''Syllipsimopodi'' is an extinct member of the

cephalopod A cephalopod is any member of the molluscan Taxonomic rank, class Cephalopoda (Greek language, Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral symm ...

subclass

Coleoidea Coleoidea or Dibranchiata is one of the two subclasses of cephalopod molluscs containing all the various taxa popularly thought of as "soft-bodied" or "shell-less" (i.e. octopus, squid and cuttlefish). Unlike its extant sister group Nauti ...

originally interpreted to belong to the clade

Vampyropoda Octopodiformes is a superorder of the subclass Coleoidea, comprising the octopuses and the vampire squid. All living members of Octopodiformes have eight arms, either lacking the two tentacles of squid (as is the case in octopuses) or modifying t ...

, which includes

octopuses An octopus (: octopuses or octopodes) is a soft-bodied, eight-limbed Mollusca, mollusc of the order (biology), order Octopoda (, ). The order consists of some 300 species and is grouped within the class Cephalopoda with squids, cuttlefish, ...

(Octopoda) and vampire squids (Vampyromorphida). The

type Type may refer to: Science and technology Computing * Typing, producing text via a keyboard, typewriter, etc. * Data type, collection of values used for computations. * File type * TYPE (DOS command), a command to display contents of a file. * ...

and only known species is ''Syllipsimopodi bideni'', named in honor of US President

Joe Biden Joseph Robinette Biden Jr. (born November 20, 1942) is an American politician who was the 46th president of the United States from 2021 to 2025. A member of the Democratic Party (United States), Democratic Party, he served as the 47th vice p ...

, and to raise awareness of his climate change policies. The

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

fossil was found in the

Bear Gulch Limestone The Bear Gulch Limestone is a limestone-rich Lens (geology), geological lens in central Montana, renowned for the quality of its marine fossils from the late Mississippian (geology), Mississippian subperiod, about 324 million years ago. It is expo ...

deposit in the US state of

Montana Montana ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States. It is bordered by Idaho to the west, North Dakota to the east, South Dakota to the southeast, Wyoming to the south, an ...

in 1988, and donated that year to the

Royal Ontario Museum The Royal Ontario Museum (ROM) is a museum of art, world culture and natural history in Toronto, Ontario, Canada. It is one of the largest museums in North America and the largest in Canada. It attracts more than one million visitors every year ...

by B. Hawes, designated ROMIP 64897. The species lived during the (

Carboniferous The Carboniferous ( ) is a Geologic time scale, geologic period and System (stratigraphy), system of the Paleozoic era (geology), era that spans 60 million years, from the end of the Devonian Period Ma (million years ago) to the beginning of the ...

)

Mississippian Mississippian may refer to: * Mississippian (geology), a subperiod of the Carboniferous period in the geologic timescale, roughly 360 to 325 million years ago * Mississippian cultures, a network of precontact cultures across the midwest and Easte ...

subperiod, 330.3 to 323.4 million years ago, pushing back the group of

cephalopods A cephalopod is any member of the molluscan Taxonomic rank, class Cephalopoda (Greek language, Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral symm ...

by 81.9 million years.

Taxonomy

A subsequent study doubted the assignment of ''Syllipsimopodi'' to Vampyropoda and suggested it to be a junior synonym of '' Gordoniconus beargulchensis''. The original authors still consider it to be a separate genus and species but suggested further analyses might be needed to firmly place it in Vampyropoda.

Description

Individuals were long and had 10 arms with suckers, with two of the arms being longer than the others. It is currently considered the oldest known vampyropod by some but certainly the oldest known cephalopod with biserial suckers on its ten robust appendages. The lead author of ''S. bideni'' states that it is possibly the only known vampyropod - if it really can considered one - that has 10 functional appendages, with all other species having eight arms, suggesting that their

ancestors An ancestor, also known as a forefather, fore-elder, or a forebear, is a parent or ( recursively) the parent of an antecedent (i.e., a grandparent, great-grandparent, great-great-grandparent and so forth). ''Ancestor'' is "any person from w ...

had ten arms. The arms measure to about ~2.1 to 2.4 mm wide at the midlength. Two of the arms measure in at ~4.0 to 4.1 cm long, making up 27% of the total body length. The elongated arms do not have obvious manus and are thinner than the other arms. The suckers are based along the midlength and are ~0.62 mm in diameter and are separated by ~0.5 mm. There is no evidence that the suckers were stalked. A possible funnel measuring ~2.4 mm long was preserved with a lateral edge of the head.

References

Octopodiformes Monotypic prehistoric cephalopod genera Mississippian cephalopods Carboniferous cephalopods of North America Fossils of the United States Fossil taxa described in 2022 {{Paleo-cephalopod-stub