Tet Zoo picture of the day # 4

i-c393738a7af80f2d4a031c153ae30d56-tanystropheus model.jpg

A not-particularly-realistic model of the Triassic protorosaur Tanystropheus. This animal is best known for its bizarre elongate neck: this consisted of 12 tube-like vertebrae. There wasn't much flexibility between them, which raises the question as to how, and how much, the animal could bend its neck. How it lived is still a mystery and there are several competing ideas. It was not a one-off freak: it was widely distributed across Europe and the Middle East for something like 20 million years, and evolved multiple species that differed in size and proportions.

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Thanks for comments. This model is at Paulton's Park in Hampshire (UK), but similar/identical models are all over the place. What are the competing ideas? Perhaps the most popular is that it was an animated fishing-rod that stood on the sea-shore and hung its neck and head over the water. Another is that it was predominantly aquatic and stalked prey while submerged (this is supported by new data showing that the skull was more 'aquatic' in character than depicted previously). My favourite idea is that it stood in a tripodal posture, sticking its neck vertically into trees to forage for small pterosaurs and other reptiles :) A Chinese relative, Dinocephalosaurus, was suggested to be an aquatic gulp-feeder. We really don't know what these animals did, and their stiff neck anatomy and various other features make them very difficult to interpret.

In view of recent phylogenetic work indicating that tanystropheids and their kin were not close relatives of Prolacerta, note that I described Tanystropheus as a protorosaur, not as a prolacertiform (see Rieppel et al. 2003). More on these animals at some stage in the future.

Ref - -

Rieppel, O., Fraser, N. C. & Nosotti, S. 2003. The monophyly of Protorosauria (Reptilia, Archosauromorpha): a preliminary analysis. Atti Soc. it. Sci. nat. Museo civ. Stor. nat. Milano 144, 359-382.

Just a thought...maybe the necks weren't used for feeding, but instead helped in either intimidating rival males and-or attracting females.

sound plausible?

By Anthony Docimo (not verified) on 29 May 2007 #permalink

Note that with just 1 degree of lateral movement 12 vertebrae does give the animal a range of 24 degrees total (12 degrees each way). I suspect the extraordinarily long neck helped the animal reach a food source before shorted necked species that swam about as fast.

I heard also already about the idea that they used the long necks to hunt prey in trees, but I highly doubt such a behavior. They could use this technique only for comparably small highs, and had also the problem that their necks are very inflexible, not comparable to snakes which catches birds in trees. Pterosaurs and other tree-living animals could very quickly adapt against such a hunting style by staying some metres higher in the trees. If a predator hunts animals in trees, it would be much more usefull to climb too, as many martens and cats do it.

It strikes me that there aren't really any modern equivalents of these long-necked forms (unless you generously include giraffes). In particular, I'm not aware of any modern aquatic animals that have the long necks which many marine reptiles used to have.

Which makes me think that either (a) these animals were occupying a niche that was very specific to that time, or (b) Anthony's sexual selection theory sounds quite plausible.

The only long-necked underwater-hunters are birds like Anghinas. But their neck is highly flexible and completely different from those of Tanystropheus.

I read on the Hairy Museum of Natural History awhile back that a new specimen of Tanystropheus preserves patches of bulky integument in the hip region. The author of the paper supposed that the animal had a sizeable backside, and that such a feature would provide a counterbalance to the long neck.

Doesn't really solve the lifestyle problem, though.

Tanystropheus were discovered in sea sediments with fish etc., which rules out many hypothesis.

I suggest they were fish hunters convergent to well-known plesiosaurs and modern sea snakes with small heads and wide tails.

Also, one modern long-necked critter: long-necked turtle Emydura