BOUCHER, LISA D. Department of Biology, University of Nebraska-Omaha, 6001 Dodge St., Omaha, NE, 68182, U.S.A.. - Cuticular features in Late Cretaceous floras from northwestern New Mexico.
The Fruitland-Kirtland Formations in the San Juan Basin contain an
excellent record of Late Campanian-early Maastrichtian macrofloras
deposited in a floodplain setting. The fossil material consists
primarily of leaf compressions, and cuticle is well-preserved at some
sites that are high in clay content. Although pteridophytes,
gymnosperms, monocots and dicots comprise the macroflora as a whole,
at these sites only dicot cuticle was preserved. In this study,
cuticle was removed from more than15 specimens representing at least
five different leaf morphotypes from four sites, and prepared using
standard techniques. Epidermal cells and stomata generally have random
orientations except over major veins. Stomatal types include paracytic
and cyclocytic with some variation on individual specimens. Trichome
bases are present on most specimens, and some have distinct secretory
glands. Papillae were present to varying degrees on the upper and
lower surfaces of all specimens. In a few specimens, surface papillae
overhang the stomatal pore. Cuticle striations over some of the
subsidiary cells were perpendicular to the long axis of the guard
cells. Most of these features are consistent with families belonging
to the Magnoliidae and comparisons with leaf architecture and extant
families will be discussed. This represents the first description of
cuticle from this flora, and with other information from entire
leaves, permineralized wood, and palynology, provides a more complete
vegetative record of this Late Cretaceous floodplain environment.
Key words: cuticle, Late Cretaceous, macroflora, New Mexico