NPS Paleontology Research Abstract Volume


PLANT BIOSTRATIGRAPHY OF THE CHINLE FORMATION
IN THE PETRIFIED FOREST AND VICINITY

Sidney R. Ash
Weber State University
Ogden, Utah 84408

The principle objective of this project is to determine the stratigraphic distribution of plant mega and microfossils in the Chinle Formation in the park and to integrate the results obtained from other areas in the Southwest. Although this concerns mainly plant fossils that have been collected in the past, data on new finds will be incorporated in it as time allows. In this project I have been cooperating with R.J.Litwin (USGS) and we have published one paper which helps relate the biostratigraphy of both the plant megafossils and the palynomorphs. Others are in preparation.

Petrified Forest National Park, Research Abstract Volume 1, 1991.




PALEOCLIMATIC STUDIES OF THE CHINLE FORMATION
IN THE PETRIFIED FOREST AND VICINITY

Sidney R. Ash
Weber State University
Ogden, Utah 84408

These studies which are being carried on in collaboration with Dr. G. Creber of the University of London began in the summer of 1984 when Dr. Jane Francis helped me excavate Walker's Stump. The object of the project is to determine if annual growth rings occur in the petrified trees in the park. If they do indicate that seasons were well developed in the park during the Late Triassic; if not they would confirm that they lived in a season-less climate such as you get in the tropics. Several dozen specimens have been published. Laboratory examination of these and other specimens seem to indicate that annual growth rings are not present. I gave a paper in early 1990 in which I discussed our findings. More recently we finished a draft of a full-blown treatment of our results. Hopefully this manuscript will be published during the coming year.

Petrified Forest National Park, Research Abstract Volume 1, 1991.





SYSTEMATIC STUDIES OF THE PLANT MEGAFOSSILS AND
RELATED FOSSILS IN THE PETRIFIED FOREST

Sidney R. Ash
Weber State University
Ogden, Utah 84408

The objective of this project is to gain a better understanding of the plant life of the Chinle Formation in the park and adjacent areas. This is an on-going project in which previously unknown fossils are described as they are found in the park and previously known fossils are redescribed on the basis of new material or on re-evaluation of old material. During the past year I described a new cycad leaf from the park, and Ron Litwin and I described the first known occurrence of Triassic amber from the Petrified Forest. Earlier, Geoff Creber and I described evidence for frugal infection of the wood in the park.

Petrified Forest National Park, Research Abstract Volume 1, 1991.




STRATIGRAPHY OF THE CHINLE FORMATION
IN THE PETRIFIED FOREST

Sidney R. Ash
Weber State University
Ogden, Utah 84408

I now have a manuscript on the Black Forest Bed in press and expect that it will appear soon. I gave a talk on the source of the volcanic debris in the Black Forest Bed at the Museum of Northern Arizona in 1989. I am cooperating with Nancy Riggs in further studies on the radiometric age of the Black Forest Bed. Also, I have almost completed a draft of a paper on the stratigraphy of the Chinle Formation throughout the park. Every effort will be made to see that this paper will be completed early in 1992 and published as soon as possible thereafter.

Petrified Forest National Park, Research Abstract Volume 1, 1991.




TAPHONOMIC ANALYSIS OF CREVASSE SPLAY BIVALVE DEATH
ASSEMBLAGES, UPPER TRIASSIC CHINLE FORMATION
PETRIFIED FOREST NATIONAL PARK

Steven C. Good
Department of Geological Sciences
University of Colorado
Boulder, CO 80309

Freshwater unionid bivalves occur in highly concentrated, localized distributions interpreted as death assemblages deposited in crevasse splay systems. These coarse-grained beds occur within fine-grained overbank deposits. Vertical stacking of crevasse splay deposits indicate reactivation of the crevasse system during multiple flooding events. The disarticulated valves of dead bivalves accumulated on the channel bed and were entrained during high energy flood events and deposited in proximal crevasse splay environments where flow velocity rapidly dissipated.
The bivalve-bearing portions of crevasse beds are less than 10m wide, 30m in length, and 20cm thick. Transects were made perpendicular and parallel to flow and the variation studied at one meter intervals for two locations. The bedding surfaces were photographed and uniform volume samples collected. Taphonomic features common to all samples are (1) >95% disarticulated valves consistently in current stable orientations and frequently imbricated, (2) valves fragmented and surfaces abraded, and (3) wide and continuous range of size from juveniles to adults. The perpendicular to flow transect samples near the center of the bed contain a higher density of valves, larger and heavier individual shells at the high end of the size distribution, and clay and granule matrix. Samples from the margins of the bed feature increased articulation, lower density of valves, and coarser matrix composed of limestone pebbles. With increasing distance from the source channel along the parallel to flow transect, sample feature a decrease in the density of valves, and decrease in the size of the high end of the size continuum.

