Is the megaraptor’s fortitude saving throw correct?

I’m trying to understand if this is an error or is there something I’m missing?

According to the System reference document a megaraptor Fort save is +10.

As an 8 hit dice animal its base save is +6 because Fort is a Good save for it and it gains a +5 bonus on its Fort save due to its Con of 21, therefore its total Fort save bonus should be +11.

Edit: I also checked the D&D 3.5 Monster Manual errata and I notice the megaraptor is amended however nothing I can find resolves this particular issue.