians plotted firmly as graviportal, defined as "a complementary set of features(more robust individual limb elements, shorter distal limb segments, and more distally placed muscle insertions)..in the limbs of animals designed to move with lower speeds."

Regarding limb proportions in ceratopsids, Christiansen & Paul (2001) would like to disagree:

Ceratopsians have rather long limbs compared to extant large mammals, such as rhinos, especially hindlimbs, and their forelimbs are not proportionally as short as is usually assumed. Limb proportions indicate that the locomotory potential of ceratopsids could-have been comparable to extant tapirs and rhinoceroses.

When comparing similar sized ceratopsids to rhinos, e.g. a Chasmosaurus belli with a predicted body mass of 1685 kg (APPENDIX I) to a 1900 kg Ceratotherium, the longest metacarpal in the former (142 mm) is considerably shorter than in the latter (192 mm). The metacarpals of Triceratops are 20% longer than in the African elephant. The moderately long metacarpals, limbs with permanent joint flexure, large limb bone muscle attachment sites and digitigrade stance of ceratopsians tend to group them with mediportal mammals. The hindlimb proportions are less equivocal (Fig. 3B), and the four categories show much less overlap than was the case for the forelimb. The lowest tibiofemoral values in ceratopsids are still within the graviportal range but overall they tend to group more closely with the mediportals. The metatarsus/femur ratios of ceratopsids clearly fall within the range of the mediportal mammals and are considerably higher than in graviportal animals. This measure apparently is a superior predictor of locomotor performance to the tibia/femur ratio (GARLAND & JANIS, 1993).

Also, the term “graviportal” is not always used in a strict sense. Hippos and rhinos, for instance, which are sometimes called mediportal (like in the reference I cited above), are also often called graviportal. Clearly, people also use the term to refer to any animal with stocky limb proportions designed primarily for weight bearing rather than fast running. In that sense, is a ceratopsid graviportal? Sure, whatever, but that doesn’t mean it has the legs of a proboscidean, which are graviportal through and through.

Barret(2017)points out:

"In all groups, the humeral head is restricted to the posterior surface of the humerus, so that the humerus was habitually retracted and could not have been protracted past the vertical (Maidment and Barrett 2012; Fig. 1). Stride length in quadrupedal ornithischians was probably strongly dictated by this constraint and, presumably, would have limited these animals to relatively slow locomotion"

And Maidment(2012):

"Quadrupedal ornithischians had habitually bent elbows and probably could not have protracted their humerus beyond vertical (Maidment and Barrett, unpublished data). The scapulae of mammals are mobile, contributing to effective forelimb length [38], while those of quadrupedal ornithischians were rigid and probably did not move significantly during the step cycle. The forelimbs are significantly shorter than the hind limbs in all quadrupedal ornithischians because they evolved from bipedal ancestors, which is not the case in mammals. These factors all indicate that ornithischians probably had shorter strides (being limited by forelimb length) than those of mammalian quadrupeds, and could not have moved as quickly"

Regarding scapular mobility in quadrupedal ornithischians, Senter & Robins (2015) would like to disagree:

It is also noteworthy that, for a given specimen, the left and right scapular blades often differ in inclination (Tables 1 and 2), even when the specimen is preserved still encased in sediment with integumentary impressions that suggest extended persistence of the skin after death (e.g. AMNH 5240, Corythosaurus casuarius, in which left and right scapular blade inclinations differ by 6°). This supports the hypothesis that dinosaurian scapulocoracoids were mobile [82], as in extant non-avian tetrapods [83–85]. Left and right scapulocoracoids of oviraptorosaurian and dromaeosaurid theropods are tightly coupled via the sternum [5,60], hence probably exhibited reduced mobility relative to each other, but such is not the case with other dinosaurian taxa. The recommended scapular blade orientations in Table 6 should therefore be treated not as immutable values but as values from which a reconstructor may safely stray a few degrees.

5.) The Triceratops clearly has much more room for thigh musculature (compare the length of its ilium to the mastodon's), and I'd imagine stronger shank muscles (the cnemial crest is well-developed in Triceratops, while it's not in proboscideans).
.

The pelvic musculature of Chasmosaurus was computer modelled by Maidment(2013) and it was found that their muscles had poor leverage, which suggested poor locomotory ability:

The fact that most muscles have very low leverage for all functions in Chasmosaurus is perhaps suggestive of relatively poor locomotor performance in this taxon and, potentially, ceratopsids in general. given the association of low moment arms with a lack of ‘cursorial features’ ( Chasmosaurus lacks elongate and slender forelimb epipodials and has a high humerus/radius ratio; ), we suggest it is more likely that Chasmosaurus possessed poor locomotor performance."

