report of a late tertiary petrified wood from yuma county, arizona

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Arizona-Nevada Academy of Science Report of a Late Tertiary Petrified Wood from Yuma County, Arizona Author(s): Michael R. Lee and Michael Zavada Source: Journal of the Arizona Academy of Science, Vol. 12, No. 1 (Feb., 1977), pp. 21-22 Published by: Arizona-Nevada Academy of Science Stable URL: http://www.jstor.org/stable/40021976 . Accessed: 16/06/2014 05:43 Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at . http://www.jstor.org/page/info/about/policies/terms.jsp . JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected]. . Arizona-Nevada Academy of Science is collaborating with JSTOR to digitize, preserve and extend access to Journal of the Arizona Academy of Science. http://www.jstor.org This content downloaded from 195.78.108.185 on Mon, 16 Jun 2014 05:43:50 AM All use subject to JSTOR Terms and Conditions

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Page 1: Report of a Late Tertiary Petrified Wood from Yuma County, Arizona

Arizona-Nevada Academy of Science

Report of a Late Tertiary Petrified Wood from Yuma County, ArizonaAuthor(s): Michael R. Lee and Michael ZavadaSource: Journal of the Arizona Academy of Science, Vol. 12, No. 1 (Feb., 1977), pp. 21-22Published by: Arizona-Nevada Academy of ScienceStable URL: http://www.jstor.org/stable/40021976 .

Accessed: 16/06/2014 05:43

Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at .http://www.jstor.org/page/info/about/policies/terms.jsp

.JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range ofcontent in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new formsof scholarship. For more information about JSTOR, please contact [email protected].

.

Arizona-Nevada Academy of Science is collaborating with JSTOR to digitize, preserve and extend access toJournal of the Arizona Academy of Science.

http://www.jstor.org

This content downloaded from 195.78.108.185 on Mon, 16 Jun 2014 05:43:50 AMAll use subject to JSTOR Terms and Conditions

Page 2: Report of a Late Tertiary Petrified Wood from Yuma County, Arizona

REPORT OF A LATE TERTIARY PETRIFIED WOOD FROM YUMA COUNTY, ARIZONA

MICHAEL R. LEE and MICHAEL ZAVADA Arizona State University, Tempe

[187]

INTRODUCTION. - Macrofossil plant remains from Tertiary sediments of Arizona have not been extensively studied (Romans, 1973). No petrified wood remains (except Palmoxylon) have been described from the Tertiary of Arizona. Laksy and Webber (1949) reported plant remains from the Eocene Artillary Formation of Mohave County. These plant fossils included palm roots and algal remains of Chara. No in depth anatomical and morphological studies were made of these remains. This represents the first detailed report of Tertiary plant remains from Arizona.

METHODS AND MATERIALS. - Wood fragments were cut into transverse, radial and tangential planes on a diamond tip trim saw. The cut sections were then polished using No. 400 carborundum powder until all saw marks were removed. Sections were stained using Bismarck brown solution, after Bartholomew, Matten and Wheeler (1970). The sections were then mounted, polished side down, on a glass slide using thermoplastic cement. After cooling, the sections were ground by hand using No. 400 and No. 600 carborundum powder until the sections were about one cell thick in cross section or slightly thicker in longitudinal sections. The wood was then examined microscopically, and features recorded on a wood analysis sheet. Determination of wood was aided by punch card keys, and consulting books by Brown, Panskin and Forsaith (1949), Metcalfe and Chalk (1950) and Cozzo (1951).

COLLECTION LOCALITY AND GEOLOGY. - The petrified wood was collected by Dr. Thomas Freeman from an unnamed formation in Yuma County. The collection site is near Imperial Dam, 4 miles west of state route 95 on the Yuma Porving Grounds (R21W, T6S). The largest fragments measured 25 cm x 15 cm and the smallest 5 cm x 4 cm.

The age of the outcrop is uncertain. However, estimates based on paleomagnetic studies range from .7 million years to 3.2 million years (D. Metzger, personal communication). The wood appears to have come from Upper Pliocene sediments as it occurs below Pleistocene river gravels.

DESCRIPTION. - The wood may be from either branch or root remains. As no pith or primary xylem was observed one is unable to determine from which plant organ the wood has come.

