Comparing Cats: A Discussion of Similarities & Differences

[Charger01]

COMPARING BIG CATS - ROBUSTNESS OF FRONT BODY AND GRAPPLING STRENGTH AND ABILITIES

#1. Studies conducted by Samuels and Van Valkenburgh, 2009, analysing various factors that play a role in the general strength and grappling strength of the felids
Credits to Reddhole (carnivora) for posting the studies - https://carnivora.net/felid-species-grappling-ability-study-t2680.html

Front Limb Segment Ratio
(Shorter front limbs are very useful for grappling with your opponent; lower score is better)

Humerus/Radius:
1. Jaguar - 81.9%
2. Tiger - 82.4%
3. Cougar - 82.7%
4. Leopard - 83.1%
5. Lion - 89.5%
(Smilodon Fatalis - 78.9%)

Humerus/MTC 3:
1. Jaguar - 32.8%
2. Tiger - 34.0%
3. Leopard – 34.9%
5. Lion – 35.0%
4. Cougar - 36.5%
(Smilodon fatalis - 25.2%)

Humerus/Ulna (the precise value here is unknown; so I'll list them in their order):
1. Xenosmilus Hodsonae
2. Smilodon Fatalis
3. Jaguar
4. Tiger
5. Cougar
6. Lion
7. Leopard
8. Homotherium aerum
9. Homotherium ischyros

Proximal Paw Width
In addition, large prey specialists have proportionally large proximal paw widths (PAW). The width of the proximal paws facilitates a stronger, more stable grip on large prey animals during the initial attack, as it would in gripping substrate (Watkins, 2003) or while climbing (Cartmill, 1985), and allows the force to be distributed more evenly across the entire paw.

1. Tiger – 79.95%
2. Jaguar – 79.81%
3. Lion – 79.73%
4. Snow Leopard – 78.46%
5. Clouded Leopard – 77.09%
6. Leopard – 73.01%
7. Cougar – 68.01%
(Smilodon Fatalis - 100%)

Brachial Index (lower value is better in this case)
With regards to brachial index (BI), Iwaniuk et al. (1999) and Gonyea (1976a) also found similar results. Arboreal felids have shorter radii relative to humeri, and therefore a smaller brachial index (BI) because shortened distal limbs increase the mechanical advantage of forelimb flexors and extensors, allowing arboreal species to climb more effectively. Shorter limbs also lower the centre of gravity for arboreal cats favouring the ability to balance on high, narrow tree branches (Cartmill, 1985).

1. Clouded Leopard – 79.90%
2. Jaguar – 83.33%
3. Leopard – 84.87%
4. Cougar – 85.35%
5. Tiger – 85.56%
6. Snow Leopard – 89.01%
7. Lion – 91.13%

Humerus Robusticity Index
The results of this study suggest that large prey specialists have relatively robust forelimbs when compared with smaller prey specialists. Both the humerus (HRI) and radius (RRI) diaphyses were found to be consistently robust. This increased robusticity functions to protect against bending and torsion when under increased stress (Ruff and Hayes, 1983; Lanyon and Rubin, 1985), such as that encountered when grappling with large prey. The increased robustness in the humeri and radii of large prey specialists may also translate into a proportionally thicker cortical area of the humerus diaphysis, a possibility that will be explored in a future study.

1. Jaguar - 8.81%
2. Tiger - 8.53%
3. Lion - 8.44%
4. Snow Leopard - 8.15%
5. Leopard/Snow Leopard - 7.98%
6. Cougar - 7.64%

Humeral - Epicondylar Index
The humeral epicondylar index (HEI) was larger in large prey specialists. The humeral epicondyles serve as the origin for many muscles that stabilize the wrist during prey capture, such as: m. pronator teres, m. extensor carpi radialis, m. extensor carpi ulnaris, m. flexor carpi radialis, and m. flexor carpi ulnaris (Hebel and Stromberg, 1976;Schaller, 1992). The humeral epicondyles are also the point of origin of many of the digital flexor and extensor muscles that facilitate grasping of large prey during capture, such as: m. extensor digitorum communis, m. extensor digitorum lateralis, m. flexor digitorum superficialis, m. palmaris longus, and m. flexor digitorum profundus, in part (Hebel and Stromberg, 1976; Schaller, 1992). These larger epicondyles allow for larger originations and thereby larger muscles.

1. Tiger – 25.98%
2. Lion – 25.55%
3. Jaguar – 25.52%
4. Clouded Leopard – 24.11%
5. Snow Leopard – 24.10%
6. Leopard – 22.50%
7. Cougar – 21.57%

Olecranon Index
As found by Iwaniuk et al. (1999), the olecranon process of the ulna was relatively larger (OI) in large prey specialists. The triceps muscles insert on the olecranon process and are used primarily in arm extension. Increased size of these muscles would proffer a greater ability to push prey to the ground and hold them down while they position themselves for a killing bite.

1. Tiger – 22.47%
2. Snow Leopard – 21.19%
3. Lion – 20.78%
4. Jaguar – 19.92%
5. Leopard – 18.73%
6. Clouded Leopard – 18.07%
7. Cougar – 17.56%

Radial Robusticity Index
This measures radius mediolateral diameter at midshaft divided by radius length. As mentioned above for humerus robusticity, a robust radius resists stresses on bones during fights and increases resistance to bites to the forelimb.

