Formerly: Streptelasma rusticum and Grewingkia rustica
Includes: Streptelasma vagans Foerste 1909, Streptelasma insolitum Foerste, 1909, and Streptelasma dispandum Foerste, 1909
Map point data provided by iDigBio.
- C6 Sequence (Elkhorn)
- C5 Sequence (Whitewater, Liberty, Waynesville)
Identification in Hand Sample
- Numerous septa (radially aligned plates) on the exterior, paired with growth lines on the interior
- Corallum straight or slightly curved with strong annulated epitheca
- Septa one hundred or more alternating in size, the larger strongly twisted at the center
- Commonly referred to as “horn” corals due to their shape
- G. canadensis is the largest solitary coral known from the Ordovician in Ohio, reaching lengths in excess of 13cm.
Grewingkia canadiensis from Liberty formation of Franklin County, Indiana (OUIP 2181)
Davis (1998) :
- Coral. Note numerous septa on the interior and growth lines on the exterior. Specimens of this species are larger and longer than specimens of species of Streptelasma. Entire Richmondian except lower Arnheim. Specimens of Grewingkia commonly are marked by borings; those that form a dendritic or reticulate network have been referred to Dictyoporus, and solitary holes have been called Trypanites (for details, see Elias, 1980).
Fossils of Ohio (1996):
- A single species of Grewingkia, G.canadensis is present in upper Ordovician strata of southwestern Ohio. It is the largest solitary rugose coral known from those rocks, specimens may reach in excess of 13cm.
McFarlan (1931) :
- (Under Streptelasma rusticum)Corallum straight or slightly curved with strong annulated epitheca. Length up to 10 cm., or more, diameter 2-4 cm., depth of calyx 1-1½ cm. Septa one hundred or more alternating in size, the larger strongly twisted at the center. Common in the Liberty, also in the Blanchester member of the Waynesville of Ohio, Indiana and Northern Kentucky, and the Whitewater of Ohio and Indiana.
Elias et al. (1990) :
- Corallum circular in cross section; major septa greatly to completely dilated in early stages, becoming slightly dilated to nondilated in late stages; cardinal and/or counter septa generally distinct in being conspicuously long and/or having prominent axial lobes at some stage during ontogeny; cardinal septum remains long up to base of calice, or becomes short
during late stages; axial region moderately large and highly variable in late stages, ranging from very complex axial structure with many septal lobes and lamellae to simple structure with
only a few septal lobes, to open axial region lacking septal elements (moderately complex axial structure with septal lobes and lamellae most common).
- Number of major septa. -The number of major septa in Grewingkia canadensis is related to an environmental parameter, most likely water depth (Elias, 1982, p. 19; Elias, 1983, p. 5). In the Cincinnati Arch region, a general increase in the number of septa through time is indicated by comparing coralla from strata of”Waynesville,” “Liberty,” and “Whitewater-Elkhornm”
ages (see Elias, 1982, fig. 10; Elias, 1983, fig. 3). This correlates with a decrease in water depth during the middle to late Richmondian regression, following introduction of solitary corals to
the Richmond Province during the early Richmondian transgressive event.