Both injuries occurred during Monday's practice. The 49ers are in their third and final week of organized team activities. The team will hold a mandatory three-day minicamp next week.
With Trent Williams absent, Skule had been starting in practice. He looked to be the 49ers' top backup to Williams and Mike McGlinchey during the upcoming season.
Shon Coleman could become the top candidate to replace Skule. Coleman opted out of last season due to COVID concerns after missing the 2019 season due to a broken fibula and ankle injury. He has not appeared in a regular-season game since the 49ers traded for him on August 31, 2018.
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"He's been here a lot this offseason, and he's really looking good, just out in workouts, which we'll see once we get on the field," general manager John Lynch said of Coleman in May. "But Shon's doing a nice job. We're pleased with that."
Moore had been starting in place of Jaquiski Tartt, who is dealing with a toe injury. San Francisco signed veteran safety Tony Jefferson on Monday.
The 49ers had already lost backup running back Jeff Wilson Jr. to what has been described as a "substantial" torn meniscus. He may not return until November.
Players will hit the practice field again today at noon, with offensive coordinator Mike McDaniel and select players scheduled to speak with reporters after the session.
San Francisco made Skule a sixth-round draft pick out of Vanderbilt in 2019. He has appeared in 31 games with 12 starts in his two seasons. The 49ers made Moore a third-round pick out of Southern Miss in 2018. He has appeared in all 48 games over the past three seasons, starting 13.
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