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A Tanystropheus from China
Figure 1. Click to enlarge GIF animation. The Tanystropheus specimen from China, GMPKU-P-1527: 1) in situ; 2) as traced by Rieppel et al. 2010; and 3) with colorized DGS tracings. Note: Rieppel et al. overlooked the interclavicle, and mistook the interclavicle + scapula for an over sized coracoid. Rieppel’s clavicle is a dorsal rib. Clavicles here are in red. The so-called heterotopic bones are merely larger, unfused chevrons. What are those blue triangles in the dorsal area? The distal opposite rib tips apparently. Let me know if there’s a better answer.
Rieppel et al. (2010)
described a new, large (trunk length 93.5 cm), Late Triassic Tanystropheus (GMPKU-P-1527, Fig. 1), the first from China. All priors had come from the Alps of Europe. This one lacks a skull plus three cervicals and the distal tail. Based on the short rib of what used to be considered dorsal 1, the authors report it is now cervical 13. That appears to be the case across all large and small specimens. The last cervical is the size and shape of a dorsal, but the associated rib is not a dorsal-type rib. Every prior worker missed that one. Rieppel et al bucked traditions and relabeled the old first dorsal. Good job guys!
New interpretations
of the clavicle, interclavicle, scapula and one coracoid are introduced above, a little different than the original interpretations.
How similar to the European specimens?
the authors report: “The new Peking University specimen (GMPKU-P-1527) is remarkably similar to the larger specimens of Tanystropheus longobardicus housed in the paleontological collections of Zurich University. If there is any difference, then it is in the extent of chevron bones in the tail and the lack of the slight swellings and associated flexure described here for the first time along the length of the longest cervical ribs in PIMUZ T 2189 (Exemplar Q, Fig. 3.“
At first glance (in situ) the Chinese specimen is indeed similar to the European specimens.
Figure 2. The Tanystropheus from China partly reconstructed using DGS methods. No foreshortening of the gastralia and limbs are present here. The preserved ilium is not a broad plate here, as in European specimens. That could be a taphonomic artifact or reality. The terminal tail vertebrae is circular suggesting the rest of the tail was preserved in another layer.
But not the same species
The China specimen is apparently more distinct from the European specimens than Rieppel et al. indicate., but then… they did not create any reconstructions. Sometimes comparisons are best seen directly with accurate reconstructions (Fig. 3). We’ve already seen that two very distinct skulls appear on the European specimens and both were distinct from the original Wild 1973 model based on a chimaera of specimens.
The China specimen
has larger girdles, larger vertebrae, more robust ribs and shorter toes (Fig. 4), among the more readily visible distinctions. The dorsal ilium appears to be much narrower, but it is obscured by an overlying femur. The interclavicle has a large, broad anterior process, making it cruciform, not T-shaped.
Figure 3. The large Tanystropheus specimens to scale. On the right the new China specimen has large girdles, larger vertebrae, more robust ribs and shorter toes, among the more visible distinctions. Click to enlarge. Above right is the new M. Witton reconstruction with erect limbs, an overly large scapula, an overly large ilium, lacks an interclavicle and other minor issues. Otherwise it is very good looking.
Check those hands and feet!
Earlier we were able to separate Rhamphorhynchus specimens into clades using pedal traits alone. Here we’ll compare a European Tanystropheus with the Chinese one (Fig. 4). If they don’t match, they are not conspecific.
Figure 4. Above the Chinese Tanystropheus. Below a large European Tanystropheus. They are not conspecific.This was overlooked by Rieppel et al. 2010. Reconstructions have value.
Mark Witton started this
A recent blog post by Mark Witton introduced a new reconstruction of Tanystropheus (Fig. 3 top right). He wondered if the neck was too heavy to use on land while reminding readers that my work was “produced with techniques of questionable reliability”. Keep that phrase in mind.
- Witton labeled Tanystropheus as a protorosaur. Actually it’s a tritosaur lepidosaur as indicated by a four-year-old cladogram that now tests 602 taxa.
- On tradition alone, Witton includes drepanosaurs, Sharovipteryx, Tanytrachelos, Langobardisaurus and Dinocephalosaurus in the protorosaurs. All are indeed related to Tanystropheus, and are likewise tritosaur lepidosaurs.
