Note: I’m not quite ready for my Nesbitt – Dinosaurs blog, which was scheduled to run today. Instead, some news with pictures.
What the bizarre neck and stomach contents of Tanystropheus tell us
The nature and use of the extremely long neck of Tanystropheus langobardicus has stymied researchers for the last hundred years. Stefania Nosotti (2000) was the last to report on this odd reptile, focusing on the much smaller species. She, like so many other workers, saw Tanystropheus as a plesiosaur-like aquatic predator with a horizontal orientation and a very stiff neck. Unfortunately, there is not much about Tanystropheus that indicates any aquatic adaptations. No flippers. No tall tail.
An aquatic cousin, Dinocephalosaurus (Fig. 1), has several traits one might expect of an aquatic sit-and-wait predator.
On the other hand, there is not very much about giant Tanystropheus that makes it look very comfortable on land! However, smaller closest relatives include Macrocnemus, Tanytrachelos and Langibardisaurus. All were previously considered terrestrial bipeds (perhaps not always correctly). So with these comparatively tiny sisters in mind, I imagined Tanystropheus among tall trees plucking small reptiles out of high boughs (Fig. 2).
There’s that stomach full of squid hooks
There’s a big problem with the terrestrial feeding hypothesis. Tanystropheus fossils are found in marine strata (but that frequently happen to terrestrial specimens washed into the sea). Most importantly the stomach contents included squid hooks and fish scales (Fig. 3).
Wild (1973) produced the last large treatise on the large Tanystropheus fossils. He described stomach contents in several large specimens. The treatise in German was translated via Google and includes some minor editing: “Stomach contents were found (Fig. 2, Exemplare C), consisting of a light brown-colored pastel, phosphate-rich area and embedded within the mass were black checkmark-shaped squid arm hooks. In form they resemble…Phragmoteuthis. Also in the stomach contents of Exemplare M were sporadic octopus hooks. … ganoid fish scales also appear there. These scales, however, could be recognized as such only by their luster and their rhombic shape. In the stomach contents of Exemplare K shed Ganoid scales are not rare. Unfortunately, even these can not be determined with certainty. The adult specimens of Tanystropheus hunted in the sea for squid.
These squid hooks are in the range of 1-2mm in size or smaller and match those associated with a 20 cm Triassic squid, Phragmoteuthis (Fig. 4).
So combining all this…
We have to put large specimens of Tanystropheus under water. But horizontal does not seem to offer much advantage, since nothing about it indicates it was a good swimmer.
Like many animal oddities, perhaps Tanystropheus as a mimic
Tanystropheus is, by any definition, an animal oddity. Other animal oddities include the frogfish, the stick insect, the flounder and the pipefish, all of which mimic their environment. So I wondered, what sort of environment would camouflage Tanystropheus underwater during the Triassic?
Among the stalked crinoids
Triassic stalked crinoids were widespread in the Triassic and spectacular specimens have been found in Germany (Fig. 7). Combining Tanystropheus with tall stalked crinoids seems to be the most parsimonious solution to the vexing problem of this strange reptile. It doesn’t have to swim. It doesn’t have to support its great neck. And the food comes to Tanystropheus likes bees to flowers. A quick trip vertically to the surface, replenishes air. Young can be hatched on land or underwater with mother protecting the egg in utero, like pterosaurs probably did.
Of course, this sheds light on the ancestors of Tanystropheus, Macrocnemus. Stalked crinoids come in a variety of heights. Perhaps the variety we find in Macrocnemus evolved to blend in with this variety in crinoids. Macrocnemus fossils are also found in marine sediments.
Perhaps tiny Tanytrachelos had a dual life, on land and in shallow waters. Together with Langobardisaurus, the dentition of these lizards points to some sort of odd diet, perhaps marine prey? Could use some stomach contents here.
As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.
Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.
Wild R 1973. Die Triasfauna der Tessiner Kalkalpen XXIII. Tanystropheus longobardicus(Bassani) (Neue Ergebnisse). – Schweizerische Paläontologische Abhandlungen 95: 1-16.
Li C, Rieppel O and LaBarbera MC 2004. A Triassic aquatic protorosaur with an extremely long neck. Science 305:1931.
Nosotti S 2007. Tanystropheus longobardicus (Reptilia, Protorosauria: Reinterpretations of the anatomy based on new specimens from the Middle Triassic of Besano (Lombardy, Northern Italy). Memorie della Società Italiana di Scienze Naturali e del Museo Civico di Storia Naturale di Milano, Vol. XXXV – Fascicolo III, pp. 1-88
Peters D, Demes B and Krause DW 2005. Suction feeding in Triassic Protorosaur? Science, 308: 1112-1113.