Revision of the conifers from the Eocene Thunder Mountain flora, Idaho, U.S.A.

Review of Palaeobotany and Palynology 137 (2005) 125 – 145 www.elsevier.com/locate/revpalbo

Revision of the conifers from the Eocene Thunder Mountain flora, Idaho, U.S.A. Diane M. Erwin *, Howard E. Schorn Museum of Paleontology, University of California, Berkeley, CA, 94720-4780, United States Received 28 March 2005; received in revised form 5 July 2005; accepted 17 September 2005

Abstract The Thunder Mountain paleoflora from the middle Eocene (46–45 Ma) of central Idaho represents an upland flora dominated by conifers. However, because many of the conifer species recognized at Thunder Mountain include a mixture of detached organs from different localities of different ages it is unclear which conifer taxa are present in or absent from the flora. Reexamination of the megaflora suggests Pseudotsuga and Cephalotaxus are equivocal, Thujopsis is not present, and the holotype ovulate cone of Larix leonardii does not show definitive features to justify its placement in Larix. The species Chamaecyparis edwardsii, Picea deweyensis and Abies deweyensis are based on fragmentary organs identifiable only to genus. Pinus baileyi is not closely related to P. longaeva (subgenus Strobus, subsection Balfourianae) but is an excentromucronate hard pine with affinities to members of subgenus Pinus, cf. subsection Pinus. Revision of the Thunder Mountain conifer megafossil assemblage is a step toward clarifying the species present in the flora to provide further understanding of the diversity, evolutionary relationships and phytogeographic history of conifers during the Tertiary. D 2005 Elsevier B.V. All rights reserved. Keywords: conifers; Cupressaceae; Eocene; Idaho; Pinaceae; Thunder Mountain flora

1. Introduction The middle Eocene Thunder Mountain megaflora of central Idaho is rich in conifers, especially members of the Pinaceae. Radiometrically dated at 46–45 Ma, it represents one of the oldest montane conifer-dominated assemblages recovered from the Northern Hemisphere (Axelrod, 1998a; Taggart and Cross, 2000), and therefore contains important records of taxa for this time interval and region. As with many Tertiary compression/impression floras, the Thunder Mountain specimens were described using the traditional practice of * Corresponding author. E-mail addresses: [email protected] (D.M. Erwin), [email protected] (H.E. Schorn). 0034-6667/$ - see front matter D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.revpalbo.2005.09.002

assigning species names to isolated organs and species concepts subsequently expanded by adding associated organs from the same flora and/or previously named organs from different floras of different ages. Consequently, over the years many species have come to include a mixture of organs that do not belong to the same species and/or genus. Although many paleobotanists are aware of the pitfalls with this approach and the literature, plant biologists and ecologists those, who also might use these published species records, are not in a position to critically evaluate them. Therefore, reports of questionable taxa and their occurrences are taken at face value and cited by authors in their studies (e.g., Hermann, 1985; Millar, 1996; Taggart and Cross, 2000). The use of unchecked records in cross-disciplinary research has also increased with the development of

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the Internet where published species lists can be quickly downloaded from online museum catalogs. Fossil conifer taxa play an important role in our understanding of the evolution, diversity, and paleobiogeography of this group, and therefore it is beneficial to have a record that is honest and accurately reflects species occurrences. Here we present our revision of the Thunder Mountain conifer species to better understand the species concepts that have developed over many decades and to reconcile which taxa are or are not present in the flora. The revision of Thunder Mountain, in conjunction with those of other Tertiary floras (e.g. Wolfe and Schorn, 1990) will add to our understanding of the Tertiary history of conifers. 2. Material and methods Remnants of ferns, conifers and angiosperms were deposited in the Thunder Mountain caldera of central Idaho approximately 46–45 Mya (Leonard and Marvin, 1984; Axelrod, 1998a). They are preserved in two horizons collectively referred to as the Dewey Beds and represent different depositional settings (Axelrod, 1998a). The black carbonized and decomposed streamborne plant debris from the lower horizon at Dewey Mine (UCMP PA959) includes coalified cones, bark, branches, leaves, winged seeds and seed wings, preserved in a gray, fine to coarse-grained sandstone. This volcaniclastic debris layer at Dewey Mine represents a relatively high-energy deposit and Axelrod considered the plant material to have been transported from the slopes of the higher elevation canyons and ravines of the Thunder Mountain caldera to the floor where they were preserved. Overlying this coarse clastic basal section are 3–4 m of flat-lying, finely laminated lacustrine shales of the Road locality (UCMP PA953). This site is approximately 0.5 km north of the mine site and 35 m higher in the section. Relatively better preserved compression/impression fossils have been recovered but still many are incomplete, abraded and decomposed. Larger more complete specimens have not been collected because the fine-grained bentonitic clay layers within the shales expand and break into small blocks (3–7 cm) (Axelrod, 1998a). We use the terminology of Wolfe and Schorn (1990) in describing the winged seeds. Specimens were photographed using one of the following: 1) MP3 Polaroid camera using Polaroid Type 55 Positive/Negativek film, the negatives scanned using a LEAF high-resolution scanner, 2) an Olympus CAMEDIA C-700 Ultrazoom 2.1 megapixel digital camera mounted on a copy stand, or 3) a Nikon Coolpix 995 camera adapted to a

Wilde binocular microscope. Camera lucida drawings were scanned and the images traced using Adobe Illustrator 9.0. All images were processed using Adobe Photoshop 6.0. The Axelrod Thunder Mountain specimens are housed in the Museum of Paleontology Paleobotany collection, University of California, Berkeley. 3. Systematic paleontology We agree with Wolfe and Schorn (1990) that the fossils must exhibit the morphological characters necessary to recognize them as belonging to the taxonomic level indicated by the author. Also, past attempts to combine isolated organs (i.e. cones, winged seeds, needles, branches) into presumed natural taxa have been fraught with difficulties, especially when organs of more than one taxon are present in an assemblage. Here we exclude fragmentary specimens and separate out the various organs to establish an inventory of what fossils are present and then only suggest possible relationships among these organs rather than combining them into supposed bnaturalQ fossil species. Nothing is really lost this way, but we expect to gain the ability to recognize temporal, spatial and morphological patterns that are now lost within the existing morass of Tertiary conifer species. Specimens are re-described and re-figured where necessary and informative. Our revisions are summarized in Table 1. Order: Filicales Family: Indeterminate (vegetative axis) (Plate I,1) 1998 Larix leonardii Axelrod—Axelrod: p. 34, Plate V, 8 only. Occurrence and material: Dewey Mine: UCMP 10978. Discussion: This specimen more closely resembles a fern rhizome. It is incomplete at both ends measuring 19.5 cm long and 1.5–2.3 cm wide and represents the impression (mold) of the internal stem surface. The oval petiole scars are 7.0 mm wide, helically arranged, and some show what appear to be involute C-shaped vascular traces (Plate I,1). The specimen co-occurs with foliage attributed to Osmunda and Polypodium (Axelrod, 1998a). Family: Cupressaceae Rich. ex Bartling Genus: Chamaecyparis Spach Species: Chamaecyparis sp. (vegetative axis) (Plate I,2,3) 1998 Chamaecyparis edwardsii Axelrod—Axelrod: p. 32, (part), not Plate IX, 13.

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Occurrence and material: Road locality: UCMP 11034, 11035. Material excluded: Road locality: UCMP 11043. Discussion: Differentiating fossil species of Chamaecyparis on fragments of vegetative axes (e.g., Plate I,2, 3) is difficult and requires relatively complete wellpreserved material to determine axis order and the range in leaf size and shape from order to order (Edwards, 1983). Chamaecyparis edwardsii Axelrod was based on vegetative axis fragments and cones from the younger Oligocene Haynes Creek flora (Axelrod, 1998b). Although this species was first mentioned in the Thunder Mountain flora, the description and naming of the holotype appeared later in the Haynes Creek monograph. However, it is unclear how the Haynes Creek and the Thunder Mountain vegetative specimens really differ from those previously described from Tertiary deposits (e.g., C. linguaefolia (Lesquereux) MacGinitie (Axelrod, 1966); C. cordillerae Edwards and Schorn (Axelrod, 1985)). Because the Thunder Mountain material is so fragmentary, and no cones or seeds have been recovered, we exclude it from this new species at this time. In addition, the specimen figured as C. edwardsii (Axelrod, 1998a, Plate IX, 13) is not UCMP 11034, but UCMP 11043 (Abies deweyensis). However, the latter specimen is not Abies, but possibly a new member of the Cupressaceae described here as Cupressaceae Taxon A. UCMP 11034 is a fragment of Chamaecyparis (Plate I,2) and it appears this specimen was the one that was meant to be figured. Genus: cf. Sequoia (D. Don) Endlicher Species: cf. Sequoia sp. (leaf) (Plate I,4) 1998 Picea magna MacGinitie—Axelrod: p. 35, (part), Plate X, 12 only. Occurrence and material: Road locality: UCMP 11076. Discussion: A needle assigned to Picea magna MacGinitie from the Road florule compares favorably to Sequoia. The leaf is broad and flattened dorsiventrally measuring 2.0 mm wide with an acute apex and two relatively wide stomatal bands. This combination of characters is more diagnostic of Sequoia than Picea or Abies. Sequoia is well represented in the Road florule by defoliated axes and a cone attached to a branch (Axelrod, 1998a, Plate IX, 16). A short poorly preserved axis fragment bearing scale leaves (UCMP 11015) assignable to Sequoia affinis Lesquereux also occurs in the Dewey Mine florule.

