"Acc[ording] to E. von Dobschütz, [the Gelasian Decree/Decretal] is not a Papal work at all, but a private compilation [(e.g. 'gelehrte Privatarbeit' (Dobschütz, Das Decretum Gelasianum (1912), 250, speaking of the List in chap. 2 specifically, and not just the Decretal as a whole))] which was composed in Italy (but not at Rome) in the early 6th cent. Other scholars, while accepting this date, think it originated in Gaul."
"Decretum Gelasianum" The Oxford Dictionary of the Christian Church. Ed. F. L. Cross and E. A. Livingstone.© Oxford University Press 2005. The Oxford Dictionary of the Christian Church: (e-reference edition). Oxford University Press. Seattle Pacific University. 5 June 2012 http://ezproxy.spu.edu/login?url=http://www.oxford-christianchurch.com/entry?entry=t257.e1942
Yet "many scholars (e.g. Thiel, Maassen, Turner, Zahn, Bardy, Di Capua) admit the
possibility that [Pope] Damasus is responsible for the first part, which would have
been composed at the Council of Rome in 382. . . ."
Patrology, volume IV: The golden age of Latin Patristic literature from the Council of Nicea to the Council of Chalcedon, ed. Angelo Di Berardino, trans. Placid Solari (Westminister, MD: Christian Classics, Inc., 1988), 277-278.