(Reuters) - Three application developers urged a U.S. appeals court on Wednesday to revive their antitrust lawsuit against Facebook over its purchase of WhatsApp and Instagram, arguing the alleged harm they suffered from the deals entitles them to sue. Plaintiffs Reveal Chat HoldCo LLC, USA Technology and Management Services Inc and Beehive Biometric Inc in a court filing told the 9th U.S. Circuit Court of Appeals that their injury means they have legal standing to sue Facebook, now owned by Meta Platforms Inc. The filing from the plaintiffs and a separate one from Facebook"s lawyers also submitted on Wednesday responded to an inquiry from the San Francisco-based 9th Circuit on Jan. 10 over whether the plaintiffs can show how Facebook"s market behavior harmed their businesses. A showing of such harm is part of the early onramp for a case to move forward in court. Courts can dismiss a lawsuit without reaching the merits if a plaintiff is shown to not have standing. Earlier briefs in the case did not address standing, and the appeals court acted on its own to raise the issue with the lawyers. The appeals court has scheduled oral argument for Feb. 17. A California federal judge dismissed the plaintiffs" complaint last year after finding claims were filed too late. The lawsuit seeks to unwind Facebook"s acquisitions of Instagram in 2012 and WhatsApp in 2014. Lawyers for Reveal Chat, Beehive and USA Technology and Management, which does business as the lending services outfit Lenddo, said they "each suffered constitutionally cognizable injury-in-fact—including actual monetary losses and the destruction or crippling of their businesses." Facebook said in its court filing on Wednesday that the application developers" "sole theory of harm from the years-ago acquisitions stacks speculation upon speculation." The company in earlier filings in the appeal called the claims "a laundry list of stale grievances." Plaintiffs" lawyer Brian Dunne of Bathaee Dunne in Los Angeles declined to comment on Thursday. A lawyer for Facebook, Sonal Mehta of Wilmer Cutler Pickering Hale and Dorr, did not immediately respond to a message seeking comment. Facebook is facing an array of antitrust lawsuits from private parties, in addition to state and U.S. government entities. A Washington, D.C., federal judge last week declined to dismiss an antitrust lawsuit the U.S. Federal Trade Commission filed last year. On Jan. 14, a California judge said Facebook must face an antitrust lawsuit from users alleging deceptive data-privacy practices. The case is Reveal Chat HoldCo LLC, et al. v. Facebook Inc, 9th U.S. Circuit Court of Appeals, No. 21-15863. For the plaintiffs: Brian Dunne of Bathaee Dunne and Christopher Burke of Scott+Scott Attorneys For Facebook: Sonal Mehta of Wilmer Cutler Pickering Hale and Dorr, and Mark Hansen of Kellogg, Hansen, Todd, Figel & Frederick