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Genus: Indeterminate Species: Indeterminate (vegetative axis) (Plate I,5; Fig. 1) 1998 Abies deweyensis Axelrod—Axelrod: p. 34, (part), Plate IX, 13 only. Occurrence and material: Road locality: UCMP 11043. Description: This specimen is here referred to as Cupressaceae Taxon A. It is known from a single foliated axis, 3.8 cm long, collected from the Road florule. The axis appears to have been part of a flattened spray that is missing both ends and so its position to other primary or lateral branches cannot be determined. The remnants of two lateral axes show they are arranged alternately along the main axis (Plate I,5, proximal branch at br; Fig. 1, branch at upper left). The leaves are dimorphic, decussate and consist of ovate facial leaves flanked by two non-adpressed needle-like lateral leaves. Some laterals show a slight flare at the base (i.e. decurrent) and are up to 1.8 mm wide then narrow becoming more needle-like and incurving distally. The more proximal leaves are longer with weakly accuminate apices, while the more terminal ones are shorter with rounded tips. Lateral leaves in the mid-region of the main axis are typically 3.0–3.5 mm long and 0.8–1.0 mm wide in the mid-region. The facials are ovate, 2.0–2.8 long and 1.0–1.5 mm wide in the mid-region. The apices appear to be acute and those in the mid-region of the main axis extend above the inner margins of their two laterals to overlap the base of the next facial above. A central keel is visible as a shallow groove (Plate I,5, at k; Fig. 1). Discussion: Confusion surrounds UCMP 11043 and its identification. It was figured as Chamaecyparis edwardsii (UCMP 11034, Axelrod, 1998a, Plate IX, 13). However, the specimen number is 11043 and listed as a hypotype under Abies deweyensis, but the specimen is not Abies or Chamaecyparis. The combination of features visible suggests it might be unique within the Cupressaceae. Although the proximal lateral axis resembles Chamaecyparis, the length and shape of the facial leaves, and non-adpressed (i.e. lax) lateral leaves excludes it from this genus and others such as Fokiena Henry and Thomas and Thujopsis (Thun. ex L. f.) Sieb. and Zucc. ex Endl. The long, lateral leaves of the fossil more closely resemble the Southern Hemisphere Libocedrus Endlicher in size and shape, especially the juvenile foliage of Libocedrus chevalieri Bucholz of New Caledonia. L. chevalieri differs from the fossil in that the tips of the facials end at the level of the inner margins of their laterals with little or no overlap of successive

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Table 1 Revision of Thunder Mountain conifer megafossils

11033 11034 11035 11041 10974 11042 USNM 315246 USNM 39596 USNM 315247 11045 11046 11047 11048* 11049 11043 11044 10973 10978 10984 10975 10977 (cpt. to 10975) 10976* (cpt. to 11001A) 11050 11055 11056 11057 (cpt. to 11099) 11051 11052 11065 USNM 315248 11001A 11064 10989 10987 10988 10990-10994 11068 11066 11069 11070 (no. dup.) 11067 11066 11072 11071 11070 10995 10996* 10998 11076

Organ Axelrod (1998a)

This report (revised)

Order or Family

Genus/Subsect.

Species

Plate Fig(s)

Order or Family Genus/Subsect.

Species

Plate Fig(s)

L VA VA OCS WS WS WS VA L L VA VA VA VA IND OC

Cephalotaxaceae Cupressaceae Cupressaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae

Cephalotaxus Chamaecyparis Thujopsis Abies A. A. A. A. A. A. Abies A. A. Larix L. L.

nevadensis Axelrod edwardsii Axelrod idahoensis Axelrod deweyensis Axelrod deweyensis Axelrod deweyensis Axelrod deweyensis Axelrod deweyensis Axelrod deweyensis Axelrod deweyensis Axelrod deweyensis Axelrod deweyensis Axelrod deweyensis Axelrod leonardii Axelrod leonardii Axelrod leonardii Axelrod

IX IX IV IX IV ++ IV 9 IX IX V V

11 19 7 8 6 ++ 8 9, 10, 14 13 7 8 4, 3, 5

Incertae sedis Cupressaceae Incertae sedis Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Cupressaceae Pinaceae Pinaceae Filicales Incertae sedis Pinaceae

Chamaecyparis Indet. cf. Abies cf. Abies cf. Abies Abies Abies Abies n. genus? Indet. Indet. Indet. Indet.

sp. Indet. sp. sp. sp. sp. sp. sp. n. sp.? Indet. Indet. Indet. Indet.

I III I I I I I I I III III

2, 3 10 7 10 8 5 6 9 1 4 1

OC WS WS L OC OC OC OC OC OC WS

Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae

L. L. L. Larix Picea P. P. P. P. P. P.

leonardii Axelrod leonardii Axelrod leonardii Axelrod leonardii Axelrod coloradensis Axelrod coloradensis Axelrod coloradensis Axelrod coloradensis Axelrod coloradensis Axelrod coloradensis Axelrod coloradensis Axelrod

IX IX IX X VI III X VI X

1 4, 5 2, 3 5 1 A 1 2–4 2–4

Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae

Indet. Larix Pinus Indet. Picea Indet. Indet. Indet. Indet. Indet. Picea

Indet. sp. sp. Indet. sp. A Indet. Indet. Indet. Indet. Indet. sp.

II I II -

9–11 13 1 -

VA L L OC OCS L

Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae

P. Picea P. P. P. P.

coloradensis Axelrod coloradensis Axelrod coloradensis Axelrod deweyenis Axelrod deweyenis Axelrod magna MacGinitie

X X X IV IV X

6, 9 7 8 5, 2 4 12

Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Cupressaceae

Picea cf. Picea Indet. Indet. Pinus cf. Sequoia

sp. sp. Indet. Indet. sp. sp.

III III I

2 3 4

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Spec. No.

WS 2FA

Pinaceae Pinaceae

Pinus P.

alvordensis Axelrod alvordensis Axelrod

X VII

14, 15 3

Pinaceae Pinaceae

Pinus Pinus

11079 11078

2FA

Pinaceae

P.

alvordensis Axelrod

X

16, 17

Pinaceae

P.

11082 11083 11084 7186 7187 11001B (cpt. to 11000) 11002 11003 11005 11009 11094 (no. dup.) USNM 39589

OC WS WS OC OC OC OC WS 5FA

Pinaceae/Balfourianae Pinaceae/Balfourianae Pinaceae/Balfourianae Pinaceae/Balfourianae Pinaceae/Balfourianae Pinaceae/Balfourianae Pinaceae/Balfourianae Pinaceae/Balfourianae Pinaceae/Balfourianae

P. P. P. Pinus P. P. P. P. P.

baileyi Axelrod baileyi Axelrod baileyi Axelrod balfouroides Axelrod balfouroidesAxelrod balfouroides Axelrod balfouroides Axelrod balfouroides Axelrod balfouroides Axelrod

XI XI XI VII + III XI ++

14 13 12 1 + B 15 ++

Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae

P./Pinus Larix Picea Pinus Pinus Pinus Pinus Larix Pinus

7188

5FA

Pinaceae/Balfourianae

P.

balfouroidesAxelrod

+

+

Pinaceae

Pinus

11004

5FA

Pinaceae/Balfourianae

P.

balfouroidesAxelrod

VII

2

Pinaceae

Pinus

11087 11086 11091 (cpt. to 11088) 11006-11008 11094 11098 11095 11097 11096* 11102 (cpt. to 11100) 11103 11010 11011 11013 (cpt. to 10979) 11014 11104 11105 11110 1110611107 11111 11112* 11109 11028

5FA

Pinaceae/Balfourianae

P.

balfouroides Axelrod XI

16-18

Pinaceae

Pinus

IFA WS 2FA 2FA 2FA OC OC WS L IND OCS WS WS L L

Pinaceae/Balfourianae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Salicaceae

Pinus P. P. P. P. Pseudotsuga P. P. P. Tsuga T. Tsuga T. T. Populus

balfouroides Axelrod resinosoides Axelrod resinosoides Axelrod resinosoides Axelrod resinosoides Axelrod glaucoides glaucoides glaucoides glaucoides mertensioides mertensioides mertensioides mertensioides mertensioides sp.

3, 4 1, 2, 5 7 8 6 6 8 9, 7 10 8

Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae Incertae Sedis Pinaceae Pinaceae Pinaceae Pinaceae Pinaceae

Pinus Pinus Pinus Pinus Pinus Pinus Larix Indet. Indet. cf. Tsuga Larix cf. Abies Indet.

XI XI VII VII VII XI XI XI XI VIII

sp. cf. sanjuanensis Axelrod cf. sanjuanensis Axelrod baileyiAxelrod sp. sp. sp. sp. sp. sp. sp. cf. crossii Knowlton cf. crossii Knowlton cf. crossii Knowlton cf. crossii Knowlton sp. sp. sp. sp. sp. sp. sp. Indet. Indet. sp. sp. sp. Indet.

-

-

-

-

II I -

5 15 -

-

-

-

-

-

-

II II III III III I -

6 7 6 7, 8 9 12 -

VA=vegetative axis, IFA=incomplete fascicle, 2FA=2-needled fascicle, 5FA=5-needled fascicle, L=leaf, OC=ovulate cone, OCS=ovulate cone scale, WS=winged seed, IND=indeterminate organ, * =specimen figured in this report, -=specimen not figured, +=figured in Axelrod (1986), ++=figured in Brown (1937). Specimen numbers are UCMP unless otherwise noted.

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11080 11081 151931 10999

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facials. Among fossil conifers, Taxon A is also reminiscent of material Stephen Edwards (2000, personal communication) recognized informally as Payettia

(Fig. 2) from the Miocene Payette flora while working on his Ph.D. thesis (Edwards, 1983), but never formally published.

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Fig. 1. Line drawing of Cupressaceae Taxon A illustrated in Fig. 5. Scale bar = 2 mm.

