But this is about the Carboniferous, about 40 million years before the first dinosaurs.

Ah, my mistake. Do you happen to have a link to this? I didn't know about other giant reptiles, except for the dinosaurs.

What sort of a link would you like, perhaps this?

https://archive.org/details/Vertebrate.Paleontology.Evolutio...

That's on chapter 9, "The Conquest of Land and the Radiation of Amphibians". Caution, this is a book from 1988, the Carboniferous era may have changed a lot since then.

(Carboniferous = Mississippian + Pennsylvanian.)

An image search for "Paleozoic and Mesozoic amphibians and reptiles" may also be gratifying. I'm fond of Moschops ("calf face"), though that's after the Carboniferous rainforest collapse.

Those links work great, thank you! Turns out, life is weird and exciting and really old!