The journal Paleontology has an interesting paper describing three new species of fossil octopi. The new fossils date to the Upper Cenomanian (the Cenomanian is part of the Cretaceous and dates to ~99-93 MYA). The paper can be found here.
The preservation was quite good, so here is one of the fossils:
TEXT-FIG. 3. Keuppia levante sp. nov. from the Upper Cenomanian (Metoicoceras geslinianum Zone) of Haˆdjoula (Lebanon). A, holotype (MSNM i26320a+b), photographs taken with UV light of part and counterpart have been put on top of each other to demonstrate the extraordinary preservation of musculature, ·0.5. B, close-up of A to show the right ventrolateral (right hand) and dorsolateral (left hand) arm. The inner surface of the ventrolateral arm bears two longitudinal rows of circular suckers, ·1.5. C, closeup of A to show the anterior part of the mantle sac. The series of lappet-like staining in the lateral mantle are interpreted as outer gill lamellae, ·1.5. D, close-up of A to show the posterior part of the mantle sac and the bipartite gladius vestige.
The authors argue that the morphology presented by the two Keuppia, particularly of the gladius – seen in D above – suggests that octobrachia (a superorder that contains both the Octopoda and the Vampyromorphida) evolved from the “…loligosepiid vampyropods; instead from teudopseids.”
For further reading you can go here and here.
The third species discovered:
Styletoctopus annae sp. nov. shows that the Recent family Octopodidae already existed in Mesozoic times. Particularly, the strongly reduced gladius vestige morphology is very similar to modern benthic octopod genera Enteroctopus, Bentoctopus and Eledone, indicating an Early Cretaceous or even Jurassic origin of the Octopoda.