The following is a compilation of the best available data on the forelimb morphologies of the two animals. Data is the standard by which any claim ought to be judged, as it is with the following and the relative strengths of the lion and the tiger.
I. SCAPULAR SIZE:
Study: Christiansen and Adolfssen, 2007.
Metric: Scapular length.
Correlated With: Space for muscle attachment in the shoulders.
Sample Size: 17 lions, 15 tigers.
Lion: 210.2-288.4 mm.
Tiger: 199.1-241.3 mm.
Edge: Lion.
II. HUMERAL ROBUSTICITY BASED ON CIRCUMFERENCE:
Study: Christiansen and Adolfssen, 2007.
Metric: Least circumference of humeral diaphysis in relation to humeral length.
Correlated With: Overall resistance of humerus to stress.
Sample Size: 17 lions, 15 tigers.
Lion: 0.318.
Tiger: 0.303.
Edge: Lion.
Study: Christiansen and Harris, 2005.
Metric: Least circumference of humeral diaphysis in relation to humeral length.
Correlated With: Overall bending strength of humerus.
Sample Size: 3 lions, 5 tigers.
Lion: 0.314.
Tiger: 0.300.
Edge: Lion.
III. HUMERAL ROBUSTICITY BASED ON ML DIAMETER:
Study: Christiansen and Harris, 2005.
Metric: ML diameter of humerus at midshaft in relation to humeral length.
Correlated With: Resistance of humerus to stresses along the ML axis.
Sample Size: 3 lions, 5 tigers.
Lion: 0.0897.
Tiger: 0.0870.
Edge: Lion.
Study: Bertram and Biewner, 1990.
Metric: ML diameter of humerus at midshaft in relation to humeral length.
Correlated With: Resistance of humerus to stresses along the ML axis.
Sample Size: 4 lions, 2 tigers.
Lion: 0.0892.
Tiger: 0.0857.
Edge: Lion.
Study: Meachen-Samuels and Van Valkenburgh, 2010.
Metric: ML diameter of humerus at midshaft in relation to humeral length.
Correlated With: Resistance of humerus to stresses along the ML axis.
Sample Size: 2 lions, 2 tigers.
Lion: 0.0824.
Tiger: 0.0909.
Edge: Tiger.
IV. HUMERAL ROBUSTICITY BASED ON AP DIAMETER:
Study: Christiansen and Harris, 2005.
Metric: AP diameter of humerus at midshaft in relation to humeral length.
Correlated With: Resistance of humerus to stresses along the AP axis.
Sample Size: 3 lions, 5 tigers.
Lion: 0.1098.
Tiger: 0.1037.
Edge: Lion.
Study: Bertram and Biewner, 1990.
Metric: AP diameter of humerus at midshaft in relation to humeral length.
Correlated With: Resistance of humerus to stresses along the AP axis.
Sample Size: 4 lions, 2 tigers.
Lion: 0.1278.
Tiger: 0.1137.
Edge: Lion.
Study: Meachen-Samuels and Van Valkenburgh, 2010.
Metric: AP diameter of humerus at midshaft in relation to humeral length.
Correlated With: Resistance of humerus to stresses along the AP axis.
Sample Size: 2 lions, 2 tigers.
Lion: 0.1144.
Tiger: 0.1096.
Edge: Lion.
V. ML CORTICAL THICKNESS:
Study: Meachen-Samuels and Van Valkenburgh, 2010.
Metric: ML k-value.
Correlated With: Resistance of humerus to stresses along the ML axis (inverse correlation).
Sample Size: 2 lions, 2 tigers.
Lion: 0.489.
Tiger: 0.561.
Edge: Lion.
VI. AP CORTICAL THICKNESS:
Study: Meachen-Samuels and Van Valkenburgh, 2010.
Metric: AP k-value.
Correlated With: Resistance of humerus to stresses along the AP axis (inverse correlation).
Sample Size: 2 lions, 2 tigers.
