scholarly journals A new fossil assemblage shows that large angiosperm trees grew in North America by the Turonian (Late Cretaceous)

2018 ◽  
Vol 4 (9) ◽  
pp. eaar8568 ◽  
Author(s):  
Nathan A. Jud ◽  
Michael D. D’Emic ◽  
Scott A. Williams ◽  
Josh C. Mathews ◽  
Katie M. Tremaine ◽  
...  
Keyword(s):  
North America ◽  
Mixed Forest ◽  
Forest Canopies ◽  
Sea Levels ◽  
Fossil Assemblage ◽  
Mancos Shale ◽  
Terrestrial Vertebrate ◽  
Ca 50 ◽  
Shale Formation ◽  
Fish Teeth

The diversification of flowering plants and marked turnover in vertebrate faunas during the mid-Cretaceous transformed terrestrial communities, but the transition is obscured by reduced terrestrial deposition attributable to high sea levels. We report a new fossil assemblage from multiple localities in the Upper Cretaceous Ferron Sandstone Member of the Mancos Shale Formation in Utah. The fossils date to the Turonian, a severely underrepresented interval in the terrestrial fossil record of North America. A large silicified log (maximum preserved diameter, 1.8 m; estimated height, ca. 50 m) is assigned to the genusParaphyllanthoxylon; it is the largest known pre-Campanian angiosperm and the earliest documented occurrence of an angiosperm tree more than 1.0 m in diameter. Foliage and palynomorphs of ferns, conifers, and angiosperms confirm the presence of mixed forest or woodland vegetation. Previously known terrestrial vertebrate remains from the Ferron Sandstone Member include fish teeth, two short dinosaur trackways, and a pterosaur; we report the first turtle and crocodilian remains and an ornithopod sacrum. Previous studies indicate that angiosperm trees were present by the Cenomanian, but this discovery demonstrates that angiosperm trees approaching 2 m in diameter were part of the forest canopies across southern North America by the Turonian (~92 million years ago), nearly 15 million years earlier than previously thought.

scholarly journals Endemicity analysis of global Cretaceous dinosaurian faunas

1992 ◽  
Vol 6 ◽  
pp. 132-132
Author(s):  
Thomas R. Holtz
Keyword(s):  
North America ◽  
South America ◽  
Late Cretaceous ◽  
Late Jurassic ◽  
Continental Drift ◽  
Gobi Desert ◽  
Western Interior Seaway ◽  
Faunal Assemblages ◽  
Terrestrial Vertebrate ◽  
Herbivore Communities

It has often been assumed that the intensively studied dinosaur faunal assemblages of western North America and the Gobi Desert of Mongolia and China represent “typical” Late Cretaceous terrestrial vertebrate communities. This assumption has led to a paleoecological scenario in which a global ecological shift occurs from the dominance of high-browsing saurischian (i.e., sauropod) to low-browsing ornithischian (i.e., iguanodontian, marginocephalian, ankylosaurian) herbivore communities. Furthermore, the assumption that the Asiamerican dinosaur faunas are communities “typical” of the Late Cretaceous has forced the conclusion that the sauropod-dominated Argentine population must have been an isolated relict ecosystem of primitive taxa (i.e., titanosaurid sauropods, abelisaurid ceratosaurs). Recent discoveries and reinterpretations of other Late Cretaceous assemblages, however, seriously challenge these assumptions.Paleogeography and paleobiogeography have demonstrated that terrestrial landmasses became progressively fractionated from the Late Jurassic (Kimmeridgian-Tithonian) to the Late Cretaceous (Campanian), owing to continental drift and the development of large epicontinental seas (the Western Interior Seaway, the Turgai Sea, etc.). The Maastrichtian regressions resulted in the reestablishment of land connection between long isolated regions (for example, western and eastern North America). These geographic changes are reflected in changes in the dinosaurian faunas. These assemblages were rather cosmopolitan in the Late Jurassic (Morrison, Tendaguru, and Upper Shaximiao Formations) but became more provincialized throughout the Cretaceous.Cluster analysis of presence/absence data for the theropod, sauropod, and ornithischian clades indicates that previous assumptions for Late Cretaceous dinosaurian paleoecology are largely in error. These analyses instead suggest that sauropod lineages remained a major faunal component in both Laurasia (Europe, Asia) and Gondwana (South America, Africa, India, and Australia). Only the pre-Maastrichtian Senonian deposits of North America were lacking sauropodomorphs. Furthermore, the abelisaurid/titanosaurid fauna of Argentina is, in fact, probably more typical of Late Cretaceous dinosaurian communities. Rather, it is the coelurosaurian/ornithischian communities of Asiamerica (and particularly North America) that are composed primarily of dinosaurs of small geographic distribution. Thus, the Judithian, Edmontonian, and Lancian faunas, rather than being typical of the Late Cretaceous, most likely represent an isolated island-continent terrestrial vertebrate population, perhaps analogous to the extremely isolated vertebrate communities of Tertiary South America. Furthermore, the shift from high-browsing to low-browsing herbivore “dynasties” more likely represents a local event in Senonian North America and does not represent a global paleoecological transformation of Late Cretaceous dinosaur community structure.

