Sidney Ash

• PhD, Reading University, UK
• Professor (Associate) at University of New Mexico

Exploring features of wood anatomy associated with fire scars found on fossil tree trunks is likely to increase our knowledge of the environmental and ecological processes that occurred in ancient forests and of the role of fire as an evolutionary force. In Petrified Forest National Park, Arizona, where Late Triassic fossil trees are exposed, we fo...

The Triassic was a time of diversification of the global floras following the mass-extinction event at the close of the Permian, with floras of low-diversity and somewhat uniform aspect in the Early Triassic developing into complex vegetation by the Late Triassic. The Earth experienced generally hothouse conditions with low equator-to-pole temperat...

The occurrence of permineralized stem fragments with diagnostic equisetophyte anatomy in Petrified Forest National Park, east-central Arizona provides an opportunity to characterize the internal structure of a Late Triassic (Norian Stage) equisetophyte. Features of Equisetocaulis muirii gen. et sp. nov. constitute the first evidence for internal an...

In this article, the remains of a nearly complete specimen of the enigmatic Sanmiguelia Brown plant (narrow stem and attached palm-like leaves) are described from the Early Jurassic (Hettangian) in the uppermost part of the Whitmore Point Member of the Moenave Formation in southwestern Utah. Previously, the fossil was only known from Upper Triassic...

Fire scars are well known to fire ecologists and dendrochronologists worldwide, and are used in dating fires and reconstructing the fire histories of modern forests. Evidence of fires in ancient forests, such as fossil charcoal (fusain), is well known to paleontologists and has been reported in geologic formations dating back to the Late Devonian....

This article summarises an investigation of three selected species of fossil gymnosperms collected from the Upper Triassic Chinle Formation of the American southwest. Included here is an emended diagnosis of Lindleycladus arizonicus (Daugherty) comb. nov., a description of Elatocladus puercoensis sp. nov., and a redescription, based on new material...

High-precision geochronology provides unprecedented insights into the depositional history of the Upper Triassic Chinle Formation of the Colorado Plateau, as well as its paleoenvironmental and paleobiological records. The Chinle succession exposed in the Petrified Forest National Park (PEFO) and vicinity, Arizona, includes two large-scale alluvial...

Fragments of the rare and distinctive palm-like leaves of the controversial Late Triassic plant Sanmiguelia have been discovered recently in both Petrified Forest National Park, Arizona and Arches National Park, Utah. Although, the new specimens do not clarify the classification of this intriguing fossil, they do confirm that it occurs in all membe...

The small Late Triassic flora described here from a new locality in Palo Duro Canyon, west Texas, USA is noteworthy because it includes specimens of a new species of the Gondwanan winged seed Fraxinopsis, F. patharrisiae sp. nov. This is only the second time that Fraxinopsis has been found in Laurasia and thus adds support to the theory that at lea...

The hybodont shark egg capsule Palaeoxyris humblei n. sp. is described here from four specimens collected from flood plain deposits in the Blue Mesa Member of the Chinle Formation of Late Triassic (Norian) age in Petrified Forest National Park, Arizona. This find is the first unequivocal record of Palaeoxyris in the Mesozoic of North America. The s...

The remains of more than 15 specimens of the oldest known fossil lianous dicotyledonous stems have been discovered embedded in the false trunks of four species of the tree fern Tempskya Corda in mainly early Late Cretaceous (Cenomanian) strata in Utah and New Mexico. These dicotyledonous stems are assigned to Munzingoxylon delevoryasii gen. et sp....

Ginkgoaleans of Late Triassic age are uncommon in North America and are known from only three widely separated parts of the continent. The productive areas are situated along the mid-Atlantic seaboard, in the Arctic Archipelago of Canada, and in the southwestern United States and adjacent parts of northwestern Mexico. Fossils that have been attribu...

The distinctive flora described in this article occurs in the Shinarump Member of the Chinle Formation of Late Triassic age and is particularly noteworthy because it offers insight into the recovery of the land flora in western North America after the end-Permian life crisis. Most of the fossils in this so-called basal flora are preserved as impres...

Williamsonia nizhonia sp. nov., the first undoubted bennettitalean flower known from the Chinle Formation of Upper Triassic age in the south - western United States, is described in detail. The species is based on a single vertically compressed specimen collected from the Lower Red Member of the Chinle Formation near Fort Wingate in west-central Ne...