The wood is semi-diffuse porous with distinct growth rings (Fig. 1). Vessels are usually in small clusters and rarely solitary (Fig. 2). Vessels also occur in long radial chains, generally occurring late in the growth ring (Fig. 3). Solitary vessels and vessels in small clusters (1-4/cluster) range from 55(93.1)120 \xm in tangential diameter. Vessels in long radial chains (2(13)38/chain) range from 6(21. 6)4 2(jm in tangential diameter. Perforation plates are simple and oblique to transverse

(Fig. 4). Rays are homogeneous, 1-6 seriate and there are 4 to 8 rays/mm (commonly 6/mm). Fibers and parenchyma are present, but due to the poor preservation in longitudinal sections patterns are not evident. No pitting was observed in any of the sections. Fungal spores, possibly from the genus Telangium (C. Leathers, personal communication), are abundant throughout the wood (Fig. 5).

DISCUSSION. - The only published account of similar petrified wood from Yuma County was by G.C. Schaeffer (1854). Schaeffer provided a brief description, figured the wood in corss section, and illustrated the nature of the rays. The cross section shows similarities to the present specimen, in being semi-diffuse porous and having narrow rays. However, the rays illustrated by Schaeffer in tangential section probably represent fungal spores similar to those which occur abundantly throughout the Yuma wood.

A similar unnamed wood was collected by R.M. Alf (1970, p. 185, Fig. B) from the Miocene Barstow Formation, San Bernadino County, California. No description accompained his figure.

Identification of the petrified wood based on preserved features indicates a close affinity to member of the Caesalpiniaceae, notably Cercidium and Parkinsonia. These two genera are difficult to distinguish based on wood anatomy. Features shared by the petrified wood and Cercidium-Parkinsonia include: semi-diffuse porosity, size and distribution of vessels, simple perforation plates and nature of the rays. Definite identification of the wood cannot be made as several features (pitting and distribution of parenchyma and fibers) are not preserved.

SUMMARY. - Wood collected from the Upper Pliocene, Yuma County, has been sectioned and described. This constitutes the first detailed report of petrified wood from the Tertiary of Arizona. Using available keys for identification, the petrified wood displays close affinities to Cercidium and Parkinsonia (Caesalpiniaceae). The poor preservation of the wood has made definite identification impossible.

LITERATURE CITED

ALF, R.M., 1970. A preliminary report on a Miocene flora from the Barstow Formation, Barstow, California. Bull, of Calif. Acad. Sci. 69(3-4); 183-189.

BARTHOLOMEW, R.L., MATTEN, L.C. and WHELLER, E.F., 1970. Staining silicified wood. Jour. Paleontol. 44(5); 905-907.

BROWN, H.P., DANSKIN, A.J., FORSAITH, C.C., 1949. Textbook of Wood Technology. Volume I. New York, McGraw-Hill.

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Page 3: Report of a Late Tertiary Petrified Wood from Yuma County, Arizona

22 JOURNAL OF THE ARIZONA ACADEMY OF SCIENCE Vol. 12

COZZO, D., 1951. Anatomia del leno secundario de las leguminosas, Mimosoides y Cesalpinialeas Argentinas. Rev. Inst. Nac. Invest. Cienc. Nat., Bot. 2(2); 63-146.

LAKSY, S.G. and WEBBER, B.N., 1949. Manganese resources of the Artillery Mountains region, Mohave County, Arizona. U.S.G.S. Bull. 961, 1-83.

LEATHERS, C. Personal communication. Dept. of Botany and Microbiology, Arizona State Univ., Tempe, Arizona.

METCALFE, C.F. and Chalk, L., 1950. Anatomy of the

Dicotyledons. Volumes I and II. Oxford, Clarendon Press.

METZGER, D., Personal communication. Sergent, Hauskins and Beckwith Consulting, Phoenix, Arizona.

ROMANS, R.C., 1973. A history of paleobotany in Arizona. Plateau 45(3); 93-101.

SCHAEFFER, G.C., 1853-1854. Description of the structure of the fossil wood from the Colorado desert. Rpt. Exploration in Calif, for RR routes. Senate Doc. 33rd Cong 2nd Sec. Vol. 13, Pt. 5; 338-339.

Figure 1. - Field view, transverse section. 25x

Figure 2. - Large vessels, transverse section. 250x

Figure 3. - Small vessels in radial chain, transverse section. 250x

Figure 4. - Vessel element, showing perforation plates (arrows) Radial section. 250x

Figure 5. - Vessel element containing spores. Note "halo" around spores (arrow) Tangential section. 400x

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