It wasn't a single discovery that caused scientists to rethink Wegener's continental drift theory, but rather a combination of evidence and explanations that finally led to the acceptance of plate tectonics.

Here's a breakdown of key developments:

* Wegener's Evidence: Wegener's theory was initially dismissed because he lacked a convincing mechanism to explain how continents could move. He suggested that continents plowed through the ocean floor, but this was physically implausible.

* The Missing Mechanism: It was the development of the theory of sea-floor spreading in the 1960s that provided the missing piece. Evidence like magnetic stripes on the ocean floor, mid-ocean ridges, and subduction zones showed how new ocean crust is created at ridges and then pulled apart as it moves away, carrying the continents along with it.

* Plate Tectonics: This understanding of how the Earth's crust moves and interacts led to the development of plate tectonics, a comprehensive theory that explains continental drift and other geological phenomena.

So, while no single discovery entirely overturned Wegener's theory, the advancement of sea-floor spreading and its incorporation into the broader framework of plate tectonics provided the necessary mechanism and evidence that made the theory scientifically acceptable.