Lion: 0.571.
Tiger: 0.610.
Edge: Lion.
VII. DISTAL BENDING STRENGTH OF HUMERUS:
Study: Christiansen and Harris, 2005.
Metric: Distal articular width of humerus in relation to humeral length.
Correlated With: Resistance of humerus to stresses at the elbow joint.
Sample Size: 3 lions, 5 tigers.
Lion: 0.1923.
Tiger: 0.1827.
Edge: Lion.
VIII. ROBUSTICITY OF RADIUS BASED ON ML DIAMETER:
Study: Bertram and Biewner, 1990.
Metric: ML diameter of radius at midshaft in relation to radial length.
Correlated With: Resistance of radius to stresses along the ML axis.
Sample Size: 4 lions, 2 tigers.
Lion: 0.0990.
Tiger: 0.0890.
Edge: Lion.
IX. ROBUSTICITY OF RADIUS BASED ON AP DIAMETER:
Study: Bertram and Biewner, 1990.
Metric: AP diameter of radius in relation to radial length.
Correlated With: Resistance of radius to stresses along the AP axis.
Sample Size: 4 lions, 2 tigers.
Lion: 0.0630.
Tiger: 0.0739.
Edge: Tiger.
X. ROBUSTICITY OF ULNA BASED ON AP DIAMETER:
Study: Christiansen and Adolfssen, 2007.
Metric: AP diameter of ulna at midshaft in relation to ulnar length.
Correlated With: Resistance of ulna to stresses along the AP axis.
Sample Size: 17 lions, 15 tigers.
Lion: 0.086.
Tiger: 0.098.
Edge: Tiger.
Study: Christiansen and Harris, 2005.
Metric: AP diameter of ulna at midshaft in relation to ulnar length.
Correlated With: Resistance of ulna to stresses along the AP axis.
Sample Size: 3 lions, 5 tigers.
Lion: 0.0736.
Tiger: 0.0830.
Edge: Tiger.
XI. OLECRANON LEVERAGE:
Study: Christiansen and Harris, 2005.
Metric: Olecranon length in relation to ulnar length.
Correlated With: Leverage of triceps muscle in extending the forearm.
Sample Size: 3 lions, 5 tigers.
Lion: 0.1852.
Tiger: 0.2081.
Edge: Tiger.
Study: Sorkin, 2006.
Metric: Olecranon length in relation to ulnar length.
Correlated With: Leverage of triceps muscle in extending the forearm.
Sample Size: 2 lions, 2 tigers.
Lion: 0.1986.
Tiger: 0.2575.
Edge: Tiger.
XII. GRIP:
Study: Iwaniuk, 1997.
Metric: MCP ratio.
Correlated With: Size of paw, strength of grip (inverse correlation).
Sample Size: 6 lions, 4 tigers.
Lion: 2.329.
Tiger: 2.072.
Edge: Tiger.
CONCLUSIONS:
The best data we have indicates that the lion has the following advantages over the tiger on average:
1. More space for shoulder muscle attachments. Mean bigger, stronger and more Robust shoulders
2. Greater ML (2/3 studies) and AP (3/3 studies) diameter of humerus at equal humeral lengths.
3. Greater cortical thickness in the humerus at equal humeral widths.
4. Greater distal width of humerus at equal humeral lengths.
5. Greater ML diameter of radius at equal radial lengths.
6. Averagely a bit longer forearms than the tiger...
The lion is slightly taller than the tiger, but the tiger's humerus makes up slightly more of its forelimb length than the lion. The result is that the lion will have a humerus of approximately equal length to that of the tiger. Thus, the advantages of greater ML diameter of humerus, greater AP diameter of humerus, and greater distal width of humerus are all advantages in absolute terms, not merely on a pound for pound basis. These, combined with the lower k-values of the lion and the greater ML diameter of the radius, indicate that the resistance of the lion's forelimb bones to stresses along the ML axis will be somewhat greater on average than the resistance of the tiger's forelimb bones to the same stresses.
