Your post didn't have any DOB, DOM, Irish placenames, etc. B/M/D registration was civil beginning in the late 19th century. These and church rcds usually recorded the parents' names for marriages. Sometimes they recorded placenames. Some of this info you can get from censuses.
You need to do some digging in these U.S. sources.
I research the Irish Family History Foundation's database. It contains 12,000,000 surviving rcds for abt 65% of Irish counties. Rcds are increasingly sparse B4 1840, rare B4 1800.
Note 1 - Without a KNOWN county, the chance of an ancestor's rcds NOT being in this database is AT LEAST 35%.
Note 2 - Only 1/2 of Co. Cork's rcds are in this database.
Note 3 - The RC church kept control over most parish rcds from Tipperary (north). These are ONLY available thru the Tipperary Family History Research center at a substantial fee (regardless of outcome).
For John McCloskey B ???? somewhere in Ireland with the father's forename unknown, I found 292 B rcds dating from 1759.
For Marion McDevitt B ???? ditto, I found 0 rcds. For the surname alone, there are 2,501 B rcds.
Google the Foundation's name to lead you to this database. Register, opt to be notified as rcds are added and browse. Pls post your search results to my genforum msg.