Dunkle was born in Winnipeg, Manitoba, and grew up in Indiana, United States.

Afterwards, he worked at the Cleveland Museum of Natural History (CMNH) as a curator of vertebrate paleontology.

[1][2] A notable object he collected for the museum was CMNH 7541, a dinosaur skull upon which the controversial proposed genus Nanotyrannus is based on.

After Dunkle collected the skull in 1942, it was first described as a new species in the tyrannosaur genus Gorgosaurus by Charles W. Gilmore in 1946.

[1] Through his lifetime, Dunkle published around fifty papers that mostly deal with the fossils of fish.