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

[peter]

(09-05-2016, 05:51 AM)GrizzlyClaws Wrote: "Quite many skulls I saw had similar dark-yellow and brown parts. In most cases, it turned out to be fat. This means the owner had died not that long ago. Although fat can remain for many decades, fossil skulls, as far as I know, never had any."


@peter Some skull that remained unclean for decades whose decayed flesh/fat could turn into dark brown color.


What is your opinion regarding to the 6.6 inches Amur tiger upper canine tooth?

*This image is copyright of its original author

1 - AMUR TIGER CANINE

The upper canine is 77-78 mm. in greatest length measured in a straight line from the gum line to the tip. At least 4 mm. or 5-6% longer than the longest I measured. The width at the gum line is unsurpassed (exceeding 40 mm.), meaning it's likely the canine belonged to a wild male Amur tiger.

As canine length and skull length seem to be related in captive Amur tigers, it's likely the skull would have been very close to 380,00 mm. in greatest total length if the owner would have been a captive male. As it's likely the relation between skull length and upper canine length is similar in wild Amur tigers, chances are the skull would have been well past that mark if the owner would have been a wild animal. Judging from the photograph you posted, chances are the tiger was a wild male.

Tigerluver couldn't find a positive link between greatest skull length and head-body length and weight in wild tigers, but his sample could have been too small. The WCS-table with measurements of wild Amur tigers suggested there could be a positive link between head length and head-body length. Based on the info I have on other tiger subspecies, I think there is, albeit not a strong one. The best indicator of weight seems to be skull width.

If I was to say a few words on the size of the owner of the canine you posted, I'd say he most probably was at least 200 cm. in head and body length (measured in a straight line). Weight would be another matter for the reason stated above (skull width).


2 - FAT AND DISCOLOURATION IN TIGER SKULLS 
 
Most of the skulls I measured were discoloured because they had not been defatted. Some of the skulls were nearly black and all of them were heavier than defatted skulls of similar age and length. The oldest (discoloured) skull I saw was acquired in the early stages of the 19th century, meaning a skull can remain discoloured for a very long time if it wasn't defatted. All very old skulls I saw (older than, say, 250 years), however, had no fat. Same for fossil skulls. 


3 - THE EFFECT OF PRESSURE ON INDIVIDUAL VARIATION IN TIGERS

Skulls of Sumatran male tigers average just over 310 mm. in greatest total length and just over 1 kg. in weight. Skulls of old males, however, are decidedly longer and heavier than those of young adult males. The longest I measured was exactly 350 mm. in greatest total length. This skull was defatted and almost 2 kg. in weight. Based on what I saw, I concluded individual variation is more pronounced in Sumatran tigers than in all other subspecies. At least, in skulls. Javan tigers, on the other hand, show little variation. Same for Amur tigers. The question is why.

Skulls of Javan tigers were acquired just before they disappeared, whereas the Amur skulls I measured belonged to tigers who descended from those who just survived the bottleneck in the first half of the last century. The conclusion for now is pressure and low numbers apparently result in a lack of individual variation in wild tigers. A lack of individual variation, therefore, is a sure sign of problems. 

Why was it not announced in Sumatran tiger skulls? The answer is nearly all skulls I measured were collected before 1950. Sumatran tigers most probably thrived until that date, that is. Their collapse, therefore, is of recent origin. Reply