Editing Nectocaris (section)

{{Short description|Extinct animal genus}}
{{Speciesbox
| genus = Nectocaris
| species = pteryx
| fossil_range = {{Fossil range|Cambrian Stage 3|Wuliuan}}
{{Distinguish| Nectocotis}}
| image = Nectocaris pteryx (ROM 60079).jpg
| image_caption = Specimen ROM 60079
| parent_authority = Conway Morris, 1976
| authority = [[Simon Conway Morris|Conway Morris]], 1976
}}

'''''Nectocaris''''' is a genus of squid-like animal of controversial affinities known from the [[Cambrian]] period. The initial fossils were described from the [[Burgess Shale]] of Canada. Other similar remains possibly referrable to the genus are known from the [[Emu Bay Shale]] of Australia and [[Chengjiang Biota]] of China.

''Nectocaris'' was a free-swimming, predatory or scavenging organism. This lifestyle is reflected in its binomial name: ''Nectocaris'' means "swimming shrimp" (from the [[Ancient Greek]] {{lang|el|νηκτόν}}, ''{{lang|el|[[:wikt:nekton|nekton]]}}'', meaning "swimmer" and {{lang|el|καρίς}}, ''{{lang|el|karis}}'', "shrimp"). Two morphs are known: a small morph, about an inch long, and a large morph, anatomically identical but around four times longer.<ref name="Smith2013c">{{cite journal |last=Smith |first=M.R. |year=2013 |title=Nectocaridid ecology, diversity and affinity: Early origin of a cephalopod-like body plan |journal=Paleobiology |volume=39 |issue=2 |pages=291–321 |doi=10.1666/12029 |bibcode=2013Pbio...39..297S |s2cid=85744624}}</ref>

Nectocaridids have controversial affinities. Some authors have suggested that they represent the earliest known [[Cephalopod|cephalopods]]. However, their morphology is strongly dissimilar to confirmed early cephalopods, and thus their affinities to cephalopods and even to [[Mollusca|molluscs]] more broadly are rejected by most authors.<ref name=":0">{{Cite journal |last1=Pohle |first1=Alexander |last2=Kröger |first2=Björn |last3=Warnock |first3=Rachel C. M. |last4=King |first4=Andy H. |last5=Evans |first5=David H. |last6=Aubrechtová |first6=Martina |last7=Cichowolski |first7=Marcela |last8=Fang |first8=Xiang |last9=Klug |first9=Christian |date=December 2022 |title=Early cephalopod evolution clarified through Bayesian phylogenetic inference |journal=BMC Biology |language=en |volume=20 |issue=1 |pages=88 |doi=10.1186/s12915-022-01284-5 |issn=1741-7007 |pmc=9008929 |pmid=35421982 |doi-access=free }}</ref><ref name=":1" /> Their affinities to any animal group beyond [[Bilateria]] are uncertain, though they have been suggested to be members of [[Lophotrochozoa]].<ref name=":1" />

The closely related Ordovician taxon ''[[Nectocotis]]'' is a second genus, closely resembling ''Nectocaris'', but suggested to have had an internal skeletal element.<ref name=Smith2019>{{cite journal |last=Smith |first=Martin R. |year=2019 |title=An Ordovician nectocaridid hints at an endocochleate origin of Cephalopoda |journal=Journal of Paleontology |pages=64–69 |volume=94 |doi=10.1017/jpa.2019.57 |s2cid=201208912 |url=http://dro.dur.ac.uk/28457/1/28457.pdf}}</ref>