MISSISSIPPI GEOLOGY 2 Figure 3
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THE DEPARTMENT OF NATURAL RESOURCES miSSISSippi• • • • geology Bureau of Geology I 2525 North West Street Volume 6, Number 3 • Jackson, Mississippi 39216 March 1986 EXCAVATION OF AN ARCHAEOCETE WHALE, BASILOSAURUS CETOIDES (OWEN), FROM MADISON, MISSISSIPPI· David T. Dockery Ill Mississippi Bureau of Geology John E. Johnston Mississippi Bureau of Geology INTRODUCTION Company, notified the Mississippi Bureau of Geology concerning the find. After examination, the excavated On October 22, 1985, backhoe operator Richard Ivy materials were identified as vertebrae, rib, and limb of Triangle Construction Company encountered some bone fragments of the large archaeocete whale hard objects while excavating for a sewer line in the Basilosaurus cetoides (Owen). Yazoo Clay at Hunter's Point subdivision just northeas: Richard Ivy reported that the bones were encountered of Madison, Mississippi (SW/4, NW/4, Sec. 10, T.7N. ten feet below the surface while excavating for a six R.2E.). At first he thought these objects were petrified foot long residential sewer pipe connecting to the main wood. Bob King, also with Triangle Constructio~• line. According to his observation, he had cut the Reconstructed skeleton of Basilosaurus cetoides (Owen). Scale bar equals 1 meter. From Thurmond and Jones, 1981 . Figure 2. John Johnston and Phillip Higdon watching and listening for the backhoe to encounter bone. of vertebrae and ribs were eventually exposed (Figures 1 and 2) . At the beginning of the excavation, the fragmentary nature of the bones ruled out any necessity for a site survey (Figure 3). The main objective was to find the skull or at least fragments of the skull and jaws. In trying to anticipate the direction in Figure 1. Richard Ivy operating backhoe In search of which the bones lay, the backhoe was repositioned Basilosaurus bones. several times. Once the course of the bones was determined. a string of connecting vertebrae was animal in half leaving bones in each side of the uncovered. and the removal of bone material from the excavated trench. This observation seemed fanciful at site ceased (Figure 4). Vertebrae and associated rib first as it is rare for an archaeocete find to have an fragments were left in situ, resting on a platform of clay articulated skeleton. The bones are usually scattered. as the excavation continued (Figures 5 and 6). Later excavation. however, proved the backhoe Once a significant part of the Basi/osaurus skeleton operator to be correct. had been uncovered, the developer of the Hunter's The excavated bones. though only fragments. were Point subdivision, Bill Shanks, contacted newspaper well mineralized, solid. and had an attractive pinkish and television personnel concerning the find. The story white patina which dried to a dull white. This patina and film of the excavation appeared on the evening Indicated that the bones rested within the weathered news and made the front page of the State's largest zone of the Yazoo Clay. Triangle Construction newspaper. Bureau geologist John Johnston and staff Company owner Buck King offered the company's member Brad Alsobrooks continued the excavation assistance and backhoe to excavate for additional over the weekend and reported large crowds on hand bones at the site. A period of rain followed which to watch. delayed further work at the site, and It was not until On February 3, the excavation was completed. The January of 1986 that the excavation began. vertebral string and presence of ribs indicated the skull Several staff members with the Mississippi Bureau of to lie under or opposite the main sewer line. A thorough Geology met Richard Ivy at the site on January 31, excavation made in this area failed to reveal the skull or 1986, and the excavation began. The T -connection of any additional bone material. Excavation then resumed the sewer line was uncovered and fragmentary pieces toward the posterior end of the skeleton. The vertebral MISSISSIPPI GEOLOGY 2 Figure 3. Fragmentary ribs and vertebra uncovered by Figure 4. John Johnston carefully removing clay matrix backhoe. from vertebral column. column rested on its left side and made a broad, BASILOSAURUS FROM THE GULF COASTAL dorsally convex arch (Figure 6) . In the posterior PLAIN direction, vertebrae became increasingly disjunct from the column (Figures 7 and 8). Near the posterior end of In 1834 Dr. Richard Harlan, a Philadelphia physician the preserved column, vertebrae were scattered and and anatomist, described the first archaeocete whale rose two feet or more within the section (Figure 9). from the United States; it had been found several years Some of these vertebrae were badly shattered by the earlier along the banks of the Ouachita River in backhoe as they were encountered in unexpected Caldwell Parish, Louisiana (Domning, 1969). He locations. thought the bones belonged to a Tertiary marine reptile A plane table survey was begun on February 3 but, and named it Basl/osaurus, which