05RAS Tiliaephyllum brooksense Moiseeva et Herman  


Moiseeva et al. (2009)



Sagwon 05-3. Prince Creek Formatlon. Sagavanirktok River. Sagwon.


Locality Map



The following is not a description of this particular specimen but a composite description of the species.

From Moiseeva, Herman, Spicer. 2009. (p. 1303-1304)

"Leaves simple, entire, medium-sized to large. Leaf lamina elliptic-ovate or broadly ovate. Leaf base asymmetric, typically deeply cordate or, more rarely, emarginate. Leaf apex acuminate to attenuate. Leaf margin unequally toothed or double-serrate. Teeth from small to large, acute, triangular, symmetric, or, more rarely, narrow asymmetric and oriented apically. Venation pinnate and craspedodromous. Secondary veins 10–13 pairs, opposite or, more rarely, alternate. The third basal pair of secondary veins the strongest and copiously branched.

Description (Figs. 2a–2c). The leaves are medium-sized or large, 5–12 cm long and 3.5–10 cm wide, simple, entire-margined, oval-ovate or broadly ovate, the maximum width is located in the middle of the leaf or below the middle. The leaf base is asymmetrical, deeply cordate or, more rarely, emarginate; the apex is acute and, as a rule, acuminate. The petiole is relatively thick, its length is about one third of the leaf lamina length. The leaf margin is unequally toothed or double-serrate. The teeth are from small to large (up to 2.5 mm high and 3–4 mm wide). Usually, they are acute, triangular, with straight or slightly concave sides, symmetrical, or, more rarely, narrower, with a concave apical side, and orientated towards the leaf apex. The notches between the teeth are mostly acute or, more rarely, rounded.

The venation is pinnate and craspedodromous. The midrib is thick, straight, or slightly sinuous. There are ten to thirteen pairs of secondary veins. Most secondary veins are opposite, some are alternating. Three lower pairs of veins are connivent with their bases. The longest and most branched pair of veins is the third (from the bottom) pair: up to six basiscopic branchlets depart from this pair of veins. Below this pair, the first two pairs of secondary veins are situated; they are also quite frequently branched (with four or five branchlets), but much shorter. They depart from the midrib at a right angle; the lowest are slightly curved downwards, the angle of deviation of other secondary veins is 40–50°. The tertiary venation is scalariform or, more rarely, branched-scalariform.

Comparison. The new species differs from Tiliaephyllum tsagajanicum from the Upper Tsagayan Flora of the Amur Region (Krassilov, 1976) by the pattern of secondary venation in the lower part of the leaf. The third (from the bottom) pair of secondary veins is longest and most branched in T. brooksense sp. nov. Unlike this species, T. tsagajanicum has the longest lower pair of secondary veins departing immediately from the leaf base."


From Moiseeva, Herman, Spicer. 2009. (p. 1303-1304)

"Genus Tiliaephyllum Newberry, 1895. Tiliaephyllum brooksense Moiseeva et Herman, sp. nov. Plate 22, figs. 1–7.

Holotype. GIN, no. 4886/21a-1, 4886/21b-1 (counterpart); leaf imprint; Sagavanirktok River, northern Alaska Peninsula; upper part of the Prince Creek Formation; Upper Paleocene (Pl. 22, fig. 2; Fig. 2a)."

"The morphologically close species Tiliaephyllum tsagajanicum was first described by Krysh- tofovich and Baikovskaya (1966) from the Tsagayan Flora of the Amur Region as Tilia L. The holotype of this species is shown in Fig. 3 (no photograph was published by Kryshtofovich and Baikovskaya). This specimen has smaller and more steeply apically oriented teeth than the majority of other specimens of T. tsagajanicum, that, in our opinion, accords with intraspecific variability.

The new species has something in common with leaves of Corylites L., which were wide-spread in many temperate floras of Asia, Europe, and North America (Boulter and Kvacek, 1989; Manchester and Guo, 1996; Akhmetiev and Golovneva, 1998; Moiseeva, 2005a; and others). Tiliaephyllum brooksense sp. nov. differs from most species of Corylites by wider and more rounded outlines of the leaf lamina and larger and usually symmetrical marginal triangular teeth. In addition, the new species is characterized by highly branched third (from the bottom) pair of secondary veins, whereas most species of Corylites usually have the lower or the second (from the bottom) pair of secondary veins most strongly developed. One of the distinguishing features of Tiliaephyllum is an acuminate leaf apex, which occurs much more rarely in Corylites.

Material. Twenty-two specimens from the type locality."