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Trochodendron nastae
Taxonomy
Trochodendron nastae was named by Pigg et al. (2001). Its type specimen is Holotype. SR 98-2-la (figs. lA, 2A). Paratypes. UWBM 31248a,b (fig. 3G), 31249 (fig. 3A, 30, 3E), 31250a,b (fig. 2B), 54868 (figs. lB, 2F), 96609a,b (fig. lC), 96612 (figs. ID, 2E), SR 88-2-2 (fig. 3B), 95-19-3a (fig. 3F, 3H), 95-23-15 (fig. 2D), UWBM 312, a leaf, and it is a compression fossil. Its type locality is Republic (Stonerose Interpretive Center collection), which is in a Ypresian lacustrine - large mudstone in the Klondike Mountain Formation of Washington.
Synonymy list
| Year | Name and author |
|---|---|
| 2001 | Trochodendron nastae Pigg et al. p. 1192 |
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If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
†Trochodendron nastae Pigg et al. 2001
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Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| K. Pigg et al. 2001 | This description is based on a total of 66 leaves (11 nearly complete and 55 fragmentary specimens), many of which are well preserved and show good detail of venation and leaf mar- gin (fig. l; fig. 2A, 2B, 2D-2F; fig. 3A, 3B, 3D-3H). The leaves are simple and symmetrical. The lamina is elliptical to more rarely obovate (fig. 1; fig. 2A, 2E, 2F) and is 3.0-7.7 cm long, with an average length of 5.3 cm (based on 24 leaves with complete lengths), and 1.5-4.0 cm wide, with an average width of 2.9 cm (based on 44 leaves with complete widths). The length-to-width ratio is 1.4-3.6 : 1 with an average of 2.5 : 1 (based on 11 leaves with both complete lengths and widths). These fossil leaves show a similar range of variability in shape when compared to extant Trochodendron aralioides and fall along the smaller side of size range in leaves we examined from herbarium sheets (table 1). Like extant T. aralioides, the apex of the lamina, when present, is acuminate (fig. 2F), and the leaf base is cuneate (fig. 1; fig. 2A, 2B, 2F). Petioles are up to 2.8 cm long and 0.7-2.1 mm wide. They are exstipulate and striate (fig. 2A, 2B, 2F). Some leaves have petioles that are slightly enlarged (up to 3 mm) at the base, possibly resulting from insect damage (C. Labandeira, written communication, 1998). Additionally, some leaves show "external foliage feed- ing in the form of excellent margin feeding with well-developed reaction rims" (fig. 20; C. Labandeira, written communica- tion, 1998). The primary venation of Trochodendron nastae is basally actinodromous, or palmate, with a central midvein and two pairs of lateral primaries (fig. 2A, 2B, 2E; fig. 3A). The width of the midvein is fairly uniform, thinning slightly in the apical portion of the lamina, and it is straight through most of its length, sometimes becoming sinuous distally and almost ex- tending to the acuminate apex of the leaf. In contrast, leaves of extant T: aralioides have pinnate primary venation with a prominent midvein that is several times thicker than the laterals (fig. 2C). The innermost lateral primary veins of T. nastae extend most of the length of the leaf, fork apically, and enter marginal teeth in the apical portion of the leaf (figs. 2A, 3A). The outer lateral primary veins arc out near the leaf margin about one-third of the distance from the base (figs. 2E, 3A). Angles between adjacent lateral primaries are fairly acute as are those between the lateral primaries and the midvein. Sec- ondary veins are produced alternately from the midvein in the upper half of the lamina, distal to the area of divergence of the lateral primaries (figs. 2E, 3Aj. Secondary veins are also produced alternately from lateral primaries (fig. 2A). Weak intersecondary veins are present between lateral primaries and parallel them in basal areas of the leaf. In more apical areas of the leaf, they occur between and run parallel to the sec- ondary veins produced by the midvein. These weak inter-secondaries meet the admedial veins that diverge from the lat- eral primaries at 40"-45". These two veins meet to form occasional chevrons or bracings across the central part of the lamina (fig. 3A, 3F, 3H), similar to those of 7: aralioides (fig.31). Tertiary veins paralleling the weak intersecondaries and quaternary veins form aeroles that are four-to-five sided, an- other feature similar to that of extant T aralioides (fig. 3531). Fifth-order veins can occasionally be recognized, but their fea- tures are obscure (fig. 3H). Toward the leaf margin, secondaries form a double set of loops, resulting in festooned brochidod- romy (fig. 34. A marginal vein runs along the leaf margin (fig. 3F, 3G). The leaf margin is unlobed crenate with numerous small, appressed glandular teeth in the apical three-fourths of the lamina (fig. 2A, 2E; fig. 3B, 30, 3E, 3G). This type of margin is similar to those in apical portions of modern examples of Trochodendron and Tetracentron (fig. 3C). The lower one- fourth portion of the lamina is entire (fig. 2A, 2E, 2F; fig. 3A). Teeth are glandular, straight apical, convex basal (Leaf Xr- chitecture Working Group 1999). The leaf texture is corinceous. Cuticle is not well preserved. |
Measurements
No measurements are available
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| Source: p = phylum | |||||
| Reference: Kiessling 2009 | |||||