''Alienum'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

animal of uncertain affinities from the late

Ediacaran The Ediacaran ( ) is a geological period of the Neoproterozoic geologic era, Era that spans 96 million years from the end of the Cryogenian Period at 635 Million years ago, Mya to the beginning of the Cambrian Period at 538.8 Mya. It is the last ...

. Estimated to be about 541 million years old, the

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

, ''A. velamenus'' demonstrates some anatomical characters reminiscent of

vetulicolia Vetulicolia is a group of bilaterian marine animals encompassing several extinct species from the Cambrian, and possibly Ediacaran, periods. As of 2023, the majority of workers favor placing Vetulicolians in the stem group of the Chordata, but ...

ns, predating the first undisputed member of this clade by 20 million years. It was described in 2024 based on a specimen from the Dengying Formation of South China.

Discovery and naming

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 of ''Alienum'' was found in the Dengying Formation of South China in 2021 during an expedition finding fossils of the ribbon-like '' Rugosusivitta'' from younger

Cambrian The Cambrian ( ) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordov ...

strata, and was officially described in 2024. The generic name ''Alienum'' is derived from the English word ''Alien'', which further derives from the

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

word ''aliēnus'', meaning "exotic/foreign". The specific name ''velamenus'' is derived from the Latin word ''velamen'', meaning "veil/sail-like", relating to the sail-like shape of the anterior of the body.

Description

''Alienum velamenus'' seems to share certain features seen in Vetulicolia, but not to the extent to allow for a proper assignment to the clade, as several defining vetulicolian features are absent. It has a rounded body in length, with the dorsal and ventral sides of the body being much thicker, suggesting it may have been soft-bodied with a cavity in the middle. The anterior part features two notches, a small arched notch further up with an unknown use, and a much deeper notch further down, suspected to be the mouth, with a little 'cashew' shaped flap nearby. Along the length of the body there is a long stripe/groove, which can be compared to the pharyngeal groove structure of vetulicolians, although in the case of ''Alienum'', this extends diagonally backwards, whilst in vetulicolians, this is an axial groove. Along this grove are three gill-like structures with large gill slits extending dorsally and ventrally through them, similar again to Vetulicolians, although they have five gill-like holes and gill slits. The posterior body features a stalk-like structure, around in length, similar to a tail. Although it has many similarities to vetulicolians, it lacks a few important features, including dorsal fin-like structures, a hard chitinous body, and a lack of lobes before the body, as well as being different in geological age. As such, it would be very primitive if its affinities lie within vetulicolia, and would support current molecular clock studies on deuterostomes if they are correct.

References

{{Taxonbar, from=Q131731727 Ediacaran life Fossils of China Enigmatic prehistoric animal genera Fossil taxa described in 2024 Vetulicolia

Discovery and naming

Description

See also

References