At least the bison age distribution and some discussion of age error brackets are in the Jefferson/Goldin paper, but, with my usual lack of foresight, I failed to read or copy all of it. The part I have does mention that adult females appear to outnumber adult males by 2.5 to 1 - this is based on analysis of horns, so it doesn't apply to juveniles. It also says, with reference to the ages mentioned on this thread, "Juveniles of intermediate ages are very poorly represented in the assemblage."
Quaternary Research is a fairly major journal, I'd think, and should be available at most any state university library. If you can't find it, Christian, I'd be glad to copy the rest and send it to you - you'd just have to email me a fax number or address, or be willing to receive a big image file by email.
The full name of the other journal is
Contributions in Science - Los Angeles County Museum and I thought I got pretty lucky to find that, with issues for many years, too, at Texas Tech. 'Course, they have a pretty active Quaternary research effort there, with Clovis, Badwater Draw, and Yellowhouse Canyon all within a couple of hours' drive.