The Most Ridiculous Notion Yet

[SBell]

As many of you know, David Peters is a genuinely talented artist who wrote some great children's books back in the late 80s and early 90s, complete with foldout pages. Since then, however, he has steadily degenerated into a bona fide crackpot with delusions of scientific grandeur. His websites, ReptileEvolution and Pterosaur Heresies, are so full of demonstrable falsehoods and nonsense, it would give anyone an excruciating headache to list even a quarter of them. For your own sake, don't ever use them as references. And this may well be his barmiest argument yet. He claims that Homotherium is not a machairodont or even a felid at all. Instead, he insists that it is a canid.

That's right, a sabre-toothed dog.

https://pterosaurheresies.wordpress.com/2023/05/20/sabertooth-homotherium-is-a-canid-not-a-cat/?mibextid=Zxz2cZ&fbclid=IwAR0l54V3HdwCzXegIpSDxY-97s2VUfRgULDpnFUgCtFL6EREs2OZNNlRBI4_aem_th_AaZzek5G-8MPXGmBVSH-C-fER6jWell6IUwwJGXr5mSUYWS76ka2wS5uo6Z3MZRU37c

Ugh. We need to stop giving DP attention of any kind.

[dinofelid]

But the extremely safe decision to base it's hind section on the closest relative is very rarely done

Are you saying it's a safe decision to reconstruct Longisquama as a glider with a membrane extending from its legs like Sharovipteryx, or are you saying it's most likely to have had long legs even in the absence of a membrane? If the latter, if we could look at the ancestors of bats or pterosaurs from some time shortly before any gliding or flying adaptations, I wouldn't expect their arms to be nearly as long proportionally as their flying descendants, though maybe it's plausible they'd be a little longer than other similar animals in the same niche since that might make them more likely to evolve in the direction of gliding/flying.

Either is more accurate than completely making up it's legs or basing them on distantly related animals. I see nothing to suggest Longisquama wasn't a gliding animal, even if a presumably less specialized one for that task than Sharovipteryx; given it lacks the shrunken arms. And if it wasn't, long legs serve as more than just attachment points for membranes, they are also great for climbing and reaching between leaves and fronds, which I feel is in-line with Longisquama's elongated forelimbs.

Weren't Sharovipteryx's hind limbs proportionally far more elongated than Longisquama's forelimbs though?

I chose a skeletal to show the proportions, not any particular posture. The newer version shows what the author considers a more accurate posture, but in doing so it by necessity obscures the proportions of the arm.

Whether it's comfortable walking posture was sprawled or upright, quadruped or biped, it had really long arms, so it likely wasn't using them the same way lizards and Drepanosaurs do/did. I again go back to new world monkeys as a point of comparison, with long limbs for reaching between pieces of foliage. Though if it sprawled while on flat surfaces perhaps sloths would be a better analogy.

When thinking about how unusual Longisquama's forelimbs were, maybe we could compare it to the Drepanosaurs many of which might have occupied a similar niche and seem to often be long-limbed compared to other contemporary reptiles (the article refers to many having 'specialized grasping limbs' and arboreal adaptations). So is it that Longisquama's arms were really long even compared to Drepanosaurs and the second skeletal is obscuring that, or is it that the first skeletal makes the length of the arms seem more unusual by having them in a near-vertical posture? This blog post has a lot of skeletals and life restorations of drepanosauromorphs (after you get past the first illustration of a long-armed synapsid), it seems like many in this group had fairly long arms, like Hypuronector: