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

[Betty]

(04-30-2018, 07:56 AM)peter Wrote:

(04-29-2018, 10:05 AM)Betty Wrote:

(04-29-2018, 02:06 AM)peter Wrote: BETTY

Thanks again. Assuming that the translation is correct, the condylobasal length of the Hamamatsu zoo skull is 380 mm. As the difference between the condylobasal length and the greatest total length in skulls of adult male tigers of large subspecies ranges between 40-55 mm., the greatest total length of the Hamamatsu zoo skull has to be at least 420 mm. This means that the skull compares to the Koln zoo tiger for length. 

The question is if this conclusion is correct. The photographs say no. 

Assuming that the zygomatic width of the Koln zoo tiger really is about 284 mm., the greatest total length has to be close to 430 mm., if not more. The reason is that the relation between greatest length and width is 1,52. 

In the Hamamatsu zoo tiger skull, assumptions are not needed. The reason is we know that the zygomatic width of the skull is 284 mm. The relation between greatest total length and greatest width, however, isn't 1,52 (as in the Koln zoo tiger), but 1,34-1,35. This means that the greatest total length has to be 380-383 mm.

Agreed?

I could have missed a few things. In order to find out if I did, you have to print both photographs. Measure the width and the greatest length of both skulls and tell me what I missed.

Here's the photograph of the Koln zoo tiger:

*This image is copyright of its original author

And here's the photograph of the Hamamatsu zoo tiger:

*This image is copyright of its original author

 
It will take a bit of time, but the outcome is of interest. Thanks in advance.

In fact, I previously measured the skull and concluded that the skull is 380mm long and 284mm wide. I confirm that there is no problem with my translation. I think it was the author who made a mistake in the use of the term.




According to the measurement of the lower jaw (240mm), the skull length is 380mm, for the calculation of the upper canine teeth, the length is 9.4 cm.

*This image is copyright of its original author

Interestingly, according to the calculation of the Scale ruler, the skull is 394mm long and 292mm wide. 

*This image is copyright of its original author

Excellent work, Betty. Thanks for the effort.

I propose to conclude the exercise. Here's what we found so far:

01 - The translation you made is ok.
02 - The photographs in the article are good. 
03 - Plate A has a 10 cm. scale.
04 - Using the scale in Plate A, the measurement for condylobasal length seems incorrect. 

The question is how to find the real condylobasal length (CBL) and greatest skull length (GSL). We have 2 options:

05 - We assume the measurements for zygomatic width and lower jaw length are correct and use these to find the GSL and the CBL. 
06 - We use the scale in Plate A to find the GSL and the CBL.

Here's the results of 05 and 06:

07 - The method described in -06- didn't yield uniform results.
08 - The method described in -05- did. Both of us got the same result for greatest skull length (380 mm.).
09 - Our result for GSL is equal to the measurement for CBL in the article.
10 - Based on -09-, the conclusion is that the authors most probably exchanged CBL for GSL.

That leaves the condylobasal length. The only way to find the CBL is to use plate B and, as you did, add a scale.

11 - Plate B and the added scale say the condylobasal length isn't 335 mm., but 327-329 mm. I propose 328 mm. for now.

If we deduct 328 (CBL) from 380 (GSL), the result is 52 mm. A significant difference, but the tiger was very old when he perished. As the sagittal crest in tigers keeps growing, a difference of 50 mm. and over between GSL and CBL can be expected in skulls of old male tigers of large subspecies.  

12 - Skull measurements of the 18-year old male Amur tiger of the Hamamatsu City Zoo (classified results):

12a - Greatest skull length (GSL): 380 mm.
12b - Condylobasal length (CBL): 328 mm.
12c - Zygomatic width (ZYG): 284 mm.
12d - Rostrum width (ROS): 114 mm.
12e - Upper canine length from tip to insertion (UCL): 94 mm. 

13 - Source:

13a - Article: 'On the unusual abrasion groove of the lowe canine of an Amur tiger'
13b - Authors: Hasegawa Y., Kimura, T. and the Hamamatsu City Zoo
13c - Published in: Bulletin of the Gunma Natu. Hist. (20), pp. 73-78, 2016

14 - Check:
 
14a - Do you agree with the summary above?
14b - If you see errors, please say so.

I have two questions. The image may have scan accuracy problems. The angle of the skull may not be standard.  I think that the measurement results of those data are correct, but they are wrongly described.

Or, the way of measurement is not the same, such as this...

*This image is copyright of its original author

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