Temporal range: Middle Cambrian
|Reconstruction of Haplophrentis|
Haplophrentis was a tiny shelled hyolithid which lived in the Cambrian Period. Its shell was long and conical, with the open end protected by an operculum, from which two fleshy arms called helens protruded at the sides. These arms probably acted as stabilisers, or were used for locomotion, rowing the animal across undersea mudflats.
Haplophrentis ranged in length between 2–6 cm.[verification needed] It is distinguished from Hyolithes by the presence of a longitudinal septum on the middle of the inner surface of the top of the shell.
The hyolithids are thought to belong to the molluscan total-group, although this is uncertain.
Specimens of Haplophrentis have been found in the gut of the predator Ottoia.
- "Haplophrentis carinatus". Burgess Shale Fossil Gallery. Virtual Museum of Canada. 2011.
- "Haplophrentis". Smithsonian Institution.
- Babcock, L. E.; Robison, R. A. (1988). "Taxonomy and paleobiology of some Middle Cambrian Scenella (Cnidaria) and Hyolithids (Mollusca) from western North America". University of Kansas Paleontological Contributions 121: 1–22. hdl:1808/3638.
- Wotte, T (2006). "New Middle Cambrian molluscs from the Láncara Formation of the Cantabrian Mountains (north-western Spain)". Revista Española de Paleontología 21 (2): 145–158.
- Caron, J. -B.; Jackson, D. A. (October 2006). "Taphonomy of the Greater Phyllopod Bed community, Burgess Shale". PALAIOS 21 (5): 451–465. doi:10.2110/palo.2003.P05-070R.
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