Yilingia

{{Short description|Species of worm-like animal}} {{Speciesbox | fossil_range = Ediacaran {{fossil range|551|539}} | image = | image_caption = | display_parents = 3 | genus = Yilingia | species = spiciformis | authority = Chen ''et al.'' 2019 }}

'''''Yilingia spiciformis''''' is a worm-like animal that lived between approximately 551 million and 539 million years ago in the Ediacaran period, around 10 million years before the Cambrian explosion. A fossil of this creature and its tracks were discovered in 2019 in Southern China.<ref name=Liu>{{cite journal |doi = 10.1038/s41586-019-1522-7|pmid = 31485079|title = Death march of a segmented and trilobate bilaterian elucidates early animal evolution|journal = Nature|volume = 573|issue = 7774|pages = 412–415|year = 2019|last1 = Chen|first1 = Zhe|last2 = Zhou|first2 = Chuanming|last3 = Yuan|first3 = Xunlai|last4 = Xiao|first4 = Shuhai| bibcode=2019Natur.573..412C }}</ref> It was a segmented bilaterian, conceivably related to panarthropods or annelids. It is a rare example of a complex Ediacaran animal that is similar to animals that existed since the Cambrian, hence suggesting that perhaps the Cambrian explosion was less sudden than often assumed.

== Discovery and naming ==

The holotype fossil, alongside 34 more fossils, of ''Yilingia'' were found in the Dengying Formation of South China, and described in 2019.<ref name=Liu/>

The generic name ''Yilingia'' is derived from the Latinised place name of Yiling, a district in the city of Yichang in China near to where the fossils were found. The specific name is derived from the Latin words ''spīca'', meaning "spike", relating to the spiky lateral lobes of the animal; and 'formis', to mean 'form'.<ref name=Liu/>

== Description ==

''Yilingia spiciformis '' has an elongated body, sometimes up to {{cvt|270|mm|1}} in length, which is made up of individual segments.<ref name=Liu/> These segments are metameric, with each metamere having three lobes, like later trilobites,<ref>{{Cite web | url=https://www.science.org/content/article/ancient-wormlike-animal-caught-its-tracks-sheds-light-early-locomotion |title = Ancient wormlike animal caught in its tracks sheds light on early locomotion|date = 2019-09-03}}</ref> with the outer two lateral lobes been spiky in appearance, and tucked beneath the central lobes. The body also starts off wide at the posterior end, and tapers inwards towards the anterior end of the body.<ref name=Liu/>

Some specimens have also been found at the end of trace fossils, suggesting that the animal was capable of movement, and also helped to understand which end was the posterior and which the anterior.<ref name=Liu/><ref name=cnn>{{cite news|url=https://www.cnn.com/2019/09/05/us/550-million-year-old-worm-scn-trnd/index.html|title=A 550-million-year-old worm was one of the first animals to move and make decisions, a new study says|first=Scottie|last=Andrew|work=CNN|date=September 5, 2019}}</ref> These trace fossils make ''Yilingia'' one of the first and possibly the oldest known true animals to be capable of making decisions and moving on its own.<ref name=cnn/>

Although the recent discovery of Uncus, which is found in the older Flinders Ranges in South Australia, changes this, as it may be related to the Ecdysozoa, which could make ''Yilingia'' the second oldest known true animal capable of moving on its own.

==See also== * List of Ediacaran genera

==References== {{Reflist}}

Category:Ediacaran life †