Fig. 2. Line drawing of vegetative axis recognized by Edwards (1983) from the Payette flora as a possible new genus that shows some resemblance to Cupressaceae Taxon A. UCMP 151933. Scale bar = 2 mm.

Family: Pinaceae Lindley The Pinaceae reported in the Thunder Mountain flora are misrepresented and several nomenclatural problems need clarification. Two specific epithets applied to the Thunder Mountain material, Picea coloradensis Axelrod and Pseudotsuga glaucoides Axelrod were earlier rejected by Wolfe and Schorn (1990, p. 15) and treated as bGenera and (or) Species IndeterminedQ because the holotypes are badly abraded and show no discernable generic characters. These two epithets are not considered valid here for the same reasons given by Wolfe and Schorn (1990).

Genus: Abies (Plin. ex Tourn.) Miller Species: Abies sp. (vegetative axes, winged seeds, leaves) (Plate I,8, 10) 1998 Abies deweyensis Axelrod—Axelrod: p. 34, (part), Plate IV, 6, 8; Plate IX, 8–10, 14. Occurrence and material: Dewey Mine: USMN 315247, 315246, 39596; Road locality: UCMP 11042, 11045–11049, 11109. Material excluded: Dewey Mine: UCMP 10973, 10974; Road locality: UCMP 11043, 11044.

Plate I. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15.

Close-up of UCMP 10978 here identified as a fern rhizome showing helically arranged petiole scars. Scale in mm. Fragment of vegetative axis here referred to Chamaecyparis sp. UCMP 11034. Scale in mm. Fragment of vegetative axis here referred to Chamaecyparis sp. UCMP 11035. Scale in mm. Leaf previously referred to Picea magna here referred to cf. Sequoia. UCMP 11076. Scale in mm. Cupressoid vegetative axis here referred to Cupressaceae Taxon A showing lateral leaves (la), keeled (k) facial leaves (f), and branch (br). UCMP 11043. Scale in mm. Abraded stem fragment previously referred to Abies here referred to Pinaceae gen. et sp. indeterminate. UCMP 11044. Scale in mm. Cone scale previously referred to Abies deweyensis here referred to Pinaceae gen. et sp. indeterminate. UCMP 10974. Scale in mm. Leaf previously attributed to A. deweyensis here referred to Abies sp. UCMP 11048. Scale in mm. Remnants of partial vegetative axis previously referred to A. deweyensis here referred to Pinaceae gen. et sp. indeterminate. UCMP 10973. Scale in mm. Winged seed previously referred to A. deweyensis showing distal portion of wing is missing. Specimen here referred to Abies sp. UCMP 11042. Scale in mm. Typical Larix seed previously referred to L. leonardii here referred to Larix sp. UCMP 151932. Scale in mm. Close-up of Larix seed showing remnants of hairs (h). UCMP 11112. Scale bar = 1.0 mm. Pinus sp. previously described as Larix leonardii. UCMP 11057. Scale in mm. Pinus sp. Counterpart to 13 and previously described as Pinus resinosoides. UCMP 11099. Scale in mm. Winged seed of Picea previously referred to Pinus baileyi. UCMP 11084. Scale in mm.

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Discussion: Abies is present at Thunder Mountain but megafossils of this genus are not abundant. Brown (1937) first recognized Abies in the Dewey Mine florule

based on a foliated axis, winged seeds, and cones. The cones are not Abies, but more likely Picea. Axelrod (1998a) later named the Thunder Mountain fir A.

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deweyensis designating Brown’s partial branch as the holotype (Brown, 1937, Plate XLVI, 2; Axelrod, 1998a, Plate IV, 8). Additional Thunder Mountain material referred to A. deweyensis included abraded branch fragments (Plate I,5,6,9) and cone scale (Plate I,7), two winged seeds (Plate I,10), and needles (Plate I,8). Brown’s foliated axis (USNM 316247) is the most definitive megafossil of Abies in the Thunder Mountain flora as it shows round leaf scars and expanded, sucker-like leaf bases diagnostic of true firs. Axelrod noted that A. deweyensis is similar to A. cuprovallis Axelrod from the Nevada Eocene Copper Basin flora, . . .especially in foliage. However, the foliage of high mountain firs is generally so similar that affinity with any one modern or fossil species cannot be established with any certainty. The chief difference as compared with A. cuprovallis. . .is that its seeds are elliptical and the wings asymmetrical.Q (Axelrod, 1998a, p. 34). Although shape of the winged seeds is consistent with Abies, the distinction between A. deweyensis and A. cuprovallis is very tenuous given it is based on one winged seed from Copper Basin (Axelrod, 1966, pg. 10, Table 2) and two from Thunder Mountain (Axelrod, 1998a, pg. 7, Table 1; pg. 11, Table 2). The Thunder Mountain winged seeds and needles do fall within the range of A. cuprovallis. Furthermore, the wing of UCMP 11042 from the Road locality was de´gaged revealing the distal portion is missing so its length cannot be determined (Plate I,10). The other Thunder Mountain specimens attributed to Abies are questionable. Specimen UCMP 11043 is re-described as a partial shoot with relatively long lateral cupressoid leaves and large narrowly ovate to elliptic facial leaves arranged in a decussate pattern (Plate I,5, Fig. 1). Specimen UCMP 11044 shows diamond-shaped bleaf scarsQ (Plate I,6) rather than

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the circular scars diagnostic of Abies. This specimen is more likely the partial remains of a degraded Pinus branch. UCMP 10973 from Dewey Mine is so poorly preserved that it is not clear where the fossil is on the rock. There appears to be remnants of a partial vegetative axis (Plate I,9), but it lacks features needed to separate it from other taxa such as Picea or Sequoia. The Dewey Mine cone scale shows no diagnostic features to assign this specimen to Abies or any other taxon with any level of confidence (Plate I,7). Therefore, it is treated here as Pinaceae genus and species indeterminate (Table 1). There are currently 11 needles in the UCMP Thunder Mountain collection assignable to Abies, once parts and counterparts are reunited, and unidentifiable specimens eliminated. No unequivocal isolated Abies needles are in the UCMP Dewey Mine collection. One needle was de´gaged and found to be 2.0 cm long, falling well outside the 7.0–8.0 mm range given for A. deweyensis (Axelrod, 1998a). In addition, only 6 specimens from the Road florule are complete showing what appear to be circular, suction-cup-like bases, which is one of the best characters for assigning isolated leaves to Abies. At this time we refer all the Thunder Mountain fir remains to Abies sp. until a more thorough review of fossil Abies is available. Genus: Larix Miller Listed below are the elements attributable to Larix. Although the new species L. leonardii was recognized, the holotype cone shows no diagnostic characters to assign it to Larix. The exserted bracts that were described are the edges of the cone scales in side view (Plate II,10,11). We refer the cone to Pinaceae gen. et sp. indeterminate and all the vegetative elements to Larix sp. Species: Larix sp. (vegetative axes, winged seeds) (Plate I,11,12)

Plate II. 1. 2. 3. 4. 5. 6, 7.

Ovulate cone previously referred to Picea coloradensis here referred to Picea sp. A. UCMP 11065. Scale in mm. Picea canadensis (Mill.) B.S.P. University of California Herbaria specimen 649768. Scale bar = 1.0 cm. Picea glauca (Moench) Voss. University of California Herbaria specimen M282574. Scale bar = 1.0 cm. Picea pungens Engelmann. University of California Herbaria specimen 590248. Scale bar = 1.0 cm. Holotype of Pinus baileyi. UCMP 11082. Scale in mm. Two-needled fascicles previously referred to the new species Pinus resinosoides here referred to Pinus sp. (section Pinus). 6. UCMP 11096. 7. UCMP 11102. Scale in mm. 8. Leaf of Tsuga showing narrow petiolate base. UCMP 11108. Scale in m. 9–11. Holotype of Larix leonardii here referred to Pinaceae gen. et sp. indeterminate. 9. Part UCMP 11050. 10–11. Counterpart UCMP 11050 showing the supposed bexserted bractsQ are the cone scales in side view. Note one-half of scales on the part the other half of scales on the counterpart. Scale in mm. 12. Keteleeria davidiana. Image from Michael P. Frankis Cone collection, Arboretum de Villardebele, http://www.pinetum.org/.

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1998 Larix leonardii Axelrod—Axelrod: p. 34, (part), Plate V, 6, 7; Plate IX, 4, 5. 1998 Pinus balfouroides Axelrod—Axelrod: p. 38, (part), Plate XI, 15. 1998 Pseudotsuga glaucoides Axelrod—Axelrod: p. 39, (part), Plate VII,8. 1998 Tsuga mertensioides Axelrod—Axelrod: p. 39– 40, (part), Plate XI, 7, 9. Occurrence and material: Dewey Mine: UCMP 10979 (ctp. 11013), 10980 (ctp. 10981), 10983, 11012; Road locality: UCMP 11055 (ctp. 11059), 11056 (ctp. 11056a), 11060–11063, 11094, 11106, 11107, 11111, 11112. Material excluded: Dewey Mine: UCMP 10978, 10984; Road locality: UCMP 11051, 11052, 11057, 11099. Description: Larix is represented in the Road assemblage by short segments of defoliated Larix twigs and winged seeds. The twigs are 3.0–4.0 cm wide and 2.0– 5.0 cm long and show brachyblasts, 2.0–3.0 mm wide. The winged seeds have a subtriangular-shaped body, convex admedial edge, and are 4.0–5.5 mm long  2.0– 2.5 mm wide (Plate I,11). Well-preserved seeds show resin vesicles not present, hairs on the seed surface (Plate I,12), and a small area of pterostegium on the proximal tip of the seed. The wings are 9.0–11.0 mm long  3.9–4.5 mm wide at the mid region, and broadly attached along the admedial edge of the seed, with a bib-like extension where it attaches to this edge. A similar condition occurs in Tsuga, but the epidermal cells in the bbibQ of Tsuga bend back toward the proximal end of the seed, whereas in Larix they run perpendicular from the seed and then bend back towards the distal end as they approach the abmedial margin of the wing. Overall the epidermal cells follow a straight course from the seed to the distal end of the wing. Discussion: Larix is well represented in the flora by winged seeds and twigs. Based on our revision we recognize six winged seeds and no twigs in the Dewey Mine florule and 25 winged seeds and four twigs in the Road florule. These numbers are considerably less than the published number of specimens, in part, because the published numbers were based on field counts and many of the specimens were either left in the field or later bjunked,Q as well as our reassignment of others. For example, UCMP 11057 (Plate I,13) was identified as L. leonardii, while its counterpart UCMP 11099 was included in Pinus resinosoides (Plate I,14). The specimen is Pinus. We refer all the Thunder Mountain larch material at this time to Larix sp. (Table 1).

