Could Plesiosaurians Move on Land??

[suspsy]

https://markwitton-com.blogspot.com/2019/01/plesiosaurs-on-rocks-terrestrial.html?m=1

Short answer: no.

[stargatedalek]

Correction, short answer, no one can really say.

They had no foreseeable need to go on land, and the larger members would have been incapable given their weight, but that doesn't exclude every member from potentially resting on land.

There is little reason for green sea turtles to ever bask on land, and yet they do, even though doing so would kill many of their close relatives.

[Brontozaurus]

Correction, short answer, no one can really say.

They had no foreseeable need to go on land, and the larger members would have been incapable given their weight, but that doesn't exclude every member from potentially resting on land.

There is little reason for green sea turtles to ever bask on land, and yet they do, even though doing so would kill many of their close relatives.

Witton points out though that there's a whole suite of anatomical features that would've made it incredibly difficult to get onto land in the first place, regardless of size. Sea turtles also don't have to worry about supporting huge necks and/or heads, which would have been a major issue for terrestrial plesiosaurs yet they appear to have no way to support them properly out of the water. While yes, animals do things that we can't logically infer from their anatomy, I find Witton's argument persuasive against plesiosaurs ending up on land for reasons other than accident.

[Vidusaurus]

Correction, short answer, no one can really say.

They had no foreseeable need to go on land, and the larger members would have been incapable given their weight, but that doesn't exclude every member from potentially resting on land.

There is little reason for green sea turtles to ever bask on land, and yet they do, even though doing so would kill many of their close relatives.

Correction to your correction: short answer: no, long answer: it's impossible to say anything with 100% certainty about extinct animals, but there are a whole suite of morphological factors that would severely inhibit their ability to go onto land

[stargatedalek]

Correction, short answer, no one can really say.

They had no foreseeable need to go on land, and the larger members would have been incapable given their weight, but that doesn't exclude every member from potentially resting on land.

There is little reason for green sea turtles to ever bask on land, and yet they do, even though doing so would kill many of their close relatives.

Correction to your correction: short answer: no, long answer: it's impossible to say anything with 100% certainty about extinct animals, but there are a whole suite of morphological factors that would severely inhibit their ability to go onto land

Witton says at the end that it's impossible to say for sure that they broadly could not go on land. My point was that just because something is extremely likely doesn't make it an absolute and we should avoid phrasing it as such. Behavioral adaptations are very different from anatomical ones and we can't rely as strictly on inference from relatives as we can for things like an animals integument or size (estimating size from proportions of relatives).