Epipubic bones

Epipubic bones are a pair of bones which project forward from the pelvic bones of modern marsupials and of some fossil mammals - multituberculates, monotremes, and even eutherians (the ancestors of placental mammals). [cite web | url=http://paleo.amnh.org/bjburger/fossilmammal/ma3.html | title=Marsupials] [Citation | last=Novacek | first=M.J. | last2=Rougier | first2=G.W. | last3=Wible | first3=J.R. | last4=McKenna | first4=M.C. | last5=Dashzeveg | first5=D | last6=Horovitz | first6=I | title=Epipubic bones in eutherian mammals from the late Cretaceous of Mongolia | journal=Nature | volume=389 | issue=6650 | pages=440-441 | year=1997 | url=http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9333234&dopt=Abstract]

In modern marsupials the epipubic bones are often called "marsupial bones" because they support the mother's pouch ("marsupium" is Latin for "pouch"). But their presence on other groups of mammals indicates that this was not their original function, which some researchers think was to assist locomotion by supporting some of the muscles that pull the thigh forwards.cite journal
author=White, T.D.
title=An analysis of epipubic bone function in mammals using scaling theory
journal=Jornal of Theoretical Biology
date=August 9 1989
volume=139
issue=3
pages=343–57
url=http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&uid=2615378&cmd=showdetailview&indexed=google
doi=10.1016/S0022-5193(89)80213-9]

References