Mustafa Caliskan, who purchased the slab of marble a year ago, was reorganizing his shop when he noticed the fossil, the Turkish daily Today's Zaman reported Monday.
He took the marble to the department of geological engineering at Istanbul's University who determined the fossil was 1.2 million years old.
Caliskan said he refused the university's request to display the fossil.
"I want to sell it because I'm in dire economic straits," he said. "I invite everyone to come and see my fossil at the shop."
He said estimated the value of the fossil at around $56,500.
In December, a fossilized skull of a rhinoceros that lived in Turkey about 9 million years ago was discovered in central Anatolia, the newspaper said. It is displayed in a museum in Nevsehir.