Palaeoxyris BRONGNIART, 1828 has been diagnosed as an egg capsule of chondrichthyan fish by most workers on the basis of its similarities in spiral morphology and size distribution to recent egg capsules, their co-occurrence with skeletal remains of sharks in the same bedding plane, and their lack of plant cuticles. Although Palaeoxyris is generall...

IntroductionNature of the evidenceHerbivory in arthropodsHerbivory in dinosaursHerbivory in mammals

Leaves from the Upper Triassic Chinle Formation in the southwestern United States show evi dence of having provided nourishment and shelter for several different types of arthropods. This evidence consists of three or four morphotypes of feeding traces and a well-defined type of gall. The feeding traces occur on the pinnules of the filicalean fern...

A seed-bearing pinnate leaf found in the Chinle Formation of Late Triassic age in Arizona appears to be an archaic seed fern that more closely resembles typical Carboniferous–Permian seed fern leaves than any younger form. The fossil, which is described here as Chilbinia lichii gen. et sp. nov., incorporates characters of several Palaeozoic taxa. T...

conifers from the Chinle impression/compression flora. In addition to providing additional evidence for Chinle co-nifer diversity, this find has potential implications for the interpretation and affinities of the famous Araucarioxy-lon arizonicum Knowlton (in Fontaine and Knowlton, 1890), tree trunks preserved in such abundance in Petri-fied Forest...

The recovery of the Triassic land flora after the end-Permian biotic crisis has not been studied in detail except in North China where examination of a complete sequence of Permian–Triassic strata containing fossil plants revealed that the recovery lasted until the end of the Middle Triassic. Our analysis of the Triassic floras of Europe shows that...

Two fossil tree species, both with unusual characteristics, occur in the Upper Triassic of the Petrified Forest National Park, Arizona, USA and adjacent areas. The first, Schilderia adamanica, has a highly idiosyncratic secondary xylem structure which contains normal uniseriate and broad complex multiseriate ‘herring-bone’ rays. The trunk cross-sec...

This paper contains a description of the only known non-banded bark in the geologic record. The bark is attached to a branch of the Araucarioxylon arizonicum tree that was found recently in the Late Triassic Chinle Formation (∼220 Mya) in Arizona. In the fossil the vascular cylinder is almost totally enclosed in rough bark 2-11 mm in thickness. The...

Examination and measurement of many of the trunks attributed to Araucarioxylon arizonicum Knowlton eroded from the Late Triassic Chinle Formation in the Petrified Forest National Park, Arizona demonstrate that the living tree did not closely resemble any of the present-day Araucaria trees of the southern hemisphere as postulated in past reconstruct...

Originally, Charliea Mamay was considered to be a pinnately compound leaf having linear–oblong ultimate segments with apices divided into two to four, nearly equal truncated lobes when it was described from the Upper Pennsylvanian of New Mexico. However, evaluation of the type material and newly collected specimens of the generitype as well as othe...

Fossil charcoal has been found in the Late Triassic Chinle Formation in Petrified Forest National Park, a location that is world famous for its silicified tree trunks. The material consists of charcoalified secondary wood, and has sufficiently well preserved plant anatomy to show it may be described as ‘araucarian type’, although it does display so...

Small coprolite-bearing borings occur in the stem of the filicalean tree fern Itopsidema vancleaveii Daugherty from the Chinle Formation of Late Triassic Age (Carnian Stage) in Petrified Forest National Park, Arizona. These borings are restricted to parenchyma within the leaf petioles and among the adventitious roots of the root mantle. Although th...

Small coprolite-bearing borings occur in the stem of the filicalean tree fern Itopsidema vancleaveii Daugherty from the Chinle Formation of Late Triassic Age (Carnian Stage) in Petrified Forest National Park, Arizona. These borings are restricted to parenchyma within the leaf petioles and among the adventitious roots of the root mantle. Although th...

Detailed study of the cone Lycostrobus chinleana Daugherty shows that the fossil was incorrectly attributed to the Lycopodiales by the author and to the quillworts by Retallack and that it actually should be assigned to the Equisetales. The cone, which occurs in the Upper Triassic Chinle Formation at several localities in the southwestern United St...

A flora consisting chiefly of the remains of plants that probably inhabited an upland region occurs in strata that correlate with the Upper Triassic Chinle Formation and has been assigned to the Upper Triassic Carita Creek Formation in north-central New Mexico. This flora includes mostly the remains of a variety of coniferous plant megafossils incl...

