why roast marrow bones at 450F? Many of the recipes for roast marrow bones suggest a short (20min), high temp roast. Are there any reasons to cook them at such a high temperature instead of, say one hour at 350&deg;F?
Bone marrow is made up of a large portion of fat.  If you roast it low and slow, you render out a good portion of that fat and are left with a liquidy mess.  Also the high heat will start to carmelize the bone marrow, providing much flavor.