A Nova Scotia family out for a walk with their dog has stumbled upon what the province is calling its most significant fossil find.

Patrick Keating and his wife Susie were walking their dog Kitty last month along the Northumberland Shore when something caught their eye.

“(It) looked like a chicken breast, you know, encapsulated in rock. But it was interesting once we found out what it was,” said Susie Keating.

It turned out to be the partial sail, ribcage and backbone of the sail-back reptile, the first to be found in Nova Scotia, the provincial government said in a press release.

"This is a great day for Nova Scotians and the world," Minister of Communities, Culture and Heritage Leonard Preyra said in a statement.

A week later, while walking along the same stretch of beach, the family found the animal’s skull, believed to be 290 million to 305 million years old.

Patrick's brother brought the fossil to the Nova Scotia Museum, which promptly gave it a nickname -- Superstar

“When I finally saw a picture all I could think of was, ‘Oh my God, oh my God,’ because this is part of the missing piece of the puzzle that we're putting together based on the fossils we're finding here in Nova Scotia,” said Ken Adams, Director of Fundy Geological Museum.

Palaeontologists knew the sail-back, a mammal-like reptile, once roamed these parts because in 1994 footprints were found in Nova Scotia's Colchester County, and isolated bones were discovered in 1845 in Prince Edward Island.

Sail-back reptiles have been found in Texas and Europe, which were attached to Nova Scotia more than more than 300 million years ago before the tectonic plates beneath them shifted.

The fossils will be exhibited at Halifax’s Museum of Natural History starting Saturday.

"A new window into our ancient world has just opened," said Deborah Skilliter, curator of geology for the Nova Scotia Museum. "This is just the beginning of the story as we undertake the task of determining exactly what type of sail-back reptile Superstar is, where, and how, it lived and died."

The exact location of the find will not be revealed in order to protect the site and any future discoveries, a spokesman for the Heritage Department said.

The find has led to the discovery of a dragonfly wing fossil at the same location, according to the government.

Nova Scotiais famous for its fossils. Since 2008, Joggins Fossil Cliffs have been a UNESCO world heritage site.

With a report from CTV Atlantic’s Sarah Plowman and files from The Canadian Press