Publication Date:
2020
Description:
〈span〉〈div〉Abstract〈/div〉Nectocaridids are soft-bodied Cambrian organisms that have been controversially interpreted as primitive cephalopods, at odds with the long-held belief that these mollusks evolved from a shell-bearing ancestor. Here, I document a new nectocaridid from the Whetstone Gulf Formation, extending the group’s range into the Late Ordovician. 〈span〉Nectocotis rusmithi〈/span〉 n. gen. n. sp. possesses a robust internal element that resembles a non-mineralized phragmocone or gladius. Nectocaridids can be accommodated in the cephalopod total group if the earliest cephalopods (1) inherited a non-mineralized shell field from the ancestral mollusk; and (2) internalized this shell field. This evolutionary scenario would overturn the traditional ectocochleate, 〈span〉Nautilus〈/span〉-like reconstruction of the ancestral cephalopod, and indicate a trend towards increased metabolic efficiency through the course of Cambrian–Ordovician evolution.UUID: http://zoobank.org/ed594200-37b9-4642-bd8f-4fb72dc544eb〈/span〉
Print ISSN:
0022-3360
Electronic ISSN:
1937-2337
Topics:
Geosciences
