Blood pressure in an elevated Tanystropheus

Yesterday we looked at the possibility of underwater leaping in Tanystropheus for snatching prey and, with a little momentum, for reaching the surface for a breath.

Just like a giraffe or an upright sauropod
Tanystropheus had to have had a specialized circulatory system and a large heart in order to raise its neck. And also like a giraffe, Tanystropheus probably another sort of system to keep blood from pooling in its legs and tail whenever the neck was raised. This post was inspired by a recent one on sauropods here at PHENOMENA, a science salon hosted by National Geographic Magazine.

Tanystropheus underwater among tall crinoids and small squids.

Figure 1. Tanystropheus in a vertical strike elevating the neck and raising its blood pressure in order to keep circulation around its brain and another system to keep blood from pooling in its hind limb and tail.

That vertical pipe of a neck would have elevated the head nearly eight feet (250 cm) above the heart in the largest Tanystropheus specimens. That’s longer than the neck height of a giraffe, but far shorter than that of a large sauropod. In giraffes the heart rate is high, up to 170 bpm. We can imagine Tanystropheus might have also had an elevated heart rate, especially for a large lizard. What does this mean? Well, phylogenetically Tanystropheus was surrounded by bipeds, some of them, the fenestrasaurs, were speedy. Some of them, the drepanosaurs, were slow.

The blood pressure of a giraffe is the highest of all animals, reaching about 300 over 200 mm Hg to pump blood up a neck seven feet long to reach its brain. The blood pressure of Tanystropheus might have been a little higher.

Perhaps related – or not
If Tanystropheus fed underwater, the trachea might have been valved in order to keep an air bubble in the lungs and restricting its rise up the windpipe whenever submerged under at least eight feet of water pressure. Likewise the blood vessels might have been similarly valved to keep blood in the “upper stories.”

Few animals are comparable to a Tanystropheus and fewer of them are alive today. All hypotheses about soft tissue can only be considered guesses.

Whatever the case… not bad for a lizard.

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.

References
Bassani F 1886. Sui Fossili e sull’ età degli schisti bituminosi triasici di Besano in Lombardia. Atti della Società Italiana di Scienze Naturali 19:15–72.
Li C 2007. A juvenile Tanystropheus sp.(Protoro sauria: Tanystropheidae) from the Middle Triassic of Guizhou, China. Vertebrata PalAsiatica 45(1): 37-42.
Meyer H von 1847–55. Die saurier des Muschelkalkes mit rücksicht auf die saurier aus Buntem Sanstein und Keuper; pp. 1-167 in Zur fauna der Vorwelt, zweite Abteilung. Frankfurt.
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
Peyer B 1931. Tanystropheus longobardicus Bass sp. Die Triasfauna der Tessiner Kalkalpen. Abhandlungen Schweizerische Paläontologie Gesellschaft 50:5-110.
Wild R 1973. Die Triasfauna der Tessiner Kalkalpen XXIII. Tanystropheus longobardicus(Bassani) (Neue Ergebnisse). – Schweizerische Paläontologische Abhandlungen 95: 1-16.

wiki/Tanystropheus

Giraffe circulation pdf

2 thoughts on “Blood pressure in an elevated Tanystropheus

  1. Nice depiction, but I doubt that Tanystropheus developed a long neck simply to help it eat crinoids. Also, a long neck would be disadvantageous to an aquatic animal, except possibly to swerve as a prow for a swimmer. There’d be significant drag when moving its neck to and fro underwater. Couldn’t Tanystropheus have simply been an early “high browser,” a precursor to the sauropods, which conquered the niche soon thereafter? Being a high browser would work even if Tanystropheus spent most of its time in water

    • It ate small cephalopods (found as stomach contents and seen here as tiny floating creatures) among the tall crinoids. See the reptileevolution.com/tanystropheus.htm page for an image of your theory.

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