He was first mentoined in Carl Barks' 1955 Uncle Scrooge comic The Heirloom Watch. In this story, Scrooge tells his nephew Donald about his famous watch, that has been in the McDuck family for two hundred years. When he demonstrates the watch to Donald, he states: "It ran faithfully for my grandfather and his grandfather, and it has run faithfully for me, for many, many years!". This story was also the first mentioned appearance of Scrooge's great-uncle Quagmire McDuck.
In the classic Barks comic The Hound of the Whiskervilles, Scrooge mentions his grandfather once again. When Huey, Dewey, and Louie explain to Scrooge that, in order to obtain a high social status, "People want to know if your grandfather also wore a silk hat!", Scrooge responds: "My grandfather wore a miner's cap!". Don Rosa used this bit of information to create a portrait of Scrooge's grandfather for his Duck Family Tree illustration (first printed in 1993).
On this tree, Dingus, was shown to have married a certain Molly Mallard, Scrooge's grandmother. In addition, he was here shown to have three sons: Captain Pothole McDuck (Scrooge's uncle mentioned in Barks' The Great Steamboat Race, 1955), Jake McDuck (Scrooge's uncle mentioned and seen in a picture in Barks' A Christmas For Shacktown, 1949), and Fergus McDuck, Scrooge's father. However, given the fact that, thoughout the years, numerous uncles of Scrooge with 'McDuck' as their surname have been introduced in the comics (such as uncle Commander McDuck, uncle Midas McDuck and numerous more), Dingus and Molly must have had more children besides the ones shown on this specific tree.
In the 1960 comic The Search for Cyril (written by Bob Gregory and drawn by Tony Strobl), Scrooge's coal miner grandfather is referred to as Titus McDuck. He was shown to be very stingy, and traditionally tested his grandchildren with his so-called 'one-pound-note test'. Titus would give them a one-pound-note and observed the kid's actions. If the kid kept the money, it had proven to be a real McDuck. However, if the kid decided to spend the money, like Scrooge's cousin Cyril McDuck did, it would be "banished to the highlands in disgrace".
Titus McDuck was also shown on a portrait on Giovan Battista Carpi's 1994 Duck family tree illustration.
Scrooge's coal miner grandpa was mentioned again in the 2008 comic Hearts of Gold. In this story, it is revealed that he was the one who actually passed the heirloom watch onto Scrooge, and that he had been working for it in the coal mines for years. Near the end of the story, Scrooge tells Huey, Dewey, and Louie that the reason why he is so attached to the watch is not because it's made of gold, but because it reminds him of his grandpa, implying that Scrooge and his grandfather had a good relationship with each other.