Typically, development databases are not started in archivelog mode. This causes a problem for hot backups but not necessarily for flashback queries. You can still flashback to any time within the online redo logs:

 alter session set nls_timestamp_format = 'dd-mon-yyyy hh24:mi:ss.ff3';
 set lines 9999
 set trims on
 set pages 9999
 set headi off
 spool old_version.sql

 select text
 from   dba_source
 as of  timestamp to_timestamp('22-sep-2011 07:30:00.000')
 where  1=1
 and    owner = 'scott'
 and    name  = 'mypackage'
 order  by type
 ,      line;

<code> spool off