Matt Perkins and his husband, who recently moved from Washington to Nevada, said pool builders discovered the bones about five feet below ground.
Police and crime scene investigators, who were called to the house on Monday, said the bones did not belong to a human and raised no law enforcement concerns.
“We had joked on Friday when while they started digging, ‘Oh great maybe they will find a dinosaur for us and it will pay for our pool,” Mr Perkins told KTNV.
“Obviously, when they told us they found some fossils, that was more of a shock to us than we were expecting,” he added.
Joshua Bonde, the director of research of the Nevada Science Center, visited the garden on Tuesday to inspect the discovery.
“What we found was when they were excavating the backyard pool, they were cutting through ice age layers of sediment and sure enough they had a skeleton of an animal,” he told the broadcaster.
Mr Bonde added that the bones are between 6,000 and 14,000 years old and are those of a horse or similar large mammal.
The discovery came near Tule Springs Fossil Beds National Monument, where rare fossils such as mammoths have been unearthed before.
