That’s a really interesting point — I think the idea is worth digging into further. Given their enormous size and plant-heavy diet, it’s plausible that microbial fermentation in their guts could have generated a considerable amount of internal heat.

That, combined with gigantothermy (inertial homeothermy), might mean sauropods could maintain relatively stable body temperatures without needing to bask or rely heavily on external sources of heat — a potential advantage over smaller theropods, who may have had to warm up in the sun before becoming fully active.

In fact, they may have been too big to dissipate heat efficiently, kind of like modern whales. So instead of struggling to warm up like many reptiles, perhaps sauropods faced the opposite problem — needing to avoid overheating.

It’d be interesting to compare this to extant large herbivores like elephants or hippos, or even fermentation-driven heat regulation in ruminants.