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06-08-2015, 12:23 AM( This post was last modified: 06-08-2015, 12:23 AM by GrizzlyClaws )
The Manchurian mandible seems to be discovered along with the fossils of Crocuta spelaea, and it indicates that the two species probably befiefly coexisted in a same period.
This should be the late Pleistocene or the mid Pleistocene? Since the Panthera youngi belonged to the mid Pleistocene.
06-08-2015, 12:45 AM( This post was last modified: 06-08-2015, 12:46 AM by tigerluver )
Do you know the location of mandible? I could find a dated site close to it for estimation. Was it Manchuria? If it's from the late Pleistocene, then it is a distinct subspecies/species from the Ngandong form of this time period based on the mandible.
Sheng et al. (2014) has the far east Asian cave hyena being present within a pandemic population earlier than 400 kya, isolated as late as 230 kya, and last being present as recent as 50 kya. The Manchurian cave hyena fossils are dated anyhwere 145-50 kya. No cave hyena specimen from Manchuria has been dated any earlier. If this mandible were found in the same faunal level as the hyenas, then that's a relatively recent specimen.
The fossil smugglers really make me go "eh." That fact pretty much ends this mandibles hope for official publication.
06-08-2015, 02:27 AM( This post was last modified: 06-08-2015, 02:43 AM by GrizzlyClaws )
I think it probably belongs to the same level, since those smugglers didn't have any professional kit to dig through into many different levels, they probably took in one shot at the same level of the fossil fauna. There are a lot of mismanagement among the local government which allowed those smugglers to overrun the fossil sites.
So it is quite clear that this mandible didn't belong to the same timeline as the Panthera youngi, although both species shared a lot of similarities as being part of the tiger clade.
The Toba eruption had definitely driven both Panthera tigris acutidens and Crocuta crocuta spelaea into extinction in China, and both species seemed to perish soon after the Toba eruption.
The ecosystems of the Asian Far East were badly damaged by that eruption, and there was an ecological vacuum for many millennia until the re-colonization by the modern tigers in the recent time.
Moreover, there should have many subfossils of the Amur tiger being sold in the local black market as well.
For example, the 6 inches tiger subfossil canine i showed before.
The canine is only partially fossilized, not fully fossilized like the mandible. Also, it looks exactly like that of the modern tiger. It could definitely belong to a more recent timeline, maybe the early population of the Amur tiger.
06-08-2015, 09:52 AM( This post was last modified: 06-08-2015, 11:32 AM by tigerluver )
The first mandible is from Ngandong, the second from Watoealang.
It's more similar to P. tigris than P. youngi in terms of symphysis curvature and distance from canine to p3. Although, the relatively taller ramus and body is a trait shared with P. youngi but not present in modern Panthera.
Regarding the length, I think I made an error based on an error made by vK (he measured the skull at resting at an angle different from Christiansen style, which I use). The correct length of the fragment is 254 mm (I fixed it in the last post). Applying this value to the modern Java mandible results in a total length of 287 mm. But, the Java mandible is not the best match to this mandible, the Trinil mandible is. The Ngandong mandible is relatively taller in body and ramus, just like that of the Trinil mandible, which has an exceptionally long ramus leading to the coronoid process. It's pictured in the last few posts. Applying this fragment's length to the Trinil mandible results in a total length of 303 mm. Using the ratio I've found to relate to mandible length to GSL of ~1.5, the GSL of this specimen would be 455 mm. The Ngandong mandible fragment scales to 280 mm, so a 420 mm GSL.
Now, what do you think the purpose of a long and tall mandible is. The extra long mandible shows in the greatest width/length ratio of the Ngandong tiger, which is smaller in this species than the Javan and other modern tigers. Specifically, the thinner skull is caused by the elongated snout that accommodates the long mandible. The palatal proportion looks to be greater. As Guate suggested, the long mandible is likely for bite force. The equation of Torque = Force x radius helps support this theory. Having the pivot point of the coronoid process further away from the canines will produce some nasty torque. This tiger likely preyed upon rhino and elephant type species, which are not only robust but have thick skin. The strong the bite, the better the chances of a successful hunt. Maybe the taller mandible as a whole also has something to do with bite force.
