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

[return 80]

(03-08-2025, 03:54 PM)return 80 Wrote:

(03-02-2025, 07:40 PM)return 80 Wrote:

The SOB and OH of tigers

The Supraoccipital breadth(SOB) relative to the Occipital height(OH) In previous studies, it was considered a significant distinguishing feature between different subspecies of tigers, and even now it has at least valuable population identification significance.

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In tigers, the relative width of SOB can be clearly defined as gradually increasing from south to north on the Asian continent, which seems to be a functional adaptation caused by their corresponding ecological environment.

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However, there does not seem to be much data on SOB in the literature, and it is generally not a major measurement value.

Its measurement method is"the smallest distance between notches of lateral margins of the occiput; the notch being situated approximately where sutura occipitoparietalis, sutura parietotemporalis and sutura occipitotemporalis meet"(Ji H. mazák 2008)

I have seen a good structural diagram(see blow, Narimane Chatar et al.2022) that can clearly distinguish these bone sutures. Please pay attention to the intersection of the occipital and parietal and the temporal in the diagram.

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In the posterior view provided by Ji H. mazak, the specific location is the highest point on the dorsal side of the mastoid process And the Dorsal view can be seen in Figure B. Búzás and B. Farkas 1996.

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In the publications of V. mazák and Ji H. mazák, it seems that I can only find specific data on island tigers and indochinese tigers (including Malayan tigers)

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However, in his publication<Recent Advance in Tiger Phylogeny, In the Evolution and Geographical Variation >(Chinese version), he listed the scatter plot data of male SOB for all subspecies.

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According to the scatter plot, we can see that the Amur tiger has a significantly widest SOB, both in terms of relative width and absolute width.Corresponding to the logarithmic axis of SOB, the SOB of some particularly wide male Amur tiger individuals may even reach around 90mm, almost 1.8 to 2 times that of some small Java and Bali tigers.

One of the male Sumatran tigers is very interesting, with a maximum recorded SOB of 83.4mm. Such a huge size makes it easy to find in scatter plots. From the graph, it can be seen that its SOB is almost as wide as the widest male Bengal tiger and comparable to many male Amur tiger individuals, which is very astonishing.

The two posts I previously posted only explained some phenomenon reports, but did not provide content explanations. Indeed, this is very necessary, so here I share some of my views

Although Hasegawa has reported multiple tiger fossils sites from Japan, unfortunately, these materials have not been systematically organized, so I can only provide some speculations on why Shiriyazaki's Late Pleistocene tigers were so large. 

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According to the ecological geographic model of tiger populations by Luo et al. 2024(https://doi.org/10.1038/s41559-023-02185-8), we can see that during the LGM (Last Glacial Maximum,Fig.B), Japan was connected to the Asian continent due to sea level decline, and at this time, Japan was also a high probability habitat suitable for tigers (red area).

Some of tigers may have migrated from China to Japan, and very large tiger fossils were also discovered during the last interglacial period(Fig.A) and the LGM in region 2(These habitats, which are considered highly likely to be suitable for tigers, have also yielded large tiger fossils in many locations). However, due to the long-term interglacial and glacial replacement during the whole Pleistocene, tiger fossils in other Pleistocene sites in Japan may be relatively small (as Peter pointed out, island dwarfism may have occurred at specific times that Japan is not connected to the Asian continent).

The second one is about the explanation of the occipital.At first, when I posted this related context, I just wanted to explain some data, but personally, I also have my own views on this phenomenon.

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Generally speaking, the occipital is directly related to the very important occlusal muscle - the temporalis muscle. In northern tigers (Amur tigers and Caspian tigers), the sagittal crest is also very developed, which indicates the need for strengthening their occlusal muscles. Amur tigers have the strongest sagittal crest and widest occipital. Relatively speaking, although the Caspian tiger is very developed, it is not as exaggerated as the Amur tiger. My viewpoint is that the size of SOB is the same as the level of development of the sagittal crest, which is also an evolutionary feature supporting the theory that Amur tigers need to gnaw on frozen meat in extremely cold regions.The same example can be seen in cave lions, where these Pleistocene cats can even be distributed within the Arctic Circle, and many of them also have very wide occipital.

This feature is not entirely related to body size, as the largest tiger in history, Panthera tigris soloensis, like Java tiger and Bali tiger, has relatively thin occipital, while the Sumatran tiger is believed to have been formed by natural hybridization between continental and island tigers, although this theory still requires more evidence

The above are some of my opinions. Everyone could share your idea~

Additionally, this is a slight supplement to my explanation

Tiger fossils from the last interglacial period in region 2

Although I still have more information and data on tiger fossils, I may discuss them in more detail later.In the Qingjiang(Chinkiang,see<What is Tiger>, But I must clarify that the tiger fossils in this area come from different eras, and the author Andrew C. Kitchener simply listed them as Middle Pleistocene tigers) River Basin between the last intergalactic period in Region 2 (90000-120000 years ago,silver carp Hill).

There are fossils from at least 3 different individuals, almost all of which are the size of male Amur tigers - super large male Amur tigers, similar to the giant Japanese tiger fossils we previously discussed.

These materials include a tiger maxilla with a length of 113mm for C-P4 and 40mm for P4 (almost the same size as the maxilla of the largest Amur tiger skull)

A mandibular anterior segment larger than any modern tiger's mandible record,Its related measurements are much larger than the mandible of a male Amur tiger(ルー)with a skull length of 380mm

A 425mm femur(The size of a large male Amur tiger)

A 340mm tibia(The usual size of male Amur tigers)

Additionally, The interesting thing is that in the research I previously cited（ https://doi.org/10.1038/s41559-023-02185-8 ）

The genetic similarity between their ancient Russian tiger samples and today's Amur tiger is not high, while an ancient tiger from nearly 2000 years ago has a relatively high genetic similarity with the Amur tiger. This suggests that today's Amur tigers may actually be very young tiger populations, and they have not been separated from other tiger populations for too long.

The other research also proving that a tiger sample(Da an Tiger) from northern China during the Late Pleistocene(more than 40000 years ago) is from an extinct branch of tigers that had been separated from modern tigers for hundreds of thousands of years(see
https://doi.org/10.1098/rspb.2022.0617) Reply