Ok, lets have a look at this: Over the last few days a new paper in Science has led to MANY discussions in the paleo community and it appears to have breached containment into the wider world, judging by headlines and google results.
"Earliest octopuses were giant top predators in Cretaceous oceans" by Ikegami et. al describes a new beak of the basal octopus genus Nanaimoteuthis. And yeah, it's a whopper! Just look at the specimen next to a giant squid beak in this figure! They also note that...
...beak shows some intense, asymmetrical wear, indicating a lot of hard objects being processed by this beak. On top of that they assign the genus to the group Cirrata (finned octopuses and relatives) instead of Vampyromorpha as it was in past papers. This is were the hard facts end though.
Don't get me wrong: This must have been a huge animal, but I also think that anything beyond this is purely speculative. The authors give a total length of 7 to 19 meters, an enormous range, with an estimated mantle length of max 4.4 m. They base this on the proportions of finned octopuses and other close relatives but I would argue that is just math for the sake of math. We know VERY little about early octopuses. Their beaks are often the only thing preserved and their diversity in the Cretaceous remains murky.
That's the size part, what I have an actual problem with though is the way they deduce behavior, died and even cognition from this fossil. Based on the size, wear and asymmetry they propose that this animal would compete, maybe even hunt large marine reptiles, in a smart way.
That's plain bullshitting in my eyes. Intense wear on a beak suggests this animal would be durophagous, going after armored or hard shelled prey. cracking the bones of marines reptiles feels very contrived and modern day octopuses (that often eat crabs) don't look much different.
The asymmetry of the beaks is an interesting detail but I would NEVER derive an argument for higher cognition from that. Cognitive abilities are next to impossible to grasp from the fossil record even IF you have the brain. Which leaves the question what was this guy doing?
Short answer is: we don't know. As I hopefully illustrated here we have simply too few data points to make any concrete arguments for this animals appearance or lifestyle. HOWEVER
As people pointed out on Discord: crushing shells in an pelagic habitat is something that was a breeze in the Mesozoic. Ammonites in the cretaceous come in many different shapes but also sizes. 50 cm plus species are not rare.
We also know from the Jurassic there were likely other cephalopods that went after ammonites. So if the ammonites grew in the Cretaceous why shouldn't their predators as well? Beyond ammonites the Late Cretaceous also gave rise to a large to gigantic bivales like many inoceramids
This abundance of durophagous prey is also reflected in the predators, large sharks, mosasaurs and even giant chimeras took advantage of this plentiful food source. I therefore think a large ammonite predator is a much more likely niche for Nanaimoteuthis.
In my interpretation I pair the octopus with the giant ammonite Parapuzosia, these animals aren't known from the same localities but their time ranges overlap which makes it plausible to me that these guys, or close relatives, could have met.
Lastly I want to quickly talk about the promotion and reception of this publication. While I don't completely fault the authors for their writing - after all LOOK AT THE MODERN ACADEMIC CLIMATE - I do think it's troubling that the editor's note, the journal itself, immediately evokes the image of the Kraken, a mythological creature, to sell it's new paper. This in combination with Science being a high profile journal makes it feel as if the claims in this publication are standing on more solid ground than they do. This is just my personal opinion but I think this is just bad science communication. It is something that will echo through the online sphere for years to come and does not in any way promote the caution that I would expect when claims like these are presented. Subsequently the ideas and evocative speech of the paper have already spawned a large amount of paleoart that goes for the largest and most speculative sides of it. Again: I think the size estimates in the paper are certainly possible, but I also think a more critical examination of the text is warranted when presented with such incredible claims. I am not here to kill your fun. But I also think that we are maybe looking at something even more interesting that the (at this point) already rather old trope of the mosasaur eating squid. At least to me a giant mollusk eats mollusk world is cooler.
AS ALWAYS, these are simply my opinions on these matters, but I thought there was enough uncritical yay and nay saying about this paper that I felt like it should warrant a reaction. I think the paper describes fascinating material and I eagerly await more!