. Bulletins of American paleontology. 82 Bulletin 292. Text-figure 15. — Comparative anal sinus configuration in five turrine genera represented in the Keasey Formation, from camera lucida tracings of growth lines. Heavy lines denote posterior and anterior sutures, light lines denote boundaries of periphery and its bisector, and dashed line denotes apex of anal sinus, a. Eoflcurotoma (?), n. sp. aff. E. (?) ornata (Dickerson) ; b. Gemmula rockcreekcnsis Hickman, n. sp.; c. Procerapex bentsonae (Durham); d. Ptychosyrinx facula Hickman, n. sp.; e. Plcurolir'ia oregonensis Hickman, n. sp. Figured
. Bulletins of American paleontology. 82 Bulletin 292. Text-figure 15. — Comparative anal sinus configuration in five turrine genera represented in the Keasey Formation, from camera lucida tracings of growth lines. Heavy lines denote posterior and anterior sutures, light lines denote boundaries of periphery and its bisector, and dashed line denotes apex of anal sinus, a. Eoflcurotoma (?), n. sp. aff. E. (?) ornata (Dickerson) ; b. Gemmula rockcreekcnsis Hickman, n. sp.; c. Procerapex bentsonae (Durham); d. Ptychosyrinx facula Hickman, n. sp.; e. Plcurolir'ia oregonensis Hickman, n. sp. Figured specimen. — USNM 216436. Localities. — Lower member, Keasey Formation: USGS 15309. Middle member: USGS 25031. Genus GEMMULA Weinkauff, 1875 (= Hemipleurotoma Cossmann, 1889) Type species (by subsequent designation, Cossmann, 1896): Pleurotoma gemmata Hinds in Reeve, 1843; non Conrad, 1835 (= Gemmula hindsiana Berry, 1958). Holocene, tropical eastern Pacific. Although the type of Gemmula is a small-shelled tropical east- ern Pacific species (PI. 7, fig. 14), the genus is of worldwide distribu- tion. A post-Miocene adaptive radiation of large-shelled (greater than 30 mm high) turrine lineages has resulted in distributional clustering of Gemmula and its allies in the Indo-West Pacific. A dif- ferent pattern prevailed during the Paleogene (Powell, 1964), when Gemmula and allied small-shelled (less than 30 mm high) turrine offshoots were clustered in Europe and the southeastern United Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Paleontological Research Institution (Ithaca, N. Y. ); Columbia University. Ithaca, N. Y. , Paleontological Research Institution [etc. ]
Size: 2150px × 1162px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorpaleontologicalresearchinstitutionit, bookcentury1900
