ON THE EDGE OF EXTINCTION - A - THE TIGER (Panthera tigris)

[Ngala]

From Big Cat's Canines and Claws thread, written by @peter:

A - THE ESSENCE OF CATS

1 - Offence

All cats are professional hunters living on the edge. As true specialists, they are able to bring down animals larger and heavier than themselves. In order to do that, they (apart from power, explosive speed, specific equipment and athleticism) need instinct, training and a kind of energy difficult to describe. Even with all that, it takes years of training to tackle large animals in a safe way.

2 - Defence

After killing an animal, they need to protect their kill from scavengers. Some scavengers operate in groups, but other scavengers are large enough to displace a cat on their own. A cat co-existing with scavengers able to take his kill has 4 options to protect his kill: eat as quickly as possible (a); move the kill out of reach (b); adopt a social lifestyle © or face the scavenger (d).

B - DEFENCE IN BIG CATS 

1 - Panthera family 

All 5 members of Panthera (P. leo, P. tigris, P. onca, P. pardus and p. uncia) are large cats (> 50 pounds). The puma compares to a degree. Of these 6 species, 3 (F. concolor, P. pardus and P. onca) are known to climb trees when cornered. Lions are social big cats, enabling them to defend their kill from scavengers. I'm not sure about the snow leopard (P. uncia), but it's likely that they face scavengers (wolves and bears) on a regular basis as well. As they live in elevated regions, they can use rocky outcrops to get safe. As they're not larger than wolves and smaller than bears, it's likely they will use this strategy when faced with a large scavenger. 

2 - Tiger

Tigers can climb trees, but I never heard of an adult tiger (male or female) climbing a tree when faced by a scavenger. In Indonesia, they face sun bears and wild boars. In mainland Asia, they face canids (wolves and dholes) and omnivores (wild boars and bears).

In the Russian Far East, wolves are hunted by Amur tigers at times. Dholes also are no match for them, but these canids have displaced tigers in the past and are able to tree leopards in India. Only very few wild boars will try to displace a tiger, but Himalayan black bears and black grizzlies of all sizes scavenge tiger kills whenever possible. If a large male Himalayan black bear can displace a male Indian tiger (see 'The Temple Tiger', Jim Corbett), a male brown bear (Ursus arctos lasiotus) should be able to displace a male Amur tiger. Research has shown that bears displace Amur tigresses or share kills made by tigresses with them, but male Amur tigers are not often displaced by bears.  

C - SKULL STRUCTURE 

A professional hunter like a cat, skullstructurewise, needs to find a balance between offence (hunting) and defence (protecting a kill). Based on the skulls I saw, I'd say that hunting is more important than defence. In brown bears, it seems to be the other way round. Their skulls, especially in the posterior part, are heavily reinforced, allowing them to take a lot of damage. 

I've seen many big cat skulls. Every species has a slightly different structure. Lion skulls, and those of old males in particular, remind me of bear skulls in that they too seem to be reinforced in a similar way. The result often is a large and 'backheavy' skull. So much so, that they seem 'overskulled' at times. 

Tiger skulls are shorter as a rule, but they have (relatively) longer and heavier canines and a wider, reinforced, rostrum. They also seem to have a different purpose in that they appear to serve as platforms for the large upper canines. In this respect, they remind me of battlecruisers. Not battleships, as these are too heavy, too slow and, for that reason, ineffective in battle.

Tiger skulls often do not seem to be as robust as lion skulls. This impression, however, is largely deceptive. Tiger skulls are more vaulted, which results in more acute angles, especially in the anterior part of the skull. Acute angles and dense bones allow tigers to generate a lot of pressure when biting. As the canines are longer and heavier compared to those of other big cat species, the result is more pressure at the tip of the canines. The relatively wide arches enable tigers to keep the pressure up in the region of the carnassials as well. All in all, the skull structure enables tigers to deliver a penetrating bite.  

Lion skulls have a somewhat different purpose. The canines serve as large 'icepicks' enabling them to penetrate the skin of a large animal and hold on. The, enlarged and elevated, maxillary bone (snout) and the wide and reinforced os frontalis (the bone on top of the skull) enable lions to deal with immense pressure generated by struggling large prey animals. 

Lion skulls seem to be the reinforced top end of a long, more or less horizontal, cable constructed with the purpose of keeping a large ship anchored, whereas tiger skulls seem to serve as big gun platforms constructed to generate maximum force from top to bottom. Hold and maul in order to tire (lion) versus pin and penetrate in order to kill as quickly as possible (tiger), one could say.

Lions are social animals. All adults participate during a hunt, but females usually take care of the hard work. For them, a functional skull matters. The result is a skull similar to a skull of a professional big game hunter, albeit somewhat longer in the anterior part (longer snout). Male lions also hunt, but not as often as females. When they participate, they often pin the victim, enabling the females to go for the kill. They can kill a large animal on their own, but their skull is reinforced to withstand pressure of struggling large prey animals and take damage in intraspecific conflicts.

This could be the reason why male lions only seldom target the skull of their opponent during a fight. Male tigers, on the other hand, deliberately target the skull of their opponent in a fight. 

D - ANALOGY

Tigers are solitary big game hunters. In order to overcome a large animal, they need to be efficient. The less time they need, the better. Tigers need power, but not too much weight. Less weight results in more speed, more agility and better angles. Strength is not a result of size or weight, but of speed, acute angles and an effective construction (simplicity). Only the teeth department needs to be reinforced and that's what we see.

For a nice analogy, read a bit about tanks. I propose to start with WWII. Watch the Russian T-34 in particular. Best tank of that war, many German generals thought. The counters they later introduced (Tiger and Panther) were as good or better, but heavier, more complicated and, therefore, less reliable. They often broke down. As spare parts were difficult to get, not a few had to be left. Production also was complicated, which had an effect as well. The Germans later turned to self-propelled antitank vehicles. They did ok, especially those with the effective 88 mm. gun. The reason, again, was simplicity. That and large numbers.    

E - NASALS

Tigers don't have narrow nasals to accomodate large canines. They don't need wide nasals. They need large canines; a reinforced rostrum; a vaulted maxillary bone to create the angles needed; wide arches; a straight or slightly concave mandible, and a strong sagittal crest slightly elevated at the end. All parts and angles are needed to enable a big bite. Tiger skulls are functional. Same for all wild animals, by the way. The exceptions (like the polar bear), often are a result of a transition. 

F - TO CONCLUDE

What you read, to an extent, was exaggerated in order to highlight the main differences between lion and tiger skulls. The differences described, however, are real and they are structural. When you have some experience, you can see it at a glance. This regarding skulls of wild animals.

Skulls of captive big cats are different in that they are flatter, wider and not as dense. Furthermore, many skulls have superfluous growths. Although lion skulls seem more affected by captivity, tiger skulls are also affected in that not a few lost a number of typical features over time. The differences between Panthera leo and Panthera leo zoo often are remarkable. Same for Panthera tigris and Panthera tigris zoo. 

Bones are a result of function, not a result of a need for more room or less. Tigers generally have longer and narrower nasals for a reason and the reason isn't canines (only). They live in a different environment and hunt in a different way than lions. Lions are social big cats. Like in humans, this will result in less adaptions over time. In solitary big cats, often specialists, the relation between function and environment generally is more outspoken. Reply