An Early Cretaceous (Berriasian) fossil-bearing locality from the Rocky Mountains of Alberta, yielding the oldest dinosaur skeletal remains from western Canada

2020 ◽  
Vol 57 (4) ◽  
pp. 542-552 ◽  
Author(s):  
Ramon S. Nagesan ◽  
James A. Campbell ◽  
Jason D. Pardo ◽  
Kendra I. Lennie ◽  
Matthew J. Vavrek ◽  
...  
Keyword(s):  
North America ◽  
Early Cretaceous ◽  
Depositional Environment ◽  
Upper Cretaceous ◽  
Upper Jurassic ◽  
High Energy ◽  
Western Canada ◽  
Western North America ◽  
Terrestrial Vertebrate ◽  
Overlying Strata

Western North America preserves iconic dinosaur faunas from the Upper Jurassic and Upper Cretaceous, but this record is interrupted by an approximately 20 Myr gap with essentially no terrestrial vertebrate fossil localities. This poorly sampled interval is nonetheless important because it is thought to include a possible mass extinction, the origin of orogenic controls on dinosaur spatial distribution, and the origin of important Upper Cretaceous dinosaur taxa. Therefore, dinosaur-bearing rocks from this interval are of particular interest to vertebrate palaeontologists. In this study, we report on one such locality from Highwood Pass, Alberta. This locality has yielded a multitaxic assemblage, with the most diagnostic material identified so far including ankylosaurian osteoderms and a turtle plastron element. The fossil horizon lies within the upper part of the Pocaterra Creek Member of the Cadomin Formation (Blairmore Group). The fossils are assigned as Berriasian (earliest Cretaceous) in age, based on previous palynomorph analyses of the Pocaterra Creek Member and underlying and overlying strata. The fossils lie within numerous cross-bedded sandstone beds separated by pebble lenses. These sediments are indicative of a relatively high-energy depositional environment, and the distribution of these fossils over multiple beds indicates that they accumulated over multiple events, possibly flash floods. The fossils exhibit a range of surface weathering, having intact to heavily weathered cortices. The presence of definitive dinosaur material from near the Jurassic–Cretaceous boundary of Alberta establishes the oldest record of dinosaur body fossils in western Canada and provides a unique opportunity to study the Early Cretaceous dinosaur faunas of western North America.

scholarly journals Olson's Extinction and the latitudinal biodiversity gradient of tetrapods in the Permian

2017 ◽  
Vol 284 (1852) ◽  
pp. 20170231 ◽  
Author(s):  
Neil Brocklehurst ◽  
Michael O. Day ◽  
Bruce S. Rubidge ◽  
Jörg Fröbisch
Keyword(s):  
North America ◽  
Mass Extinction ◽  
Fossil Record ◽  
Middle Permian ◽  
Lower Permian ◽  
Vertebrate Fauna ◽  
Terrestrial Vertebrate ◽  
Substantial Change

