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Lancian flora summary



This is a short summary of the data I have on the plants of the Lance
and Hell Creek Formations.  It mostly includes only the more common or
characteristic leaf species.

Common Trees and Shrubs                                 Aprox. Modern
                                                        Analog

Dryophyllum subfalcatum (most common sp.)               chestnut/walnut

Sequoiites artus (formerly S. dakotensis)               bald cypress

Salix lancensis                                         willow

Laurophyllum salicifolium                               willow

Platanophyllum montanum                                 sycamore (US)

Quercophyllum gardneri                                  ?scrub oak

Gingko adiantoides                                      ginkgo

Araucarites longifolia (localized)                      monkey puzzle

"Ficus" planicostata                                    buckthorn
"Fixus" trinervis                                       buckthorn
Rhamnus cleburni                                        buckthorn

Trochodendroides arctica (ex Cercidiphyllum a.)

"Vitis" stantoni                                   witch hazel/mulberry

Sabalites eocenica                                      palmetto
Sabalites montana                                       palmetto

Annona robusta                                          pawpaw

"Celastrinites" insignis                                (Eucommiaceae)
----------------------------------------------------------------------

Other Plants                                            Modern Analog

"Cissus" marginatus                                     vine

Nymphaeites angulatus                                   water lily
Nymphaeites dawsoni                                     water lily

"Dryopteris" carbonensis                                wood fern

Woodwardia crenata                                      wood fern

Cyperacites/"Typha"                             sedges and/or rushes

[The last is a collection of rather indeterminate monocot fragments
with parallel venation, which I include because they are fairly
frequent in the collections; exact identity is very uncertain, and
asignment to "Cyperacites" or "Typha" was originally based mostly
on size, with "Typha" holding the larger variants; all I can really
say is that they apparently belong to vaguely grass-like plants].

As can be seen, this flora is that of a warm temperate deciduous
floodplain forest complex.  Both my data set and other, already
published, analyses show that the _Sequoiites_ is characteristic
of peat swamps and the margins of sloughs, while the _Dryophyllum_
is typical of better-drained parts of the floodplain.  My data suggests
that there is even more ecological segregation than that, with several
different floodplain communities recognizable.

Very similar (and I do mean *very* similar) floras are known from
both earlier times and from Paleocene, or even Early Eocene times.

swf@elsegundoca.ncr.com         sarima@ix.netcom.com

The peace of God be with you.