Alienum
 | This article relies largely or entirely on a single source. (January 2025) |
| Alienum Temporal range: Ediacaran
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Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade?: | †Vetulicolia |
| Genus: | †Alienum Liu et al., 2024 |
| Species: | †A. velamenus
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| Binomial name | |
| †Alienum velamenus Liu et al., 2024
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Alienum velamenus is an extinct lifeform from the late Ediacaran, with possible affinities to the Vetulicolia Clade. Estimated to be about 541 million years old, A. velamenus has been identified as possibly being the oldest known Vetulicolian, predating the first known species by 20 Ma. Its fossil was discovered in 2024 from Dengying Formation in South China.[1]
Discovery and name
[edit]The holotype fossil of Alienum was found from the Dengying Formation of South China, and described in 2024.[1]
The generic name Alienum is derived from the English word Alien, which further derives from the Latin 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.[1]
Description
[edit]Alienum velamenus is the first possible Vetulicolian found in the Ediacaran, partially sharing certain features seen in the clade, but not to the extent to allow for a proper assignment to the clade, including several missing features.
It has a rounded body, which grew up to a max of 17.4 mm (1.7 cm), 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 a 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 9 mm long stripe/groove, which can be compared to the pharyngeal groove structure of Vetulicolia, although in the case of Alienum, this extends diagonally backwards, whilst in Vetulicolians, this is a 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 of the body features a stalk-like structure, around 5 mm in length, which is suggested to be the tail.[1]
Although it has many similarities to Vetulicolians, it misses a few important features, including dorsal fin-like structures, a hard chitinous body and no lobes before the body, as well as being different in geological age, showing it is quite clearly more primitive if related to the Vetulicolia clade. [1]