Petrified Forest National Park, Research Abstract Volume 1, 1991.




TRACE FOSSILS OF THE PETRIFIED FOREST MEMBER,
PETRIFIED FOREST NATIONAL PARK, ARIZONA

Stephen T. Hasiotis
Dept. Geological Sciences
University of Colorado
Campus Box 250
Boulder, CO 80309-0250

Preliminary field work at the Petrified Forest National Park revealed that diverse and important trace fossil assemblages occur in the Petrified Forest Member and possibly in the Owl Rock Member of the Upper Triassic Chinle Formation. Many of these traces are the earliest known of their kind and are important assets of the park.
Invertebrate traces include horseshoe crab tracks and trails, millipede trails, adult and juvenile insect burrows and nests, beetle borings and gallery nests in wood, annelid burrows, and Scoyenia (an insect larvae burrow). Crayfish burrows may exist in the park, with some found in crevasse splays and loose in the washes near Tiponi Point.
Plant traces include individual and intertwined root systems and pith casts of the horsetail Neocalamites. Stages of calcium carbonate root concretions may exist in the paleosols throughout the park.
Trace fossil assemblages in continentally deposited units, such as the Petrified Forest and Owl Rock Members of the Upper Triassic Chinle Formation are very important because they are rarely described, often go unnoticed, and hold a wealth of information waiting to be tapped.





TAXONOMY AND BIOSTRATIGRAPHY OF METOPOSAURID
AMPHIBIANS FROM PETRIFIED FOREST NATIONAL PARK

Adrian P. Hunt and Spencer G. Lucas
New Mexico Museum of Natural History
Albuquerque, NM 87801

Metoposaurid amphibians have been recovered from the Blue Mesa and Painted Desert Members of the Petrified Forest Formation (Upper Triassic) in Petrified Forest National Park (PFNP). No amphibian specimens have been collected from the Owl Rock Formation. Two taxa of metoposaurids are present in PFNP. One taxon is a large-skulled species with relatively short intercentra. The oldest valid name for this taxon is Buettneria perfecta. B. perfecta is most common at localities in the Blue Mesa Member including Devil's Playground, the Teepees Blue Mesa, King's Throne, Lot's Wife, Jasper Forest and Giant Logs. This taxon is rarely present at a few localities in the Painted Desert Member including the Flattops and near Lacey Point. Specimens include several skulls and much postcrania. The second taxon is a small metoposaurid with elongate intercentra which represents a new genus. This taxon has a distribution which contrasts strikingly with the distribution of B. perfecta at PFNP. Thus, it is rare in the Blue Mesa Member (e.g., The Teepees and Blue Mesa) and relatively common in the Painted Desert Member (e.g., Lacey Point and Flattops). The only skull of this taxon is from Lacey Point. Most other occurrences are of the characteristic intercentra. This pattern of metoposaurid distribution is also characteristic of other areas of the Chinle Group. The only Chinle Group metoposaurid which is not present in PFNP is Metoposaurus bakeri which is characteristic of early Tuvalian strata older than those exposed at PFNP.


Petrified Forest National Park, Research Abstract Volume 1, 1991.




TRIASSIC AMBER AND POLLEN AT PETRIFIED FOREST NP

Ron Litwin
U.S. Geological Survey
Reston, VA 22092

This past field season Sidney Ash and I collected at several of our established Triassic amber sites in order to do spectroscopic analyses of samples from these sites this winter with Vicki Comer (USGS, Coal Branch). We prospected and discovered several additional amber producing sites as well, and collected samples for the paleoecological pollen analyses I am beginning on the lacustrine deposits in the park (I hope to begin multivariate pollen analyses of them before spring). Additionally, I collected rock samples for biostratigraphic analyses from the western sections of the park, but need to return to the Flattops area for additional collecting so that I can augment my current data on the pollen assemblage transition across the Carnian-Norian stage boundary.

