KNAUS, M. JANE1* and SPENCER G. LUCAS2. 1Dept. of Biology, Southwest Texas State University, San Marcos, TX 78666; 2New Mexico Museum of Natural History and Science, 1801 Mountain Road NW, Albuquerque, NM 87104. - Upper Paleozoic Floras of New Mexico.
With the exception of the Virgilian Kinney Brick Quarry, information
available on Upper Paleozoic floras of New Mexico consists primarily
of sporadic preliminary reports. Sites currently under study include
El Cobre Canyon (Missourian?), Carrizo Arroyo (3 quarries - uppermost
Pennsylvanian or Permian), and Placitas (Lower Permian); with focus on
providing time-ordered documentation of the "great drying"
of the Late Carboniferous. Historically, these "transition"
floras were viewed as admixtures of relictual coal swamp elements and
newly-evolved "upland" plants. In the absence of reliable
taxonomic age indicators, tentative age estimates have been proposed
based on relative abundances of swampy to dry-climate taxa. If such
estimated ratios are to serve as a proxy for age, it is required that
draining through lowered eustatic sea level was a continuous process
and accompanied by regional shifts toward dryer climatic patterns
without localized backsliding into temporary coal-swamp conditions.
Resurgences of humid-indicator floras into the Permian indicates that
global drying was not strictly progressive. In addition, the picture
of depositional environments in New Mexico is complicated by
elevational relief associated with tectonics of the Ancestral Rockies
and progradation within fragmented north-south trending intermontane
basins. Idiosyncratic depositional characteristic may possibly obscure
a regional signal. A new neuropterid frond reconstructed from
specimens from Carrizo Arroyo site L- 3431 indicates that
"typical" coal swamp elements were also simultaneously
evolving into dryer climate forms. As an alternative interpretation,
DiMichele has proposed that "transition" floras are more
accurately viewed as having been mixed by transport within fragmented
habitats characterized by localized topographic highs and lows, a
condition typified by the depositional characteristics of New Mexico.
Analyses in progress show El Cobre Canyon as a Appalachian equivalent
coal-measures flora, Carrizo Arroyo as a mixed conifer, Cordaites,
medullosan flora, and Placitas as a streamside peltasperm flora.
Key words: , Carboniferous, Fossil plants, New Mexico, Peltasperms, Permian