Our official English website, www.x-mol.net, welcomes your
feedback! (Note: you will need to create a separate account there.)
Restudy of some plectronocerid nautiloids (Cephalopoda) from the late Cambrian of China; discussion on nautiloid evolution and origin of the siphuncle
GFF ( IF 1.2 ) Pub Date : 2020-04-02 , DOI: 10.1080/11035897.2020.1739742 Harry Mutvei 1
GFF ( IF 1.2 ) Pub Date : 2020-04-02 , DOI: 10.1080/11035897.2020.1739742 Harry Mutvei 1
Affiliation
ABSTRACT The sub-class Nautiloidea is divided into two super-orders, Nautilosiphonata and Calciosiphonata, based on different structural types of the connecting rings. The late Cambrian order Plectronocerida has the calciosiphonate type of connecting ring similar to that in post-Cambrian orthocerids. It is structurally more complex than the nautilosiphonate connecting ring in late Cambrian ellesemerocerid-like nautiloids. The plectronocerid nautiloids, therefore, evolved from the ellesmerocerid-like nautiloids and not vice versa. As indicated by the complex siphuncular structure in plectronocerids, cephalopod evolution began earlier than previously estimated, probably in the early Cambrian. The siphuncle in cephalopods originated from a calcareous septum that became partially non-calcified and formed the connecting ring.
更新日期：2020-04-02
京公网安备 11010802027423号