👉 The term "eopalaeozoic" refers to the geological period between the Cambrian and the Eocene, which spans approximately 4.5 billion years ago. This period is considered a transition phase in the Earth's history due to its abrupt change from an ancient marine environment to a terrestrial one. The eopalaeozoic era marked the end of the Paleozoic era, characterized by the dominance of the Cambrian and Ordovician periods.