Czerkas then agreed .
Sloan says that he flew to Utah in the spring of 1999 to convince Stephen Czerkas to return the fossil to China immediately after publication , or he would not write about it for National Geographic and Currie would not work on it .
Stephen Czerkas then agreed .
Sloan says that he flew to Utah in the spring of 1999 to convince Stephen Czerkas to return the fossil to China immediately after publication , or he would not write about it for National Geographic and Currie would not work on it .