310 million to 245 million years BP : Pennsylvanian to Permian

310 million to 245 million years BP : Pennsylvanian to Permian

The Pennsylvanian Period began around 310 million years ago. Dropping global

temperatures culminated in an ice age beginning around 300 million BP and ending

in the middle of the Permian Period. The North American continent then was probably

centered on the equator, placing this area just south of the equator. A tropical climate

persisted here on a fairly level land mass near sea level. The Appalachian Mountains

were still uplifting, and the Ozark dome had begun to rise in the east. At this time large

basins existed to the northeast, northwest, south, and southeast of the Ozark Dome.

Lower Pennsylvanian deposits are sparse in Newton and McDonald Co.s, Mo., but the

Morrowian Series Hale and/or Graydon sandstone formations may be found in pockets.

Hale sandstone caps some hills in southwest Barry Co., and can be seen at the top of

the exposure on Oakleigh Mountain. There, it is a brown sandstone lying on top of a

shale pellet conglomerate and containing many plant fossils.

Northeast Oklahoma has Pennsylvanian shale deposits of a few feet to over 200 feet,

thinning near the Missouri border. A very small volume of thick residual oil occurs locally

in these shale deposits. These appear to be primarily Middle Pennsylvanian Desmoinesian

Series deposits including the Weir-Pittsburg, Cherokee (mostly), and Marmaton coals.

Vesicaspora species spores have been found in these and an examination of the Drywood

Formation fossil flora, of the same time, found in neighboring counties to the north and

east of this area has identified 11 species of the Lepidodendrales order, 11 species of the

Equisetales order, 3 species of the Sphenophyllales order, 29 species of the Filicales and

Cycadofilicales orders, and 7 species of the Cordaitales order.

The Middle Pennsylvanian deposits are the last I am aware of in this section up until

the Pleistocene glacial deposition. This is a period of over 290 million years. Inferences

only, from neighboring geology and paleontology, will let us recreate these times.

Cotylosaurs appeared around 300 million BP and became the first vertebrates to lay

their eggs on land. Dinoflagellates, coelacanths, and mesosaurs invade the seas, land

snails, daddy longlegs, cockroaches, salamanders, pre-frogs, and Dimetrodon invade the

lands, and true ferns, horsetails, conifers, and bisaccate pollen appear in the flora of the

Pennsylvanian Period.

The final period of the Paleozoic Era, the Permian Period, began around 280 million

years ago. The earliest bipedal reptile, found in central Germany, has been dated to

280 million years BP, and early Permian remains from Las Cruces, New Mexico, indicate

the evolution of giant reptiles, mammal-like reptiles, and horseshoe crabs. The Permian

Period produced the monstrous crocodile-like reptiles like the pelycosaur and the

ichthyosaur, while a reef deposit built up in New Mexico later to become Carlsbad Caverns.

Other new creatures of the Permian include dragonflies, crickets, mayflies, beetles, flies,

cicadas, leafhoppers, and pre-turtles. It was a cooler, dryer period early on and the

conifer was probably the most common tree here. Global temperatures began rising in the

middle Permian producing warmer, dryer, and possibly desert conditions in this area. Near

the end of the Permian, average global temperatures spiked beyond any others we have

indications of, possibly to around 24 degrees C. For contrast, current global average

temperatures are around 13-14 degrees C., and other warm periods in earth's history

appear to have only reached 22 degrees C. At the end of the Permian and the close of the

Paleozoic Era, continental uplift occurred, and the Ozark region and the Ouachita Province

of Arkansas and Oklahoma have since been a continuous land area with concomitant plant

evolution. Rising temperatures and loss of habitat through uplift may have contributed

to the mass extinction occurring around 250 million BP in which 54% of living families

and over 90% of animal species, mostly marine invertebrates, perished. Trilobites, Rugosa

corals, Tabulata corals, and the Blastoidea, to name a few, disappeared from the fossil

record.

_________________

REFERENCES

Asimov, I., 1987, Beginnings: The Story of Origins.

Basson, P.W., 1969, Fossil Flora of the Drywood Formation of Southwest Missouri.

Univ. of Missouri Press

Fenton, C.L., Fenton, M.A., 1958, The Fossil Book. Doubleday

Fowler, G.M., Lyden, J.P., Gregory, F.E., Agar, W.M., 1934, Chertification in the Tri-

State (OK-KS-MO) Mining District. Am. Inst. of Mining and Metallurgical

Engineers, Technical Publication no. 532

Fowler, G.M., 1960, Structural Deformation and Ore Deposits. Engineering and Mining

Journal, June, p.183-188, vol. 161, no. 6

Gentile, R.J., 1968, Influence of Structural Movement on Sedimentation during the

Pennsylvanian Period in Western Missouri. Univ. of Missouri Press

King, L.C., 1983, Wandering Continents and Spreading Sea Floors on an Expanding

Earth. John Wiley and Sons

National Geographic Magazine

Netzeband, W.F., General Geology of the Tri-State District--Missouri-Oklahoma-Kansas

Paleomap Project

Stearn, C.W., Carroll, R.L., Clark, T.H., 1979, Geological Evolution of North America.

John Wiley and Sons

Steyermark, J.A., 1959, Vegetational History of the Ozark Forest. University of

Missouri Studies, v.31

Thompson, T.L., 1986, Paleozoic Succession in Missouri, Part 4 - Mississippian

System. Missouri Dept. of Natural Resources, Division of Geology and Land

Survey, Report of Investigations 70

Tschudy, R.H., Scott, R.A., 1969, Aspects of Palynology. John Wiley and Sons

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