The early Pleistocene (ca. 2.588–1.806 Ma) Santa Fe River 1B fossil site (SF1B) of Gilchrist County, Florida has yielded turtle fossils representing nine genera and at least 10 species. Of these, at least six genera are aquatic turtles (Macrochelys and/or Chelydra, Apalone, Trachemys, Pseudemys, Sternotherus, and Kinosternon) and three are terrestrial (Hesperotestudo, Gopherus, and Terrapene). Hesperotestudo and an undescribed cf. Trachemys are the only extinct turtles identified in the paleoherpetofauna. Overall, the generic composition of the turtle fauna is predominantly modern and indicative of the southeastern United States today.

/pdf/turtles-of-the-early-pleistocene-santa-fe-river-1b-locality-2kasrg77n6.pdf

Pleistocene Mammals of North America

Turtles of the Early Pleistocene Santa Fe River 1B Locality

The remains of a mastodont and mammoth were recovered from Pleistocene deposits in southeastern Arizona. These new proboscidean remains have characteristics distinguishing them from their more typical late Pleistocene forms. The mastodont (Mammut americanum), has traits similar to those of other female mastodonts, but includes mandibular tusks. This may indicate an early Pleistocene Age or supports evidence that female mastodonts had mandibular tusks. The partial mammoth jaw and molar display characteristics similar to Mammuthus columbi, but appears to be a variant or earlier form approaching those displayed in Mammuthus meridionalis. The presence of different proboscideans with different diets, although within the same geologic unit, cannot be confirmed as being sympatric. If so, it would indicate a partitioning of resources. Mammoths are grazers, and more common in Arizona than the browsing mastodonts.

background

https://bioone.org/journals/journal-of-the-arizona-nevada-academy-of-science/volume-44/issue-1/036.044.0104/New-Mastodont-and-Mammoth-Remains-from-Pleistocene-Deposits-in-Southeastern/10.2181/036.044.0104.pdf

New Mastodont and Mammoth Remains from Pleistocene Deposits in Southeastern Arizona

Object Manipulation in Captive Polar Bears

Population-level interactions

During August, 1998, a well-preserved bison skull was found in gully fill on the western bank of the Missouri River. The skull was resting upside down near the bottom of a gully incised into the upper part of the Niobrara Formation. The gully was subsequently filled with poorly sorted unconsolidated material consisting of small to large, poorly-rounded chips of Niobrara chalk in a matrix of tan clay. The gully fill also contains a few chips of the Pierre Shale which crops out at the top of the hill. Sediment in the gully fill surrounding the skull resembles sheetwash deposits. A soil profile with vegetation was developed on the gully fill. The cranium was excavated and jacketed for removal, and later prepared at the New Jersey State Museum. The specimen belongs to a male bison, based on the presence of horn burrs, with a tip-to-tip horn core width (780mm) slightly larger than the published range for Bison bison bison horn cores (510778mm for males). Morphology of the skull is similar to Bison antiquus occidentalis, but its radiometric age is only 710±40 14

Pleistocene Mammals of North America

Citations

Turtles of the Early Pleistocene Santa Fe River 1B Locality

New Mastodont and Mammoth Remains from Pleistocene Deposits in Southeastern Arizona

Object Manipulation in Captive Polar Bears

Population-level interactions

A bison skull from lyman county, south dakota

Related Papers (5)

The Mammals of North America

Walker's mammals of the world

Mammal Species of the World: A Taxonomic and Geographic Reference

MODELTEST: testing the model of DNA substitution.

Some genetic consequences of ice ages, and their role in divergence and speciation