Carbactinoceratidae is a family of extinct cephalopods with external shells that lived around 325 million years ago, during the Carboniferous period.

One specimen of the carbactinoceratid species Rayonnoceras solidiforme, recently found in Arkansas, was measured at 2.5 metres (8.2 ft) long.

The first siphuncle segment is elongated, subsequent ones formed during growth of the animal are subglobular (rounded but not spherical).

Organic deposits are formed within the siphuncle through which run central, and radial canals along with a seam along the connecting rings known as a perispatium.

[5] Furthermore, carbactinoceratids share key characters from the early development of pseudorthocerids missing from actinocerids.