Genus: Picea A. Dietrich Species: Picea sp. A (ovulate cone) (Plate II,1) 1998 Picea coloradensis Axelrod—Axelrod: p. 36, (part), Plate X, 5 only. Occurrence and material: Road locality: UCMP 11065. Description: Ovulate cone with its base and apex missing. The cone is curved, narrowly oblong, 5.0+ cm long and 1.8 cm wide, with cone scales appearing rigid (woody). Cone scales are obtuse to broadly obtuse, 7–8 mm wide, 6–8 mm long, with a smooth margin. An average angle of 758 (range 73–78; n = 6) is found between left and right orthostichies (i.e. scale rows). Discussion: Picea coloradensis Axelrod was first described from the Oligocene Creede flora (Axelrod, 1987), but Wolfe and Schorn (1990) recommended rejecting the name due to the poorly preserved holotype (refigured in Wolfe and Schorn, 1990; Plate II,5) and the other specimens included. All the cones are abraded and show no diagnostic features. They included the taxon under bGenera and (or) Species Indetermined (cone fragments).Q All the P. coloradensis cones from the Dewey Mine and Road locality, except UCMP 11065 (Plate II,1), are fragmentary and badly abraded having undergone transport, exposure and possible herbivory prior to burial. We exclude the Thunder Mountain cones from this taxon and refer them to Pinaceae gen. et sp. indeterminate (Table 1). Picea coloradensis was allied to the Colorado blue spruce, P. pungens. However, UCMP 11065 shows more similarities to P. glauca (Moench) Voss (White spruce) in the broad sense and in particular to P. canadensis (Mill.) Britton, Sterns and Poggenb. (Plate II,2) which has been synonymized with P. glauca. Unlike P. glauca, the fossil cone scales are slightly more obtuse and narrower than the broader, weakly bi-lobed scales of P. glauca (Plate II,3). However, like P. glauca the scales appear woody, broadly rounded and have relatively smooth margins, whereas scales of P. pungens are thin and more triangular with truncate erose apices (Plate II,4). Although we consider UCMP 11065 to be closer to P. glauca, Taylor (1993) notes in the bFlora of North AmericaQ that P. glauca and P. engelmannii Parry ex Engelmann regularly hybridize and intergrade completely bgreatlyQ complicating the taxonomy of P. glauca. Species: Picea sp. (winged seeds) 1998 Picea coloradensis Axelrod—Axelrod: p. 34, (part), Plate X, 2–4 only. 1998 Picea magna MacGinitie—Axelrod: 35, Plate X, 10–13.

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1998 Pinus baileyi Axelrod—Axelrod: p. 37, Plate XI, 12. Occurrence and material: Road locality: UCMP 11068–11070, 11073, 11073–11076, 11084. Discussion: All the winged seeds of Picea are from the Road locality. The smallest is 7.0 mm long (seed = 2.0 mm long, wing = 5.0 mm long), while the largest seed is 14.0 mm long (seed = 4.0 mm long, wing = 10.0 mm). Although the smaller seeds were attributed to P. coloradensis and the larger to P. magna, the wing morphology is the same in all specimens and therefore all could represent the range of variation in one species. The seeds from a single cone of P. sitchensis for example show a similar range of variation in seed and wing size (personal observation). We refer all the seeds to Picea sp., including the one previously assigned to Pinus baileyi (Plate I,15) until a more quantitative method is developed to meaningfully sort out the variation in the size and shape of winged seeds. Species: Picea sp. (vegetative axes, leaves) 1998 Picea coloradensis Axelrod—Axelrod: p. 34, (part), Plate X, 6, 7 only. Occurrence and material: Road locality: UCMP 11066, 11067, 11071. Material excluded: Road locality: UCMP 11070. Discussion: Several vegetative axes and isolated needles were attributed to two species of spruce, Picea magna and P. coloradensis. Included in P. coloradensis was a foliated axis, 3.5 cm long  2.0 mm wide, with leaves 7.0–10.0 mm long  1.0 mm wide and two defoliated axes measuring up to 4.5 mm long and bearing numerous pulvinae, 0.3–1.0 mm long. The isolated leaves are 12.0  1.0 mm wide. The needle attributed to P. magna appears to be more similar to Sequoia (Plate I,4). It is over 12.0 mm long and 2.0 mm wide. The type of P. magna is a winged seed and even if this specimen was a spruce needle it is not clear why it was attributed to this species. We refer these remains to Picea sp. until better criteria are established for recognizing isolated leaves as belonging to the same taxon. Genus: Pinus Linnaeus Four species of pine based on megafossils were reported from Thunder Mountain (Axelrod, 1998a). The type specimens included 6 ovulate cones, 10 winged seeds, and 38 fascicles and leaves. Recognized among this material were two species of hard pines (subgenus Pinus), P. alvordensis Axelrod and P. resinosoides Axelrod, and two soft pines (subgenus Strobus), P. balfouroides Axelrod and P. baileyi Axelrod.

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We also recognize the remains of hard and soft pines but propose the following revisions based on the material available. Subgenus: Pinus sensu Gernandt et al., 2005 Section: Pinus sensu Gernandt et al., 2005 cf. Subsection: Pinus sensu Gernandt et al., 2005 Species: Pinus baileyi (sic) Axelrod emend. Erwin and Schorn (ovulate cones) (Plate II,5) 1998 Pinus baileyii Axelrod—Axelrod: p. 37, (part), Plate XI, 14 only. 1998 Pinus baileyii Axelrod—Axelrod: p. 44, Plate IV, 9, 10. 1998 Picea deweyensis Axelrod—Axelrod (1998b): p. 43, (part), Plate IV 12. Occurrence and material: Road locality: Holotype UCMP 11082. Material excluded: Road locality: UCMP 11083, 11084. Description: Pinus baileyi has been re-described by the authors (Erwin and Schorn, in press) so we give only a brief account of it here. The four cones now referred to P. baileyi show possible slight asymmetry and they measure 4.0–6.0 cm long and 2.5 cm wide. The apophyses in plane view are 4–6-sided, the sides are straight but upper sides of some scales appear rounded, 9.0– 11.0 mm wide, 5.0–6.0 mm high. The width to height ratio is approximately 1.8 : 1. The dorsal umbo is prominent and raised above the surface of the apophysis, 2.0–4.0 mm wide and 1.5–2.5 mm high. Umbos are excentromucronate (i.e. the mucro is in the upper umbo field above the keel) (Klaus, 1980), not centro-erectomucronate (centromucronate) (Axelrod, 1998a). The mucro is erect, curved, sharply pointed, up to 0.5 mm long, and lies above and is separate from the keel (Erwin and Schorn, in press). Discussion: Pinus baileyi was described from the Thunder Mountain Road locality based on a partial ovulate cone and two winged seeds (Axelrod, 1998a). It was later described from the Oligocene Haynes Creek flora based on cones (Axelrod, 1998b). Although a holotype was named from each flora, the Thunder Mountain cone takes priority as the valid holotype since it was published first. Pinus baileyi was related to the extant Great Basin bristlecone pine P. longaeva Bailey (subgenus Strobus; section Parrya Mayr; subsection Balfourianae Engelmann) of California, Nevada, and Utah. However, cones of P. longaeva differ from those of P. baileyi in being centromucronate, with a relatively long mucro typically reflexed toward the base, whereas P. baileyi is excentromucronate and the mucro is erect. Further-

