Crassidenticulum trilobum Dilcher and Wang, 2006a

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 : 6-8

cf. Crassidenticulum trilobum Dilcher and Wang, 2006a

Figure 4.3-4

Description. Leaf simple, five-lobed; lobe shape lanceolate; medial lobe base symmetrical while lateral lobe base strongly asymmetrical; margin of lobes toothed except on the extreme base of lamina; axes of serrations inclined to the tangent of the margin, apical angle acute; serration type convex (basal side)-convex (apical side); sinus of tooth rounded; eight to 10 teeth per cm, regularly spaced; teeth simple (all of one size); sinus between lobes rounded, bracing accomplished by primary veins (lamina structure lacking or less than 0.5 mm wide on the sinus). Petiole thin; observed petiole 5 cm long and 0.5 mm wide. Secondary venation of lamina lobes pinnate; secondary veins thin. Veins of higher order not observed.

Number of specimens examined. 1.

Specimens illustrated. UF 15706-24684 ( Figure 4.3-4 ).

Occurrences. Hoisington III locality, Kansas.

Remarks. The single specimen examined lacks the details of higher order venation pattern. The five-lobed leaf appears to be compound, but there is lamina tissue connecting adjacent lobes ( Figure 4.4 ). The secondary venation pattern of the lamina lobes and the tooth type on the margin are similar to those of Crassidenticulum trilobum Dilcher and Wang (2006a) . It is possible that this species is a variant of C. trilobum .

This species differs from those compound leaves with several petiolulate leaflets from the mid-Cretaceous Cedar Mountain Formation, Utah, i.e., Morphotype CM 15 (Harris and Arens, 2016, p. 654-655, figure 7.1-4) and Europe, i.e., Debeya insignis (Hosius and von der Marck) Knobloch from southern Poland and western Ukraine (Halamski, 2013) and Austria (Herman and Kvaček, 2007a, 2007b, 2010), in that the leaf from the Hoisington III locality is simple with five lobes connected at the base with lamina tissue.

Figures

FIGURE 4. 1, Crassidenticulum decurrens (Lesquereux) Upchurch and Dilcher, 1990, UF15706-24648, fragment of leaf lamina. Note fine teeth on margin (indicated by arrow). Scale bar equals 2 mm. 2, Crassidenticulum trilobum Dilcher and Wang, 2006a, UF15706-24677, a trilobed leaf. Note thin and long petiole. Scale bar equals 1 cm. 3-4, cf. Crassidenticulum trilobum Dilcher and Wang, 2006a, UF15706-24684, a five lobed leaf (scale bar equals 1 cm) (3) and an enlargement of Figure 4.3 to show decurrent lamina tissue between two adjacent lobes (indicated by arrow) (scale bar equals 1 mm) (4).