This indicates that there is some pressure for increased resistance to stress in the forelimb on the lion that is absent--or at least reduced in intensity--to the tiger. Whatever this pressure may be, if the bones need to be stronger to meet the demand, so will the musculature. For instance, if running is the factor requiring resistance to stress from the lion's bones, it will also require tremendous muscle force production for the purpose of attaining and maintaining high speeds. Now, running would place stress only along the AP axis, and thus is unlikely to be the factor we're looking for, but it illustrates the point quite nicely. Whatever produces a pressure for increased bone bending strength along a certain axis will also produce a pressure for increased torque production from the muscles powering the motions of the bone along the same axis.
The conclusion to be drawn from the best data we have, then, would be that the lion will tend to have greater strength than the tiger when moving the forelimb through the ML axis.
The best data we have also indicates that the tiger will have the following advantages over the lion on average:
1. Increased AP robusticity in the bones of the forearm.
2. Better leverage when extending the forearm.
3. Better grip.
Despite the lion's longer radius and ulna, the raw data (prior to calculating robusticities) shows that the AP diameter of the tiger's radius and ulna are greater than those of the lion in absolute terms. This indicates that the tiger's forearm bones, on average, will have greater resistance to stresses along the AP axis than the lion's. Therefore, as stated above, there is some pressure for increased bending strength along the AP axis placed on the tiger's forearm bones that is absent or reduced on the lion, and thus also a pressure for increased strength in the muscles powering the motions of the forearm along the AP axis. This, combined with the tiger's greater leverage when extending the forearm, would appear to indicate that the tiger will have greater strength in motions like pushing and pulling.
The conclusion to be drawn from the best data we have, then, would be that the tiger will tend to have greater strength than the lion in terms of motions of the forearm through the AP axis (eg, pushing and pulling), as well as in terms of strength of grip.
As we can see most of the data on bone robusticity favours the lion over tiger.Lion has more robust humerus which is directly correlated with body mass/muscle mass and hence directly with strength.
Thus,because of this data I maintain that lions have not only more robust bones than tiger but pound for pound they are also more powerful.
PS:Lions have advantage over tiger in scapular size and cortical thickness/robustness of bones as well.
Here are some animal types - triceps mass (g) - body masses (kg):
Animal type Triceps mass (g) BM (kg)
Ferret 3.50648 0.83
Genet 14.13741 1.9
Domestic cat 18.36865 2.5
White-tailed mongoose 30.07272 4.1
Black-backed jackal 85.99199 7.2
Red fox 120.34722 8
Domestic dog 324.47482 25
Spotted hyena 543.39254 41
Lion 2103.78726 150
Cheetah 383 31.05166
American badger 66.2 7.6
Greyhound 594 31.4
body mass/triceps mass (kg/g):
Ferret 0.2367
Genet 0.1344
Domestic cat 0.1361
White-tailed mongoose 0.13634
Black-backed jackal 0.08373
Red fox 0.06647
Domestic dog 0.07705
Spotted hyena 0.07545
Lion 0.0713
Cheetah 0.08107
American badger 0.1148
Greyhound 0.05286
triceps mass/body mass:
Ferret 4.22467
Genet 7.44074
Domestic cat 7.34746
White-tailed mongoose 7.33481
Black-backed jackal 11.94333
Red fox 15.0434
Domestic dog 12.97899
Spotted hyena 13.25348
Lion 14.02525
Cheetah 12.33429
American badger 8.71053
Greyhound 18.9172
Humerus ML diameter/length values from Samuels et al (2013):
Ferret 0.0762
Genet 0.0665
White-tailed mongoose 0.0739
Black-backed jackal 0.0676
Red fox 0.062
Spotted hyena 0.0834
Lion 0.0859
Cheetah 0.0693
American badger 0.0928
Sources:
Alexander, R. M. C. N., Jayes, A. S., Maloiy, G. M. O., & Wathuta, E. M. (1981). Allometry of the leg muscles of mammals. Journal of Zoology, 194(4), 539-552.
