Yanhecerida Explained

Yanhecerida is a small order of Late Cambrian (mid-Stage 10)^[1] nautiloid cephalopods. They were similar to the more diverse Plectronocerida and Ellesmerocerida, with short shells, closely spaced septa, and diaphragms (partitions) within the siphuncle. Their most distinctive trait is the conical shape of the diaphragms, similar to the endocones which characterize the later nautiloid order Endocerida.^{[2] [3]} While some authors have argued that Yanhecerida should be lumped into Ellesmerocerida,^[4] a phylogenetic analysis has maintained that Yanhecerida is a valid clade of early cephalopods closely related to a paraphyletic Ellesmerocerida (and by extension all post-Cambian cephalopods).

Notes and References

1. Fang . Xiang . Kröger . Björn . Zhang . Yuan-Dong . Zhang . Yun-Bai . Chen . Ting-En . 2019-03-01 . Palaeogeographic distribution and diversity of cephalopods during the Cambrian–Ordovician transition . Palaeoworld . Onset of the GOBE . en . 28 . 1 . 51–57 . 10.1016/j.palwor.2018.08.007 . 10138/308817 . 134586179 . 1871-174X. free .
2. Jun-Yuan . Chen . Teichert . Curt . 1983 . Cambrian cephalopods . Geology . 11 . 11 . 647 . 1983Geo....11..647J . 10.1130/0091-7613(1983)11<647:CC>2.0.CO;2.
3. 6 . Pohle A, Kröger B, Warnock RC, King AH, Evans DH, Aubrechtová M, Cichowolski M, Fang X, Klug C . April 2022 . Early cephalopod evolution clarified through Bayesian phylogenetic inference . BMC Biology . 20 . 1 . 88 . 10.1186/s12915-022-01284-5 . 9008929 . 35421982 . free .
4. Mutvei . Harry . 2020-04-02 . Restudy of some plectronocerid nautiloids (Cephalopoda) from the late Cambrian of China; discussion on nautiloid evolution and origin of the siphuncle . GFF . en . 142 . 2 . 115–124 . 10.1080/11035897.2020.1739742 . 2020GFF...142..115M . 219047374 . 1103-5897.