Michael E. Nelson

A Fossil Grass (Gramineae: Chloridoideae) from the Miocene with Kranz Anatomy

A fossil leaf fragment collected from the Ogallala Formation of northwestern Kansas exhibits features found in taxa of the modern grass subfamily Chloridoideae. These include bullet-shaped, bicellular microhairs, dumbbell-shaped silica bodies, cross-shaped suberin cells, papillae, stomata with low dome- to triangular-shaped subsidiary cells, and Kranz leaf anatomy. The leaf fragment extends the fossil record of plants that show both anatomical and external micromorphological features indicating C4 photo-synthesis back to the Miocene. On the basis of associated mammals, the leaf fragment is assigned a Hemphillian age (7 to 5 million years ago).

A Giant Short-faced Bear (Arctodus simus) from the Pleistocene of Northern Utah

A large arctodont bear is reported from Pleistocene shoreline deposits of Lake Bonneville in Salt Lake County, Utah. Although these bones are 6-47 percent larger than other known arctodont bones, the material evidently represents Arctodus simus. Sexual dimorphism probably is responsible for this large variation in size. Several elements of a large arctodont bear, Arctodus simus, were recovered in Salt Lake County, Utah from deposits of late Pleistocene age. These bones were discovered by Mr. John Yackovich, a heavy equipment operator for MONROC, while loading sand and gravel from a pit in the southwestern part of Salt Lake Valley. Physical evidence, together with a radiocarbon date of 12,650 ? 70 Y.B.P., suggests that the sand and gravel might have been deposited along the Provo shoreline of Lake Bonneville during the Bonneville cycle. Exact locality and stratigraphic data are on file in the Utah Division

Pleistocene Musk Oxen from Kansas

Nine musk oxen specimens representing the genera Symbos, Soergelia, and Euceratherium are reported from Kansas. The late Pleistocene (Wisconsin) specimens of Symbos and Euceratherium were collected from gravel bars in the Kansas River near Kansas City and from terrace deposits along major drainages in western Kansas. The single specimen of Soergelia was collected from early Pleistocene (Kansan) sediments exposed along an irrigation canal in northcentral Kansas.

A New Oligocene Faunule from Northeastern Utah

A small collection of fossil vertebrates from Summit County, Utah includes the rodent Paradjidaumo minor and two small artiodactyls. This assemblage, the Peoa local faunule, is early Oligocene in age. Trans. Kans. Acad. Sci. 79 (1-2), 1976.

The Duck Creek Molluscan Fauna (Illinoian) from Ellis County, Kansas

A late Pleistocene molluscan fauna containing 35 species is reported from sediments deposited by the ancestral Smoky Hill River in Ellis County, Kansas. The presence of Pisidium compressum and Sphaerium striatinum within cross-bedded sands indicates a perennial stream with some current action, while the abundance of Valvata tricarinata suggests the stream was lake-like in places. The abundance of several strictly woodland species, such as Cionella lubrica, suggests that a continuous stand of trees bordered the stream, while valley slopes were possibly covered with grasses and scattered trees. Likewise, cooler summers and winters than at present are indicated for Ellis County at the time these taxa lived by the predominance of species with a northern distribution. The climatic implications of the molluscs, faunal comparisons with other molluscan faunas, and the topographic position of the deposits suggest an Ilminoian age for the fauna. Trans. Kans. Acad. Sci., Vol. 78 (1-2), 1975.

Miocene Three-Toed Horse from the Salt Lake Group of Southeastern Idaho

A partial skull of a three-toed horse is described from the Salt Lake Group of southeastern Idaho. This specimen is referred to Merychippus isoneKsus based on the development of facial fossae, size, hypsodonty, and dental pattern. This species also is known from the Barstovian Mascall Formation of the John Day Basin of Oregon and numerous other localities in western North America. Based on the biochronology of this species, a Barstovian (medial Miocene) age is assigned to part of the Salt Lake Group of southeastern Idaho.