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more, the Thunder Mountain winged seeds are not Pinus; one is Larix, the other Picea (Plate I,15). Pinus baileyi cone size and scale morphology is most similar to that described as perexcentromucronate by Klaus (1980). Perexcentromucronate pines include P. brutia Ten., P. halepensis Mill., P. pinea L., P. resinosa Aiton, P. massoniana Lamb., and P. kesiya Royle ex Gordon (Klaus, 1980). Among these, P. baileyi shows closest resemblance in cone scale morphology to members of subsection Pinus sensu Gernandt et al., 2005 especially the two Southeast Asian pines P. kesiya and P. massoniana. Today, P. kesiya is a three-needled form with the mucro mostly reflexed (Farjon, 1984, personal observation). This species is found at altitudes of 800– 1500 m in dry areas in Thailand, Myanmar, and the southwestern Chinese provinces of Sichuan and Yunnan. Pinus massoniana also shares similarities in cone morphology. It is 2-needled (but also produces 3-needled fascicles [Wu and Raven, 1999]) and the mucro is typically erect. This pine apparently grows in extreme environments from a few hundred to 2000 m in moist river valleys to the dry mountain plateaus of China’s interior (Critchfield and Little, 1966; Farjon, 1984). It is also found on Taiwan and Hainan Islands (Farjon, 1984). Subgenus: Pinus sensu Gernandt et al., 2005 Species: Pinus sp. (long 2-needled fascicles) (Plate II,6,7) 1998 Pinus resinosoides Axelrod—Axelrod: p. 38, Plate XI, 1, 2, 5. Occurrence and material: Road locality: UCMP 11095–11097, 11100–11103. Discussion: Two-needled fascicles over 7.5 cm long  1.0–1.2 mm wide with a bilateral base and persistent leaf sheath (Plate II,6) were included in the new species Pinus resinosoides and compared to P. resinosa (Axelrod, 1998a). Among fossil species the fascicles were compared to P. tiptoniana Chaney and Axelrod from the Miocene Blue Mountains flora of Oregon. Earlier P. tiptoniana had been compared to P. halapensis, P. nigra Arnold, P. echinata Miller, and P. resinosa (Chaney and Axelrod, 1959). However, because the type of P. tiptoniana is a partial ovulate cone (Chaney and Axelrod, 1959) that was later transferred (along with the 2-needled fascicle) to subsection Oocarpae Little and Critchfield (Axelrod, 1986) this species became allied to the Mexican hard pines, in particular, P. patula Scheide and Deppe and P. pringlei Shaw. However, with P. baileyi now recognized as a member of subsection Pinus sensu Gernandt et al. (2005) (Erwin and Schorn, in press), and since species in this group produce long needles in fascicles of two to three, it is

possible that the P. resinosoides-type fascicles were produced by the P. baileyi pine. However, it is unknown whether P. baileyi is in fact closer to the Asian members of this subsection or to the North American member of the group P. resinosa. Therefore, we refer the P. resinosoides leaves to P. sp. Subgenus: Strobus Lemmon Subsection: Balfourianae Engelmann Species: cf. Pinus crossii Knowlton (5-needled fascicles) 1998 Pinus balfouroides Axelrod—Axelrod: p.38, Plate VII, 2; Plate VIII, 7; Plate XI, 16–18. Occurrence and material: Dewey Mine: UCMP 11004, USNM 39589; Road locality: UCMP 11086–11091. Discussion: Short five-needled fascicles with a circular shoot and deciduous sheath occur at both the Dewey Mine and Road localities. Leaves are curved, 2.0–3.0 cm long and V 0.5 mm wide. These fascicles were included in P. balfouroides, but fall within the size range of five other fossil species: P. crossii, P. florissantii Lesquereux, P. coloradensis Knowlton, P. wasonii Axelrod and P. anthrarivus Axelrod. Wolfe and Schorn (1990) referred all the Creede fascicles of P. florissantii, P. coloradensis, and P. wasonii to P. crossii. The holotype of P. crossii is the fascicle; however, these authors also included cones and winged seeds in their circumcription of P. crossii. At this time we refer the Thunder Mountain fascicles to cf. P. crossii. Subsection: ?Cembroides Engelmann Species: cf. Pinus sanjuanensis Axelrod (short 2needled fascicles) 1998 Pinus alvordensis Axelrod—Axelrod: p. 37, Plate X16, 17. Occurrence and material: Dewey Mine: UCMP 10999; Road locality: UCMP 11078, 11079. Discussion: Short, two-needled fascicles from the Dewey Mine and Road locality were attributed to P. alvordensis. The Road locality fascicles are 2.0–3.0 cm long and 1.0 mm wide and show a circular shoot and deciduous sheath, features characteristic of the soft pines (subgenus Strobus). The fascicle from Dewey Mine (UCMP 10999) is poorly preserved and could possibly be a 5-needled type. The short 2-needled fascicles were assigned to P. alvordensis along with winged seeds. However, the type of P. alvordensis is a winged seed of a hard pine (Axelrod, 1944) whereas the Thunder Mountain fascicles are characteristic of soft pines, yet Axelrod combined these organs and related them to the hard pine, P. contorta (lodgepole pine). The two-needled fascicles of the P. alvordensis type were earlier trans-

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ferred to P. sanjuanensis (Section Parrya; Wolfe and Schorn, 1990). The short, 2-needled fascicles from Thunder Mountain compare favorably to P. sanjuanensis based on the revision of fascicle types by Wolfe and Schorn (1990) and here are referred to this species. Subgenus: Indeterminate Species: Pinus sp. (winged seeds) 1998 Pinus alvordensis Axelrod—Axelrod: p. 37, Plate VII 3; Plate X 14–17. 1998 Pinus resinosoides Axelrod—Axelrod: pp. 38– 39, Plate XI, 3, 4. Occurrence and material: Road locality: UCMP 11080, 11081, 11094 (no. dupl. P. resinosoides), 11098, 11099. Material excluded: Road locality: UCMP 11083, 111084, 11094 (no. dupl., P. balfouroides). Discussion: Determining the affinity of isolated winged seeds is a challenge, especially when the collection is small. One of the primary distinctions between hard and soft pines is that the wing in hard pines detaches from the seed, whereas in soft pines it remains attached. Obviously it is difficult to determine if these characters are natural or due to taphonomic processes in a plant assemblage that has undergone transport prior to fossilization. With that said, three winged seeds from the Road locality were referred to P. alvordensis and two to the new species P. resinosoides. The type seed of P. alvordensis is a hard pine from the Miocene Alvord Creek locality of Oregon (Axelrod, 1944). It is 1.5 cm long the seed body is 5.0 mm long  2.0 mm wide, with an incomplete wing, 1.0+ cm long  4.0+ mm wide. The winged seeds from the Road locality differ somewhat in their dimensions from the type. They are 1.5–1.9 cm long, with wings 1.4–1.5 cm long  4.0–6.0 mm wide, and the seed body is 2.0–3.0 mm long  1.5–2.0 mm wide. However, because of the small sample size it is difficult to know whether the fossil seeds represent those fully mature and shed from the central part of the cone (i.e., typical) or those aborted, atypical seeds shed from the apex or near the base. Therefore, because of the small sample size, combined with the difference in age and the observation that the winged seeds of P. resinosoides have the same dimensions as P. alvordensis we refer the specimens to Pinus sp. (Table 1). Subgenus: Indeterminate Species: Pinus sp. (ovulate cones) (Plate III,5,7,8) 1998 Pinus balfouroides Axelrod—Axelrod: p. 38, Plate III, B, Plate VII, 1. 1998 Pseudotsuga glaucoides Axelrod—Axelrod: p. 39, unfigured specimen.

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Occurrence and material: Dewey Mine: (Pinus balfouroides) UCMP 7186, 7187, 11001B (cpt. to 11000), 11002, 11003, 11005, 11009. Dewey Mine: (Pseudotsuga glaucoides) UCMP 11011. Discussion: Pinus balfouroides: Axelrod (1998a) applied the name P. balfouroides to ovulate cones and 5needled fascicles from Dewey Mine and the 5-needled fascicles and winged seeds from the Road locality. History of the name shows it was never formally diagnosed or accurately described, but casually introduced in the discussion of Pinus sturgisii Cockerell from Florissant (Axelrod, 1980, pp. 107 and 209), bAs for the species listed in the synonomy above, the cone in the Chalk Hills flora [see Axelrod, 1986; Fig. 28] previously identified as P. florissantii Lesquereux is not a yellow pine either. The cone scales are not pyramidal, and do not have prominant umbos or bristles. A latex impression of the cone, when compared with modern cones of subsect. Balfourianae, which includes P. aristata, P. balfouriana, and P. longavea, clearly show that it is most similar to balfouriana. This is especially apparent in the cone scales, which give the appearance of drooping breasts. [Note Axelrod described ovulate cones with the apices pointed toward the bottom of the plate. Thus his terminology is reversed from convention and so the bbreastsQ would be bpert,Q not bdrooping.Q]. Furthermore, the umbos are neither prominent nor pyramidal in shape, and they are not terminated by sharp bristles, as in aristata and longaeva. To emphasize the close relationship between the fossil and the living foxtail pine, the name balfouroides is herewith chosenQ (Axelrod, 1980, p. 107). The Nevada Chalk Hills cone figured in Axelrod (1962, Plate XLII, 9; UCMP 8007) was implied as the holotype in the text and the appendix (Axelrod, 1980). Examination of the Chalk Hills cone has revealed that it is poorly preserved, covered with shellac, may be asymmetrical, and shows little detail of the apophyses, umbo and mucro. Prior to 1986, P. balfouroides was recognized on the basis of an ovulate cone, winged seeds, seed wings and 5-needled fascicles from several ~ 15.5–12.5 Ma sites in west-central Nevada (Axelrod, 1962, 1976, 1980, 1985). Pinus balfouroides is then mentioned in the bCenozoic History of some western American PinesQ (Axelrod 1986, p. 613). Here UCMP 8007 from Chalk Hills is listed in the synonomy as the holotype of the species. Still no formal description is provided. Additional ma-

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terial is referred to this species from Sharktooth Hill, California, and Coal Creek and Thunder Mountain, Idaho. The inclusion of the Thunder Mountain material

extended the stratigraphic range back to the middle Eocene (~46 Ma). In 1991, winged seeds, seed wings, and 5-needled fascicles from the Nevada Miocene

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Buffalo Canyon flora were added to P. balfouroides (Axelrod, 1991, p. 37). Later added in 1995 were two ovulate cones, winged seeds, seed wings, and 5-needled fascicles from the Nevada Miocene Purple Mountain flora (Axelrod, 1995). Here the cone description included, b. . .apophyses rounded, smooth with dorsal umbosQ (Axelrod, 1995, p. 39). Again characters common to many pines. Adding to the confusion was the listing of a Purple Mountain cone (UCMP 5501) as the holotype in the caption to Plate V, 17 (note figure captions are switched). The specimen is UCMP 7177, a hypoptype. UCMP 5501 is a winged seed (Axelrod, 1986; Fig. 27). The P. balfouroides cones from Thunder Mountain are too badly abraded to be identified beyond genus. Several cones show inflated cone scale apices suggesting they belong to Pinus (e.g. Plate III,5) but nothing more. The 5-needled fascicles are assignable to P. crossii and the seed wing (UCMP 11092) is here referred to Pinus sp. As is the case with many Tertiary conifer species, the concept of P. balfouroides has evolved from the inclusion over time of often poorly preserved cones, winged seeds and fascicles of different ages and localities that belong to other genera and are assignable to existing species. Therefore, we refer the Thunder Mountain P. balfouroides cones showing inflated apices to Pinus sp., those unidentifiable to Pinaceae gen. et sp. indeterminate (Table 1). Pseudotsuga glaucoides: The two cones, UCMP 11010 and 11011, from Dewey Mine were identified as P. glaucoides. UCMP 11010 is too badly abraded to assign it to genus and in this report is treated as Pinaceae genus et sp. indeterminate. UCMP 11011 shows two attached cone scales with inflated apices with apparent dorsal umbos (Plate III,7,8, arrows) indicative of Pinus. We refer this specimen to Pinus sp.

