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Jack A. Wolfe

Publications and source records attributed to Jack A. Wolfe.

17 recordsLinked to original sources
USGS2016

Alaskan Cretaceous-Tertiary floras and Arctic origins

Cretaceous floras in Alaska, when compared to those at mid-latitudes, generally indicate later appearances in Alaska of major clades and major leaf morphologies. Compared to mid-latitude floras , Alaskan Late Cretaceous floras contain few major clades. The Alaskan clades diversified but at a low taxonomic level. Migrational pathways into high latitudes were probably along streams. Similar patterns characterized the Alaskan Tertiary , although some southward migrations of lineages occurred during the Neogene. Review of other Arctic paleontological data from Ellesmere Island, previously used to suggest that the Arctic was a major center of origin during the Late Cretaceous , indicates that the ages of supposedly substantiating dinoflagellate floras were misinterpreted. When the dinoflagellate data are interpreted according to standard methodology, first occurrences of genera and species groups on Ellesmere are, like the Alaskan occurrences, later than first occurrences at middle latitudes.

Paleobiology↗
USGS1988

Rosaceous Chamaebatiaria-like foliage from the Paleogene of western North America

Chamaebatiaria and Chamaebatia, two characteristic genera of the Californian floristic province, are traditionally placed in different subfamilies of Rosaceae, Spiraeoideae and Rosoideae, respectively. Analysis of the foliar and reproductive characters of the extant species of these genera indicates that the two genera could be closely related and the assignment of Chamaebatia to Rosoideae invalid. Fossil leaves of lineages of both genera occur in the Paleogene montane floras of the Rocky Mountain region and provide evidence that the two lineages diverged from a common ancestor in the Eocene. The common ancestor probably was adapted to sunny habitats in mesic coniferous forest, and, during the post-Eocene, the two lineages were able to adapt to progressively drier climates. A third extant genus, the east Asian Sorbaria, also appears to be closely related to the California genera and to have been derived from the same common ancestor. New taxa and combinations proposed are: St onebergia columbiana. n. gen. and n. sp.; Salmonensea prefoliolosa (R. W. Br.), n. gen. and n. comb.; Stockeya creedensis (R. W. Br.), n. gen. and n. comb.; Stockeya montana, n. sp.; and Sorbaria wahrhaftigii, n. sp.

Aliso↗
USGS1973

Fossil forms of Amentiferae

Review of the procedures used in determining fossil plant organs indicates that the many Cretaceous records of extant genera of “Amentiferae” based on leaves should be rejected as theoretically unreliable. Palynological data, in combination with some valid megafossil data, indicate that most recognizable members of “Amentiferae” are no older than the later part of the Late Cretaceous. Juglandales appear to be derivatives of the ancient Normapolles complex and unrelated to other “Amentiferae.” A preliminary account of some of the comparative foliar morphology of extant “Amentiferae” indicates that some—particularly Betulaceae and Fagaceae—are closely related to Hamamelidales but that other families—notably Rhoipteleaceae, Juglandaceae, Didymelaceae, and Leitneriaceae—are unrelated to this order.

Brittonia↗
USGS1969

Cretaceous, Tertiary, and early Pleistocene rocks from the continental margin in the Bering Sea

Rocks dredged from the continental margin in eastern Bering Sea in and near the Pribilof Canyon indicate that the acoustic basement represents the upper surface of thoroughly lithified turbidite beds of graywacke and siltstone of Late Cretaceous age. The stratified sequence covering the acoustic basement is gently deformed and includes marine clastic and diatomaceous sediments ranging in age from middle or late Miocene through early Pleistocene. Dense argillite, siltstone, and calcareous sandstone of early Tertiary age in and near the Zhemchug Canyon probably represent an older part of this sequence. The main layered sequence accumulated above the acoustic basement in shallow water, and, because the older beds now lie as much as 1000 m below sea level, the continental margin must have undergone considerable subsidence during late Tertiary and Quaternary time. A rich pollen flora indicates that the shoreline lay only a few tens of kilometers away from the site of the Pribilof Canyon during late Miocene time.

