The mandatory reduction to 53-man active rosters Saturday provides an opportunity to pass along average age ranks for NFL active rosters overall as well as for offense, defense and specialists.

2013 Age Ranks: Active Rosters, Aug. 31

The chart shows the Detroit Lions as the oldest team and the St. Louis Rams as the youngest. Where the Rams rank comes as no surprise if you've been following their building process in the NFC West recently.

The Seattle Seahawks rank among the younger teams overall. They have the youngest offensive players after releasing fullback Michael Robinson.

The rankings exclude players placed on various reserve lists (physically unable to perform, non-football injury, injured and suspended). Note also that rankings are based on ages calculated to the day, not rounded backward to the nearest birthday. A player born in January will be older than a player born in October of the same year, for example. I've taken into account the difference in making these calculations. Rounding backward to the nearest birthday shaves about a half-year off the average ages.

I've shaded the NFC West teams in the chart for easier reference.

While the Arizona Cardinals did part with older players such as Adrian Wilson, they still have veteran flavor with Yeremiah Bell, John Abraham, Carson Palmer, Darnell Dockett, Daryn Colledge, Larry Fitzgerald and the NFL's oldest specialists.

Seattle got younger by releasing Robinson and 36-year-old cornerback Antoine Winfield. No player on the active roster has had his 32nd birthday. By comparison, six San Francisco 49ers are at least 32 years old.

The 49ers parted with 36-year-old long snapper Brian Jennings, 33-year-old Kassim Osgood and 33-year-old Seneca Wallace. They also added some veteran players this offseason, including Anquan Boldin, Phil Dawson, Nnamdi Asomugha and Adam Snyder. Asomugha and 32-year-old Carlos Rogers help give the 49ers the NFL's oldest defensive backs by average age. We should expect the team to get younger there over the next year, possibly by using an early draft choice for a cornerback.

Note: I have not visited courthouses to pull birth records for NFL players. Neither have teams. As someone who has tracked dates of birth for NFL players since 2007, I know there are times when listed birth dates change or conflict with records listed elsewhere. I make efforts to verify the dates. The team rankings at the extremes are more valuable than the ones in the middle because there is very little difference in average age for some teams.