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Genus: Tsuga (Endlicher) Carrie`re Species: Tsuga sp. (leaf) (Plate II,8) 1998 Tsuga mertensioides Axelrod—Axelrod: p. 39, (part), Plate XI, 11 only. Occurrence and material: Road locality: UCMP 11108. Material excluded: Road locality: UCMP 11109. Discussion: Tsuga was recognized only in the Road florule. Among the cone scales, winged seeds, and needles, only one needle is confidently assigned to Tsuga (Table 1). It shows the short, narrow, petiolate base and nearly equal width along its length, both characteristics of Tsuga. Needles of Abies look similar but are apetiolate, have a broader attachment, and show a gradual narrowing proximally due to the twisting of the leaf base. Species: Tsuga sp. (winged seeds) 1998 Tsuga mertensioides Axelrod—Axelrod: p. 39, (part), 11, 9 only. Occurrence and material: Road locality: UCMP 11110. Material excluded: Road locality: UCMP 11106, 11107, 11111, 11112. Discussion: Identifying Tsuga winged seeds is more difficult since they resemble Larix if preserved abfacial side up. However, there are features that when preserved can help distinguish the two (Wolfe and Schorn, 1990). Tsuga seeds have resin vesicles, whereas Larix does not. The vesicles are most prominent on the adfacial surface of the seed and when preserved in a fine grain matrix will often appear as small depressions or raised areas on the seed surface. Because of the finegrained matrix of the Road locality, we would expect to see remnants of the resin vesicles but none have been observed. In addition, the surfaces of Larix seeds may show the remnants of the tomentose surface of the cone

Plate III. 1.

Ovulate cone previously referred to the new species Larix leonardii. UCMP 10976. Note this specimen is the counterpart to the cone at bAQ (UCMP 11001) in bottom left of Axelrod (1998a, Plate III), which was referred to Picea coloradensis. Here it is referred to Pinaceae gen. et sp. indeterminate. Scale in mm. 2. Cone previously referred to new species Picea deweyensis. Note lower portion shows rhombic shaped scales more reminiscent of Pinus. Specimen here referred to Pinaceae gen. et sp. indeterminate. UCMP 10995. Scale in mm. 3. Cone scale previously referred to Picea deweyensis here referred to Pinus sp. Note remnant of dorsal umbo (arrow). UCMP 10998. Scale in mm. 4. Axis previously referred to Larix leonardii here referred to Incertae sedis. UCMP 10984. Scale in mm. 5. Close-up of Pinus balfouroides cone scales showing inflated apices typical of Pinus, but no other details. Specimen here referred to Pinus sp. UCMP 11001B. Scale in mm. 6–8. Cones previously referred to Pseudotsuga glaucoides. 6. UCMP 11010 here referred to Pinaceae gen. et sp. indeterminate. 7, 8. UCMP 11011. Note remnants of attached cone scales with inflated apices typical of Pinus at arrows in 8. Specimen referred to Pinus sp. Scale in mm. 9. Winged seed previously referred to Pseudotsuga glaucoides here referred to Larix. UCMP 11013. Note UCMP 10979 is counterpart to this specimen. Scale in mm. 10. Vegetative axis previously referred to the new species Thujopsis idahoensis here referred to Incertae sedis. UCMP 11041. Scale in mm.

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scales, whereas seeds of Tsuga do not. Both Larix and Tsuga have a proximal bib-like extension where the seed attaches to the wing. In Tsuga, the cellular pattern of the bib shows a tendency to curve forward toward the micropylar end of the seed, whereas in Larix the cells generally curve toward the distal end of the seed and wing (Wolfe and Schorn, 1990). Among the Tsuga winged seeds identified only UCMP 11110 compares favorably to this genus, the others to Larix (Table 1). Genus: Indeterminate Species: Indeterminate (ovulate cones) (Plate II,9–11; Plate III,1,2,6) 1998 Larix leonardii Axelrod—Axelrod: p. 34, (part), Plate IX, 1. 1998 Picea coloradensis Axelrod—Axelrod: p. 36, (part), Plate III, A; VI, 1–4; Plate X, 1. 1998 Picea deweyensis Axelrod—Axelrod: p. 36, Plate IV, 2, 3, 5. 1998 Pseudotsuga glaucoides Axelrod—Axelrod: p. 39, Plate VII, 7. Occurrence and material: Dewey Mine: UCMP 10975–10977, 10982, 10985, 10987–10997, 11010; Road locality: UCMP 11050, 11064. Discussion: Larix leonardii: Axelrod (1998a) established the new species L. leonardii in the Thunder Mountain flora attributing 381 specimens of associated cones, seeds, needles, and branches to this species. An ovulate cone from the Road locality was designated as the holotype and described as having conspicuous exserted, awl-like bracts extending 1.0 cm from the body of the cone (Axelrod, 1998a, p. 35). Neither the holotype (UCMP 11050, Plate II,9–11) nor any of the paratype cones from Dewey Mine (UCMP 10975– 10977, 10982, 10985) show long, exserted bracts. All the Dewey Mine cones are highly abraded (e.g. Plate III,1,2,5–8). De´gaging shows the supposed bexsertedQ bracts of the holotype and Dewey Mine cones are the scales of the part and counterpart that have broken apart and appear in side view (e.g. Plate II,9–11; Plate III,1). The cone scales are obtuse, broad at the base and narrowing distally, some scales appear erose (Plate II,11, terminal scale), but this may be an artifact of preservation. To further illustrate the difficulty in identifying abraded cones UCMP 10976 was included in L. leonardii (Axelrod, 1998a) (Plate III,1); however, this specimen is counterpart to UCMP 11001 (Axelrod, 1998a, Plate III, cone at lower left at A), which was referred to Picea coloradensis. Because the cone and cone scale morphology of the holotype also compare favorably to Picea, showing resemblance to P. engelmannii and other papery coned spruces (e.g.

Plate II,4), there is no justification based on the material collected to date for its description as and assignment to a long-bracted species of Larix. Moreover, the holotype of L. leonardii is reminiscent of the cones of Keteleeria davidiana (Plate II,12). Keteleeria pollen has been recognized in the flora (Axelrod, 1998a; Taggart and Cross, 2000) as well as a portion of a broad needle with a conspicuous midrib. The needle was referred to Cephalotaxus, but Keteleeria also produces broad, falcate leaves. Although Larix is well documented in the Road florule by defoliated axes with attached brachyoblasts and well-preserved winged seeds, larch is rare at Dewey Mine represented by only three winged seeds. The cones are highly abraded and show no features diagnostic of Larix (Plate III,1) and are best treated as Pinaceae gen. et sp. indeterminate, since their assignment to Picea or Pinus cannot be ruled out. The Dewey Mine branches identified as Larix are not Larix. One of is a fern rhizome (UCMP 10978, see Axelrod, 1998a, Plate V, 8) (Plate I,1) and the other, UCMP 10984 may be also (Plate III,4), but it lacks any definitive characters to confidently assign it to this group or any other (see Incertae sedis section). Picea coloradensis: Wolfe and Schorn (1990) rejected the holotype specimen on which P. coloradensis was named since it showed no characters to justify its recognition as a species of Picea. They referred it to their bGenera and Species IndeterminedQ and referred the other P. coloradensis specimens to bPinus Species Indetermined.Q All the Thunder Mountain cones assigned to this species, except UCMP 11065, are too abraded to discern if they are Picea. Therefore, we refer all the Thunder Mountain cone material to Pinaceae gen. et sp. indeterminate, except UCMP 11065, which is here referred to Picea sp. A. Picea deweyensis: This was a new Thunder Mountain species (also recognized in the Haynes Creek flora, Axelrod, 1998b) described from cones, needles, winged seeds, and a cone scale. Although it included winged seeds and needles, there are no numbered specimens in the collection identified as P. deweyensis. The material listed is only the cones and cone scale (UCMP 10995– 10998). It is unclear which specimen was intended as the holotype, UCMP 10995 is listed as the holotype in the text, but UCMP 10996 is listed as the holotype in the figure caption (Axelrod, 1998a, Plate IV 2). We recommend rejecting this species since the Thunder Mountain cones are too badly abraded to tell if they are Picea or Pinus. Some scales in the basal part of the specimen in Plate III,2 appear more reminiscent of rhombic apophyses with dorsal umbos typical of

