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

[peter]

BIG CAT SKULLS

a - Introduction

The article below (see the link at the bottom) was posted before, but not in this thread. Although some of the info on size is incorrect (leopard skulls can reach a greatest total length of 280 mm., and are not, as is stated in the article, limited to 200 mm.), the information on the differences between skulls of big and small cats is largely correct. Same for the information on the differences between lion and tiger skulls.    

The scaled photographs showing skulls of different species next to each other are interesting, as they enable you to see the main differences between different species at a glance.

b - Lion and tiger skulls

Compared to lion skulls, tigers have relatively short faces and a relatively narrow os frontalis. The tiger is the only cat of which the rostrum is widening towards the teeth. Whereas lion skulls are generally large and robust in all departments, tiger skulls seem to be adapted to a more specialized way of hunting in that they seem reinforced near the rostrum (canines) and the occiput, where muscles used to bite and drag are attached.  

Although some male tiger skulls of large subspecies (P.t. altaica, P.t. tigris and P.t. corbetti) compare to male lion skulls for greatest total length (355 mm. and over in greatest total length), most are a bit shorter, more rounded and turned downward. They have shorter 'snouts' and mandibulas, but more or less compare for zygomatic width. Most tiger skulls have (relatively) longer and more robust upper canines. In order to accomodate large canines, tiger skulls usually are more vaulted and strengthened near the rostrum.

c - Skull publications

Most articles in which skulls feature are based on skulls that ended up in natural history museums in Europe, the US, Japan, Russia and China. Most unfortunately, most of them only have skulls from some regions. In European natural history museums, it isn't easy to find skulls of wild tigers from southeastern Asia (P.t. corbetti), southern and central China (P.t. amoyensis), northeastern Asia (P.t. altaica) and central and western Asia (P.t. virgata).  

Those who published about tiger skulls not seldom used limited samples. Would a larger sample result in different conclusions? Not likely, but my guess is the range (referring to measurements) would be wider. That guess is based both on new information and a number of photographs of wild tigers.

d - Wild tigers with large skulls

d1 - Russia

Although skulls of male lions of large subspecies are a bit longer (averages), skulls of captive male Amur tigers have the longest upper canines and the widest rostrums of all big cats. By a margin, I can add. Although they are a bit smaller than their wild relatives, my guess is it wouldn't be different in wild Amur tigers.

Here's 3 photographs of wild Amur tigers with wide rostrums and 1 photograph of a skull of what seems to have been a young adult male. That tiger was poached. His skull has the longest upper canines I saw.   

*This image is copyright of its original author

*This image is copyright of its original author

*This image is copyright of its original author

*This image is copyright of its original author

d2 - Nepal

Some years ago, I bought a book written by a former hunter who later accomodated would-be hunters in the western part of Nepal. He wrote male Nepal tigers have large skulls and shortish tails as a general rule. Here's 2 photographs of large males and 1 photograph showing the skull of the famous Sauraha tiger.

Apart from the photograph, nothing is known about the skull of the Sauraha tiger. I'm quite sure it isn't in a natural history museum:

*This image is copyright of its original author

*This image is copyright of its original author

*This image is copyright of its original author

d3 - Northern India

A century ago, Nepal male tigers had about 4 inches in total length on male tigers shot in northern India. The reason was tigers in Nepal were not often hunted. In northern India, they were hunted most of the year every year for decades. 

Today, tigers are protected in India. Tigers in northern India could be the largest wild big cats today. Although there's no good information on the size of tigers in that part of India, some males seem out of this world.   

Skulls of captive adult male Amur tigers are longer than those of captive adult male Indian tigers (the labels I saw said they had true Indian tigers in European zoos half a century ago), but skulls of Indian tigers are a bit more massive. With 'massive', I'm not referring to zygomatic width (most captive big cats have wide skulls), but to general appearance and (relative) weight.

Amur tiger skulls compare to overgunned battle cruisers, whereas Indian tiger skulls compare to battle ships. The guns are as large or a bit smaller, but the ship is able to take more damage. 

Indian tiger skulls are more vaulted, more rounded and a bit more dense. The reason is Indian tigers hunt larger animals. More strain resulted in dense skulls. Wild Amur tigers, apart from deer, hunt wild boars and quite a few bears. Adult wild boars (Ussuri wild boars are the largest in the world) and female brown bears are agile and powerful. Furthermore, they can take a lot of damage. In order to decide a struggle, Amur tigers developed wide rostrums and long and strong canines.

