Yezoteuthis
extinct genus of squids
Yezoteuthis ("Yezo squid") is an extinct genus of very large oegopsid squid that inhabited the seas around Japan in the Late Cretaceous period. It contains a single species, Y. giganteus from the early Campanian Osousyunai Formation of the Yezo Group in Hokkaido. It is possibly the largest fossil coleoid ever described.
Yezoteuthis is known from a single upper jaw that shares close similarities with those of oegopsids, hence its assignment to that order. These jaws are very large, and a comparison to modern squid indicates that Yezoteuthis would have rivalled the extant giant squid (Architeuthis) in size, reaching about 1.7 metres (5.6 ft) in mantle length, and more than 5 metres (16 ft) in total length. Yezoteuthis was likely a major predator of its ecosystem and existed at a high trophic level.
A second set of oegopsid jaws closely resembling those of Yezoteuthis was described from the Yezo Group in 2023, but was found to be even larger and have different proportions of those from Yezoteuthis, indicating that it is a different species, with its genus also remaining uncertain. Yezoteuthis also coexisted with the slightly smaller but still very large oegopsid Haboroteuthis, although it is possible that Haboroteuthis may be conspecific with Yezoteuthis.
The public source identifies “Yezoteuthis” as extinct genus of squids. This brief keeps that definition visible, then builds a research path around Yezoteuthis, extinct and genus.
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Datasets, specimens, observations and peer-reviewed methods provide the appropriate test for the technical claims summarized here. The source revision retrieved here is dated Apr 10, 2026. The linked authority identifier is Q72432251. None of the 0 selected statements returned an explicit reference. The first chronological checks are 2023.
Current terminology should not be projected backward without checking the classification used when the underlying evidence was created. The source lead contains qualifying language; that uncertainty should survive quotation, summary and reuse. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
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This entry incorporates text from “Yezoteuthis” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.