Literally ALL giant land animals have suboptimal limb leverage/effective mechanical advantage. While animals can gain more effective mechanical advantage as they get larger, this scaling relationship only works up to a certain point (by around 300 kg in mammals). Beyond that point (which BOTH the Triceratops and the mastodon are literally one or two orders of magnitude beyond), locomotory abilities are reduced, in part thanks to reduced limb leverage (Hutchinson, 2021).

Insights from scaling of the leverage of limbs and trends in maximal speed reinforce the idea that, beyond 100–300 kg of body mass, tetrapods reduce their locomotor abilities, and eventually may lose entire behaviours such as galloping or even running.

Fig. 3 illustrates the concept of the effective mechanical advantage (EMA; see Glossary) of limbs in tetrapods (Biewener, 1989, 1990, 2005; McMahon, 1975a,b). EMA is the ratio of extensor muscle moment arms r (see Glossary; internal; anti-gravity) to moment arms R (external; inertially induced) resulting from the ground reaction force (GRF; see Glossary) around joints, which can be averaged for limbs (around mid-stance of locomotion, or as a weighted mean across the stance phase). A higher EMA indicates better overall supportive leverage. Limb postures become straighter as many parasagittally locomoting (i.e. erect; giant taxa in particular) terrestrial tetrapods become larger (Biewener, 1989, 1990, 2005; Osborn, 1900; Reilly et al., 2007). Concurrently, limb muscle moment arms become allometrically larger (Alexander et al., 1981; Biewener, 1990; Maloiy et al., 1979). These changes allometrically increase EMA (Biewener, 2005). However, EMA scaling reaches a plateau around horse-size (perhaps 300 kg in mammals) – big animals cannot become more straight-limbed (limiting minimal R) once they are straight-limbed (see below). But as Fig. 3A illustrates, EMA still varies in large land animals – there is not just a simple plateau at EMA ∼1. This variation indicates differential, lineage-specific evolution (i.e. scaling) of EMA in some land giants. Giant tetrapods, then, are not canalized to have a uniform (fully ‘columnar’) limb posture and antigravity support abilities, despite the importance of such abilities in gigantism. Multiple extant giants (e.g. rhinos, hippos) remain unmeasured, and estimates are yet to be made for many extinct taxa; thus, there is likely to be further variation.

For instance, elephants have poor leg muscle leverage (Ren et al., 2010):

Relatively poor muscle leverage in running elephants has a direct impact on the metabolic cost of locomotion (Fig. 3). The normalized muscle volume recruitment (Vmusc; 45–70 cm3 kg−1 m−1) in elephants is relatively 2- to 4-fold greater than in humans but comparable to estimates for other quadrupeds (15, 20, 21).

This is a problem literally ALL giant land animals would be expected to have, not just ceratopsians.


Read what I actually said again:

“Note that ceratopsians like Triceratops were about as anatomically adapted for speed as rhinos, which in turn are more cursorial than proboscideans. Considering that the mastodon's limbs are seemingly more muscular and stockier than a modern elephant's, I don't know if it would, if anything, be faster or slower than an elephant (when it comes to fast running, muscle power helps, but stockier limb proportions hurt). At any rate though, I kind of doubt it would match the ceratopsid in speed.”

“5.) The Triceratops clearly has much more room for thigh musculature (compare the length of its ilium to the mastodon's), and I'd imagine stronger shank muscles (the cnemial crest is well-developed in Triceratops, while it's not in proboscideans).”

Notice what I DIDN’T say? I DIDN’T say that giant ceratopsians were especially fast runners. Not one land animal that’s this gigantic is a good or fast runner. What I said was that the Triceratops would have better locomotory ability than the mastodon. BOTH have suboptimal limb leverage compared to much smaller cursors. BOTH have more graviportal limb proportions than actual specialized cursors (although, the ceratopsian’s are more mediportal). But COMPARED TO EACH OTHER the Triceratops wins out from an anatomical perspective.

[Supercommunist]

Literally ALL giant land animals have suboptimal limb leverage/effective mechanical advantage. While animals can gain more effective mechanical advantage as they get larger, this scaling relationship only works up to a certain point (by around 300 kg in mammals).

Just a small nitpick, while I agree that animals larger than horses start becoming slower, the 300 kg figure doesn't seem accurate. The fastest horse breeds are thoroughbreds, animals quite a bit heavier than 300 kg. I couldn't find a good source for average thoroughbreds weights but the famous race horse Secretariat weighed 524 kg.

His weight before the Gotham Stakes in April 1973 was 1,155 pounds (524 kg).[30] After completing the grueling Triple Crown, his weight on June 15 had dropped only 24 pounds, to 1,131 pounds (513 kg).[23] Secretariat was known for his appetite—during his three-year-old campaign, he ate 15 quarts of oats a day—and to keep his muscles in good condition, he needed fast workouts that could have won many a stakes race.[31]