page_title: Paleontology in Louisiana
section_title: Cenozoic
hierarchical_section_title: Paleontology in Louisiana / Prehistory / Cenozoic
caption_attribution_description: Basilosaurus.
context_page_description: Paleontology in Louisiana refers to paleontological research occurring within or conducted by people from the U.S. state of Louisiana. Outcrops of fossil-bearing sediments and sedimentary rocks within Louisiana are quite rare. In part, this is because Louisiana’s semi-humid climate results in the rapid weathering and erosion of any exposures and the growth of thick vegetation that conceal any fossil-bearing strata. In addition, Holocene alluvial sediments left behind by rivers like the Mississippi, Red, and Ouachita, as well as marsh deposits, cover about 55% of Louisiana and deeply bury local fossiliferous strata.
  Nevertheless, paleontologists and geologists have succeeded in reconstructing much of the state's prehistory. Around the beginning of the Cambrian, Louisiana was part of a landmass called Rodinia. This supercontinent began to break up into the northern Laurentia and southern Gondwana. This division split off local rock which would become part of the southern supercontinent. The Iapetus Ocean filled the region between these landmasses, submerging Louisiana.
context_section_description: Since the beginning of the Cenozoic, the shoreline of the Gulf of Mexico has shifted back and forth across Louisiana in response to sea level fluctuations, sediment accumulation, and tectonic subsidence. A great diversity of life flourished in the Paleogene seawater that periodically transgressed on the state. Invertebrates from these environments included bryozoans, corals, foraminifera, gastropods, ostracods, pelecypods, and more. During the Late Eocene, the Montgomery Landing area was home to more than 50 different kinds of mollusc. Their remains would be preserved in a glauconitic marl deposit known formally as the Moodys Branch Marl. About 150 different species of marine invertebrate and vertebrate fossils were preserved in the Cane River Formation. The primitive whale Basilosaurus also made its home in the state and left behind fossils that would be preserved in the Yazoo clay. Many of the marine fossils from this period of the state's history were preserved in the Midway, Wilcox, Claiborne and Jackson groups. This stratigraphic interval documents the local terrestrial environments as well. Even in the Paleogene, Louisiana was home to rivers and deltas. Paleogene terrestrial deposits in Louisiana tend to lack fossils, so little information is available about what might have lived in these habitats. Nevertheless, poorly preserved petrified wood and leaf fossils document the flora of this period in some places. Later, during the Oligocene, the marine life of Louisiana included corals, foraminifera, gastropods, ostracods, and pelecypods. These were preserved in what is now the Vicksburg Group. The presence of bodies of flowing water like rivers or streams is recorded in the terrestrial sediments of the Catahoula Formation. Fossils from this ancient environment are rare, but include petrified wood.
  During the Miocene epoch of the ensuing Neogene period west-central Louisiana held a coastal plain. The inhabitants of this environment were preserved in the sediments that became the Fleming Group. Research by Judith Schiebout has recovered a rich fauna, including numerous taxa of fossil vertebrates, from caliche conglomerates from this unit. Within Louisiana, the Pliocene strata consist of highly weathered and oxidized fluvial sand and gravel. East of the Mississippi River Valley, these sediments are called the Citronelle Formation, while west of the Mississippi River Valley, they are known as the Willis Formation. These strata are actually younger than their preserved fossils, which are the remains of Paleozoic life from central Tennessee. The Tennessean fossils were preserved in chert, which was broken down into gravel and transported into the area by the Tennessee River during the Neogene.
  By the late Pleistocene, the Mississippi River Valley had formed and much of the state was a coastal plain environment. Pleistocene sediments cover roughly 20% of the surface of Louisiana largely in the southern part of the state. Nevertheless, fossils of this age are rare. Mollusks inhabited the state's brackish and marine waters. Terrestrial invertebrates included snails, who were preserved in the loess that blankets the uplands bordering either side of the Mississippi River Valley. More spectacular inhabitants of Pleistocene Louisiana included megafauna like camels and mastodons.
caption: Restoration of Basilosaurus.
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