Abies milleri
Abies milleri Temporal range: [1]
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Fossil Abies milleri foliage and axis | |
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Gymnospermae |
Division: | Pinophyta |
Class: | Pinopsida |
Order: | Pinales |
Family: | Pinaceae |
Genus: | Abies |
Species: | A. milleri
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Binomial name | |
Abies milleri Wehr |
Abies milleri, an
History and classification
The species was described from 81 fossil specimens collected from
A. milleri has been placed in the
The 81 specimens studied for the A. milleri description included 40 cone scales, 21 wing seeds, 10 foliated axes, and two detached needles.[2] Schorn and Wehr placed the different detached organ fossils in the same species based on a number of factors. Where visible, all the cone scales have bracts and are morphologically similar.[2] The scales display impressions on the admedial surface of wing seeds that match the fossil seed dimensions. The needle arrangement is consistent on both foliated and defoliated axes, with attached needles matching isolated needles. All of the fossils occurred in the same stratigraphic layers.[2]
Description
The cone scales are up to 32 by 20 millimetres (1.26 by 0.79 in) and 1.25-2 times as long as wide, have a generally triangular to cuneate shape with the distal edge turned upwards and the stalk on half the length of the scale.[2] Sometimes preserved with cone scales are the bracts which average 5 by 4 millimetres (0.20 by 0.16 in) and have a central accuminate flanked by thinner laminae. The wing seeds are up to 27 by 14 millimetres (1.06 by 0.55 in) and have a pterostegium which covers on average three-quarters of the seed.[2] The narrow obovate seed is generally 12 by 4 millimetres (0.47 by 0.16 in), 1-1.5 times the length of the upper wing edge while the wing itself is widest in the distal half. Needles of A. milleri reach up to 38 millimetres (1.5 in) long, but have a width of only 1 millimetre (0.039 in) at the base. The leaf base is generally as wide to slightly wider than the leaf and round, with the leaf angled approximately 70 degrees upward from the attachment. Leaf scars on axes are circular to slightly oval, 1.5 by 2 millimetres (0.059 by 0.079 in), and show a vascular bundle scar in the center.[2] Oval leaf scars are oriented with the long axis parallel to the length of the stem axis. While the scars show the leaves to be in a helical arrangement, the leaves would have had a flattened orientation on either side of the axis.[2]