The lifestyle of Tanystropheus is controversial, with different studies favoring a terrestrial or aquatic lifestyle for the animal.
In the 1980s, various studies determined that Tanystropheus lacked the musculature to raise its neck above the ground, and that it was likely completely aquatic, swimming by undulating its body and tail side-to-side like a snake or crocodile.

However, in 2005 Renesto found that Tanystropheus lacked many aquatic adaptations.
Although the tail of Tanystropheus was flattened, it was compressed from top-to-bottom, so that it would have been useless for side-to-side movement.
The long neck and short front limbs compared to the long hind limbs would have made four-limbed swimming inefficient and unstable if that was the preferred form of locomotion.
Thrusting with only the hind limbs, as in swimming frogs, was also considered an inefficient form of locomotion for a large animal such as Tanystropheus, although a later study found support for this hypothesis.
Renesto's study also found that the neck was lighter than previously suggested, and that the entire front half of the body was more lightly-built than the rear half, which would have possessed a large amount of muscle mass.
In addition to containing powerful hind limb muscles, this unusually large muscle mass would have shifted the animal's weight to its rear, stabilizing the animal as it swung and maneuvered its massive neck.


Renesto's analysis was the basis for later analyses of the genus.
In 2015, paleoartist Mark Witton concluded that, although the neck made up half of the entire animal's length, it made up only 20% of the entire animal's mass due to having light and hollow vertebrae.
In comparison, the heads and necks of pterosaurs of the family Azhdarchidae made up almost 50% of the animal's mass, yet they were clearly land based carnivores.
The animal is also poorly equipped for aquatic life, with the only adaptation being a lengthened fifth toe, which suggests that it visited the water some of the time, though was not wholly dependent on it.
This same research has also shown that Tanystropheus would have hunted prey like a heron.
This interpretation is supported by taphonomic evidence, which indicates that the preservation of Tanystropheus specimens is more similar to the terrestrial Macrocnemus than the aquatic Serpianosaurus where all three co-occur.

Renesto and Franco Saller's 2018 follow-up to Renesto (2005)'s study offered more information on the reconstructed musculature of Tanystropheus.
This study determined that the first few tail vertebrae of Tanystropheus would have housed powerful tendons and ligaments that would have made the body more stiff, keeping the belly off the ground and preventing the neck from pulling the body over.
In addition, the hind limbs would have been quite flexible and powerful according to muscle correlations on the legs, pelvis, and tail vertebrae.
This analysis shows that Tanystropheus was capable of a specific mode of movement while swimming.
Namely, a Tanystropheus could extend its hind limbs forward and then simultaneously retract them, creating a powerful 'jump' forward.
Further support for this hypothesis lies in the fact that a close relative of Tanystropheus, likely the small Tanytrachelos, is believed to have left an ichnogenus (trackway fossil) called Gwyneddichnium.
Some Gwyneddichnium tracks seem to represent a succession of paired footprints that can be assigned to the hind limbs, but with no hand prints.
These tracks were almost certainly created by the same form of movement which Renesto and Saller theorized was the preferred form of swimming in Tanystropheus.

With this information, the most likely lifestyle for Tanystropheus was that the animal was a shallow-water predator that used its long neck to stealthily approach schools of fish or squid without disturbing its prey due to its large body size.
Upon selecting a suitable prey item, it would have dashed forward by propelling itself along the seabed or through the water, with both hind limbs pushing off at the same time.
However, this
The lifestyle of Tanystropheus is controversial, with different studies favoring a terrestrial or aquatic lifestyle for the animal. In the 1980s, various studies determined that Tanystropheus lacked the musculature to raise its neck above the ground, and that it was likely completely aquatic, swimming by undulating its body and tail side-to-side like a snake or crocodile.
However, in 2005 Renesto found that Tanystropheus lacked many aquatic adaptations. Although the tail of Tanystropheus was flattened, it was compressed from top-to-bottom, so that it would have been useless for side-to-side movement. The long neck and short front limbs compared to the long hind limbs would have made four-limbed swimming inefficient and unstable if that was the preferred form of locomotion. Thrusting with only the hind limbs, as in swimming frogs, was also considered an inefficient form of locomotion for a large animal such as Tanystropheus, although a later study found support for this hypothesis. Renesto's study also found that the neck was lighter than previously suggested, and that the entire front half of the body was more lightly-built than the rear half, which would have possessed a large amount of muscle mass. In addition to containing powerful hind limb muscles, this unusually large muscle mass would have shifted the animal's weight to its rear, stabilizing the animal as it swung and maneuvered its massive neck.

Renesto's analysis was the basis for later analyses of the genus. In 2015, paleoartist Mark Witton concluded that, although the neck made up half of the entire animal's length, it made up only 20% of the entire animal's mass due to having light and hollow vertebrae. In comparison, the heads and necks of pterosaurs of the family Azhdarchidae made up almost 50% of the animal's mass, yet they were clearly land based carnivores. The animal is also poorly equipped for aquatic life, with the only adaptation being a lengthened fifth toe, which suggests that it visited the water some of the time, though was not wholly dependent on it. This same research has also shown that Tanystropheus would have hunted prey like a heron. This interpretation is supported by taphonomic evidence, which indicates that the preservation of Tanystropheus specimens is more similar to the terrestrial Macrocnemus than the aquatic Serpianosaurus where all three co-occur.
Renesto and Franco Saller's 2018 follow-up to Renesto (2005)'s study offered more information on the reconstructed musculature of Tanystropheus. This study determined that the first few tail vertebrae of Tanystropheus would have housed powerful tendons and ligaments that would have made the body more stiff, keeping the belly off the ground and preventing the neck from pulling the body over. In addition, the hind limbs would have been quite flexible and powerful according to muscle correlations on the legs, pelvis, and tail vertebrae. This analysis shows that Tanystropheus was capable of a specific mode of movement while swimming. Namely, a Tanystropheus could extend its hind limbs forward and then simultaneously retract them, creating a powerful 'jump' forward. Further support for this hypothesis lies in the fact that a close relative of Tanystropheus, likely the small Tanytrachelos, is believed to have left an ichnogenus (trackway fossil) called Gwyneddichnium. Some Gwyneddichnium tracks seem to represent a succession of paired footprints that can be assigned to the hind limbs, but with no hand prints. These tracks were almost certainly created by the same form of movement which Renesto and Saller theorized was the preferred form of swimming in Tanystropheus.
With this information, the most likely lifestyle for Tanystropheus was that the animal was a shallow-water predator that used its long neck to stealthily approach schools of fish or squid without disturbing its prey due to its large body size. Upon selecting a suitable prey item, it would have dashed forward by propelling itself along the seabed or through the water, with both hind limbs pushing off at the same time. However, this 
Tanystropheus