When Connor Temple found Helen Cutter's Anomaly Opening Device in the Cretaceous and used it to open this Anomaly. Shortly after the Anomaly was opened, Connor and Abby Maitland escaped through from a Spinosaurus back to the Present. The Anomaly Research Centre arrived shortly after and locked the Anomaly with an Anomaly Locking Mechanism.
Connor subsequently tried to close the Anomaly with the Opening Device, but instead accidentally unlocked it. A Spinosaurus then came through the Anomaly to the present before the ARC locked it again. The Spinosaurus was ultimately sent through another Anomaly to an unknown time period.
By the time of the Liverpool art museum incursion, the Anomaly had closed.