Musings on Hanyusuchus

Every year a handful of new croc taxa are described. If you're strictly in this business for the dinosaurs, you ought to see what the croc side of Archosauria has been up to from time to time; they were quite versatile in palmier days. Even though they aren't quite as diversified as they used to be, it turns out they had hitherto-unsuspected tricks up their sleeves even as recently as a few hundred years ago. This spring a new genus and species of gavialid was described from the Holocene of south China: Hanyusuchus sinensis. This is fascinating, for many reasons. The obvious is that here we have a species of [insert expletive of choice] 20-foot-long gavial that existed up to perhaps a few hundred years ago in full contact with one of the most thoroughly documented civilizations in history, and it was completely overlooked. It may not have gone extinct until the time of the Ming dynasty. This is something like discovering that bears in Greek and Roman mythology were actually Arctodus, only if Arctodus was the size of a pickup truck. China, of course, is noted for the extant Alligator sinensis, but although the Chinese alligator is many things, not even on its best days has it been a 20-foot-long gavial.

Figure 2(s) from Iijima et al. (2022). Depicted: Hanyusuchus sinensis (composite, scaled to holotype) and 1.8 m (5.9 ft) tall human. Not pictured: Alligator sinensis (to imagine, mentally scale the Hanyusuchus to be about the same size as the human). CC BY 4.0.

Another fascinating aspect is the namesake. Han Yu was a significant writer, philosopher, and politician of the Tang dynasty. At one point in his life, he got in trouble at court and was packed off to Chaozhou in Guangdong, southeastern China to serve as prefect. In this capacity, he issued a proclamation in 819 concerning the crocodilian population. This in itself is not remarkable, except for the audience: he issued it to the crocodiles themselves. A translation of the statement can be found here (well worth a read). The icing on the cake is that the crocodiles reportedly did as instructed and departed, although we can presume that if they *did* indeed vanish from the area, strong hands wielding metal implements (like the Bronze Age weapons that left marks on some specimens) were more important in enforcing the departure. The reader may suppose that Han Yu's action was just a quaint old-time delusion; after all, there is a long history of animals being prosecuted for crimes. However, as the author of the translation notes drily, "Tang prefects did not habitually make formal verbal addresses to the local fauna" (footnote 7, p. 60). One wonders if perhaps Han Yu, who was noted for a sense of humor, had his tongue firmly in cheek.

There's also a melancholic existential aspect to the discussion. H. sinensis was part of the fabric of life in southern China for thousands of years. Descriptions of the species can be identified in historical sources, now that we know what to look for. Dynasties, cultural flowerings and renaissances, wars, conquerors, travelers like Marco Polo and Ibn Battuta, all came and went while 6-m gavials patrolled the southern rivers. They took livestock and killed people. They were apparently very noisy, probably the source of reportedly "thunder-like sounds in the night". Then they were driven into extinction and basically forgotten for hundreds of years.

References

Iijima M, Qiao Y, Lin W, Peng Y, Yoneda M, and Liu J. 2022. An intermediate crocodylian linking two extant gharials from the Bronze Age of China and its human-induced extinction. Proceedings of the Royal Society B: Biological Sciences 289:20220085. doi:10.1098/rspb.2022.0085.

Your Friends The Titanosaurs: Caieiria allocaudata

This edition of "Your Friends The Titanosaurs" is a little different in that not only are we welcoming a new friend, we are saying goodbye to an old friend. The latter is something that should come as no surprise; with well over a hundred species, notorious for incomplete material, some of them are eventually going to turn out to be the same.

(Also, I should have mentioned this, but I moved the external links to a separate page to conserve space on the sidebar.)

Quick Guide to Fossils at Uŋčí Makhá Park

So I went back to Uŋčí Makhá Park last weekend and spent a couple of hours taking photos of fossils, because it makes such an ideal place to see the upper Platteville fauna. After all, a winter of freezes and thaws may not leave these new exposures looking as nice as they do now. Here's a quick guide to what can be seen there. (Let's see how many photos I can squeeze into one post, and how many species I can misidentify!)

Determining where you are stratigraphically

First of all, I'd just like to reiterate the stratigraphy. Most of the vertical extent is in the Magnolia Member of the Platteville Formation, with the upper part composed of the Carimona Member of the Decorah Shale. I'm thinking more or less the entire extent of the Carimona is exposed, based on thickness; at any rate the next thing up would be the shaly part of the Decorah, and there isn't a trace of it to be seen. I'm suspicious because the difference is just so darn clear, but at this site there is an unmistakable color change between the two units: the Carimona is the upper blue-gray interval and the Magnolia is the light tan-gray interval below. The Deicke K-bentonite is the lower and thicker of the two bentonite gaps in the Carimona. (Note that the Carimona is sometimes supplemented or replaced by landscaping, but this is pretty obvious.) As you walk from south to north, the "floor" goes up stratigraphically, so it's not all one bedding plane but a gently rising series of planes, until by the exit you're close to the color change.

The color change is quite evident here. The Deicke K-bentonite is the cut-in about halfway up the blue-gray Carimona (above the scale bar in the center of the photo).

Here we've gone north, and the floor has risen. The Deicke is still the seam in the middle of the blue-gray rocks.