Petra.

Not longer after they had that discussion about him in the cave, Mort's phone started to get bombarded by pictures sent from his new phone, with a different number of course. It was a good thing they gave him a new phone, his own, that's in Elton's pocket, is almost 10 years old and the quality of its camera is what it is.
He is so hopeless when it comes to renew things, the problem is when he is in possession of something that doesn't get broken, therefore would last forever but would still need to be changed, every few years, to match the new quality standards.

Anyhow, the super HD pictures he sends them depict more wall paintings, much better quality inscriptions preserved really well and also more modern and advanced forms of expression, artefacts and even a book. He sends some pictures of the pages, that are written in a more complex code but still completely unknown. What seems clear, though, is that the writings in the book are a connected to the ones they found in the inscriptions. It's safe to say that the more simple symbols they found were the precursor of the more complex writing.
The culture they are observing certainly is ancient, but there are plenty of hints at the fact that it didn't disappear ages before, but continued developing, probably throughout the centuries and… even after the arrival of auriold.
The wall paintings still depicted many foxes, but also wolves, jackals and dogs. All these animals are represented in different contexts, as if they were deities.
*The wall paintings are all extremely ancient and they haven't yet found any more modern expression of art, besides the few drawings from the book, that mostly depict unknown, mysterious plants, including the one they found in that forest.

The very last picture WonPil sends them is the entrance of another underground labyrinth. This one, though, is not just digged into the earth, it's sculpted finely, with walls covering from ceiling to ground.