Looking at Smilodon, which is said to have a weak bite force, we see two things. One, the ramus is very small. Two, the body of the mandible is relatively thin. Going with the idea of opposites, the Ngandong tiger's mandible may suggest a species with a stronger bite force pound for pound than modern tigers.
Sorry if I'm slow on revealing info, I'm checking and rechecking measurements while I edit my database and wait on a friend for some other fossil information. I've also reread Hertler and Volmer and found the fossil IDs, so I will post a table showing which fossil was used for which mass estimate.
06-08-2015, 11:31 PM( This post was last modified: 06-08-2015, 11:32 PM by tigerluver )
The Trinil specimen I know of are quite small. I measured both pictured mandibles and the complete length would be around 210 cm. There is also a small femur mentioned in Brongersma. All in all, these specimens were likely no heavier than 130 kg. At the same time, tigers found in Ngandong had some specimens which were just as small. So is the Trinil variety conspecific or an ancestor? Is the size difference due to random chance? Prehistoric animals had much more variation in size. Gruwier et al. 2015 showed this in cervids.
There are some differences in the mandible between Ngandong and Trinil. It's hard to say whether this is interspecific variation or intraspecific variation due to the small sample size. At the moment, I'm leaning to intraspecific variation as the four Ngandong mandibles at hand have variations between each other in the same manner they differ from the Trinil mandibles.
With that, Trinil and Ngandong are very similar to each other. From what I see, the Manchurian mandible is closer to P. youngi than it is to the Javan mandibles. The Javan mandibles are more concave and softly curved. P. youngi and the Manchurian mandible are more convex and have squarish, sharper curve symphysis. The Longdan tiger mandible is also quite similar to the Manchurian one.
06-09-2015, 02:31 AM( This post was last modified: 06-09-2015, 02:32 AM by GrizzlyClaws )
Maybe the Manchurian mandible belongs to another offshoot species of the tiger clade. They could be conspecific with the Panthera youngi which both were the descendant of the Longdan tiger.
BTW, what is the species of the 303 mm Trinil mandible?
06-09-2015, 03:03 AM( This post was last modified: 06-09-2015, 03:12 AM by GrizzlyClaws )
Maybe there were two major lineages evolved parallely within the tiger clade.
Panthera zdanskyi perhaps also had its lineage survived until the late Pleistocene, they were also evolved to be giant that specialized to hunt down the big preys.
So Panthera zdanskyi should be evolved in the North China, whilst Panthera tigris should be evolved in the South China, and Panthera tigris didn't colonize North China until Panthera zdanskyi got driven into extinction after the Toba eruption.
06-09-2015, 04:07 AM( This post was last modified: 06-09-2015, 04:07 AM by tigerluver )
Very good hypothesis, I agree.
I think the Trinil tiger is likely not the parent of the Wahnsien tiger. Beyond the morphological differences, we have a chronological issue.
ShaoKun (2013) (see attached) brings to light the issue with the dating of the P.t. acutiden faunal level of Granger and Hooijer in Wahnsien. This document states, " The Dayakou fauna and the Upper Cave fauna of Pingba, both in the Yanjinggou area (Wahnsien), are correlated to the middle Early Pleistocene and the early Middle Pleistocene in age, respectively."
This is early, as early as the previous Trinil date. Now I'll turn our understanding of tiger evolution upside down.
I've just read that abstract of Joordens et al. (2014). This has left us with more questions of tiger evolution than answers: "We dated sediment contained in the shells with 40Ar/39Ar and luminescence dating methods, obtaining a maximum age of 0.54 ± 0.10 million years and a minimum age of 0.43 ± 0.05 million years. This implies that the Trinil Hauptknochenschicht is younger than previously estimated.
540 kya-430 kya, that's just about a 100 kya than the Ngandong site. Not significantly more primitive than P.t. soloensis. Rather, my suspicion might be correct, there is no difference P.t. soloensis and P.t. trinilensis. 100 kya is likely not enough to cause gigantism between the two fossil types in my opinion, especially as there were not any major environmental pressure difference within this time range.
von Koenigswald had the Trinil and Ngandong sites as representing the same species (ignoring his Felis paleojavanica tag for the giant specimens). There's no early Pleistocene true tiger on record as we thought the Trinil tiger was supposed to be.
From this, we're missing a major chunk of the tiger lineage of the lower Pleistocene or some Pantherine has been misidentified.
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