Browsing by Subject "Vertebrates, Fossil"
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Item Depositional environment and taphonomy of some fossil vertebrate occurrences in Lower Permian redbeds in Archer County, Texas(1984-12) Sander, Paul Martin; Langston, Wann, 1921-The Lower Permian Admiral Formation redbeds in north-central Texas are famous for their well-studied vertebrate fauna. Taphonomical and paleoecological aspects, however, are inadequately understood. The prerequisite for taphonomical interpretations is an analysis of the depositional environments. Low relief and low regional dip expose extensive paleoslopes in western Archer County. Three major depositional systems may be recognized: a fine-grained meanderbelt, a low sinuosity fine-grained fluvial system, and a tidal flat. The small scale of the sedimentation (average sandstone thickness 1. 5 m) is remarkable. Four types of vertebrate occurrences can be distinguished: Type 1: Mass death bonebeds are situated in a floodbasin facies comprised of gray and red mudstones with abundant Psaronius roots (a swamp-dwelling tree fern) which is associated with the fluvial systems. Such basins were covered by a dense swamp forest with a high diversity of vertebrates. This type is exemplified by the Geraldine Bonebed, which has yielded at least 45 partly articulated skeletons representing 4 genera of tetrapods, and remains of another 8 vertebrate taxa. The bones were found on a layer of fern, seed fern, and conifer foliage and wood. This occurrence was formed by a single catastrophic event, possibly a forest fire, which drove the animals of the swamp forest into a pond, where they died of suffocation and were concentrated into a bonebed by physical processes (wind). Type 2: Lag bonebeds, situated on the landward margin of tidal flat environments, are represented by the Rattlesnake Canyon Bonebed which consists mainly of a calcareous concretion conglomerate, which contains fragmentary bone, serpulid worm colonies (brackish water!), and calamitelean wood. The diversity of forms represented by articulated material is low. The ubiquitous predator Dimetrodon and an amphibian, Trimerorachis, which tolerates brackish water, are common. This type was deposited as lag in a storm washover deposit. Type 3: Ponds (abandoned channels, etc.) which contained a fauna dominated by aquatic forms (the fishes Xenacanthus and Ectosteorachis, and the amphibian Archeria) were gradually filled by fine-grained sediment and organic debris (vertebrates, plants). These oxbow lakes were probably rimmed by stands of Calamites. Four examples are described. Type 4: Single, complete skeletons examplified here by Diadectes are occasionally found in red floodplain mudstones.Item Descriptions of some fossil vertebrates found in Texas(University of Texas at Austin, 1916) Hay, Oliver Perry, 1846-1930Item Fossil vertebrates from the late Pleistocene Ingleside fauna, San Patricio County, Texas(University of Texas at Austin. Bureau of Economic Geology, 1972) Lundelius, Ernest L., Jr.Fresh-water pond deposits at Ingleside, San Patricio County, Texas, have yielded a large Pleistocene vertebrate fauna. The bones are derived from calcareous sands and marls which overlie a marine lagoonal clay. The locality is located just west of the axis of Live Oak Ridge. This ridge, along with the Ingleside Terrace to the east, was formed as a barrier island and lagoon when sea level was higher than at present. The Ingleside barrier and lagoon are correlated with the Pamlico Terrace of the east coast of the United States, which is currently correlated with the Sangamon interglacial stage. The fresh-water pond formed after the barrier and lagoon, probably by wind deflation during a time when the water table was low, corresponding to a period of lowered sea level. The fauna contains a diverse assemblage of Pleistocene mammals, birds, reptiles, amphibians, and fish; it consists of two principal elements:(1) extinct forms such as Tanupolama, Camelops, Mammuthus, Mammut, Paramylodon, Megalonyx, Equus complicatus, Canis dirus, Platygonus, Bison antiquus, Geochelone crassiscutata, and Gopherus hexagonata; and (2) extant forms such as Odocoileus virginianus, Canis latrans, Peromyscus leucopus, and Mephitis mephitis. A third element usually well represented in Pleistocene faunas extant forms no longer found in the area is represented by a very few forms such as Cynomys. Thescarcity of this element is a result of the poor representation of the small-sized animals in the fauna. Several species, such as Tanupolama mirifica and Paramylodon harlani, are represented by samples large enough to give information on variability. The diversity of the large mammalian fauna indicates the presence of diverse habitats in the Ingleside area. The presence of large tortoises, such as Geochelone and Gopherus hexagonata, indicates mild winters. The age structure of the Tanupolama mirifica sample indicates the existence of seasonality of some climatic factor, probably rainfall.'Item Recognition of Hipparions and other horses in the middle Miocene mammalian faunas of the Texas Gulf region(University of Texas at Austin. Bureau of Economic Geology, 1952) Quinn, James HarrisonNew information concerning the ancestry of the later Tertiary horses, Calippus, Protohippus (in the original sense), Hipparion, Neohipparion, and Nannippus, has been obtained from a restudy of the various mammalian farmas of the Coastal Plain in Texas, based in the main on the extensive collections of the Bureau of Economic Geology, The University of Texas. The age, stratigraphic correlation, and composition of these faunas have been reevaluated, and the results provide new evidence that has important bearing on Miocene and Pliocene intercontinental correlations of mammalian faunas. It is the opinion of the writer that these five genera of horses, among which the three genera Hipparion, Neohipparion, and Nannippus are commonly called the Hipparion group, originated from the lower Jv[:iocene genus Parahippus and hence made their first appearance in the middle Miocene.