View source for Yohoia

{{Short description|Extinct genus of arthropods}}
{{Automatic taxobox
| image = 20191020 Yohoia tenuis.png
| image_caption = Life restoration of ''Y. tenuis''
| image2 = 20210701 Yohoia tenuis great appendage mobility.gif
| image2_caption = The suggested movement of the great appendage of ''Y. tenuis''
| fossil_range = {{fossil range|Middle Cambrian}}
| display_parents = 4
| grandparent_authority = Simonetta & Delle Cave, 1975
| parent_authority = Henriksen, 1928
| taxon = Yohoia
| authority = [[Charles Doolittle Walcott|Walcott]], 1912
| subdivision_ranks = Species
| subdivision = {{species list
|Y. tenuis|Walcott, 1912
|Y. utahana|Conway Morris ''et al.'', 2015<ref name=ConwayMorris2015>{{Cite journal |last1=Morris |first1=Simon Conway |last2=Selden |first2=Paul A. |last3=Gunther |first3=Glade |last4=Jamison |first4=Paul G. |last5=Robison |first5=Richard A. |date=2015 |title=New records of Burgess Shale-type taxa from the middle Cambrian of Utah |journal=Journal of Paleontology |language=en |volume=89 |issue=3 |pages=411–423 |doi=10.1017/jpa.2015.26 |bibcode=2015JPal...89..411C |s2cid=55050961 |issn=0022-3360|doi-access=free }}</ref>}}
}}
'''''Yohoia''''' is an extinct genus of [[Megacheira|megacheiran]] arthropod from the [[Cambrian]] period that has been found as [[fossil]]s in the [[Burgess Shale]] formation of [[British Columbia]], Canada. The type species, ''Yohoia tenuis'', was described in 1912 by [[Charles Doolittle Walcott|Walcott]], who considered it an [[anostraca]]n crustacean. 711 specimens of ''Yohoia'' are known from the Greater [[Phyllopod bed]], where they comprise 1.35% of the community.<ref name=Caron2006>{{cite journal|last1=Caron |first1=Jean-Bernard|last2=Jackson |first2=Donald A.|title=Taphonomy of the Greater Phyllopod Bed community, Burgess Shale|journal=PALAIOS |volume=21 |issue=5 |pages=451–65|date=October 2006|doi=10.2110/palo.2003.P05-070R|jstor=20173022|bibcode=2006Palai..21..451C |s2cid=53646959 }}</ref> In 2015, [[Simon Conway Morris|Conway Morris]] ''et al.'' reported another species, ''Y. utahana'', from the [[Marjum Formation]], Utah.<ref name="ConwayMorris2015"/>
== Description ==
[[File:20210328 Yohoia tenuis great appendage.png|thumb|left|''Yohoia tenuis'' has two [[Polymorphism (biology)|morphotypes]],<ref>{{Cite journal |last1=Haug |first1=Joachim T. |last2=Waloszek |first2=Dieter |last3=Maas |first3=Andreas |last4=Liu |first4=Yu |last5=Haug |first5=Carolin |date=2012 |title=Functional morphology, ontogeny and evolution of mantis shrimp-like predators in the Cambrian: MANTIS SHRIMP-LIKE CAMBRIAN PREDATORS |journal=Palaeontology |language=en |volume=55 |issue=2 |pages=369–399 |doi=10.1111/j.1475-4983.2011.01124.x|s2cid=82841481 |doi-access=free }}</ref> a common feature seen in several arthropods of the Burgess Shale|310px]]
Fossil specimens of ''Yohoia'' range in size from 7 to 23&nbsp;mm, they have a head shield which is followed by 13 trunk [[tergites]], or plates. On both sides, the bottom side of the first 10 of these ended in backward-pointing, triangular points or projections. The last three plates were complete tubes, circling the entire trunk. At the end of the trunk was a paddle-like tail. There were also a pair of large extensions at the front of the head shield. They had a pronounced "elbow" and ended in four long spines, looking rather like fingers. There were three appendages on the bottom of the head shield on each side, and these are assumed to have supported the creature on the sandy or silty sea bottom. There were also single appendages hanging down under the body plates which were flap-like and fringed with setae, probably used for swimming and [[Respiration (physiology)|respiration]]. Specimens also show some bulbous formations at the front of the head shield that may have served as eyes.<ref>Briggs, Derek; Erwin, Douglas; Collier, Frederick. ''The Fossils of the Burgess Shale''. Smithsonian Books (1994).</ref>
== Classification ==
''Yohoia'' is one of the "[[great appendage]]" arthropods. All taxa have a single pair of large pre-oral jointed limbs  with branched spiny ends for grasping, impaling, or filtering food items. "Great appendage" arthropods have been seen as a [[polyphyletic]] group where the appendage has independently evolved, or as a class [[Megacheira]] including ''Yohoia'' (with ''[[Leanchoilia]]'', ''[[Alalcomenaeus]]'', ''[[Oestokerkus]]'', ''[[Fortiforceps]]'', ''[[Jianfengia]]'', ''[[Yawunik]]'') defined as euarthropods, plus the [[Radiodonta|radiodonts]], defined as a sister group to arthropods. ''Yohoia-''like genera are small and have biramous limbs with a walking segment, while radiodonts are larger animals without limbs except for the great appendage. (Although biramous limbs have been described in the Devonian radiodont ''[[Schinderhannes bartelsi|Schinderhannes]]'',<ref>{{Cite journal|last1=Kühl|first1=Gabriele|last2=Briggs|first2=Derek E. G.|last3=Rust|first3=Jes|date=2009-02-06|title=A Great-Appendage Arthropod with a Radial Mouth from the Lower Devonian Hunsrück Slate, Germany|journal=Science|language=en|volume=323|issue=5915|pages=771–773|doi=10.1126/science.1166586|issn=0036-8075|pmid=19197061|bibcode=2009Sci...323..771K |s2cid=47555807 }}</ref> this interpretation is highly questioned and it is more likely to be bands of gill lamellae instead.<ref>{{Cite journal |last1=Moysiuk |first1=Joseph |last2=Caron |first2=Jean-Bernard |date=2022-07-08 |title=A three-eyed radiodont with fossilized neuroanatomy informs the origin of the arthropod head and segmentation |journal=Current Biology |volume=32 |issue=15 |pages=3302–3316.e2 |language=en |doi=10.1016/j.cub.2022.06.027 |pmid=35809569 |s2cid=250361698 |issn=0960-9822|doi-access=free }}</ref>)
== Ecology ==
''Yohoia'' is assumed to have been a mainly benthic (bottom-dwelling) creature that swam just above the muddy ocean floor, using its appendages to scavenge or capture prey.
== See also ==
* [[Paleobiota of the Burgess Shale]]
==References==
{{Reflist}}
== External links ==
* [http://burgess-shale.rom.on.ca/en/fossil-gallery/view-species.php?id=135 "Yohoia tenuis"]. Burgess Shale Fossil Gallery. Virtual Museum of Canada. 2011. (Burgess Shale species 135)
{{Megacheira}}
{{Taxonbar|from=Q135578}}
[[Category:Burgess Shale fossils]]
[[Category:Megacheira]]
[[Category:Prehistoric arthropod genera]]
[[Category:Burgess Shale animals]]
[[Category:Taxa named by Charles Doolittle Walcott]]
[[Category:Cambrian arthropods]]
[[Category:Cambrian genus extinctions]]
[[Category:Fossil taxa described in 1912]]