MARBLEHEAD, Ohio—For more than five decades, the fiberglass dinosaurs of Prehistoric Forest have loomed goofily over the entrance to this Lake Erie tourist town. Now they are facing extinction.

Len and Denise Tieman, who have owned the roadside attraction since 1995, feel they have had a good run. They intend to close Prehistoric Forest on Sept. 12, after one last Labor Day rush, and retire. So far, they haven't found anyone eager to carry on the tradition.

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