There is a world somewhere between reality and fiction. Although ignored by many, it is very real and so are those living in it. This forum is about the natural world. Here, wild animals will be heard and respected. The forum offers a glimpse into an unknown world as well as a room with a view on the present and the future. Anyone able to speak on behalf of those living in the emerald forest and the deep blue sea is invited to join.
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.
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).
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.
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.
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.
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.
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.
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).
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).
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.
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).
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.
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).
are male african Lion more muscular and robust than the Tigers?