1. Jaguar - 10.16%
2. Clouded Leopard - 9.69%
3. Tiger - 9.45%
4. Lion - 9.15%
5. Cougar - 8.99%
6. Leopard - 8.89%
7. Snow Leopard - 8.82%

Manus Proportions
Small prey specialists also have elongated phalanges relative to metacarpals (MCP), which again shows distal elongation. Distal elongation likely provides a velocity advantage for catching small, elusive prey.

1. Clouded Leopard – 60.53%
2. Snow Leopard – 56.04%
3. Tiger – 48.91%
4. Jaguar – 47.36%
5. Lion – 39.01%
6. Cougar – 29.33%
7. Leopard – 27.19%

Radial Articular Area
In addition, large prey specialists differed significantly from both of the other groups in having relatively broader paws (PAW), and larger distal radial and metacarpal articular surface areas (RAI, RAA, and MC3RAA).

1. Tiger – 13.11%
2. Jaguar – 12.19%
3. Clouded Leopard – 11.47%
4. Cougar – 11.38%
5. Lion – 11.30%
6. Snow Leopard – 11.18%
7. Leopard – 11.00%

Humeral Condylar Index
The distal articulation of the humerus (HCI) is also relatively larger in large prey specialists. Andersson (2004) also found increased distal articular area of the humerus in forelimb grappling carnivorans. This portion of the humerus articulates with the ulna and is responsible  for unilateral extension of the forearm and pronation and supination of the antebrachium. A larger articular area would provide more stability for antebrachial extension and non-parasagittal movements (Gonyea and Ashworth, 1975; Gonyea, 1978; Andersson, 2004), a wider range of motion for forearm positioning and prey grappling and also an increased ability to better distribute large loads (Ruff, 1988).

1. Lion – 18.00%
2. Jaguar/Tiger – 17.21%
3. Clouded Leopard – 16.63%
4. Snow Leopard – 16.43%
5. Leopard – 15.38%
6. Cougar – 14.35%

Metacarpal 3 Robustness Index
This measures the robusticity of metacarpal 3 or longest finger/digit. More robust metacarpal 3 may assist with grappling or stresses exerted with feet on ground during a fight.

1. Jaguar – 13.41%
2. Lion – 12.52%
3. Clouded Leopard – 12.19%
4. Tiger – 12.09%
5. Snow Leopard – 12.08%
6. Leopard – 11.95%
7. Cougar – 11.30%

Humeral Distal Articular Area
Andersson (2004) also found increased distal articular area of the humerus in forelimb grappling carnivorans. This portion of the humerus articulates with the ulna and is responsible for unilateral extension of the forearm and pronation and supination of the antebrachium. A larger articular area would provide more stability for antebrachial extension and non-parasagittal movements (Gonyea and Ashworth, 1975; Gonyea,1978; Andersson, 2004), a wider range of motion for forearm positioning and prey grappling and also an increased ability to better distribute larger loads (Ruff, 1988).

1. Tiger – 17.61%
2. Lion – 17.17%
3. Jaguar – 16.25%
4. Snow Leopard – 15.51%

Radial Articular Area
Even if the same scaling processes that act on the skull do not act on the forelimbs, negative allometry in limb bone lengths and positive allometry in muscle attachment sites and articular areas helps to reinforce the forelimbs against the stresses encountered by large, struggling prey.


1. Tiger – 13.11%
2. Jaguar – 12.19%
3. Clouded Leopard – 11.47%
4. Cougar – 11.38%
5. Lion – 11.30%
6. Snow Leopard – 11.18%
7. Leopard – 11.00%

Metacarpal 3 Distal Articular Area
Proximal paw width (PAW) and the distal articular area of the third metacarpal (MC3RAA) differed significantly among prey size and locomotor groups. Both variables would confer an advantage while climbing. As in large prey specialists, a wider paw would increase the surface area of the manus while climbing and increase frictional resistance (Cartmill, 1985). Greater distal articular area of the metacarpals would increase the range of motion in the digits to assure a better grip while climbing on thinner branches (Ruff,1988).

1. Jaguar – 13.41%
2. Lion – 12.52%
3. Clouded Leopard – 12.19%
4. Tiger – 12.09%
5. Snow Leopard – 12.08%
6. Leopard – 11.95%

Canine ML Diameter
(Basically, measures the robusticity of the canines using a length/width - ratio)

1. Tiger - 18.26
2. Lion - 17.07
3. Jaguar - 13.43
4. Leopard - 11.27
5. Cougar - 9.84
6. Clouded Leopard - 8.50
7. Snow Leopard - 5.93
(Panthera atrox - 21.28)
(Smilodon fatalis - 18.80)


#2. Osteology and ecology of Megantereon cultridens SE311 (Mammalia; Felidae; Machairodontinae) [Christiansen and Adolfssen, 2007]
https://onlinelibrary.wiley.com/doi/10.1111/j.1096-3642.2007.00333.x

This study by Christiansen and Adolfssen, 2007 shows great extent of Humerus robustness overlap among Lions and Tigers suggesting it is an individual characteristic

   

□, Panthera leo (N = 17) ◊, Panthera tigris (N = 19)



Thus it can be concluded that robustness of various bones and parts of body varies greatly among felines and depends directly on size. When comparing different species of felines, there is no species that can be considered absolutely more robust than other at same size, as it can be seen that robustness is an individual characteristic. Reply