The incident took place around 10 a.m. Thursday. In a statement, the museum said security staff followed procedures to “ensure the safety of visitors,” and called police, who took the activist into custody.

The mischief is the latest demonstration by Last Generation Canada, previously known as On2Ottawa, a civil disobedience group that formed in 2023. The group says its actions are intended to draw attention to the climate crisis and to demand Canadian government action.

The activists said Thursday they chose a dinosaur skeleton to highlight the risk of mass extinction prompted by the climate crisis.