Extent of erosion
Well, the first clue is that there is no upraised rim or obvious ejecta blanket. It would appear that the shattered rock was an easy target for wind erosion in the billion years or so since the original crater was formed (I have no idea how old the crater is - could be anything from 3.5 billion to about 500 million years old).
Everything raised above the Meridiani plain has been stripped away by the winds of time.