Alnus sp.

Smith, MacKenzie A., Greenwalt, Dale E. & Manchester, Steven R., 2023, Diverse Fruits And Seeds Of The Mid-Eocene Kishenehn Formation, Northwestern Montana, Usa, And Their Implications For Biogeography, Fossil Imprint 79 (1), pp. 37-88 : 57

Alnus sp. L1

Text-fig. 8a–c

M a t e r i a l. DMNH L6933, DMNH EPI.48136a&b,

DMNH EPI.48179.

L o c a l i t y. Dishbrow Creek.

D e s c r i p t i o n. Leaves simple, elliptical, 5.5–9.2 cm long, 0.7–2.2 mm wide; base and apex acute; petioles 1.6– 2.2 cm long, 0.8–1.1 mm wide; venation pinnate, secondaries arising decurrently, arising at 51° craspedodromous, entering sinuses of large teeth; 0.84 secondaries/cm; tertiaries veins percurrent, opposite and alternate; higher venation not visible; teeth compound, with one large and or two small teeth; large teeth with retroflexed proximal flank, rounded apex and straight distal flank; smaller teeth with concave proximal and distal flanks with acute or rounded apices; 2.68 teeth per cm.

R e m a r k s. Alnus is a microthermal taxon that can be found in riparian areas ( Wing 1987). Fossils of Alnus are known from the early Eocene McAbee, Quilchena and Falkner floras of British Columbia ( Lowe et al. 2018, Mathewes et al. 2016, Smith et al. 2012), Republic flora of Washington ( Pigg et al. 2011), Yellowstone flora of Wyoming ( Wing 1987), the Golden Valley Formation of North Dakota ( Hickey 1977, Wing 1987), mid-Eocene Thunder Mountain flora of Idaho ( Axelrod 1998), White Cliffs flora of the Clarno Formation of Oregon ( Liu et al. 2014), late Eocene Copper Basin flora of Nevada ( Wing 1987), Bull Run flora of Nevada ( Wing 1987), Whitecap Knoll flora of the John Day Formation, Oregon ( Manchester 2000) and Oligocene Ruby Basin of Montana ( Becker 1959) .

Figures

Text-fig. 8. Betulaceae and Juglandaceae from the Kishenehn Formation. a: DMNH L6933 Alnus sp. L1 leaves. Scale bar 2cm. b: DMNH EPI.48179 Alnus sp. leaf. Scale bar 2cm. c: DMNH EPI.48136b Alnus sp. leaf. Scale bar 2cm. d: USNM PAL 622756 Alnus sp. I1 infructescence attached to branch. Scale bar 1cm. e: USNM PAL 623160 Betuloideae showing wing, seed body and two persistent styles. Scale bar 1mm. f: USNM PAL 622732 Alnus sp. F1 samara showing two persistent styles. Scale bar 1mm. g: USNM PAL 624925 Betula sp. samara showing wing, seed body and two persistent styles. Scale bar 1mm. h: USNM PAL 623147 Alnus sp. F2 samara showing. Scale bar 1mm. i: USNM PAL 622690 Palaeocarya sp. samara showing three wings with reticulate venation and hairs at base. Scale bar 1cm.