Tertiary sirenians from the New World have been recently reviewed by Reinhart (1976) and Savage (1976). The earliest New World sirenians are known from the presence of pachyostose ribs in Eocene strata of the southeastern United States and from an Eocene skull and mandible from Jamaica

Martin, Larry D.

Whetstone, Kenneth

English

Tulane University Journal Publishing

AN OLIGOCENE (ORELLAN) SIRENIAN FROM THE BUCATUNNA FORMATION OF ALABAMA KENNETH WHETSTONE and LARRY D. MARTIN DEPARTMENT OF SYSTEMATICS AND ECOLOGY AND MUSEUM OF NATU UNIVERSITY OF KANSAS, LAWRENCE, KANSAS RAL HISTORY INTRODUCTION Tertiary sirenians from the New World have been recently reviewed by Reinhart (1976) and Savage (1976). The earliest New World sirenians are known from the presence of pachyostose ribs in Eocene strata of the southeastern United States and from an Eocene skull and mandible from Jamaica. Eocene sirenians have been reported from the Gosport Formation (Bridgerian) of Alabama (Siler, 1964; Russell, 1955) and the Avon Park Limestone (Uintan) of Florida (Reinhart, 1976 ). The middle Eocene Pro-rastomus sirenoides is based on a single specimen from Jamaica. Several occurrences of Oligocene sirenians have previously been reported in the New World. Two pach y-ostosc ribs were described from Chiapas, Mexico, by Mullerried ( 19 32) and Maldo-nado ( 19 53). A skull from the middle Oligo-cene of Puerto Rico was described as Cari-bosiren turneri by Reinhart (1 959), and Trelles (1936) noted the occurrence of siren-ians in the Oligocene deposits of Cuba. Arata and Jackson (1965) reported sirenians from the Oligocene Red Bluff and Chickasawhay Formations in Mississippi. The age of the Mexican records is uncertain, and Savage (1976) refers to these as "Eocene/Oligo-cene". The reference by Reinhart (1976, p. 236) to an Oligocene Halitherium from Florida is an error; elsewhere in this descrip-tion these specimens are referred to the Mio-cene. The specimens described herein, there-fore, represent the first Oligocene sirenians reported from Alabama. In 197 3 a field party from the University of Alabama led by D. E. Jones collected the first of the sirenian remains from the Lone Star Cement Quarry on the Tombigbee River 2.2 miles (3.5 km) northeast of St. Stephens, Alabama. Subsequent collections by R. C. Price and K. N. Whetstone produced several additional specimens including the figured portion of a right mandible. The specimens were recovered from the top of the Buca-tunna Formation at its upper contact with the Chickasawhay Limestone. The Bucatunna clay in Alabama and Mis-sissippi is predominantly composed of dark carbonaceous clays and. silts. l t is locally sandy and bentonitic (Murray, 1961) and is about 2 5 feet ( 7.62 m) thick at the Lone Star Quarry (Glawe, 1967). The Bucatunna is middle Oligocene (Orellan) in age and cor-relates with rocks of Rupelian age in Europe (Cooke et al., 1943). Although the Bucatun-na is sometimes grouped with the underlying Byram Marl and Glendon Limestone as the Byram Formation, we have followed Murray ( 1961) in considering these units to be sepa-rate formations. Fossil vertebrates have not previously been described from Oligocene strata of Alabama, although Cooke ( 1926, p. 2 91 J noted the occurrence of otoliths in the Byram Marl. The sircnian specimens from the Lone Star Quarry were associated with crocodilian scutcs (GSA-V -108 5), spines and dental plates of myliobatid rdys (GSA V 1083, I 084), sharks teeth of the genera Odontaspis, Galeocerdo and lo;urus (GSA-V-1089), and vertebrae and otoliths of several teleost fishes. These specimens arc catalogued into the collections of the Geo-logical Survey of Alabama (GSA) and the University of Kansas (KUVP). DESCRIPTION The specimens reported here include part of a left ramus (KUVP 43130), part of d neural arch (GSA-V-1086), and several ribs ~KUVP 43131, GSA-V-1090). Thev are from a small sircnian with very short pachyostosc ribs. The mandible appears to be relatively short and moderately deep. The mandibular canal is large and exits posterior to the last molar just below the anterior edge of· the ascending ramus. The