Trainer Daniel Rafo had (mixed) Amur tigers and true Indian tigers. Every now and then, he had to accept a fight to release tensions as the Indians and the Amurs didn't get along. In his opinion, Indian tigers had more endurance. The Amurs, however, were bigger and knew a fight would be short.

This regarding captive tigers. In wild tigers, things seem to be rather different in that tigers from central and northern India, compared to wild Amur tigers, seem about as large. Furthermore, they're heavier. 

Skullwise, the difference seems to be limited as well. The tigers below all have large and massive skulls:      

*This image is copyright of its original author

*This image is copyright of its original author

*This image is copyright of its original author

d4 - Northeastern India

A century ago, male tigers shot in northeastern India, averaging about 9.8 in total length measured 'over curves', were a bit shorter than those shot in northern India and, in particular, Nepal. Information provided by the Maharajah of Cooch Behar (as well as some others), however, suggests they, skullsizewise, were right up there. I'm not sure about the absolutes, but in relative terms tigers in northeastern India seem to have very heavy skulls.

This male featured in a National Geographic documentary some years ago:  

*This image is copyright of its original author

Another heavy-skulled male from Kaziranga:

*This image is copyright of its original author

This male was killed in a fight. His body is inflated as a result of death, but his skull was big no matter what:

*This image is copyright of its original author

d5 - Large tigers compared to humans

It's always difficult to judge the size of a tiger from a photograph. In most old photographs, hunters positioned themselves behind the tiger. Not seldom, it resulted in giants. Jim Corbett, however, could be trusted in the department of size. The Bachelor of Powalgarh, measured three times by Corbett and his sister, was 10.7 in total length measured 'over curves'. It wasn't the only tiger exceeding ten feet 'over curves' he saw, but it most probably was the most robust: 

*This image is copyright of its original author

There are no hunters in zoos, meaning photographs with tigers often are more realistic. That, however, doesn't mean tigers are smaller than hunters said. In European zoos, Amur tigers in particular often are impressive animals. Most of them are longer, taller and more robust than their wild relatives today.

The Duisburg zoo tiger was 320 cm. in total length measured 'between pegs'. His head and body length was 210 cm. and he was 110 cm. at the shoulder while standing. In his prime, he was estimated at 280-300 kg. According to V. Mazak (1983), his head length was 50 cm.

I don't know what happened to his skull, but chances are it was well over 400 mm. in greatest total length, as the skull length of 2 male Amur tigers with a head length of 40-45 cm. in the Prague zoo was over 370 mm. Both tigers were measured by V. Mazak himself. Same for the skulls:

*This image is copyright of its original author

   
 
One has to see an Amur tiger with a head length of 400-500 mm. up close to understand how large a head of that size really is. Not seldom, captive Amur tigers with large heads are robust in all departments.

Some years ago, the Odense zoo had a tiger that could have compared to the Duisburg zoo tiger. Tiger 'Igor' was known for his size. Although not as long as a few other captive Amur tigers, he was tall and robust. In his prime, 'Igor', judging from what I read, ranged between 250-300 kg. At that weight, he wasn't obese. Big would be the right word, I think: 

*This image is copyright of its original author

e - Conclusion
 
What I'm saying is things, regarding skulls of wild tigers, are a bit unclear. According to R. Pocock (1929) and V. Mazak (1983), the largest tiger skulls are about 15 inches (381 mm.) in greatest total length. Recent information, however, says exceptional tiger skulls well exceeded 390 mm. in greatest total length. Photographs of the skull of the Amur tiger shot in the Köln zoo (after he had killed a keeper) discussed some time ago (this thread) suggest it was over 16 inches (406,40 mm.) in greatest total length. All photographs in the article had scales and they were not made by a hunter, but by a professional.  

Skulls of exceptional wild male tigers in Russia and northern India, if anything, could be a tad longer. I measured well over a hundred skulls of Sumatran and Javan tigers and distinguished between captive and wild tigers. Skulls of wild tigers were longer, more elevated and denser than skulls of captive tigers. My guess is it isn't different in other tiger subspecies.   

Skulls of that size, however, are few. I never saw one. Skulls of male lions, on the other hand, not seldom reach a greatest total length of 15 inches. The longest I measured was just over 16 inches in greatest total length, but it wasn't the most robust or heaviest lion skull I saw.   

One wonders why biologists only very seldom visit natural history museums in western, northeastern and southeastern Asia.                

f - Link to the article on skulls

https://animalalmanacblog.wordpress.com/2016/03/09/pantherinae-skull-and-larynx-comparison/ Reply