Ankalodous

{{Short description|Cambrian genus of chaetognath}} {{Speciesbox | fossil_range = {{fossil_range|Cambrian Stage 3}} | image = | image_caption = | genus = Ankalodous | species = sericus | authority = Shu et al, 2017<ref name=silky>{{cite journal |last1=Shu |first1=Degan |last2=Conway Morris |first2=Simon |last3=Han |first3=Jian |last4=Hoyal Cuthill |first4=Jennifer F. |last5=Zhang |first5=Zhifei |last6=Cheng |first6=Meirong |last7=Huang |first7=Hai |title=Multi-jawed chaetognaths from the Chengjiang Lagerstätte (Cambrian, Series 2, Stage 3) of Yunnan, China |journal=Palaeontology |date=November 2017 |volume=60 |issue=6 |pages=763–772 |doi=10.1111/pala.12325|bibcode=2017Palgy..60..763S }}</ref> }}

'''''Ankalodous''''' is a Cambrian genus of [[chaetognath]] from the [[Maotianshan Shales]] of China. It contains one species, '''''Ankalodous sericus'''''.

''Ankalodous'' is only known from unusual bundles of spines alongside a few plate-like structures. The bundles of spines typically consist of six or seven spines each, although those closer to the mouth have only two to three. These spines are roughly 7 mm long at most, but decrease towards the mouth, likely to enable closing the jaws. While the spines closest to the mouth are essentially straight, the rest are slender, long and slightly recurved with smooth surfaces. These spines seem to be made of a resistant [[wikt:carbonaceous|carbonaceous]] material, likely chitin due to it being used in modern chaetognath jaws. The plate-like structures are located between the spines and also seem to be carbonaceous, however due to the dissimilarity to any Maotianshan Shales fauna they are likely not trapped prey. The location between the spines suggests they may be a cephalic shield, and a similar structure in modern chaetognaths helps protect the area against struggling prey.<ref name=silky/> ''Ankalodous'' was likely predatory, due to its elongate spines. Due to the lack of postcranial material, its habitat is uncertain. If it was benthic, it may have behaved somewhat like an [[antlion]] larva.<ref name=silky/> This fossil was interpreted as transitional between modern chaetognaths and ''[[Dakorhachis]]'',<ref>{{cite journal |last1=Conway Morris |first1=Simon |last2=Smith |first2=Ru D.A. |last3=Cuthill |first3=Jennifer F. Hoyal |last4=Bonino |first4=Enrico |last5=Lerosey-Aubril |first5=Rudy |title=A possible Cambrian stem-group gnathiferan-chaetognath from the Weeks Formation (Miaolingian) of Utah |journal=Journal of Paleontology |date=July 2020 |volume=94 |issue=4 |pages=624–636 |doi=10.1017/jpa.2020.4|bibcode=2020JPal...94..624C |url=http://repository.essex.ac.uk/26923/3/a_benthic_ambush_predator_-_rev_4_JHC_edit.pdf }}</ref> however a 2022 study<ref>{{cite journal |last1=Bekkouche |first1=Nicolas |last2=Gąsiorowski |first2=Ludwik |title=Careful amendment of morphological data sets improves phylogenetic frameworks: re-evaluating placement of the fossil Amiskwia sagittiformis |journal=Journal of Systematic Palaeontology |date=31 December 2022 |volume=20 |issue=1 |pages=1–14 |doi=10.1080/14772019.2022.2109217|url=https://hal.sorbonne-universite.fr/hal-03828531/file/Manuscript_Amiskwia_Bekkouche_and_Gasiorowski_Hall_version_compressed.pdf }}</ref> found Dakorhachis to not be a chaetognath at all.

The genus name ''Ankalodous'' is derived from the words ''ankalos'' "bundle", and ''odous'' "teeth". The species name ''sericus'' translates to "silk", as an oblique reference to [[Xi'an]], the starting point of the [[Silk Road]].<ref name=silky/>

== References == {{reflist}}

[[Category:Cambrian invertebrates]] [[Category:Fossils of China]] [[Category:Maotianshan shales fossils]] [[Category:Chaetognatha]] [[Category:Fossil taxa described in 2017]] [[Category:Cambrian genus extinctions]]