The Chicago Field Museum is offering early retirement packages for some of its employees. The museum, best known for its research and Sue the Tyrannosaurus Rex, is shouldering a heavy debt burden and has been trying to find ways to cut back.

Field Museum spokeswoman Nancy O’Shea says the museum is offering retirement packages to more than half of its 27 curators. The 16 eligible employees were selected based on age and the length of their employment with the Field. They have until May 10 of this year to decide if they’ll take the offer or not.

The museum announced in December that it was looking for ways to cut $5 million in costs, and boost endowment by $100 million. O’Shea says they’ve already identified ways to trim $2 million from their science initatives without cutting staff, but they’re still looking for another million in cuts. This is the third time in the last five years that retirement incentive offers have been made to Field employees.

The museum has said in the past they were also considering admission rate hikes as a possible revenue booster, but O’Shea said she has nothing to announce on that topic.