Alfred Traverse

New evidence for land plants from the lower Middle Ordovician of Saudi Arabia

Macerations of Middle Ordovician (Llanvirnian) shales from Saudi Arabia yield an assemblage of spores of probable land plants (cryptospores), acritarchs, and chitinozoa. The production of sporopollenin-containing, sporelike tetrads is considered a fundamental character of the embryophytes, because no extant algae produce spores of this type. No trilete spores were found at this horizon, reinforcing previous assertions that obligate meiotic tetrads predate the earliest trilete spores. Sporomorph tetrads and dyads, in conjunction with cuticlelike fragments, were probably derived from terrestrial plants at a bryophyte grade. Although there are reports of possibly older cryptospores, the Hanadir assemblage described herein clearly establishes their presence by Llanvirnian time.

Plant microfossils from Llandoverian and Wenlockian rocks of Pennsylvania

Abstract Macerations of greenish shales from the Tuscarora Formation (Llandoverian) and Clinton? strata (Wenlockian) in central and eastern Pennsylvania yield a remarkable assemblage of spores and probable spores, dyads, spore tetrads, tubular and cuticle‐like structures. These are considered as remains of a pre‐vascular plant, terrestrial flora and are discussed according to this interpretation. Although this study is preliminary in nature, we have described the following new taxa: Rugosphaera tuscarorensis (n.gen., n.sp.), Tetrahedraletes medinensis (n.gen., n.sp.), Nodospora burnhamensis (n.gen., n.sp.), Nodospora rugosa (n.sp.), Nodospora oyleri (n.sp.), Dyadospora murusattenuata (n.gen., n.sp.) and Dyadospora murusdensa (n.sp.).

Palynological contributions to the chronology and stratigraphy of the Hartford basin in Connecticut and Massachusetts

Abstract Recent discoveries of palynoflorules at numerous localities in the Newark Group basins of the eastern United States provide new evidence for correlation of deposits in these basins. Floras from the Shuttle Meadow and Portland Formations of the Newark Group rocks in the Hartford Basin of Connecticut and Massachusetts indicate that the Triassic‐Jurassic boundary is located within the rocks of this basin: a shift of Corollina from more than 90% C. meyeriana to more than 90% C. torosus occurs somewhere between the Shuttle Meadow and Portland Formations and generally indicates a Rhaeto‐Liassic age. In the Shuttle Meadow Formation, the overall shape of the palynoflora (particularly the presence of Convolutispora klukiforma), associated fish, paleomagnetic data, and radiometric dates, as well as megafossil evidence of Brachyphyllum scotii and Clathropteris menis‐coides, support a basal Liassic age for this formation. Reptilean evidence in older strata of the Hartford Basin suggests that the Triassic‐Jur...

Preliminary palynological zonation of the Chinle Formation, southwestern U.S.A., and its correlation to the Newark Supergroup (eastern U.S.A.)

Abstract 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, Arizona and New Mexico); the youngest zone (zone III) is in the upper Petrified Forest Member and silstone member in Arizona and Utah and the silstone member in northcentral New Mexico. Present palynological evidence suggests that Chinle deposition on the Colorado Plateau began locally in late Carnian time and continued at least into the early part of Norian time of the Late Triassic period. Because the upper boundary of the Chinle Formation is an unconformity and the overlying formations are palynologically barren, the length of time represented by this stratigraphic hiatus is not known with certainty. Current palynological evidence suggests, however, that the unconformity at the top of the Chinle cannot be older than early Norian nor younger than Hettangian. Zones I, II and III can now be recognized in the palynomorph assemblage sequences from the Eastern Mesozoic basins, which modifies earlier palynological zonations for the lower portions of the Newark Supergroup. This is based on our identification of palynomorphs not previously known from portions of the Newark Supergroup and the discovery that specific biomarker taxa combinations are the same for both the western and eastern palynomorph sequences. At present palynomorph assemblages from the Chinle Formation and Newark Supergroup compare more closely for zones II and III than they do for zone I, but research is still in progress.

Human-environment interactions in a tropical watershed : The paleoecology of Laguna Tamarindito, El Petén, Guatemala

AbstractQuestions of past human-environment interactions are best addressed by a research agenda that recovers complementary archaeological and paleoenvironmental data. We have used such an approach in our investigations at Laguna Tamarindito, a small lake located in the SW part of the Peten rainforest of Guatemala. In 1991, a sediment core was taken from the lake as part of a larger program of research examining the history of human-environment interactions in the Petexbatun region. We employ a conjunctive analytic approach to interpret the core, including archaeological survey of the lakes watershed, physical and chemical analysis of sediments, palynology, and molluscan ecology. Our analysis of this core reveals substantial paleoecological information about the past 10,000 years in this region. Study of the lake sediments, pollen, and gastropod populations indicates variation in regional climate, including two periods of significant drying. Changes in the rate of sediment at ion in the lake can be rela...

