Gw. Rothwell et al., LATE PALEOZOIC CONIFERS OF NORTH-AMERICA - STRUCTURE, DIVERSITY AND OCCURRENCES, Review of palaeobotany and palynology, 95(1-4), 1997, pp. 95-113
Late Paleozoic conifer communities originated in moisture-stressed env
ironments along the paleoequator on the Laurussian continent. By Late
Permian time, northward movement of the continent displaced these comm
unities toward subequatorial regions. North American deposits provide
the most abundant and best preserved pre-Permian conifer fossils. They
represent a wide spectrum of preservational modes including compressi
on/impression, mold/cast, and cellular permineralization by carbonates
, phosphates, iron sulfides, iron oxides and iron hydroxides. Some mod
es are associated with distinct biotic assemblages, and to some extent
each can be correlated with certain depositional environments and tap
honomic histories. Exceptional floras containing extensive conifer rem
ains occur in the Rocky Mountains, the Midcontinent, and the Appalachi
an regions. These include: estuarine carbonates at Hamilton and Pomona
, Kansas; transitional terrestrial to marine clastics at Kinney Brick
Quarry, New Mexico, Garnett, Kansas and the 7-11 Mine in northeastern
Ohio; and offshore marine shales in Kansas, Oklahoma and Texas that we
re deposited in dysoxic environments. Most specimens have been assigne
d to the form genus Walchia, but exceptionally well preserved specimen
s conform to species of Emporia (Emporiaceae) and to one or more undes
cribed species that may represent additional genera and/or families. T
hese species add significantly to the growing diversity of Paleozoic c
onifers, and provide valuable data for testing hypotheses of conifer a
nd coniferophyte relationships.