| 
Suborder:
 | 
Goniatitina 
 | 
| 
Superfamily:
 | 
Dimorphoceratoidea 
 | 
| 
Family:
 | 
Girtyoceratidae 
 | 
| 
Subfamily:
 | 
Girtyoceratinae 
 | 
| 
Genus:
 | 
Girtyoceras 
 | 
| 
Species:
 | 
endicottense | 
| 
Qualifier:
 | 
ss | 
| 
Author:
 | 
	Gordon 1957,p.51	 
 | 
| 
Lower Boundary:
 | 
UAK Alapah Lst. base, 333.5 million years
 
 | 
| 
Upper Boundary:
 | 
UAK Alapah Lst. top, 326.4 million years
 
 |