- Witton reports, “I decided to try my hand at producing a new skeletal reconstruction based on the large, near complete Tanystropheus skeleton described in detail by Rieppel et al. (2010): PIMUZ T 2189.” Unfortunately the skeleton described by Rieppel et al. and traced by Witton is GMPKU-P-1527, the Chinese specimen (Figs. 1, 2). The 2189 specimen is European (Fig. 3), represented by a skull and neck only (Fig. 3). Witton’s technique was to trace a published photo. He makes no mention of visiting the specimen first hand. If you’ll remember, the “technique of questionable reliability” mentioned above is my sin of tracing fossil from photographs. So Witton is doing exactly what I do. Is Witton aware of this possible hypocrisy?
- Witton reports, “I reconstructed missing parts using smaller Tanystropheus specimens (from Nosotti 2007) and Wild’s widely-used ‘adult’ skull reconstruction.” So he created a chimaera. That is almost never a good idea going as far back as to putting a Camarasaurus skull on a Brontosaurus body. It’s easy, but it’s wrong. “Widely used” doesn’t mean it is correct. As mentioned above, that skull is a chimaera, too.
- Witton’s reconstruction admits to cheating on the true sprawling pose for his geometrical analysis. That’s fine. I laid limb elements out straight,too, but not in a walking pose. That would be confusing to someone who didn’t know what the illustration was being used for.
- Adding to the confusion, Witton draws a medially directed femoral head which is not present in this lepidosaur.
- Witton’s Tanystropheus scapula is too large (see above). The pelvis is a chimaera and a shade too large. Otherwise it’s a beautiful reconstruction and part of that beauty comes from free handing certain elements. I won’t say Witton’s work as a whole is produced with techniques of questionable reliability.l like tracing, free handing and creating chimaeras… but I will say that free handing and creating chimaeras is not reliable. Tracing from photographs can be very reliable! Ad hominem blackwashing (see Witton’s comment) is never appropriate for colleagues. Everyone should realize that inappropriate habits, like creating chimaeras, never last forever. And everybody makes honest mistakes (like overlooking the interclavicle). Finally holding a grudge or never granting forgiveness for past errors is never good… Right guys? Okay. Let’s move on…
- Witton reports, “Our problem here is that finding a long-necked terrestrial carnivore to compare with Tanystropheus is challenging.” I realize that Witton is wondering if a large Tanystropheus could walk on land, but gut contents are marine organisms and fossils are found in marine sediments. So… what’s the point? And why were these factoids ignored? The big Tanystropheus doesn’t seem to be a terrestrial animal.
- Ironically, Witton compares the long neck of Tanystropheus to his favorite pterosaurs, the azhdarchids. And that’s a fair comparison. They are distantly related in the large reptile tree, but for Witton’s purposes shapes are more important.
- Witton’s technique for determining mass at every segment of a lateral view misses the greater mass in the wider dorsal and caudal areas visible only in dorsal view. There’s a fat rump there, but you can’t see it in lateral view.
- Little known pertinent fact: I once made a full scale model in wood of Tanystropheus and sold it to the AMNH. I had to add lead weights aft of the hind limbs to make it not tip over. All segments being equal, it was front heavy as a 3-D model, not just on paper. In vivo the torso and tail would have been more dense, even with large lungs. And the air-filled cervical series and trachea would have been less dense.
- Check this out for a possible marine lifestyle that seems to fit the facts for Tanystropheus.
References
Rieppel O, Jiang D-Y, Fraser NC, Hao W-C, Motani R, Sun Y-L & Sun ZY 2010. Tanystropheus cf. T. longobardicus from the early Late Triassic of Guizhou Province, southwestern China. Journal of Vertebrate Paleontology 30(4):1082-1089.
Wild R 1973. Die Triasfauna der Tessiner Kalkalpen XXIII. Tanystropheus longobardicus(Bassani) (Neue Ergebnisse). – Schweizerische Paläontologische Abhandlungen 95: 1-162 plus plates.
Witton blog post: here
Source: https://pterosaurheresies.wordpress.com/2015/11/15/a-tanystropheus-from-china/
