Blog
About

  • Record: found
  • Abstract: found
  • Article: not found

Lower vertebrates from an Arikareean (earliest Miocene) fauna near the Toledo Bend Dam, Newton County, Texas

Journal of Paleontology

Cambridge University Press (CUP)

Read this article at

ScienceOpenPublisher
Bookmark
      There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

      Abstract

      A recently discovered vertebrate fossil-bearing locality in the Fleming Formation of easternmost Texas has revealed a highly diverse fauna that contains a minimum of 44 early Miocene vertebrate taxa. At least 17 different species of lower vertebrates were recovered including five fish, two amphibians, one lizard, two snakes, at least five chelonians, and two crocodilians. A tiny boid that compares favorably withAnilioides nebraskensisis the first record in the Gulf Coastal Plain, and remains of a large aquatic turtle referred to the genusDermatemyspossibly represent its first fossil occurrence. Other rare genera represented include the largemouth bassMicropterus, possibly the snookCentropomus, and the crocodilianGavialosuchus.In addition, temporal and spatial range extensions are recorded forMicropterusandAlligator olseni.These taxa, along with the mammalian component to be discussed elsewhere, document the rare preservation of a forested subtropical to tropical coastal lowland paleoenvironment and provide evidence to imply that separation into mid-continent and coastal plain paleobiogeographic provinces had not yet occurred.

      Related collections

      Most cited references 18

      • Record: found
      • Abstract: found
      • Article: not found

      Time resolution in fluvial vertebrate assemblages

      Calibrating levels of time resolution that are accessible in the fossil record is important in understanding what evolutionary phenomena can be profitably studied using fossils. A model for attritional bone assemblage formation in fluvial deposits, based on observations of taphonomic processes in modern environments, provides order-of-magnitude estimates for time intervals represented in single unit, ‘contemporaneous' vertebrate samples. In order to form units with adequate material for analysis of morphological variation or paleoecological associations, it appears that bones must be spatially concentrated or stratigraphically condensed by sedimentary processes or biological agencies. In many cases this means that significant periods of time will be represented by single unit assemblages. According to predictions from modern environments, carcasses contributed through normal attrition can accumulate in the soil to ‘fossiliferous' densities over time intervals of 102–104 yrs. Attritional channel assemblages include bones from three sources: floodplain land surfaces, floodplain deposits, and the active channel, and represent time intervals on the order of 102–104 yrs. Given additional limitations on the composition of the fossil sample imposed by circumstances of preservation, outcrop availability and collecting strategy, attritional fluvial assemblages probably can be resolved only to 103 years even under the best conditions. Time intervals represented by fossils are not necessarily the same as those represented by sedimentary events in fluvial systems because bones can continue to accumulate and may be concentrated during times of erosion or non-deposition. Fluvial vertebrate assemblages of comparable taphonomic history can be used to document evolutionary changes over periods longer than their finest level of time resolution. While they may not be applicable to questions of punctuated or gradual transitions over shorter time scales, the longer-term patterns should have their own evolutionary significance.
        Bookmark
        • Record: found
        • Abstract: not found
        • Article: not found

        Turtle, crocodilian, and champsosaur diversity changes in the Cenozoic of the north-central region of western United States

          Bookmark
          • Record: found
          • Abstract: found
          • Article: not found

          Completeness of the rock and fossil record: some estimates using fossil soils

          Surprisingly, there is a relationship between rates of sediment accumulation and the time spans for which they have been calculated. This relationship can be used to estimate expected rates for specific sedimentary environments and time spans. The most probable completeness of a given sedimentary section at a given short time span can be calculated by the ratio of the measured long-term rate of sediment accumulation to the expected short-term rate. Although the measured time span is usually based on radiometric and paleomagnetic data, the cumulative time of formation estimated from fossil soils in a sequence may also be used to calculate rates and may be useful in comparing the completeness and rate of accumulation of different sequences. By both kinds of estimates, terrestrial sedimentary successions are disappointingly incomplete. Some reasons for incompleteness are illustrated with a simple model of episodic flooding, exceeding a threshold for destruction and sedimentation over a particular kind of vegetation, and thus initiating a new cycle of soil formation. In such a model, rock record is lost to erosion during cutting and filling cycles, to overprinting of weakly developed soils by later, better-developed soils, and to continued development, near steady state, of the soils preserved.
            Bookmark

            Author and article information

            Journal
            applab
            Journal of Paleontology
            J. Paleontol.
            Cambridge University Press (CUP)
            0022-3360
            1937-2337
            September 1994
            May 20 2016
            September 1994
            : 68
            : 05
            : 1131-1145
            10.1017/S002233600002672X
            © 1994

            Comments

            Comment on this article