Credneria cyclophylla (Heer) Wang and Dilcher, 2009

Wang, Hongshan & Dilcher, David L., 2018, Early Cretaceous angiosperm leaves from the Dakota Formation, Hoisington III locality, Kansas, USA, Palaeontologia Electronica (34 A) 21 (3), pp. 1-49 : 20

Credneria cyclophylla (Heer) Wang and Dilcher, 2009

Figure 11.3

Description. Whole lamina and base symmetrical, very wide ovate, L / W <1, 8 cm long (estimated length) and 8.5 cm wide. Apex missing. Base obtuse, decurrent. Margin toothed; tooth simple, extending on upper two-thirds of the margin, spacing irregular, two or three teeth per cm on middle portion of margin; dentate axes approximately perpendicular to the tangent of the margin; dentate apex obtuse (>90º), mucronate; toothed type concave on both sides; sinus rounded, shallow (less than 1 mm deep-vertical distance from tooth apex to bottom of sinus). Observed petiole 3 cm long and 1 mm wide. Primary venation pinnate; primary vein stout, multi-stranded, course straight. Secondary venation simple craspedodromous (all of the secondary veins and their branches terminating at the margin); secondary veins thick relative to primary veins, multi-stranded, ca. five pairs per leaf lamina, opposite or subopposite; angle of divergence narrow acute (<45º) with uniform variation; secondary vein course straight or slightly curved, all terminating at the margin; two or three exmedial branches from basal two pairs of secondary veins also terminating on the margin. Intersecondary vein absent. Tertiary veins thick, percurrent, course convex (middle portion of vein curve away from the center of the leaf); angle of origin AA (acute on both sides of secondary veins); arrangement on secondary veins close (interval between veins less than 0.5 cm). Quaternary veins percurrent (perpendicular to tertiary veins), course straight; quinternary veins orthogonal reticulate, forming quadrangular well-developed areoles. Veinlets simple, linear or curved.

Number of specimens examined. 3.

Specimen illustrated. UF 15706-14821 ( Figure 11.3 ).

Occurrences. Hoisington III locality, Kansas and Courtland I locality, Minnesota .

Remarks. The specimens from Hoisington III locality are less variable in leaf shape and they are less abundant than those from the Courtland I locality, Minnesota.

Figures

FIGURE 11. 1, Jarzenia kanbrasota Wang and Dilcher, 2009, UF15706-3171, showing elliptic leaf shape and secondary venation. Scale bar equals 1 cm. 2, Liriophyllum kansense Dilcher and Crane, 1984, UF15826-3188, showing deeply lobed leaf, long petiole, and secondary venation. Scale bar equals 1 cm. 3, Credneria cyclophylla (Heer) Wang and Dilcher, 2009, UF15706-14821, leaf showing craspedodromous venation. Note all secondary veins and their exmedial branches terminating on leaf margin, resulting in a wavy appearance of leaf margin. Scale bar equals 1 cm.