Discovery of new material attributable to Sphenopteris arizonica Daugherty permits a more complete reevaluation of one of the rarest fossil leaves found in the Upper Triassic Chinle Formation in the southwestern United States. This fossil is particularly interesting because it is apparently one of the few surviving Paleozoic floral elements found i...

Every fall since 1950, the New Mexico Geological Society (NMGS) has held an annual Fall Field Conference that explores some region of New Mexico (or surrounding states). Always well attended, these conferences provide a guidebook to participants. Besides detailed road logs, the guidebooks contain many well written, edited, and peer-reviewed geoscie...

Two new species of the enigmatic gymnosperm microsporophyll Pramelreuthia, found in the Upper Triassic Chinle Formation at five localities in the southwestern United States, provide significant new evidence on key morphological characters of the genus and extend its known geographical range. These new fossils also demonstrate that the genus was pol...

Two new species of the enigmatic gymnosperm microsporophyll Pramelreuthia, found in the Upper Triassic Chinle Formation at five localities in the southwestern United States, provide significant new evidence on key morphological characters of the genus and extend its known geographical range. These new fossils also demonstrate that the genus was pol...

Charles Brian Read (1907-1979), paleobotanist and geologist, spent his entire 42-year career with the U.S. Geological Survey. His mentor was the noted geologist and paleobotanist David White, who introduced Read to late Paleozoic floras. In the 1930s, Read became interested in the floral zonation of the Pennsylvanian; this study was to culminate in...

The distinctive filiform leaf Czekanowskia has recently been recognized for the first time in the United States in the Late Jurassic Morrison Formation of the Colorado Plateau Region. In this region, the taxon is represented at two localities by the new species C. turneri sp. nov., and at two other localities by fragments which cannot be identified...

Palynoflorules containing sparse but regularly occurring chitinous-walled fungal, probably ascomycete, spores have been obtained from silty limestone nodules in the Jurassic Coon Hollow Formation in the Wallowa Terrane in Hells Canyon, Idaho. The fungal spores are associated with moderately abundant embryophytic spores and pollen that suggest late...

After becoming nearly extinct during the Permian, the ferns began a slow recovery during the Triassic as the climate of the earth moderated. As a result, a considerable number and variety were present and widely distributed during the Jurassic and Early Cretaceous. However, with the rapid expansion of the angiosperms during the Late Cretaceous, the...

Paleontological evidence from the Upper Triassic Chatham Group in the three subbasins of the Deep River basin (North Carolina, USA) supports a significant revision of the ages assigned to most of this non-marine continental sedimentary sequence. This study confirms an early(?) or mid-Carnian age in the Sanford subbasin for the base of the Pekin For...

In the green sandstone and mudstone facies of the Monitor Butte Member of the Upper Triassic Chinle Formation, steeply dipping (30° to 9{)0) to vertical, overturned, and contorted bedding is a common feature previously recognized throughout the Colorado Plateau by many workers (Green, 1956; Stewart et al., 1972; Byers, 1980; Blakey and Gubitosa, 19...

Typically, the fossil woods in the Upper Triassic Chinle Formation in Petrified Forest National Park, Arizona, USA do not show annual growth rings but contain irregular growth interruptions similar to those found in trees now growing in the humid tropics. These interruptions could be due to endogenous hormonal effects or to occasional local variati...

Middle Jurassic strata atop the Wallowa terrane in northeastern Oregon link the Wallowa, Izee, and Olds Ferry terranes as related elements of a single long-lived and complex oceanic feature, the Blue Mountains island arc. Middle Jurassic strata in the Wallowa terrane include a dacitic ash-flow deposit and contain fossil corals and bivalves of North...

A new species of the quillwort Isoetites, L rolandii sp. nov. Ash and Pigg, is described from the Middle Jurassic Coon Hollow Formation in the Wallowa terrane in Hells Canyon, Oregon and Idaho. The new species is based on coalified impressions and mold-casts of an isoetaceous corm with narrow, elongate leaves, and isolated masses of leaves that hav...

A new species of the quillwort Isoetites, I. rolandii sp. nov. Ash and Pigg, is described from the Middle Jurassic Coon Hollow Formation in the Wallowa terrane in Hells Canyon, Oregon and Idaho. The new species is based on coalified impressions and mold-casts of an isoetaceous corm with narrow, elongate leaves, and isolated masses of leaves that ha...

Three informal palynological assemblage zones can be distinguished in samples from Chinle Formation outcrops in Utah, Arizona and New Mexico. The oldest zone (zone I) is in the Temple Mountain Member in southeastern Utah; the middle zone (zone II) is in the Shinarump, Moss Back, Monitor Butte and (lower part of the) Petrified Forest Members (Utah,...

