Juniperus 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 : 42

Juniperus sp.

Text-fig. 2h, i

M a t e r i a l. USNM PAL 621667, 722223.

L o c a l i t i e s. Disbrow Creek and Tunnel Creek.

D e s c r i p t i o n. Awl-shaped leaves 2.1–2.8 mm long, arranged helically around an axis 15.5 mm long and 1 mm wide; each leaf having a convex abaxial surface and concave adaxial surface, with a medial ridge extending from base to apex; three leaves apparently emerging from the axis at each node; wide leaf base and acute apex; ridge running down the center of each leaf from base to apex.

R e m a r k s. Juniperus can have scale or needle leaves. These fossils possess needle leaves of the kind that generally occur on young trees or parts of the tree that are exposed to low light ( Zhang et al. 2021). We also compared these leaves to those of Cryptomeria D. DON but their needle leaves continuously taper from their base to apex whereas Juniperus leaves become more acute part way up the to the leaf apex as in our fossils (pers. obs.). Juniperus is also known from the Oligocene Beaverhead Basin floras and considered a subhumid element ( Wing 1987) and pollen with possible affinities to the genus has been reported from the early Eocene McAbee fossil beds in British Columbia ( Lowe et al. 2018).

Subfamily Cupressoideae RICH. ex SWEET

Cupressoideae 1

Text-fig. 2j

M a t e r i a l. USNM PAL 623467.

L o c a l i t y. Dakin.

D e s c r i p t i o n. Scale leaves on an axis measuring 7.4 mm long and 1.7 mm wide; branchlets on one side, leaves decussate, 0.8–1.2 mm wide, wide bases and rounded acute apices 86°, distance between apices in the facial leaves (which is also the length of each leaf) ranges 0.9–1.1 mm; facial leaf apex covers junction of subsequent lateral leaves.

R e m a r k s. Cupressoideae 1 differs from Cupressoideae 4 by having shorter leaves that are closely spaced and more rounded apices. Some foliage from cupressaceous genera can be indistinguishable, and we did not recover cones that would enable a more refined determination. It differs from Cupressoideae 2 by having leaf apices that overlap subsequent lateral leaf junctions. Leaves conforming to this description can be found in Juniperus L., Thuja L. and Chamaecyparis SPACH. Cupressoideae 1 may be the same as Cupressoideae 3. Leaves may be abscised in this specimen and not in Cupressoideae 3. Abscission can occur in genera like Chamaecyparis , so the facial leaves can either cover or not cover the junction of the subsequent lateral leaves ( Kotyk et al. 2003).

Figures

Text-fig. 2. Equisetum and conifers from the Kishenehn Formation. a: USNM PAL 620616 Equisetum sp. stem apex. Scale bar 3mm. b: USNM PAL 622297 Coniferae 1. Scale bar 5mm. c: USNM PAL 622081 Coniferae 2. Scale bar 2mm. d: USNM PAL 717666 cf. Metasequoia sp. seed. Scale bar 1mm. e: USNM PAL 622101 cf. Metasequoia sp. seed. Scale bar 1mm. f: USNM PAL 776571 Metasequoia sp. twig showing opposite leaves. Scale bar 10mm g: USNM PAL 776572 Metasequoia sp. twigs. Scale bar 10 mm. h: USNM PAL 621667 Juniperus sp. leafy twig. Scale bar 5mm. i: USNM PAL 722223 Juniperus sp. twig. Scale bar 2mm. Scale bar 3mm. j: USNM PAL 623467 unidentified Cupressoideae 1. Scale bar 3mm. k: USNM PAL 620274 unidentified Cupressoidae 2 leaves. l: USNM PAL 620087 unidentified Cupressoideae 2. Scale bar 1mm. m: USNM PAL 620184 unidentified Cupresseoideae 3 shoot. Scale bar 2mm. n: USNM PAL 621863 Cupressoideae 4 leafy twig. Scale bar 5mm.