Paired pleural disks in Dicaulograptus cumdiscus n. sp.
Article first published online: 9 OCT 2007
Volume 18, Issue 4, pages 361–368, October 1985
How to Cite
FINNEY, S. C. (1985), Paired pleural disks in Dicaulograptus cumdiscus n. sp. Lethaia, 18: 361–368. doi: 10.1111/j.1502-3931.1985.tb00717.x
- Issue published online: 9 OCT 2007
- Article first published online: 9 OCT 2007
- Ordovician graptolites;
- mode of life
A diplograptid graptolite with strongly introverted thecae and unusual thecal processes was isolated from limestones of the Ordovician Pratt Ferry Formation of Alabama and is described as a new species Dicaulograptus cumdiscus. The thecal processes are referred to as pleural disks. They occur in pairs above every thecal aperture and are inferred to have functioned as suspension processes receiving uplift from small-scale turbulent water motion. Such a function is compatible with a passively buoyant mode of life and is difficult to reconcile with an automobile mode of life.