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Pinus (Plate III,2, arrow). The cone scale attributed to P. deweyensis is Pinus (Plate III,3). Also, the one Haynes Creek P. deweyensis cone has been transferred to Pinus baileyi (Axelrod, 1998b, Plate IV, 12; Erwin and Schorn, in press). Pseudotsuga glaucoides: This species was recognized in the Dewey Mine florule based on four cones, two winged seeds, and an isolated needle. However, there are just two cones in the collection (Plate III,6,7) and only two cones were listed in Table 1 of Axelrod (1998a). Both are badly abraded with UCMP 11010 (Plate III,6) here referred to Pinaceae gen. et sp. indeterminate and UCMP 11011 referred to Pinus sp. (Plate III,7,8). One of the two winged seeds, UCMP 11013 (Plate III,9) is the counterpart to UCMP 10979, which was assigned to Larix (Axelrod, 1998a, Plate V, 6). The other winged seed is more similar to Larix. We reject the cones, winged seeds and needle as representing macrofossils of Pseudotsuga. Taggart (in Axelrod, 1998a, pg. 12) reported Pseudotsuga pollen in the Thunder Mountain flora, however, Taggart and Cross (2000) discuss the difficulty in distinguishing between the pollen of Pseudotsuga and Larix since they are nearly identical. These authors treat the pollen recovered as Larix/Pseudotsuga attributing most of it to Larix. At this time we consider the occurrence of Pseudotsuga in the Thunder Mountain flora dubious. Incertae sedis Vegetative axis? (Plate III,4) 1998 Larix leonardii Axelrod—Axelrod: p. 34, (part) (was not figured). Occurrence and material: Dewey Mine: UCMP 10984. Discussion: This specimen included as a Larix branch is 5.0 cm long and 2.5 cm wide, incomplete at the margins and both ends, shows a ribbed impression covered with low conical bumps, 2.0–3.0 mm wide, that are uniformly spaced. The bumps were apparently interpreted as brachyoblasts however they could be interpreted as either root or leaf traces of a rhizomatous plant (fern?, monocot?). There are no diagnostic features to support its interpretation as Larix and so we treat it as Incertae sedis. Vegetative axis (Plate III,10) 1998 Thujopsis idahoensis Axelrod—Axelrod: p. 33, Plate IX, 19. Occurrence and material: Road locality: UCMP 11041. Discussion: This specimen was identified as Thujopsis. However, the leaves of Thujopsis are dimorphic and

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decussate. They show well-developed facial leaves flanked on each side by laterals 4.0–6.0 mm long with incurved tips. Leaves of UCMP 11041 are not dimorphic. They are isomorphic and awl-shaped and alternately arranged with facial leaves lacking. Sequoia produces similar leaves on cone-bearing axes and terminal branchlets higher up in the tree, specifically those more exposed to direct sunlight. This specimen is also somewhat reminiscent of smaller twigs of Cunninghamia lanceolata var. konishii (Hayata) Fujita. Moreover, there is the possibility that it is not a conifer. Because the specimen is so poorly preserved and other affinities cannot be ruled out, we treat it as Incertae sedis. We do not recognize the occurrence of Thujopsis in the Thunder Mountain flora. Leaf 1998 Cephalotaxis nevadensis Axelrod—Axelrod: p. 33, Plate IX, 11. Occurrence and material: Road locality: UCMP 11033. Discussion: Cephalotaxus was recognized at Thunder Mountain based on a broad, falcate needle-like leaf, 2.8 cm long and 2.5–3.0 mm wide, and missing both ends. This specimen was assigned to Cephalotaxus but it is unclear why. When viewed closely there are no distinctive features that unequivocally identify this specimen as Cephalotaxus, such as broad stomatal areas on the abaxial surface. In fact the stomatal bands are narrow and more like Torreya. The midrib was described as prominent, but this character is not specific to Cephalotaxus. Keteleeria and Podocarpus have long broad leaves with a prominent midrib and pollen of these genera was reported in the flora (Axelrod, 1998a; Taggart and Cross, 2000). There is also the possibility that this is not a conifer leaf. Therefore we refer this specimen to Incertae sedis. 4. Discussion 4.1. Problems with combining isolated organs into one species concept The North American conifer megafossil compression record consists of numerous species concepts that are based on combined isolated organs. Since one does often recover vegetative axes, leaves, winged seeds, seed wings, ovulate and pollen cones from a locality the practice of creating bwhole plantsQ from these associated yet disarticulated remains is common. Unfortunately, many associated organs from the same locality that have been included in the same species have been found to belong to different taxa. The prob-

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lem is further compounded by the inclusion into these species of additional isolated organs from other Tertiary sites of the same and/or different ages. The concept of Pinus baileyi, a species related to the extant Great Basin bristlecone pine, P. longaeva (Axelrod, 1998a, p. 37, Plate XI, 12–14), illustrates the complexity of the problem. The description of P. baileyi included one ovulate cone and two winged seeds from Thunder Mountain, two ovulate cones from the Oligocene Haynes Creek flora of Idaho and several winged seeds and a 5-needled fascicle from the Nevada Eocene Copper Basin flora. The Copper Basin specimens were previously assigned to P. crossii (Axelrod, 1966). However, the Copper Basin winged seeds (Axelrod, 1966; Plate VII, 6–9) and one from Thunder Mountain belong to Picea, while the other Thunder Mountain winged seed is Larix (UCMP 11083, Axelrod, 1998a, Plate XI, 13). Except for the latter specimen, all the seeds have a slight indentation (notch) on the proximal admedial edge of the seed body, a character diagnostic of Picea (see Wolfe and Schorn, 1990, p. 7). Although Axelrod states that the wings have b. . .cross marks from shrinkage. . .Q (Axelrod, 1998a, p. 37), these bmarksQ are not visible on the fossils. Pinus winged seeds are readily identifiable based on the characteristic wavy pattern of the wing epidermal cells, whereas the epidermal pattern of Picea is straight. The Thunder Mountain and Copper Basin specimens have the straight pattern as in Picea. The Copper Basin 5-needled fascicle (UCMP 8873) has a deciduous sheath and cylindrically shaped short shoot characteristic of soft pines (subgenus Strobus), but this specimen cannot be distinguished from those of similar morphology from the Colorado Oligocene Creede flora referred to P. crossii (Wolfe and Schorn, 1990) or the fascicles from Thunder Mountain (Axelrod, 1998a) and the Nevada Eocene Bull Run flora assigned to P. balfouroides. In addition, Erwin and Schorn (in press) found the cones of P. baileyi to be more similar to several Asian hard pines of subgenus Pinus, subsection Pinus, not those of the North American bristlecone group (subgenus Strobus, subsection Balfourianae). Therefore, in this example, combining different detached organs from different localities into a single species concept has placed together the winged seeds of Picea and Larix, a soft pine fascicle (subgenus Strobus), and a hard pine ovulate cone related to subgenus Pinus, subsection Pinus. Thunder Mountain represents one of the many Tertiary floras where isolated vegetative and reproductive remains have been lumped into a species. The conifer species recognized included: Cephalotaxis nevadensis, Chamaecyparis edwardsii, Thuja dimor-

pha, Thujopsis idahoensis, Sequoia affinis, Abies deweyensis, Larix leonardii, Picea magna, P. coloradensis, P. deweyensis, Pinus alvordensis, P. baileyi, P. balfouroides, P. resinosoides, Pseudotsuga glaucoides, and Tsuga mertensioides (Axelrod, 1998a). Six of these species were described as new: T. idahoensis, A. deweyensis, L. leonardii, P. deweyensis, P. baileyi, and P. resinosoides. 4.2. Cephalotaxaceae Based on our revision we do not recognize the presence of Cephalotaxus in the Thunder Mountain flora. The fragment of one leaf was compared to the isolated leaves found at Copper Basin (Axelrod, 1966), however, the Copper Basin leaves do not show enough detail to definitively assign them to Cephalotaxus. The Copper Basin leaves are broken off at the base and also many of the tips, they have two narrow stomatal bands, and it is not clear if the margin is smooth or serrate. Because there are other taxa that have long, broad falcate leaves such as Taxus, Amentotaxus, Keteleeria, Cunninghamia (serrate margin), and Torreya, and there are no cones, seeds, leaves, more complete vegetative axes, or pollen to support the Cephalotaxus identification, we treat it as Incertae sedis until more conclusive material is recovered. Taxa such as Amentotaxus (Cephalotaxus californica Potbury, 1935) do occur in the California Eocene La Porte flora, Torreya and Keteleeria are known from the Oregon Oligocene Bridge Creek flora (Meyer and Manchester, 1998) and Cunninghamia from Oligocene and Miocene sites. These floras include the Oligocene Lyons (Meyer, 1973), Rujada, and Bridge Creek floras of Oregon (Rember et al., 2000), the Washington Gumboot (Rember et al., 2000) and Idaho Haynes Creek floras (Axelrod, 1998b; Rember et al., 2000); and the Miocene Idaho Clarkia flora (Smiley and Rember, 1985; Rember et al., 2000). In addition, Taggart and Cross (2000) did report Keteleeria pollen from the Road florule but no Cephalotaxus, and the holotype cone of L. leonardii does show some similarity to cones of K. davidiana (Bertrand) Beissner. 4.3. Cupressaceae We do not recognize the new species Thujopsis idahoensis. Today Thujopsis contains two species, T. dolobrata and T. hondai, both native to Japan. The Thunder Mountain specimen was compared to T. dolobrata (Axelrod, 1998a), however, the isomorphic awlshaped leaves of the fossil appear to be either spirally or alternately arranged which is unlike the dimorphic, de-

