"It is with deep sadness and disbelief that I must report the passing of Cory Wells, my beloved bandmate for over 45 years," said fellow Three Dog Night singer Danny Hutton in a statement on the band's website, threedognight.com
. "Cory was like a brother in so many ways. We had been together since 1965 and I am in shock at this sudden loss."
Wells, 74, a native of Buffalo, New York, died Tuesday at his home in Dunkirk, about an hour southwest of his hometown.
He left the band last month when he developed severe back pain, the band said in the statement. The band postponed several shows because of his ailment.
At one point in the early 1970s, Three Dog Night was perhaps the most popular band in the United States. The group had three No. 1 singles -- "Mama Told Me (Not to Come)," "Joy to the World" and "Black and White" -- and seven other Top 10 hits, Including "One," "An Old Fashioned Love Song" and "Never Been to Spain." "Joy to the World" was Billboard's No. 1 song of the year in 1971.
The band also had 12 gold albums.
Three Dog Night was distinctive for having three lead singers: Wells, Hutton and Chuck Negron. They drew from a variety of influences, Wells and Hutton told CNN in 2004
"I loved Little Richard. ... And folkie-Celtic European kinds of things," the Ireland-born Hutton said.
"I was a big fan of black gospel," added Wells. "As a kid there were black groups I sang with from my teen years to my early 20s."
That breadth allowed them to draw from many sources. In its prime, Three Dog Night was known for spotlighting then little-known or rising songwriters, including Randy Newman ("Mama Told Me"), Harry Nilsson ("One"), Laura Nyro ("Eli's Coming"), Hoyt Axton ("Joy to the World") and Leo Sayer ("The Show Must Go On").
"Our focus was on good music, instead of a theme," Hutton said. "The songs came from everywhere -- demos that came in, friends."
Negron left the band in 1977, and Wells and Hutton embarked on other things. For a time, Wells said, he lived in famed arranger Nelson Riddle's old house, getting the place over a rival when Riddle told the real estate agent, "Sell it to the musician."
Wells was born Emil Lewandowski on February 2, 1941. An Air Force veteran, he formed rock bands after his service in the early '60s and eventually moved to Los Angeles, where he met Hutton, then a solo singer.
The group's success with singles sometimes led critics to be dismissive. (Three Dog Night is not in the Rock and Roll Hall of Fame.) But, Wells told CNN, it was record buyers who made the individual songs popular.
"We never released a single. We released albums," he said. "The public picked the singles."
Wells is survived by Mary, his wife of 50 years, two daughters and five grandchildren.