The terrestrial vertebrate fauna underwent a substantial change in composition between the lower and middle Permian. The lower Permian fauna was characterized by diverse and abundant amphibians and pelycosaurian-grade synapsids. During the middle Permian, a therapsid-dominated fauna, containing a diverse array of parareptiles and a considerably reduced richness of amphibians, replaced this. However, it is debated whether the transition is a genuine event, accompanied by a mass extinction, or whether it is merely an artefact of the shift in sampling from the palaeoequatorial latitudes to the palaeotemperate latitudes. Here we use an up-to-date biostratigraphy and incorporate recent discoveries to thoroughly review the Permian tetrapod fossil record. We suggest that the faunal transition represents a genuine event; the lower Permian temperate faunas are more similar to lower Permian equatorial faunas than middle Permian temperate faunas. The transition was not consistent across latitudes; the turnover occurred more rapidly in Russia, but was delayed in North America. The argument that the mass extinction is an artefact of a latitudinal biodiversity gradient and a shift in sampling localities is rejected: sampling correction demonstrates an inverse latitudinal biodiversity gradient was prevalent during the Permian, with peak diversity in the temperate latitudes.

Upper Ordovician graptolites from the top Lower Hartfell Shale Formation (D. clingani and P. linearis zones) near Moffat, southern Scotland

1982 ◽  
Vol 72 (4) ◽  
pp. 229-255 ◽  
Author(s):  
S. Henry Williams
Keyword(s):  
New Species ◽  
North America ◽  
Upper Ordovician ◽  
The North ◽  
Continuous Sequence ◽  
Two New Species ◽  
Shale Formation ◽  
First Time

ABSTRACTThe top 9 m of Lower Hartfell Shale has been collected in 10 cm samples through a continuous sequence on the North Cliff at Dob's Linn. The boundary between the Dicranograptus clingani and Pleurograptus linearis zones is denned for the first time in a measured section, 5.0 m below the top of the Lower Hartfell Shale, with the excavation of the North Cliff proposed as stratotype. The late D. clingani Zone is characterised by Dicranograptus ramosus?, Dicellograptus moffatensis, D. flexuosus [= D. forchhammeri], Climacograptus dorotheus, Glyptograptus daviesi sp. nov., Diplograptus? pilatus sp. nov., Neurograptus margaritatus and Corynoides calicularis. The P. linearis Zone is characterised by Pleurograptus linearis linearis, Amphigraptus divergens divergens, Leptograptus capillaris, Dicellograptus elegans elegans, D. pumilis, D. carruthersi and Climacograptus tubuliferus. A range chart is provided and an attempt is made at a revised correlation of the Scottish succession with coeval zonal sequences in North America and Australia. Twenty-one taxa are described including the two new species noted above.

scholarly journals First record of Mesozoic terrestrial vertebrates from Lithuania: phytosaurs (Diapsida: Archosauriformes) of probable Late Triassic age, with a review of phytosaur biogeography

2012 ◽  
Vol 150 (1) ◽  
pp. 110-122 ◽  
Author(s):  
STEPHEN L. BRUSATTE ◽  
RICHARD J. BUTLER ◽  
GRZEGORZ NIEDŹWIEDZKI ◽  
TOMASZ SULEJ ◽  
ROBERT BRONOWICZ ◽  
...  
Keyword(s):  
North America ◽  
Arid Regions ◽  
First Record ◽  
Upper Triassic ◽  
Late Triassic ◽  
Early Triassic ◽  
Baltic Region ◽  
Terrestrial Vertebrates ◽  
Terrestrial Vertebrate

AbstractFossils of Mesozoic terrestrial vertebrates from Lithuania and the wider East Baltic region of Europe have previously been unknown. We here report the first Mesozoic terrestrial vertebrate fossils from Lithuania: two premaxillary specimens and three teeth that belong to Phytosauria, a common clade of semiaquatic Triassic archosauriforms. These specimens represent an uncrested phytosaur, similar to several species within the generaPaleorhinus,Parasuchus,RutiodonandNicrosaurus. Because phytosaurs are currently only known from the Upper Triassic, their discovery in northwestern Lithuania (the Šaltiškiai clay-pit) suggests that at least part of the Triassic succession in this region is Late Triassic in age, and is not solely Early Triassic as has been previously considered. The new specimens are among the most northerly occurrences of phytosaurs in the Late Triassic, as Lithuania was approximately 7–10° further north than classic phytosaur-bearing localities in nearby Germany and Poland, and as much as 40° further north than the best-sampled phytosaur localities in North America. The far northerly occurrence of the Lithuanian fossils prompts a review of phytosaur biogeography and distribution, which suggests that these predators were widely distributed in the Triassic monsoonal belt but rarer in more arid regions.