Occurrence of the oil-forming alga Botryococcus in lignites and other Tertiary sediments

Certain Paleozoic oil-bearing rocks-boghead coals or torbanites, and others-derive their oil con- tent from the hydrocarbon-producing alga Botryococcus. The same genus produces fatty sediments in modern brackish and fresh-water lakes. It has seemed likely that the organism was important in the Cenozoic also. The appearance is noted here of a number of recently reported Tertiary records of Botryococcus in India and Australia, and the first American Tertiary record, in the organic silt overlying the Brandon lignite, Vermont, is described. Botryococcus microfossils from the Warlands Creek locality, Australia, are very closely comparable

Plant evolution dances to a different beat

Land plants have origination rates comparable to those of some animal groups, but the driving forces for evolution of plants differ. Floral transformations have been due to gradual replacement and piecemeal, not mass extinction. Plant “geoevents”; have not been synchronous with epochal animal originations/ extinctions and hence may not be attributable to the same causes. Initiation of new plant forms probably results primarily from intrinsic genetic factors. Plant taxa are much less subject to extrinsic factors than are comparable animal groups. Plants evolve related forms adapted to very different environments; hybridity and polyploidy produce variants with different qualities in some organs. Mosaic evolution is thus characteristic of plants. Heterochrony has probably permitted rapid shifts in timing of ontogeny to produce new life‐forms. Vegetative reproduction and persistence, indeterminate growth, potential long dormancy of propagules, comparative freedom from demands of population size, and comparati...

Fossil spores, pollen, and fishes from connecticut indicate early jurassic age for part of the newark group.

Palynologically productive localities have been found in the United States throughout the Newark Group basins, most of which had previously been assumed to be barren. Rich palynoflorules dominated by coniferous pollen of Circulina-Classopollis type, and well-preserved fossil fishes, including possible new semionotids, have been found in the Hartford basin. Palynological data indicate that the Newark Group has considerable time-stratigraphic range: Upper Triassic for the Cumnock Formation (North Carolina), the Vinita Beds (Virginia), and the upper New Oxford Formation (Pennsylvania), Rhaeto-Liassic for the Brunswick Formation (New Jersey), Portland Formation (Connecticut and Massachusetts), and the Shuttle Meadow Formation (Connecticut).

Palynology and age of the upper Blomidon Formation, Fundy basin, Nova Scotia

The detailed palynostratigraphy established for basins of the Newark Supergroup south of the Canadian border has proven inapplicable to the oxidized, palynologically barren outcrops typical of the Fundy basin of the Maritime Provinces. Dating of the Fundy stratigraphic section has thus been based on lithostratigraphic correlations, radiometric dates, and rare palynomorphs. Palynofloral assemblages recently recovered from an outcrop of the uppermost Blomidon Formation in the Nova Scotia arm of the Fundy basin permit the first correlations with Triassic/Jurassic boundary palynofloras throughout the Newark Supergroup. The well-preserved palynofloras are all dominated by the genus Corollina, but examination of the less common elements indicates that only those assemblages at the top of the Blomidon Formation, immediately below the North Mountain Basalt, are of Early Jurassic age. These palynofloras contain species that are also present in earliest Jurassic assemblages from the Hartford basin. Palynomorph assemblages 30 cm downsection from the basalt contain rare specimens of the Late Triassic index species Patinasporites densus and an array of monosulcate grains correlative with late Rhaetian assemblages from the Newark basin. Three new monosulcate species (Cycadopites ginker, C. tattoo, and C. schlischii) are described herein.

Response of world vegetation to Neogene tectonic and climatic events

The last 10 × 106 years, called here the ‘Ultimogene’, approximately the last half of the Neogene, is palynologically significant, because a level of near 100 per cent of extant genera pertains. This means that the methods of Flandrian (‘post-glacial’) pollen-analysis can be applied. This time-segment also makes sense palaeoclimatologically and palaeogeographically. Within the ‘Ultimogene’, repeated sudden changes in climate, as well as a general slide toward colder temperatures, cause corresponding changes in vegetation and palynofloras. Orogeny is responsible for some of the changes, for example in the Andes. Continental drift is a relatively minor factor, but has considerably affected plant distribution in India and Australia. ‘Ultimogene’ modernization of floras in response to all factors permits practical stratigraphy based on spores/pollen in western Eurasia, but this is difficult in North America because of plant migration pathways. Though there are exceptions, for the most part colder means drier ...