portion of the as-cending ram us preserved is straight but is not 161 162 Tu lane Studies in Geology and Paleontology Vol. 14 complete enough to rule out the possibility that it may have inclined forward as in the manatee, Trichecus. The four roots pre-served on the ramus are probably from two molars. The anterior tooth has two broad, flat roots, while the posterior too th has a flat anterior root and a round posterior root indicating that this is the last molar. No alveolae occur anterior to the roots pre-served on the fragment, and it wo uld appear that only two molars were present. Very few systematic inferences can be made from such fragmentary material. How-ever, the apparent tooth reductio n would suggest that it should not be referred to the Trichechidae . I t is also not from a dugong as it possesses rooted tee th an d shor t massive ribs. It might be relate d to Hy drodamalis as this genus is eden tulous with ve ry massive dense ribs (Simpson, 1932 ). Of the fossil taxa, Metaxythe rium does not show the tooth reduction that appe ars to be present in the Alabama fos sil. At the present time the best assignment th at we can make for this mat erial is D ugongidae , genus undetermined. If the tooth reduction suggested here should prove to be real, then a new generic taxon w ould be requ ired. ACKNOWLEDGEMENTS We thank S. W. Shannon of the Geologi-cal Survey of Alabama for the loan of material under his c;:are. Jessie a Harrison read an earlier version ~f the manuscript and D awn Adams prepared the illustrations. REFERENCES CITED ARATA , A. A. , and C. G . JACKSON, 1965, Ceno-zoic vertebrates from the Gulf Coastal Plain -I: Tulane Stud. Geol., vol. 3, p. 175-177. COOKE, C. W., 1926, The Cenozoic formations in Geology of Alabama (G . I. Adams, C. Butts, L. W. Stephenson and W. Cooke, ed.): Geol. Surv. Alabama Special Report 14, p. 251-297. COOKE, C. W., J. A. GARDNER and W. P. WOODRING, 1943, Correlation of the Ceno-zoic form at ions of the Atlantic and Gulf Coast-al Plain and the Caribbean region: Geol. Soc. Amer., Bull., vol. 54, p. 1713-1722. G LAWE, L. N., 1967, Geologic section exposed in Lone Star Cement Company Quarry in Geology of the Coastal Plain of Alabama (D. E. Jones, ed .) . Geo l. Soc. Am er., Guidebook, p. J 10-113. MALDONADO-KOERDELL, MANUEL, 1953, Segundo hallazgo de sirenidos fosiles en Mexi-co : Ciencia (Mexico ), vol. 13, p. 146-148 . . MULLERRIED, F. K. G., 1932, Primer hallazgo de un sirenido fosil en Ia republica Mexicana: Uni-versidad Instituto Biologica Anales, vol. 3, p. 71-73. MURRAY, G. E. , 1961, Geology of the Atlantic and Gulf Coastal provinces of North America. New York, Harper Bro. 692 p. REINHART, R. H., 1959, A review of the sirenia and desmostyla : Univ. Calif., Publ. Geol. Sci., vol. 36, 146 p. REINHART, R. H., 1976, Fossil sirenians and desmostylids from Florida and elsewhere: Florida State Museum, Bull., vol. 20, p. 187-300. RUSSELL, R. J. (ed.), 1955, Guides to South-eastern Geology: Geological Soc. Amer., p. 1-592. SAVAGE , R. J. G., 1976, Review of early sirenia: Systematic Zoology, vol. 25, p. 344-351. SILER, W. S., 1964, Middle Eocene sirenian m Alabama: Jour. Paleontology, vol. 38, p. 1108-1109. SIMPSON, G. G., 1932, Fossil sirenia of Florida and the evolution of the sirenia: American Museum Nat. Hist., Bull., vol. 59, p. 419-503. TRELLES, DUELO, L., 1936, Restos fosilizados de un manati extinguido del periodo Oligocene Inferior: Sociedad Cubana de Historia Natural 'Felipe Poey' Havana, Mem., vol. 9, p. 269-270. December 28, 1978 PLATE 1 Oligoce~e s1remans from the Bucatunna Formation of Alabama. 1. right mandible (KUVP 43130) m lateral (la.) , dorsal ( lb.), and medial view (lc.); 2. and 3. ribs (KUVP 43131 and GSA V-1090 respectively) . Scale is 2 em. No.4 l I \ \ \ \ la \ \ \ \ \ lb Oligocene Sirenian from Alabama ---·-... \ I \ I I PLATE 1 \ \ ' ........ - .. -163 2 em lc 3 

An Oligocene (Orellan) Sirenian Fron the Bucatunna Formation of Alabama

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An Oligocene (Orellan) Sirenian Fron the Bucatunna Formation of Alabama

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