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Mesocyparis umbonata
Mesocyparis umbonata McIver, Aulenb. Canad. J. Bot., 72(3): 275. 12 May 1994
- Name
- Mesocyparis umbonata
- Rank
- Species
- Generic Name
- [Genus] Mesocyparis
- Authors (Pub.)
- McIver E. E.
Aulenback K. R.
- Publication
- Morphology and relationships of Mesocyparis umbonata sp.nov.: fossil Cupressaceae from the Late Cretaceous of Alberta, Canada [1994/5]
- Journal
- Canadian Journal of Botany
- Volume
- 72
- Issue
- 3
- Page number
- 275
- Year
- 1994
- Fossil Status
- leafy twigs (with cones)
- Stratigraphy
- Maastrichtian
- Strat. comment
- Horseshoe Canyon Formation
- Location
- 4 km north of Drumheller, Alberta, Canada
- Paleoregion
- America (North)
Data for Holotypus
- Repository
- Royal Tyrrell Museum of Palaeontology, Drumheller, Canada
- Repository Number
- TMP
88.232.1003
Data for Paratypus
- Repository
- Royal Tyrrell Museum of Palaeontology, Drumheller, Canada
- Repository Number
- TMP
88.232.975, Fig. 15; TMP 88.232.960; Fig. 5; TMP
88.232.122, Fig. 16
- Diagnosis
- Branches pinnate, forming flat frond-like sprays; branching
opposite, less commonly alternate; branches and branchlets
arising in the axils of lateral leaves, rarely overlapping; basal
pair of facial leaves persistentjn axils of branch lateral leaves
after branchlet abscision. Branchlets pinnate, flattened, slender,
3.0-6.5 mm apart, well separated on axis, becoming more
crowded at apex. Leaves persistent, decussate, scalelike, overlapping;
facia and lateral leaves dissimilar, approximately equal
in length; facial leaves closely appressed, without apparent
midrib; lateral leaves folded, apices free distally; branch and
branchlet leaves dissimilar. Facial leaves of branches 1.4-
4.0 mm long, 0.5-0.9 mm wide, apex acute to acuminate,
thickened. Lateral leaves of branches 1.5-3.8 mm long,
0.2-0.6 mm wide, decurrent, falcate, equal to or slightly
shorter than facial leaves, apex acute, juncture of lateral leaves
commonly concealed by preceding facial leaf. Facial leaves
of branchlets 0.8-2.0 mm long, 0.6- 1.2 mm wide, ovate
to orbiculate, apex acuminate, thickened. Lateral leaves of
branchlet, 0.5-2.0 mm long, 0.1-0.4 mm wide, decurrent,
partially overlapping facial leaves, apices acute, lateral margins
thickened. Leaves of fertile shoots not dissimilar: leaves of
axes bearing seed cones 1.5 -4.8 mm long and 1.1' mm wide,
decurrent, falcate, apices free; leaves proximal to cone-bearing
region 1.5-2.2 mm long, 1.4-1.7 mm wide, ovate and
acuminate, falcate, apex commonly free. Seed cones erect,
decussate, 1.5 -4.8 mm apart on unbranched axis bearing leafy
branch distally, orbicular to oblong, 2.8-5.0 mm long and
1.9-4.0 mm wide, persistent on axis after seed dispersal,
terminating short stalks 0.3-0.6 mm long; dehisced cones
about 5.0 mm wide at apex. Cone scales 4, woody, obovate,
2.3-4.0 mm long, 1.8-3.9 mm wide, 0.5 mm thick, attached
to a short, erect-central axis; scales approximately equal in
size, basal pair commonly slightly narrower than distal pair;
margin of scale irregular; umbo near center of scale, leaflike,
conspicuous, nonreflexed, 0.3 mm long, apex acute. Seeds
two per ovuliferous scale, orbiculate, 1.9-2.2 mm long,
1.5 -2.0 mm wide; seed body elliptical, tapering distally,
1.9-2.2 mm long, 0.7 mm broad, longitudinally striate,
apparently nonresinous; micropylar beak pronounced, up to
0.2 mm long; seed wings two, bilaterally symmetrical, semicircular,
approximately equal in width to seed body. Pollen
cones up to 2.1 mm long, 1.1 mm in diameter; sporophylls
decussate, attached to slender axis by stalks approximately
0.4 mm long; 3-7 decussate pairs, 0.1-0.4 mm apart; distal
lamina hastate, acute-tipped, 0.5 -0.6 mm long, 0.5 mm wide;
sporangia two per sp6~ophyll,a baxial, globose to obovate,
0.4 mm long, 0.3 mm in diameter. Pollen about 17 -20 pm in
diameter, elliptical to circular in outline; exine psilate with
small gemmae 0.5 - 1.0 pm in diameter irregularly distributed
in clusters or solitary.
