Palmatolepis triangularis Sannemann, 1955

Day, Jed & Over, D. Jeffrey, 2002, Post-extinction survivor fauna from the lowermost Famennian of eastern North America, Acta Palaeontologica Polonica 47 (2), pp. 189-202 : 199

Palmatolepis triangularis Sannemann, 1955

Fig. 5A–C .

Palmatolepis triangularis ; Sannemann 1955: 327–328, pl. 24: 3 [= holotype]; Over 1997: 172, 10.1, 10.5.

Remarks.—The lowest occurrence of Palmatolepis triangularis has been used to define the base of the Famennian and the Lower Pa. triangularis Zone , although rare specimens occur in the uppermost Frasnian prior to the final extinction event and horizon recognized as the Frasnian–Famennian boundary ( Klapper et al. 1994; Schülke 1995; Over 1997). In practice the boundary is recognized by the absence (extinction) of Frasnian conodont species and the lowest abundant occurrence of Pa. triangularis .

Figures

Fig. 5. Digital images from scanning electron microscope of conodont P1 (Pa) elements from the Hanover Shale Member of the Java Formation, brachiopod bed approximately 1.4 m above the Frasnian–Famennian boundary at Glade Creek, Bartz Road, Wyoming County, New York. All × 60. A–C. Palmatolepis triangularis Sannemann, 1955. A, B. Lower view and inverse mirror−image of mold of upper surface of P1 (Pa) element, NYSM 15682. C. Inverse mirror−image of mold of upper surface of P1 (Pa) element, NYSM 15683. D–F. Icriodus alternatus alternatus Branson and Mehl, 1934. D, E. Upper and oblique outer views of broken P1 (Pa, I) element showing internal mold of posterior end, NYSM 15684. F. Upper view of P1 (Pa, I) element with missing inner posterior margin, NYSM 15685. G. Icriodus alternatus helmsi Sandberg and Dreesen, 1984, upper view of fractured and covered P1 (Pa, I) element, NYSM 15686 (specimen lost).