means "king of the due to rain on the following day, was not finished until lizards." On his visit to London in 1839, Harlan showed February 7. The surveyor for this project was Bureau some Basi/osaurus specimens from Alabama to the geologist Chuck Peel. This survey and the in situ famous paleontologist Sir Richard Owen. Owen orientation of the bones is given in Figure 12. Upon realized the animal was a mammal and later changed completion of the survey, final excavation and removal the name to Zeuglodon cetoides. However, due to of the skeleton was turned over to the Mississippi modern rules of taxonomic r:~omenclature , Harlan's Museum of Natural Science. The museum's vertebrate original genus name prevailed so that the correct name paleontologist, Eleanor Daly, directed the removal of of the whale is Basi/osaurus cetoides (Owen). the bones (Figure 10). The vertebrae were supported The 1840's saw a surge of fossil whale hunting in by steel pipe splints and then covered with a protective Louisiana, Mississippi and Alabama. In 1843 B. L. C. plaster jacket. This phase of the excavation was Wailes, a prominent Natchez planter and scientist, completed within two weeks following the completion obtained the partial remains of a Basilosaurus found of the survey. The skeleton now resides in the along the banks of the Pearl River (Wailes, 1854). museum's collections and will be used as a research Wailes notes in his report on the geology and specimen. agriculture of Mississippi that detached vertebrae had 3 MARCH 1988 Figure 5. Two closely oonnected vertebrae at anterior end of vertebral oolumn and associated rib fragments. Figure 6. Central region of vertebral column showing a progressive dislocation of vertebrae in the posterior direction. The anterior end is at the left of the picture. MISSISSIPPI GEOLOGY 4 Figure 7. Anterior end of vertebral column with associ Figure 8. Dislocated vertebrae in the central region of ated rib fragments. the vertebral column. been found in Hinds (in the city limits of Jackson), PRESERVATION Madison, Scott, Smith, and Clarke counties. The vertebrae were so common in some areas that local The Basi/osaurus skeleton was located in the brown residents used them as andirons (Domning, 1969). L. weathered zone of the Yazoo Clay just above a less Harper (1857) mentions in his report on the geology of weathered brownish gray zone. As a result of Mississippi that the vertebrae were frequently used as weathering, the bones had a hard pinkish white outer foundation supports for cabins. patina. Rib bones at the site had been fragmented prior Some selected references which further discuss to burial and generally lay near the vertebral column fossil whales from the Gulf Coastal Plain include along the anterior part. Rib fragments were generally Kellogg, 1936; Dockery, 1974; Frazier, 1980; Thurmond hard and solid, though some were fragile. and Jones, 1981; Lancaster, 1982; and Carpenter and All vertebrae found were fragile. Each had a fractured Dockery, 1985. hard outer patina which readily, though undesirably, 5 MARCH 1986 Figure 9. View from the posterior end of the skeleton Figure 10. Geologist Chuck Peel watches as Mississippi showing the scattered posterior vertebrae. Museum of Natural Science staff members Eleanor Daly, Paul Hartfield, and Roger Weill collect rib fragments. separated from the vertebral core during excavation. The core of each vertebra was a black, poorly mineralized, fragile, porous mass. Many vertebrae were flippers (in part) could have separated from the trunk readily shattered when encountered by the backhoe. during this flotation stage. The same postmortem Extreme care was required in their excavation and process could account for the isolated Metamynodon removal. The neural processes of all anterior vertebrae skull reported in the December 1985 issue of were fragmented or absent. Despite the fragility of the Mississippi Geology. This skull, that of a large land vertebrae, their size and in situ arrangement along the mammal, was found in Lower Oligocene marine beds vertebral column was an impressive sight to the visiting exposed along the Big Black River in central public. Mississippi. It was presumably washed out to sea via an A few fragmentary bones found on the initial sewer ancient river system and then separated from the body. excavation were from one of the front flippers. Another explanation for the skull not being found Subsequent excavation failed to reveal any additional can be attributed to scavengers. Upon death the head limb bones. is often the first part of the body attacked by The lack of a skull or jaws at the anterior end of the scavengers due to easy access of soft parts such as the vertebral column was a disappointment. A large animal brain. Increased feeding activity on the head may result such as the Basi/osaurus may have floated for days In dislocation and separation from the body since the after its death supported by gasses formed as a by neck is comprised of small vertebrae that may product of decay.