Back
Fromea gordonwoodii
Plate 1, figures 17–20
Derivation of name
In honor of the late Dr Gordon D. Wood, my close friend and long-time colleague, to whom this volume is dedicated.
Holotype Plate 1, figure 19. ARCO Nigliq 1 7950–7980 ft., slide 1, EF Z27/4, 81.7 µm apex–antapex.
Description
Cyst oblong in outline, with broadly rounded antapex, slightly convex to nearly straight sides, narrowing at apex. Pylome presumably circular, with no marginal modification. Operculum always detached, not observed. Cyst wall relatively thick (∼2 µm at medial width, thickening slightly toward apex and antapex), with a vaguely rugose external sculpture that gives it a ‘spongiose’ appearance.
Dimensions
66.8–83.5 (77.1 average) µm apex–antapex; 56.8–65.1 (61.0 average) µm maximum width; 16.7–23.4 (18.8 average) µm pylome width (12 specimens measured).
Comments
Fromea gordonwoodii resembles F. cylindrica (Cookson & Eisenack) Stover & Evitt Citation1978 in general morphology, but has a vaguely rugose external sculpture, in contrast to the reticulate sculpture of the latter. It is also somewhat larger than F. cylindrica, and occurs in much older strata (F. cylindrica is recorded from strata of Late Jurassic to Early Cretaceous age in the southern hemisphere). Fromea tornatilis, known from strata of Late Jurassic age, displays similar sculptural characteristics, but is smaller and more ovoid, with a narrow apex and thinned pylome margin. Fromea gordonwoodii is the oldest species of Fromea documented in this report.
Occurrence
Rare, Toarcian, lower Kingak Formation, North Alaska.
Derivation of name
In honor of the late Dr Gordon D. Wood, my close friend and long-time colleague, to whom this volume is dedicated.
Holotype Plate 1, figure 19. ARCO Nigliq 1 7950–7980 ft., slide 1, EF Z27/4, 81.7 µm apex–antapex.
Description
Cyst oblong in outline, with broadly rounded antapex, slightly convex to nearly straight sides, narrowing at apex. Pylome presumably circular, with no marginal modification. Operculum always detached, not observed. Cyst wall relatively thick (∼2 µm at medial width, thickening slightly toward apex and antapex), with a vaguely rugose external sculpture that gives it a ‘spongiose’ appearance.
Dimensions
66.8–83.5 (77.1 average) µm apex–antapex; 56.8–65.1 (61.0 average) µm maximum width; 16.7–23.4 (18.8 average) µm pylome width (12 specimens measured).
Comments
Fromea gordonwoodii resembles F. cylindrica (Cookson & Eisenack) Stover & Evitt Citation1978 in general morphology, but has a vaguely rugose external sculpture, in contrast to the reticulate sculpture of the latter. It is also somewhat larger than F. cylindrica, and occurs in much older strata (F. cylindrica is recorded from strata of Late Jurassic to Early Cretaceous age in the southern hemisphere). Fromea tornatilis, known from strata of Late Jurassic age, displays similar sculptural characteristics, but is smaller and more ovoid, with a narrow apex and thinned pylome margin. Fromea gordonwoodii is the oldest species of Fromea documented in this report.
Occurrence
Rare, Toarcian, lower Kingak Formation, North Alaska.