Citation: Globigerina graysonensis Tappan 1940Rank: SpeciesType specimens: 25117Type sample (& lithostrat): Washita group, Grayson formationType age (chronostrat): Lower CretaceousType locality: Grayson Bluff, a high, southwest-facing bluff on Denton Creek, 3.5 miles northeast of Roanoke, 2 miles by road east of the Fort Worth-Denton highway, Denton County, Texas.Type repository: Washington; USNM
Original Description "Test tiny, trochoid, dorsal side varying from flattened to a rather high spire; chambers numerous, inflated, globular, from three to five in a whorl; sutures distinct, depressed; wall calcareous, smooth; aperture slit-like, at the lower margin of the last chamber, extending from a point near the center of the ventral side outward to a point approximately one-half the distance to the periphery, partially covered by a lip. Greatest diameter of holotype, 0.21 mm.; least diameter, 0.17 mm.; width through center, 0.16 mm.; average diameter, 0.135 to 0.17 mm.
This species is fairly common throughout the Grayson formation. G. graysonensis is similar in general appearance and chamber arrangement to Candeina nitida d'Orbigny, having approximately the same number of chambers, low spire and smooth wall. It differs in lacking the multiple aperture of the adult Candeina, is approximately one-fifth as large, and has smooth chambers throughout. The generic identification of this species is somewhat in doubt. It resembles Globigerina in being trochoid and in having nearly globular chambers, but differs somewhat in the character of the aperture, as this species has an aperture which extends toward the periphery. It resembles Rotatiatina in being fairly high-spired, having only a few chambers in a whorl, but differs in that the aperture extends to the center of the ventral side, the chambers are globular and the spire is lower. It resembles Eponides in the trochoid character and aperture but is not as biconvex and has more globular chambers than the typical Eponides."
Tappan, H. (1940). Foraminifera from the Grayson formation of Northern Texas. Journal of Paleontology. 14(2): 93-126. gs
Globigerina graysonensis compiled by the pforams@mikrotax project teamviewed: 29-5-2023