Abstract
The trace fossil record implies that large worm-like animals were in place along with the skeletonizing organisms during the initial stage of the Cambrian explosion. Body fossils of large worms, however, have so far not been found. Here, we describe a large, soft-bodied, worm-like organism, Vittatusivermis annularius gen. et sp. nov. from the lowest Cambrian of South China, which is constrained to the Fortunian Age (541–529 Ma) of the Cambrian Period. The elongate body of Vittatusivermis was large enough to have supported organ systems and a fluid skeleton that facilitated peristaltic locomotion, thus allowing for more complex patterns of movement than those of flatworms. Its occurrence on the same bedding surface as trace fossils suggests that Vittatusivermis might have produced epichnial trails and shallow burrows on and within sediments. Therefore, Vittatusivermis is likely to have been one of the long expected producers of trace fossils in the earliest Cambrian.
Highlights
The Cambrian explosion was an evolutionary event of great magnitude, as evidenced by the abrupt appearances of diverse animal lineages in the fossil record during the early Cambrian (~541–509 Ma)[1,2,3,4]
The index fossil Anabarites trisulcatus which was known to range from Beds 2 to 8 in the Baideng section[10] is abundant on the fossil surface (Supplementary Fig. 1b,c)
The presence of horizontal, infaunal traces suggests the presence of vermiform animals with fluid skeletons to facilitate peristaltic locomotion
Summary
The Cambrian explosion was an evolutionary event of great magnitude, as evidenced by the abrupt appearances of diverse animal lineages in the fossil record during the early Cambrian (~541–509 Ma)[1,2,3,4]. Preserved soft-bodied faunas in subsequent Cambrian Epoch 2 (~521–509 Ma) reveal a more complete faunal composition of the Cambrian explosion[7,8]. The presence of large burrows and trails (1 cm or more in diameter) implies that soft-bodied, worm-like animals with a hydrostatic skeleton evolved immediately before the earliest Cambrian. No confirmed body fossils that could have produced such trace fossils have as yet been found before or during the Terreneuvian Epoch, largely because macroscopic soft-bodied faunas are absent from this period. The co-occurrence of trace fossils on the same bedding surface in the immediate vicinity of body fossils as well as specimens interpreted to have been preserved in burrowing position hint that Vittatusivermis annularius might have been an active trace producer. Our finding would provide a potential trace maker of contemporary traces such as Psammichnites
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
