This seems to match the introduced dung beetle Bubas bison except for the matt upper surface; in available images of B. bison - e.g. https://bie.ala.org.au/species/urn:lsid:biodiversity.org.au:afd.taxon:c1108575-d58a-48cd-9daa-87c6d23435b7#gallery - the surface is shiny.
Re-examination of this one. A better match is a female Onthophagus binodis, a southern African species deliberately introduced. https://agriculture.vic.gov.au/support-and-resources/funds-grants-programs/farming-systems-demonstrations-program/onthophagus-binodis