I have a Great grandfather named Michael Joseph
Shanahan b.Sept 14,1849 d Jan 24,1911.That part matches your info. His wife was Margaret Mary
McDermott. They lived in Crowland,
Welland County Canada. I have some information that his father was John
Shanahan b.approx 1811 Killarney,
Kerry County, Ireland.I believe his wife, based on records I have was Johanna Casham.I have Michael and Margaret's Marriage certificate and it states mother as Johanna Shannon but also uses Shannon as
Michaels last name.The other 2 places she shows up are on John's death cert and in the cemetery where they are buried together. That is the Japanese Martyrs Catholic Cemetery in
Welland Canada.
I have not been able to trace Johanna back any farther,any where.
Michael who died in 1911 had a son Michael Joseph b. June 17 1898 in
Welland Ontario Canada d. June 1973 in
Polk Livingston Co,
Texas.
He was married to Grace
Herdman b.June 11 1901 in
Welland Canada d.Jan 1980 Batavia
Genesee Co NY.
Going the other way from John I think but am not sure his Parent were Eugene(Patrick) and
Bridget Connor.I have found a John
Shannahan christened on Jun 10 1811 which matches his death date minus his age.
I have more info but that's about enough for now. If you think its a match let me know