/kloc-were there four seasons in the middle Cretaceous 0/100 million years ago?

Logically, the sentence "A year is divided into four seasons: spring, summer, autumn and winter" is mistaken for division, which is decomposition, not division. Just like "people can be divided into head, neck, trunk and limbs", they are all decomposed.

After division, we get children, and each child has the attributes of the parent. For example, "literary works are divided into novels, poems, plays and essays" is a kind of division, and "novels, poems, plays and essays" all have the attribute of "literary works".

After decomposition, parts are obtained, and each part has no overall attributes. For example, the "spring, summer, autumn and winter" in your question is not a "year", but only a "year" component.