''Ankalodous'' is a Cambrian genus of

chaetognath The Chaetognatha or chaetognaths (meaning ''bristle-jaws'') are a phylum of predatory marine worms that are a major component of plankton worldwide. Commonly known as arrow worms, they are mostly pelagic; however about 20% of the known species ...

from the

Maotianshan Shales The Maotianshan Shales () are a series of Early Cambrian sedimentary deposits in the Chiungchussu Formation or Heilinpu Formation, famous for their '' Konservat Lagerstätten'', deposits known for the exceptional preservation of fossilized orga ...

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

carbonaceous Carbonaceous refers to something relating to, containing, or composed of carbon. It is a descriptor used for the attribute of any substance rich in carbon. Particularly, ''carbonaceous hydrocarbons'' are very unsaturated, high- molecular-weight h ...

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. ''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 The antlions are a group of about 2,000 species of insect in the neuropteran family (biology), family Myrmeleontidae. They are known for the predation, predatory habits of their larvae, which mostly dig pits to trap passing ants or other prey. ...

larva. This fossil was interpreted as transitional between modern chaetognaths and '' Dakorhachis'', however a 2022 study 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 Xi'an is the list of capitals in China, capital of the Chinese province of Shaanxi. A sub-provincial city on the Guanzhong plain, the city is the third-most populous city in Western China after Chongqing and Chengdu, as well as the most populou ...

, the starting point of the

Silk Road The Silk Road was a network of Asian trade routes active from the second century BCE until the mid-15th century. Spanning over , it played a central role in facilitating economic, cultural, political, and religious interactions between the ...

References

{{Taxonbar, from=Q132344651 Cambrian invertebrates Fossils of China Maotianshan shales fossils Chaetognatha Animals described in 2017 Fossil taxa described in 2017 Cambrian genus extinctions