Fagus (Fagaceae) fruits, foliage, and pollen from the Middle Eocene of Pacific Northwestern North America

2004 ◽  
Vol 82 (10) ◽  
pp. 1509-1517 ◽  
Author(s):  
Steven R Manchester ◽  
Richard M Dillhoff
Keyword(s):  
British Columbia ◽  
North America ◽  
Middle Eocene ◽  
Molecular Evidence ◽  
Secondary Vein ◽  
Early Oligocene ◽  
Fossil Evidence ◽  
Ca 50 ◽  
Northwestern North America

Fruits and leaves from the Middle Eocene of McAbee, British Columbia, and Republic, Washington, provide an earlier record for the genus Fagus than previously accepted for this member of the Fagaceae. The fruits are trigonal nuts borne within spiny four-valved cupules on long peduncles. The leaves are borne alternately on the twigs and are ovate to elliptic with craspedodromous secondary veins and simple teeth distributed one per secondary vein. The shale preserving these megafossils also contains dispersed pollen with morphology and ornamentation diagnostic of Fagus. Previously, the oldest Fagus occurrences confirmed by fruits were early Oligocene (ca. 32 Ma). The recognition of Middle Eocene (ca. 50 Ma) representatives helps to reduce the disparity between molecular evidence favoring Fagus as a primitive genus within Fagaceae, and fossil evidence, which had indicated older occurrences of Castanea and Quercus than Fagus.Key words: Eocene, Fagus, fossil, foliage, fruits, British Columbia.

Forage selection by elk in habitats common to the French River - Burwash region of Ontario

1999 ◽  
Vol 77 (9) ◽  
pp. 1429-1438 ◽  
Author(s):  
M A Jost ◽  
J Hamr ◽  
I Filion ◽  
F F Mallory
Keyword(s):  
North America ◽  
Mixed Forest ◽  
Habitat Type ◽  
Acer Rubrum ◽  
Rocky Mountain ◽  
Phleum Pratense ◽  
Western North America ◽  
Rocky Mountain Elk ◽  
Grassland Habitats ◽  
French River

A study of two herds of Rocky Mountain elk (Cervus elaphus nelsoni) introduced into the French River - Burwash regions of Ontario in the 1940s was undertaken to assess forage selection and availability. Studies in western North America have shown that the diets of elk vary seasonally, spatially, and in response to forage availability, palatability, plant phenology, plant species diversity, and habitat type. These studies have concluded that grasses, browse, and forbs were preferred forage items and that indigenous grass was used most. In an attempt to obtain a more detailed understanding of forage use in relation to habitat type, selection and availability of forage in ridge, mixed-forest, and grassland habitats was analyzed by tracking elk during a 2-year period. More than 1000 forage occasions were recorded from approximately 60 animals. It was hypothesized that Rocky Mountain elk in the French River - Burwash region would select forage species similar to those found in western North America. The results of this study support the following conclusions: (i) elk in the French River - Burwash regions of Ontario use ridge, mixed-forest, and grassland habitats for foraging; (ii) most forage consumed by elk in this region is woody species, grasses, or forbs, common in mixed-forest habitats; (iii) open grasslands increased forage diversity minimally and appeared to be the least important for foraging; (iv) uncultivated grasslands dominated by Old World agricultural gaminoid species, such as timothy (Phleum pratense), quack grass (Elymus repens), wire grass (Poa compressa), and redtop (Agrostis gigantea), or by indigenous graminoid species, such as white-grained mountain rice (Oryzopsis asperifolia), Canada blue joint (Calamagrostis canadensis), poverty oat grass (Danthonia spicata), and (or) fringed brome grass (Bromus ciliatus), may provide little nutritional support for elk in this region; (v) habitats containing large amounts of willow (Salix spp.), red maple (Acer rubrum), and common hairgrass (Deschampsia flexuosa) provide a significant forage base for elk in the Great Lakes - St. Lawrence ectone; and (vi) relocated Rocky Mountain elk in Ontario use forage classes similar to those utilized by elk in western North America; however, woody browse is the dominant forage used.

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