Animals in Prehistory that May Have Been Intelligent

Here, I speculated an omnivorous species of Pachycephalosaurid dinosaur with a larger brain case than Pachycephalosaurus, rivaling the intelligence of modern humans, having somewhat longer arms than Pachycephalosaurus and being very social, making stone tools to hunt other animals, including larger dinosaurs.

Believe it or not, Jack Horner showed that Pachycephalosaurus was probably not a head-butting brute as what people once thought, so they have been, according to my theory, may have been omnivorous and the most intelligent non-avian dinosaur, even smarter than Troodonts, despite having a small brain case. Their brains may have been comparable to that of early hominids, but they may have used their feet for grasping (if their feet were determined to have grasped like some modern birds and/or if their arms were too short) or used their hands for grasping (we don't know about the arms of Pachycephalosaurus yet).

Although this may be unlikely, the Stegoceras would have been very smart, about as smart as some early hominids (despite some reports of fossils showing head-butting behavior, they probably were not head-butters, but the damages of their skulls were probably results of falling and/or fights from weaponry (like stone tools, etc), using their feet for grasping tools due to their arms being short.

Just like Stegoceras, Prenocephale's arms were too short for grasping and picking up tools, but their feet may have been used for grasping, and they were probably about as smart as early hominids, making stone tools to defend themselves, fight other intelligent Pachycephalosaurs, and/or for hunting other animals, including larger dinosaurs.

A recently discovered species of Pachycephalosaurid, Alaskacephale's arms were likely too short for grasping or making tool, but it's feet were probably were used instead to make and use stone tools, and was probably about as smart as early hominids.

Just like Stegoceras and Prenocephale, this species probably had arms that were too small to manipulate objects or use stone tools, but they probably had manipulative grasping feet to make and use stone tools, they were probably omnivorous and about as smart as early hominids.

Like most other Pachycephalosaurids, this species was likely omnivorous, and like most high-domed Pachycephalosaurids, it was probably intelligent like early hominids and may have used grasping feet to make and use stone tools (if their arms were too short).

Texacephale was probably very intelligent, about as intelligent as early hominids, and may as well have made and used stone tools with their feet (if their arms were too short), and most likely omnivorous like most Pachycephalosaurids.

Like other high-domed Pachycephalosaurids, the Foraminacephale was probably about as intelligent as early hominids, and may have created and used stone tools with their feet (if their arms were too short) and were most likely omnivorous.

This may be unlikely, but due to the shape of its skull, maybe giving it a larger brain case, it may be much smarter than any modern cetaceans, probably giving this animal the ability to communicate in wide languages (not human language, but at least a wider range of languages than modern cetaceans), unlikely, but possibly culture (unlike modern cetaceans).

Even though mammoths were intelligent, they were probably only as smart as other elephants. When I said intelligent, I meant like very sentient (I mean sapient), using stone tools, having culture, etc.

Does this really count as the most intelligent prehistoric animal? It just has a similar skull to true cats, which aren't the smartest mammals (although they aren't unintelligent neither, they just follow instincts).