Alaska↗
USGS1969

Paleogene floras from the Gulf of Alaska

Numerous collections of fossil plants from the Gulf of Alaska region were obtained from rocks that are well dated by marine mollusks. The mollusks indicate that the oldest possible age for the lowest plant assemblage is middle Eocene (Domengine) and that the youngest possible age for the highest Paleogene plant assemblage is middle Oligocene (Lincoln). Paleobotanical correlations indicate that the lowest plant assemblage is of early late Eocene (early Ravenian) age and the highest plant assemblage is of early Oligocene (Kummerian) age. A new provincial stage--the Angoonian--is proposed, based on assemblages from rocks in southeastern Alaska. The Angoonian is thought to be of late Oligocene (early Blakeley) age. Only one stratigraphically isolated assemblage from the Gulf of Alaska region has been recognized as of Angoonian age. The biostratigraphy of the Gulf of Alaska region and of other regions in Alaska indicates that the Seldovian, Homerian, and Clamgulchian Stages are probably entirely of Neogene age. The early Ravenian assemblages represent Paratropical Rain forest (that is, similar to vegetation of a narrow region bordering the Tropical Rain forest) based on the physiognomic analysis of foliage; the most diverse families represented are Menispermaceae and Icacinaceae. These are accompanied by palms, Anonaceae, tjristicaceae, Dipterocarpaceae, Barringtoniaceae, and Myrtaceae. A minor element is represented by broad-leaved deciduous plants. The middle Ravenian was somewhat cooler, as indicated by foliar physiognomy, the fewer Tropical Rain forest elements, and the diversity of Lauraceae. The late Ravenian assemblage represents a broad-leaved deciduous forest indicating a temperate climate. The Kummerian assemblages were again dominated by Lauraceae, and the physiognomic characters of the foliage indicate that Subtropical forest was again represented. The existence of a broad-leaved evergreen forest in Alaska such as that of the early Ravenian indicates that extended periods of darkness could probably not have existed at that time. The Alaskan Paleogene floras, as well as those from other regions, indicate that the earth's axis of rotation may not have had as great an inclination in the past. Strong climatic fluctuations evidenced by foliar physiognomy of Tertiary floras is thought to have been the result of changes in the inclination of the earth's axis. The history of the development of the Arcto-Tertiary concept is reviewed, and the fundamental lack of evidence for this concept is shown. An alternative, more complex, concept is proposed for the development of the Mixed Mesophytic forest. Paleobotanical evidence indicates that tolerances of many genera have changed during the Tertiary. Many Mixed Mesophytic genera--particularly those that are today temperate outliers of basically tropical groups--may have had a wide distribution in the Paleogene Paratropical Rain and Subtropical forests and have entered the warm temperate forests only during the later Paleogene or Neogene. Some Mixed Mesophytic groups appear to be of later Neogene origin and have been significant members of the warm temperate forests since that time. Some Mixed Mesophytic genera apparently were members of the Paratropical Rain forest only in the earliest Paleogene and became adapted to warm temperate climates by the late Eocene or perhaps even earlier. The Mixed Mesophytic forest may have developed independently in Eurasia, western North America, and eastern North America.

Alaska↗
USGS1964

Miocene floras from Fingerrock Wash, southwestern Nevada

Two floras of Miocene age, the Fingerrock and Stewart Spring, are found in a stratigraphic section that also contains fossil mammals. The Fingerrock flora occurs in beds below the Stewart Spring local fauna of transitional Hemingfordian-Barstovian (middle-late Miocene) age, and the Stewart Spring flora occurs above that fauna but below the Cedar Mountain local fauna of Cerrotejonian (earliest Pliocene) age. The late Hemingfordian Fingerrock flora was dominated by the live oak, Quercus chrysolepis, but most of the flora is composed of species found in contemporaneous floras of the Columbia Plateau. These species include lobed Quercus, Carya, Ulmus, Zelkova, Platamis, and Acer. The lack here of certain other species found in this association to the north indicates that the Fingerrock flora lived in a drier climate than prevailed at the same time on the Columbia Plateau. Nevertheless the Fingerrock flora was a warm-temperate mesophytic flora. Twenty-four species are described from the Fingerrock flora, none of which are new. The early, or more probably middle, Barstovian Stewart Spring flora is, besides the expected lacustrine element, dominated by Quercus chrysolepis, Picea breweriana, and Chamaecyparis nootkatensis. This assemblage is typically found only in western Nevada and is further restricted to floras of Barstovian and Clarendonian age. Most of the species in the Stewart Spring flora appear to be descended from northern mesophytic forms, although the flora has a subhumid aspect different from the northern floras. Only a small element in the Stewart Spring flora may contain species of southern origin. Several phylads in the Stewart Spring flora are now found on the margins of and in the Great Basin. The Stewart Spring flora contains 42 described species, 9 of which are new.

Nevada↗