Petrified Forest National Park, Research Abstract Volume 1, 1991.




UPPER TRIASSIC (CARNIAN AND NORIAN) AMPHIBIANS AND REPTILES
FROM PETRIFIED FOREST NATIONAL PARK
Robert A. Long
University of California
Berkeley, CA 94720
Philip A. Murry
Tarleton State University
Stephenville, TX 76402

The Chinle Formation of Petrified Forest National Park, Arizona, has yielded numerous Carnian and Norian age vertebrate fossils. Metoposaurus fraasi is a large metoposaurid amphibian that is very common in Carnian age sediments below the Sonsela Sandstone. A smaller new metoposaur taxon is found primarily in strata of Norian age. A unique archosauromorph whose long, slender skull was covered with large osteoderms has been recovered from the Carnian age Crocodile Hill locality. Another unique archosauromorph is based largely on postcranial material recovered from Carnian age deposits in the park. Its body is covered with three armored morphotypes, the vertebrae are long and low, and the pelvic and appendicular elements are of proterosuchian grade. Postosuchus kirkpatricki is a 4-5 m long, heavily built, large skulled, short necked quadrupedal rauisuchid. The pelvis exhibits a short, anteriorly directed iliac blade, two sacral rib attachments, a moderate sized pubic foot and rod like weakly fused ischia. Postosuchus has been recovered from both Carnian and Norian age sediments within Petrified Forest NP. A new two to three meter long gracile rauisuchian has been recovered from the Upper Petrified Forest Member within the park. It is known from Carnian and Norian age deposits and from the Owl Rock Member elsewhere. The cervical centra of this taxon are much more elongate than in other rauisuchians, the humerus and lower hind limb elements are long and slender, the pelvis has a large anteriorly directed iliac blade, a huge pubic foot, and flattened, strongly fused ischia. Calyptosuchus wellesi is a common three to four meter long Carnian age aetosaur. It may be differentiated from the Carnian and Norian aged Desmatosuchus haploceras in its relatively delicate build with long and slender limbs. The Norian age Typothorax coccinarum may be differentiated from Calyptosuchus and Desmatosuchus in its extremely wide and flat body, shortened cervical vertebrae, ilia and high, dorsolaterally directed supracetabular blades and relatively small appendicular elements as compared to overall body size. Paratypothorax andressi is only known on the basis of its distinctive dermal armor from the Carnian and Norian. A moderately large (3-4 m) new staurikosaurid saurischian was recovered from three localities in the Upper Petrified Forest Member in Petrified Forest NP. The dorsal centra are short and wide, the femur is relatively long, the ilium has a relatively long posteriorly directed blade and the astragalus is similar to that seen in sauropodomorphs.




REVISED UPPER TRIASSIC STRATIGRAPHY
PETRIFIED FOREST NATIONAL PARK

Spencer G. Lucas
New Mexico Museum of Natural History]
Albuquerque, NM 87104

Approximately 575 m of Upper Triassic nonmarine strata are exposed in the Petrified Forest National Park (PFNP). These strata have long been assigned to the Chinle Formation, divided (in ascending order) into the lower Petrified Forest Member, Sonsela Sandstone Bed, upper Petrified Forest Member and Owl Rock Member. Informal stratigraphic terminology also exists for persistent sandstone beds in the lower and upper Petrified Forest Members. A revised stratigraphic nomenclature of the Upper Triassic strata in the PFNP is consistent with that of other Upper Triassic nonmarine strata in the western United States, assigns the PFNP strata to the Chinle Group divided (in ascending order) in to the Blue Mesa, Sonsela and Painted Desert Members of the Petrified Forest Formation overlain by the Owl Rock Formation. The Blue Mesa and Painted Desert Members of the Petrified Forest Formation take their names from features in the PFNP where their type sections are located. Late Carnian (Tuvalian) fossils from the upper part of the Blue Mesa Member and early Norian fossils from the lower part of the Painted Desert Member provide significant standards for the correlation of Chinle Group fossils throughout the western United States.

Petrified Forest National Park, Research Abstract Volume 1, 1991.




