Archotuba
{{Short description|Genus of fossil tubes}}
{{Speciesbox
| fossil_range = 518
| genus = Archotuba
| species = elongata
| authority = Hou et al 1999
| synonyms = Archotuba conoidalis
}}
Archotuba is a genus of elongated conical tubes that were seemingly deposited by colonial organisms. Known from the Chengjiang, its biological affinity is uncertain; it somewhat resembles the tubes of the 'priapulid' Selkirkia, but a cnidarian affinity is also possible.{{Cite book|url=https://books.google.com/books?id=NBP4bvxp1loC&q=Archotuba+conoidalis&pg=PA14|title=Nematomorpha, Priapulida, Kinorhyncha, Loricifera|isbn=9783110272536|last1=Schmidt-Rhaesa|first1=Andreas|date=2012-12-21|publisher=Walter de Gruyter }} In the absence of soft parts, there is insufficient data to confirm a biological affiliation.{{Cite book|url=https://books.google.com/books?id=LZD-MQtfMt0C&q=Archotuba+conoidalis&pg=PA72 | title=Genus Archotuba Hou, Bergström, Wang, Feng, Chen, 1999| isbn=9780470999943| last1=Xianguag| first1=Hou| last2=Aldridge| first2=Richard J.| last3=Bergstrom| first3=Jan| last4=Siveter| first4=David J.| last5=Siveter| first5=Derek J.| last6=Feng| first6=Xiang-Hong| date=15 April 2008| publisher=John Wiley & Sons}}
''Archotuba elongata''
The extinct species Archotuba elongata is a debated priapulid from the Early Cambrian,{{Cite web|url=http://www.fossilmuseum.net/Fossil_Sites/Chengjiang.htm|title=Chengjiang Maotianshan Shales|website=www.fossilmuseum.net|access-date=2018-12-03}} discovered by Luo and Hu in 1999. Recorded only in the Chengjiang Biota of Yunnan Province, this species was initially found to be part of the phylum Priapulida, but some have raised the question that A. elongata may be related to the cnidarians.{{Cite book|title=The Cambrian fossils of Chengjiang, China : the flowering of early animal life|others=Hou, Xianguang.|isbn=9781118896310|edition= Second|location=Chichester, West Sussex|oclc=970396735|last1 = Xian-Guang|first1 = Hou|last2=Siveter|first2=David J.|last3=Siveter|first3=Derek J.|last4=Aldridge|first4=Richard J.|last5=Pei-Yun|first5=Cong|last6=Gabbott|first6=Sarah E.|last7=Xiao-Ya|first7=Ma|last8=Purnell|first8=Mark A.|last9=Williams|first9=Mark|date=2017-03-08}} In fact, due to the lack of soft body preservation, not only does confusion remain as to the placement of A. elongata, another described species, Archotuba conoidalis, has been found to be a synonym of A. elongata.{{Cite book|title=Gastrotricha, Cycloneuralia, and Gnathifera. Volume 1, Nematomorpha, Priapulida, Kinorhyncha, Loricifera|date=2013|publisher=De Gruyter|others=Schmidt-Rhaesa, Andreas.|isbn=9783110272536|location=Berlin|oclc=834618851}}
The available specimens consist of hundreds of compressed tubes, white with some rust-colored blotches, each in shape a long cone at most 5 cm in length and 6 mm in width. The posterior is pointed, but save for a few rare annulations, the fossil is unadorned. The creature's intestine is visible along its midline, and its dark color may indicate a carnivorous nature.{{Cite journal|last1=Han|first1=Jian|last2=Zhang|first2=Zhifei|last3=Liu|first3=Jianni|last4=Shu|first4=Degan|date=2007|title=Evidence of Priapulid Scavenging from the Early Cambrian Chengjiang Deposits, Southern China|journal=PALAIOS|volume=22|issue=6|pages=691–694|jstor=27670470|doi=10.2110/palo.2006.p06-117r|bibcode=2007Palai..22..691H|s2cid=86584623}} The habits of A. elongata are disputable: a popular explanation is that because this species is often found fixed to other creatures, and even clustered together with its own kind in similar orientations, it perhaps did not move, highly unlike the current understanding of priapulids. However, if indeed they were sedentary like the cnidarians, no tentacles have been preserved to support such a conjecture.
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