Davis, D. D. (1962). Allometric relationships in lions vs. domestic cats. Evolution, 505-514.
Hudson, P. E., Corr, S. A., Payne‐Davis, R. C., Clancy, S. N., Lane, E., & Wilson, A. M. (2011). Functional anatomy of the cheetah (Acinonyx jubatus) forelimb. Journal of Anatomy, 218(4), 375-385.
Moore, A. L., Budny, J. E., Russell, A. P., & Butcher, M. T. (2013). Architectural specialization of the intrinsic thoracic limb musculature of the American badger (Taxidea taxus). Journal of Morphology, 274(1), 35-48.
Muchlinski, M. N., SNODGRASS, J., & Terranova, C. J. (2012). Muscle mass scaling in primates: an energetic and ecological perspective. American Journal of Primatology, 74(5), 395-407.
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Lions-as all the study points out have generally better reinforced upper arm bones but tigers generally have slightly bigger upper arm/more muscle mass.Lionclaws has provided very good explanation here.
Individual variation is a problem for any study, and it is a problem here too. For that reason, I arranged the studies under each given heading in descending order of sample size. The confidence we can have in a conclusion is directly proportional to the sample size of the study we draw the conclusion from. For that reason, I am VERY confident about robusticity of humerus based on least circumference. I am fairly confident about distal robusticity of humerus, AP robusticity of humerus, and ML robusticity of humerus. I am somewhat tentative about the k-values.
As to relating things to the size of the animals involved, our best bet for doing that would be Christiansen and Harris, 2005. In addition to measurements of the limb bones of the three lions and five tigers in their study, they also included weights. Taking the averages, the lions in the study weighed 174.3 kg and had humeri averaging 343.3 mm in length. The tigers in the study had an average weight of 187.2 kg and had humeri averaging 335.5 mm in length. Using the square-cube law to scale the tigers up to a more representative 200 kg, we find humeral length of 346.8 mm. ~1% longer than those of the lion. Reasonably weighted lions and tigers would appear (though are by no means guaranteed) to have very similar humeral lengths.
As to the "inconsistencies" between the studies and real life (the tiger actually has bulkier upper arms, yet the lion's upper arm bones are better reinforced), I believe that the difference can be explained rather easily.
The tiger has better reinforced forearm bones, based on AP robusticity of ulna and radius. That implies that the tiger experiences the need for resistance to stress in motions of the forearm through the AP axis. If the bones need to resist stress in such motions, odds are that the muscles would also need to be able to overcome stresses in the same motions. And just as the bones were reinforced to withstand such stress, odds are that the muscles would need to have greater torque output to overcome such stress. And in the case of the forearm bones, those muscles would be in the biceps and triceps muscle groups. The muscles of the upper arm power the motions of the forearm. And just as the bones of the forearm display greater reinforcement, the bones of the upper arm display greater power output. Similarly the MCP ratio implies that the tiger is better adapted for gripping things. The muscles that power the motions of the hand are located in the forearm. Again, the tiger is seen to have greater girth of forearm.
The bones of the upper arm are better reinforced in the lion than they are in the tiger. Like you've said elsewhere, the lion tends to be more solidly built in the chest area, though it isn't always, many tigers can be more solidly built in the chest area, and Bengals are particularly prone to doing so. Many lion supporters also claim that the lion has more power in the shoulders. The chest and shoulder muscles power the humerus. We see that reinforcement in the bones is yet again correlated with the development of the muscles powering motions of those bones. Interestingly, Christiansen and Harris, 2005, included information on what subspecies of tiger each specimen was. There were two Bengals and three Siberians. The Bengal tigers had more robust humeri than the Siberian tigers did. You've noticed that Bengals are more heavily built and "lion-like" than Siberians when it comes to chest musculature. Even this observation is reflected in the bones!