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cussate leaves of Thujopsis. The Thunder Mountain fossil more closely resembles Sequoia or possibly Sequoiadendron. We do recognize the presence of Sequoia and Thuja at Thunder Mountain. A cone and vegetative axes assigned to S. affinis Lesquereux appear to belong to this taxon. However, fossil Sequoia is in need of further revision to determine if distinct types can be recognized from cones and foliage, as many fossil species attributed to Sequoia have been transferred to other taxa (e.g. Taxodium, Metasequoia, and Glyptostrobus) (LaMotte, 1952)). Fragments of vegetative axes do show leaf morphology and arrangement diagnostic of Thuja. However, a more thorough review and description of the fossil material currently assigned to T. dimorpha from Tertiary floras needs to be done to determine the affinity of the Thuja at Thunder Mountain. 4.4. Pinaceae Abies, Larix, Picea, Pinus, and Tsuga are represented at Thunder Mountain by megafossils and pollen (Taggart and Cross, 2000). However because the compression fossils are not well enough preserved or the sample size is too small we think it best at this time not to recognize many of the Thunder Mountain species. Our approach here has been to separate out the organs and only compare them to a level allowable given their quality of preservation. Consequently, we do not recognize the new species A. deweyensis, P. deweyensis, L. leonardii, and P. resinosoides. Soft and hard pines are represented among the fascicles, cones, and seeds at Thunder Mountain. Among the fascicles there are at least two soft pines (Pinus, subgenus Strobus): a 2- and 5-needled form. Both have short circular bases and deciduous sheaths characteristic of soft pines. The short 2-needled form compares favorably to other fascicles assigned to P. sanjuanensis, while the 5-needled form is similar to those attributed to P. crossii. This species has been allied to the extant bristlecone pine, P. aristata. However, there are several other 5-needled fossil species, P. florissantii, P. coloradensis, P. wasonii and P. anthrarivus Axelrod that are similar in form and size. Therefore, a more thorough description and review of the representative fossils of these species is necessary to determine their justification as valid species and their relationship to each another. At least one cone and several 2-needled fascicles are assignable to the hard pine subgenus Pinus. These include the ovulate cone P. baileyi, which has dorsal umbos that are excentromucronate (Plate II,5), and the long 2-needled fascicles with a bilateral base and per-

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sistent sheath that are here referred to Pinus sp. (Table 1). However, because the fascicles may belong to P. baileyi these organs may represent the same pine. 4.5. Implications for phytogeographic reconstructions Several examples from Thunder Mountain emphasize the importance of sample size, reuniting part and counterparts, the quality of preservation, and accurate identification of the fossil organs and their inferred taxonomic affinities. Based on a single poorly preserved leaf fragment Cephalotaxus was recognized at Thunder Mountain (Axelrod, 1998a, Table 2). This specimen shows no diagnostic characters to specifically ally it to this genus. The same is true for Thujopsis. Its presence was based on one plant fragment that does not show Thujopsis morphology (Axelrod, 1998a; Table 2). Currently there is no evidence that this genus was present at Thunder Mountain. The presence of Pseudotsuga in the flora was based on two ovulate cones, two winged seeds and a leaf (Axelrod, 1998a, pg. 39, Plate VII, 6–8; Table 1). The ovulate cones show no morphological features diagnostic of Pseudotsuga. It is stated that exserted bracts are present; however, close examination shows there are none. One of the two cones is unidentifiable to genus, whereas the other shows inflated cone scale apices typical of Pinus. One non-figured winged seed identified as Pseudotsuga (UCMP 11013) has its counterpart identified and figured as Larix (UCMP 10979; Plate V, 6), while another is identified and figured as Pseudotsuga (UCMP 11012; Plate VII, 8), but the latter is Larix based on wing shape, attachment, and cellular pattern, hairs on the seed surface, and the absence of resin vesicles. The single leaf attributed to Pseudotsuga (UCMP 11014; Axelrod, 1998a, Fig. 6) shows it is indistinguishable from leaves assigned to L. leonardii or P. balfouroides. It has no diagnostic features that relate it exclusively to Pseudotsuga. The leaf and ovulate cones as shown here are either too abraded to identity or are misidentified, and the winged seeds are Larix. Therefore, Pseudotsuga cannot be unequivocally recognized based on the existing megafossil collections. Taggart and Cross (2000) did identify Larix/Pseudotsuga pollen in the Road florule, but as these authors noted, Pseudotsuga pollen is nearly identical to Larix and therefore they did not distinguish between the two genera. The record of conifer species known from Tertiary compression floras of western North America and the interpretation of their paleoecology, evolutionary and phytogeographic histories largely comes from the numerous monographs written by D. I. Axelrod over the last six decades (see Schorn and Fields, 1998). How-

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ever, over the years many of the species concepts have become unclear due to 1) problems with nomenclature, 2) species that are based on or include detached organs that are fragmentary and too poorly preserved to identify accurately, and/or 3) species that include isolated organs from different localities of different ages that often belong to different species or genera. Today, with the incorporation of fossil occurrences into biogeographic and phylogenetic analyses becoming more important (e.g., Geada Lo´pez et al., 2002) it seems appropriate to update the megafossil record of conifer species and their geologic ages. Here we take the approach with the Thunder Mountain flora of separating out organs previously assigned to species and reassigning them, if necessary, based on closer comparisons with modern taxa and described fossil species, and exclude them if they do not show sufficient diagnostic features. Once these data are compiled for Tertiary floras yielding conifers it should further our understanding of this group’s diversity, evolutionary history and past geographic distribution. Acknowledgements We thank Caroline Stromberg, Patricia Holroyd, and the reviewers for their comments and suggestions that greatly improved this paper. We also acknowledge the Miss Annie Alexander Endowment to the University of California Museum of Paleontology for partial support of this project. This is UCMP Contribution No. 1886. References Axelrod, D.I., 1944. The Alvord Creek flora. Carnegie Institution of Washington Publication 553 (9), 225 – 262. Axelrod, D.I., 1962. A Pliocene Sequoiadendron forest from western Nevada. University of California Publications in Geological Sciences 39 (3), 195 – 267. Axelrod, D.I., 1966. The Eocene Copper Basin flora of northeastern Nevada. University of California Publications in Geological Sciences 59, 1 – 124. Axelrod, D.I., 1976. History of the coniferous forests, California and Nevada. University of California Publications in Botany 70, 1 – 62. Axelrod, D.I., 1980. Contributions to the Neogene Paleobotany of central California. University of California Publications in Geological Sciences 121, 1 – 212. Axelrod, D.I., 1985. Miocene floras from the Middlegate Basin, westcentral Nevada. University of California Publications in Geological Sciences 129, 1 – 279. Axelrod, D.I., 1986. Cenozoic history of some western American pines. Annals of the Missouri Botanical Garden 73 (3), 565 – 641.

Axelrod, D.I., 1987. The Late Oligocene Creede flora, Colorado. University of California Publications in Geological Sciences 130, 1 – 235. Axelrod, D.I., 1991. The early Miocene Buffalo Canyon flora of western Nevada. University of California Publications in Geological Sciences 135, 1 – 76. Axelrod, D.I., 1995. The Miocene Purple Mountain flora of western Nevada. University of California Publications in Geological Sciences 139, 1 – 62. Axelrod, D.I., 1998. The Eocene Thunder Mountain flora of central Idaho. University of California Publications in Geological Sciences 142, 1 – 61. Axelrod, D.I., 1998. The Oligocene Haynes Creek flora of eastern Idaho. University of California Publications in Geological Sciences 143, 1 – 160. Brown, R.W., 1937. Additions to some fossil floras of the western United States. U.S. Geological Survey Professional Paper 186-J, 163 – 206. Chaney, R.W., Axelrod, D.I., 1959. Miocene floras of the Columbia Plateau: Part II. Systematic considerations. Carnegie Institution of Washington Publication 617, 135 – 327. Part II. Critchfield, W.B., Little Jr., E.L., 1966. Geographic distibution of thepines of the world. USDA Forest Service Misc. Publication 991. Edwards, S. 1983. Cenozoic History of Alaskan and Port Orford Chamaecyparis cedars. Unpublished Ph. D. dissertation University of California, Berkeley, 271 pp. Erwin, D.M., Schorn, H.E., in press. Pinus baileyi Axelrod (section Pinus) from the Paleogene of Idaho USA. American Journal of Botany. Farjon, A., 1984. Pines. Drawings and Descriptions of the Genus Pinus. E.J. Brill, The Netherlands. 220 pp. Geada Lo´pez, G., Kamiya, K., Harada, K., 2002. Phylogenetic relationships of Diploxylon pines (subgenus Pinus) based on plastid sequence data. International Journal of Plant Sciences 165, 737 – 747. Gernandt, D.S., Gaeda Lo´pez, G., Ortiz Garcı´a, S., Liston, A., 2005. Phylogeny and classification of Pinus. Taxon 54, 29 – 42. Hermann, R.K., 1985. The genus Pseudotsuga: ancestral history and past distribution. Special Publication, vol. 2b. Forest Research Laboratory, Oregon State University, Corvallis. 32 pp. Klaus, W., 1980. New observations on the morphology of Pinus cones and their bearing on taxonomy, fossil determination, distribution, and evolution of the genus. Plant Systematics and Evolution 134, 137 – 171. (in German). LaMotte, R.S., 1952. Catalogue of the Cenozoic Plants of North America through 1950. The Geological Society of America Memoir 51 (381 pp.). Leonard, B.F., Marvin, R.F., 1984. Temporal evolution of the Thunder Mountain caldera and related features, central Idaho. Idaho Bureau of Mines and Geology Bulletin 26, 34 – 41. Meyer, H.W., 1973. The Oligocene Lyons flora of northwestern Oregon. The Ore Bin 35, 37 – 51. Meyer, H.W., Manchester, S.R., 1998. The Oligocene Bridge Creek flora of the John Day Formation, Oregon. University of California Publications in Geological Sciences 141, 1 – 195. Millar, C.I., 1996. Tertiary vegetation history. Sierra Nevada Ecosystem Project, Final Report to Congress. University of California Centers for Water and Wildlife Resources, Davis, pp. 71 – 122. Potbury, S.S., 1935. The La Porte flora of Plumas County, California. Carnegie Institution of Washington Publication 465, 29 – 81.

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