Last I heard it was was completely made up, there's basically no way to tell from fossilized remains. Edit: It's explained a bit more in the book, where they say "they have great visual acuity, but a simple amphibian visual system, that's highly attuned to motion". The dinosaurs in JP were partially mixed with amphibian DNA, so it was probably intended to be a consequence of that in universe. But in real life, there's no way to know.
Dinosaurs! I suspect Miyamutuu was so on edge this entire chapter because she knows that dinosaurs are here.
Also, we have an exclamation mark ‼️ We saw a bit of it in chapter 1 (during the held-at-gunpoint exchange), but I'm still excited to see it again.
We are closer to understanding this language. This chapter has Miyamutuu thinking once again, which involves several very interesting things going on.
Before any of that, though, I think I figured out that "oupu jaa sui goma'ei" might mean "nothing can be understood." It's on the Volume 1 cover, and Miyamutuu also says it when she realizes that Ryouta is completely foreign to this world's culture.
If true, this is huge news. First of all, it implies that the syntax of Myaasanese is likely different from that of Japanese.
Japanese: "Nani mo Wakaranai," where "nani" means "what[ever thing]", "mo" means "also," and "wakaranai" means "cannot be understood." "Whatever thing also cannot be understood." It doesn't make much sense when translated word-for-word to English, but trust me: this means "Nothing Can Be Understood."
Myaasanese: "Oupu jaa sui Goma'ei," where "oupu" means "not" (a negation), "jaa sui" is an indefinite pronoun, and "goma'ei" as either "can be understood" or "cannot be understood." There are two ways to interpret this:
"Nothing (oupu jaa sui) can be understood (goma'ei)." Here, "oupu" negates "jaa sui" to form a compound negative pronoun – "not anything" to "nothing."
"Everything / Anything / What[ever thing] (jaa sui) cannot (oupu) be understood (goma'ei)." Here, "oupu" negates the verb "goma'ei," acting as a negative particle in the conventional sense – "not can be understood" to "cannot be understood."
I'm inclined to believe in the second interpretation, since verb conjugations already exist in Myaasanese. If the mangaka is Japanese, they should be used to negating verbs by adding -nai to a verb, right? The first interpretation would be like asking English speakers to suddenly start using ne... rien constructions like the average French loony instead of saying "nothing". A total nightmare.
Anyways, back to Miyamutuu's inner thoughts this chapter. I roughly translated it based on the words we know, though of course, many things are probably off.
First of all, "pemedodi'ei" makes an appearance once again. This phrase seems to be a discourse marker that roughly means "of course" or "I see" in English; think naruhodo in Japanese.
Second of all, notice how in Miyamutuu's thoughts this chapter, "oupu" comes after "jaa sui?" In the "oupu jaa sui goma'ei" example, it came before... Why is that???
If you're confused about any of this, you might want to refer to my analysis of the previous chapter to better understand my current theories about the Myaasanese language.