A recently discovered Upper Triassic leaf shows many of the characters of the leaves of the living cycads and is assigned to the Cycadales. The leaf, however, does not match any previously described fossil or living cycad leaf in all features and is assigned to a new genus and species, Aricycas paulae. The leaf bears oppositely arranged linear-lanc...

A new species of the fern Phlebopteris, P. tracyi n. sp., is described from the Jurassic Coon Hollow formation in the Wallowa Terrane in the Snake River Canyon, Oregon and Idaho. The leaf is as large or larger than all specimens of previously described species of Phlebopteris. The pinnae of the new species are divided into many widely spaced, narro...

Detrital amber pebbles and granules have been discovered in Upper Triassic strata on the Colorado Plateau. Although amber pre-viously has been reported from Pennsylvanian, Jurassic, Cretaceous, and Tertiary strata, we know of no other reported Triassic occurrence in North America or the Western Hemisphere. The newly discovered occurrences of amber...

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Certain Upper Triassic tree trunks in the southwestern U.S.A. show evidence of damage similar to that caused in tree trunks at the present day by pocket rot fungi such as Polyporus amarus Hedgc. and Heterobasidion annosum (Fries) Bref. The damaged trunks occur in a relatively thin stratum at the same horizon over a wide area in the Petrified Forest...

Stems bearing the leaf Pelourdea poleoensis (Daugherty) Arnold have recently been collected from a new locality in the upper part of the Chinle Formation, Upper Triassic of Utah, U.S.A. The fossils show that the Pelourdea poleoensis plant was short, had a narrow stem with little wood and that the leaves had a broad clasping base. This last feature...

A nearly complete juvenile fernlike plant is described from Lower Permian rocks of New Mexico. It consists of a horizontal rhizome with roots, a short thick upright aerial branch, and a tuft of dimorphic leaves and is assigned to Arnoldia kuesii gen. et sp.n. and appears to be the first juvenile fernlike plant known from the Upper Paleozoic. Abunda...

Phlebopteris smithii (Daugherty) Arnold is a palmate fern leaf that appears to be monopodial, with an odd number (5 to 15) of spreading pinnatifid pinnae. The sori occur in a single row on either side of the pinnule midrib and presumably are not protected by indusia. Each sorus typically contains 14 to 20 sporangia which have oblique annulii. The s...

Skilliostrobus australis gen. et sp. nov. is a large, ovoid, pedunculate cone present in rocks of Early Triassic age in three areas in southeastern Australia and Tasmania. The cone is heterosporous and its unisporangiate sporophylls are wedge-shaped with long horizontal limbs. Microsporophylls occur above megasporophylls in the cone and the sporang...

Eoginkgoites is a fan-shaped, imparipinnate leaf with a short rachis and long petiole. It was first described from the Upper Triassic Newark Group of Pennsylvania by Bock who assigned the fossil to the Ginkgoales. The fossil has also been found in the Upper Triassic Chinle Formation in Utah and Arizona and in the Newark Group in North Carolina. Inv...

The fern Piazopteris branneri (White) Lorch and several other plant fossils are reported for the first time from rocks formerly thought to be of Triassic age near Ain Sukhana in the Gulf of Suez area of Egypt. Probably the florule is of Early Jurassic age.

A sequence of continental rocks overlies the Lower Triassic Thaynes Formation in a poorly exposed syncline near Currie in northeastern NV. The authors recognize four lithostratigraphic units above the Thaynes near Currie and provide new paleontologic data. In ascending order, unit 1 (120 ft) consists of reddish-brown, very fine grained sandstone. U...

A small, diverse flora occurs in the Lower Jurassic Dinosaur Canyon Member of the Moenave Forma-tion at the St. George Dinosaur Discovery Site at Johnson Farm locality in St. George, Utah. The flora consists of poorly preserved impressions that represent seven species of conifers, ferns and horsetails. The coniferous fossils are assigned to Araucar...

Thesis (M.S.)--University of New Mexico. Includes bibliographical references (leaves 61-66). Microfilm (positive and negative). Albuquerque : University of New Mexico Library, [197-?]. -- 1 reel ; 35 mm. Filmed with Edmonds, R.J. Geology of the Nutria monocline. Albuquerque, 1961. Emerson, J.W.A petrographic and environmental study of the Upper Cre...