Excavations at the quarry was stopped in 1881 , although it was not exhausted of fossils , as recent drilling operations have shown . During World War I , when the town was occupied by German forces , preparations was made to reopen the mine for palaeontology , and Otto Jaekel was sent from Berlin to supervise . The Allies recaptured Bernissart just as the first fossiliferous layer was about to be uncovered . Further attempts to reopen the mine was hindered by financial problems and was stopped altogether in 1921 when the mine flooded .