Locality

Amaam Lagoon Locality 11

 

Description

From Moiseeva (2012) (p. 61)

"Medium-sized to large leaves 5.5 to 13.0 cm long and 5.0 to 12.5 cm wide; width of leaves often exceeds their length. Leaf blades are tri- to pentalobate. In the latter, below three main lobes, which are most developed, there is one pair of additional shorter lobes with ending branches of basal veins. Lobes with dentate margins are symmetric or slightly asymmetrical. Shape of the leaf blade varies from wide- to transovate; leaf base cordate or emarginate, leaf apex rounded, petiole unpreserved.

Leaves dentate in general are entire-margined at the base. Teeth large, simple, 0.3–0.9 cm high and 0.6–1.2 cm wide, broadly triangular, asymmetrical. Basal and apical sides of teeth are convex, although the latter can sometimes be slightly concave. Secondary veins reach apical ends of teeth; tertiary ones form one or two series of areoles on both sides of the secondary vein.

Venation actinodromous craspedodromous. Thick primary veins depart from the mid rib at the angle of 50°, or slightly curve toward apex. They have three to five basiscopic and up to three acroscopic branches. The lower basiscopic veins also ramify sometimes. Above the primary veins there are three to five secondary veins alternately or nearly oppositely arranged at angles of 45° to 50° relative to the midrib. In the lower pair there are several (one to three) basiscopic branchlets either ending in a tooth or joining one another. There is also one pair of thin infrabasal veins often curving downward and occasionally departing from the midrib at the angle of 90°. Together with the lower ramifications of basal veins, they produce several loops rarely terminating in marginal teeth.

The tertiary venation is opposite- to alternate-percurrent. Thin, slightly curved tertiary veins orthogonally deviating from secondary veins bifurcate several times. One or two rows of areoles decreasing in size toward the margin and produced by tertiary venation are distinguishable in lobes and large teeth below the basal veins. Venation of the fourth order is polygonal reticulate, very fine. Small polygonal areoles are more or less identical in size."

 

Remarks

From Moiseeva (2012) (p. 61)

"GIN RAS, no. 4843/463; Koryak Upland, the Amaam Lagoon area, left side of the
Emima River, Medvezhii Creek; upper subformation of the Koryak Formation, upper Maastrichtian (Moiseeva, 2005a, pl. XI, fig. 1)."