LATE TRIASSIC CALCAREOUS MICROFOSSILS FROM THE
PETRIFIED FOREST NATIONAL PARK

Spencer G. Lucas and Kenneth K. Keitzke
New Mexico Museum of Natural History
Albuquerque, NM 87104

We processed more than 500 rock samples to recover calcareous microfossils (charophytes and ostracods) from Upper Triassic strata in the Petrified Forest National Park (PFNP). The samples were collected from distinctive lithologic units throughout the entire 575 m of Chinle Group strata exposed in PFNP and from selected strata that produce unionid bivalves. However, only rock samples from the upper part of the Painted Desert Member of the Petrified Forest Formation produced calcareous microfossils.
These microfossils pertain to one taxon of charophyte (Stellatochara sp.) and two taxa of darwinolid ostracods (Darwinula aff. D. liulungchuanensis and Gerdalia sp.). They most resemble microfossils from the lower Norian Bull Canyon Formation of east-central New Mexico and thus support tetrapod-based correlation of the Bull Canyon Formation and the Painted Desert Member. The Painted Desert Member microfossils also indicate the presence of highly mineralized, permanent limnic environments with water depths of 6-8 m or less. The absence of calcareous microfossils throughout most of the Chinle Group section in the PFNP probably reflects the rarity of such environments.

Petrified Forest National Park, Research Abstract Volume 1, 1991.




THE STRATIGRAPHY AND VERTEBRATE MICROFAUNAS OF THE
UPPER TRIASSIC CHINLE FM., PETRIFIED FOREST NP

Philip A. Murry
Tarleton State University
Stephenville, TX 76402

The Petrified Forest Member of the Triassic Chinle Formation in Petrified Forest National Park, Arizona, may be divided into a lower and upper unit by means of the Sonsela Sandstone Bed. Analysis of fossil vertebrates indicates that the Sonsela Sandstone Bed and Upper Petrified Forest Member are characterized by a fauna distinct from that within the lower portion of the Petrified Forest Member. These faunas are believed to be of Norian and Carnian age respectively. Utilizing fossil vertebrates and certain lithostratigraphic units, especially the Sonsela Sandstone Bed and Black Forest Tuff, exposures have been correlated within and between the Rainbow Forest, Blue Mesa and Painted Desert areas of Petrified Forest National Park.
An upper Carnian age fauna may be indicated by localities below the Sonsela Sandstone. At these localities numerous teeth of the freshwater shark Xenacanthus were found (the most abundant element in the lower unit faunas) and rare elements of the polyacrodont Lissodus. Lungfish typically represent rare components in these faunas. Redfieldiid and colobodontid fish elements are common. Rare identifiable reptile elements include Trilophosaurus teeth and jaw fragments of neodiapsids or lepidosauromorphs. Numerous teeth of small archosauromorphs are found, including abundant, distinctive, laterally compressed teeth bearing compound serrae.
The dipnoan and hybodont faunas of the Sonsela Sandstone and Upper Petrified Forest Member are quite different than those within the lower member. No xenacanth or Lissodus specimens have yet been recovered. A new species of shark has been described from the Sonsela Sandstone, Upper Petrified and Owl Rock Members. The new shark is characterized by low crowned teeth that typically bear a reticulate tooth sculpture. Colobodontid fish toothplates of distinctive morphology are also present. Large numbers of lungfish toothplates have been obtained from the Upper Petrified Forest Member. Toothplate morphologies are very similar to those of Arganodos from the Upper Triassic of the Atlas Mountains, Morocco. A small distinctive metoposaurid amphibian has been recovered from the upper member, along with asphenodontid and distinctive isolated teeth of dinosaurs and numerous other carnivorous archosauromorphs.

Petrified Forest National Park, Research Abstract Volume 1, 1991.




SUMMARY OF PALEONTOLOGICAL RESEARCH IN PETRIFIED FOREST NP

J. Michael Parrish
Northern Illinois University
DeKalb, IL 60115

My most recent research in Petrified Forest has involved characterizing the important fossil localities in a variety of ways and relating their biological content and mode of preservation to the geological nature of the localities. In particular, the degree of the development as fossil soils and the positions of localities relative to ancient bodies of water, specifically fossil channels and ponds. This work has been accomplished in part with Russell Dubiel of the USGS and Steve Good of the University of Colorado. I have worked with J.T.Parrish, of the University of Arizona, on the arrangement of fossil logs in the Long Logs area as a method of determining the position of the channel and direction of flow during the deposition of the logs. I have also been interested in Chinle climates and a survey of the climates of the Triassic in Arizona has just been published.
I have also been working on a number of the large archosaurs from the park, specifically an articulated phytosaur skeleton that was collected south of Lacey Point, and a large crocodylomorph from the same area. More extended work on the classification of the archosaurs is utilizing material from the park and from the Chinle and Dockum formations in other areas of the southwest.

