A park employee spotted the body part at Abyss Pool, which led to a temporary closure in the area.
Yellowstone park spokesperson Morgan Warthin said the park didn't have additional details related to the ongoing investigation to share publicly on Thursday.
Abyss Pool, which is located on the south side of the southern loop and west of the West Thumb, is a 53-foot deep hot spring with an estimated temperature of 140 degrees Fahrenheit, according to park officials.
Superheated water cools as it reaches the surface of the hot spring before sinking and being replaced by hotter water below as part of a circulation process preventing the water from reaching a temperature capable of setting off an eruption similar to geysers at the national park, according to information shared on Yellowstone's website via the AP.
Earlier this week, video shared online shows a bison headbutting a vehicle at Yellowstone National Park amid several other recent dangerous incidents within the area.
The incident took place weeks after a 25-year-old woman was gored to death and tossed 10-feet into the air by a bison at Yellowstone on March 30.
The National Park Service confirmed the woman, who was not identified, was visiting from Ohio in a news release obtained by NBC News on March 31.
Park officials said the woman approached a female bison after it had come near a boardwalk located at Black Sand Basin, in an area close to Old Faithful geyser at the national park.
Officials confirmed the 25-year-old woman was within 10 feet of the bison prior to it impaling and "tossing" her 10 feet in the air on Monday, which caused puncture wounds and multiple other injuries.
The woman was taken to a hospital in Idaho, however, it wasn't clear where she was pronounced dead, according to the National Park Service.
Two other people were also close to the bison when it gored the woman, however, officials didn't confirm whether they experienced injuries.