The unique new fossil Pokémon of Sword and Shield and their even more unique mix-and-match gimmick are a reference to Paleontological history. Some of the earliest recorded Dinosaur bones and discoveries were found by British scientists (the Galar Region is based on the United Kingdom) and during the earliest discoveries many of those scientists, due to knowledge of these newly-discovered prehistoric beasts being very primitive at the time, did reckless things and made a lot of rather egregious mistakes including taking bones from one species of Dinosaur and applying them to another species' bones, both believing and claiming that they were of the same species. This is reflected in the gimmick where two of the player's fossils are fused into one of four Pokémon that clearly look like the parts used to fuse them do not match to the point that even the Pokédex descriptions seem baffled at their existence and how they are still alive. The scientist in-game who does this is called Cara Liss, or "careless".