Petrified Forest National Park, Research Abstract Volume 1, 1991.




ENERGY DISPERSIVE X-RAY ANALYSIS OF PETRIFIED WOOD SAMPLES
FROM PETRIFIED FOREST NATIONAL PARK, ARIZONA

Vincent L. Santucci
Petrified Forest National Park
Petrified Forest, AZ 86028

Petrified Forest National Park preserves outstanding exposures of fossilized wood from the Triassic. To date, three genera of trees have been recognized from the park (Araucarioxylon, Schilderia, and Woodworthia). The different morphologic and histologic characters have been identified for each genus. These characters can influence the preservational and taphonomic history of the wood. A series of very fundamental questions related to the actual fossilization of the wood are not fully understood. Some of these questions include:
(1) how does the mineral composition of each type of fossil
wood vary both in content and percent composition?
(2) do the variances reflect different processes of fossil-
ization in each type of fossil wood?
(3) how does the mineral composition in each fossil wood vary
with respect to internal morphology of the plant and the
depositional setting in which preserved?
A pilot study was initiated in order to gain some understanding of the elemental and mineral composition of each type of fossil wood and the percentage composition of each component. Energy Dispersal X-Ray (EDX) analysis was performed on each of the three genera of fossil wood found in the park. The technique involved the utilization of a small piece (2-3" hand sample) of fossil wood. In this procedure a non-destructive electron beam is emitted onto each sample. Secondary electrons are released by the sample and recorded by both X-ray and EDX detectors. A multi-channel analyzer determines both the elemental content and percent composition of each element.
Analyses revealed that all samples were primarily rich in oxygen (O) and silicon (Si), suggesting silicates. Smaller amounts of iron (Fe), aluminum (Al), calcium (Ca) and potassium (K). Woodworthia specimens were the only genus to contain manganese (Mn). A significantly higher percent composition of aluminum and calcium were measured in Schilderia. Sulfer and titanium occurred in both Woodworthia and Schilderia, but was absent in Araucarioxylon.




STRATIGRAPHIC CORRELATION OF THE MIO-PLIOCENE BIDAHOCHI FORMATION
IN PETRIFIED FOREST NATIONAL PARK AND LOCALITIES IN NE ARIZONA

Vincent L. Santucci
Petrified Forest National Park
Petrified Forest, AZ 86028
Michael Whitelaw
University of Texas, El Paso
El Paso, TX 79968

The Upper Tertiary Bidahochi Formation is well exposed in northeastern Arizona and western New Mexico. Extensive outcrops of this fossiliferous formation can be found both at Petrified Forest National Park and on the Navajo Reservation. Within the Bidahochi is an important Late Miocene and Early Pliocene fossil mammal zone. This mammalian fauna is referred to as the "White Cone" fauna and represents the earliest Late Hemphillian fossil remains known.
The type locality for the Bidahochi Formation and the fossil producing localities will be paleomagnetically sampled in order to facilitate local correlation. The establishment of a paleomagnetic polarity profile for the Bidahochi formation will additionally permit correlation to the world wide polarity time scale.




SOURCE STUDY BY NEUTRON ACTIVATION ANALYSIS OF PETRIFIED WOODS
FROM THE PETRIFIED FOREST NATIONAL PARK, ARIZONA

Phil C. Weigand
Museum of Northern Arizona
Flagstaff, AZ 86001

The purpose of this study is twofold: 1) to characterize the trace element composition(s) of petrified wood from different localities within the forests in order to supply the geological community with the full range of chemical compositional and trace elements from those that are now available. In this sense, the study is a major amplification of Sigleo's trace element study; 2) to try to establish "provenience postulate(s)" for various outcrops of petrified woods. Briefly, provenience postulates are the unique trace element structures, or fingerprints, that compounds show in their chemistry that mark their source areas to the exclusion of all others. We do not yet know whether provenience postulates can be established for petrified woods. That will be the goal of the first stage of this study

Petrified Forest National Park, Research Abstract Volume 1, 1991.


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