I went into the middle chamber thinking it would be easy as pie, encountered one of these guys along with about 10 arthros, on my sp max level in wild is 30, my lvl 61 wolf and I didn’t stand a chance. My flak all broke, my wolf nearly died, had to sprint out of there oml. Be prepared!! Maybe it’s coz my armour was nearly broken anyway but either way, my op wolf would have died. Be careful, if you think you’ll encounter them, do it in the Daytime!!! They’re debuffed during daytime, but super powerful at night!!
Fun fact: megalosaurus (name translates to “big lizard”) was the first true dinosaur found. Discovered by Richard Owen, he thought it was quadrupedal (walked on all fours) and resembled a crocodile-lion cross. Later he would correct his data and soon classify this group of extinct line of ancient lizards as “Dinosaurs”.
To the mobile person who doesn’t know where to find them, they are mostly found in the middle chamber, I only found one while going for the artifact, so it might be near the onyc, araneo or the other creepies, just be careful before you get off your mount to get the artefact.