Prior to the Industrial Revolution, has the Earth been hotter than it is now?

Ok, the thermometer has not been around for thousands of years to compare numbers. So look at temperature from a geologists point of view. Look at the large widespread coal deposit around the world from England, U.S. China etc, It took a lot of vegetation and years to build up the layer upon layer of coal. Vegetation definitely is greater in a warmer climate. Travel north and watch the vegetation decline as it gets colder