Pabiania

Name

Pabiania

Rank

Genus

Authors (Pub.)

Upchurch G. R., Jr. Dilcher D. L.  

Publication

Cenomanian angiosperm leaf megafossils, Dakota Formation, Rose Creek locality, Jefferson County, southeastern Nebraska [1990/12]

Journal

Bulletin of the United States Geological Survey

Issue

1915

Page number

21

Year

1990

Parent Taxon

[Order] Laurales

Fossil Status

leaves

Type

Pabiania variiloba

Diagnosis

Lamina predominantly 3-lobed rarely 2-lobed or unlobed; margin entire. Primary venation of lobed forms suprabasal palinactinodromous; lateral primary veins decurrent on midvein, at lower angle than superadjacent secondary veins. Basilaminar secondary veins strongly developed, at same angle as the lateral primary veins or (in unlobed forms) superadjacent pair of secondary veins. Sinus bracing accomplished by the lowest pair of secondary veins on the midvein, these running directly to the sinus and bifurcating at the laminar margin, with each branch of the bracing vein running subparallel to laminar margin and connecting with the secondary veins of the lobes. Tertiary venation irregularly branched; tertiary veins thin and oriented at right or low obtuse angles to primary veins. Quaternary venation non-orthogonal. Quinternary venation weak, irregular; quinternary veins highly branched and showing a strong tendency to ramify within the areoles. Guard cell pair elongate, elliptic to spindle shaped; lamellar cuticular thickenings present to absent, sometimes on the same leaf. Stomatal complex generally brachyparacytic, but with some leaves having rare laterocytic, hemiparacytic, and weakly cyclocytic to anomocytic stomata. Trichome bases (when present) consisting of an angular, heavily cutinized pore and associated cells that are scarcely modified but show a strong tendency to be radially oriented.