The classic example of this is the claim in textbooks that the early horse Eohippus was the size of a fox terrier. Stephen Jay Gould analyzes the history of tha

The classic example of this is the claim in textbooks that the early horse Eohippus was the size of a fox terrier. Stephen Jay Gould analyzes the history of that strangely specific description: https://archive.org/details/B-001-016-956/page/155/mode/1up https://archive.org/details/B-001-016-956/page/155/mode/1up