Previous assumptions about the age of ancient plant species is being thrown into question today, as new research suggests that flora took root here on Earth over 100 million years earlier than scientists presumed. A study published this week in the Proceedings of the National Academy of Sciences used a new calculation method to determine where on Earths’ timeline plants initially appeared. As it turns out, all previous guesses may have been way, way off.

The study has some pretty serious implications in regards to how scientists view the very earliest phases of life’s spread across the globe, and could help us better understand the long and winding road that eventually resulted in the planet we inhabit today.

To get a better idea of how far back plant life dates, the researchers used what they call a “molecular clock” method to analyze genetic changes over time and link them to their predecessors. This work, which is a bit like painting a massive family tree of the earliest plant life which can be used to calculate how far back in time it truly stretches. Needless to say, the resulting data doesn’t match well with previously-held assumptions.

“The fossil record is too sparse and incomplete to be a reliable guide to date the origin of land plants. Instead of relying on the fossil record alone, we used a ‘molecular clock’ approach to compare differences in the make-up of genes of living species – these relative genetic differences were then converted into ages by using the fossil ages as a loose framework,” Mark Puttick, co-lead author of the study, explains. “Our results show the ancestor of land plants was alive in the middle Cambrian Period, which was similar to the age for the first known terrestrial animals.”

This new work could be an important addition to future research into the emergence of plants and animals on Earth, as well as a helpful tool in modeling how climate changed in the earliest days of life on this planet.