Additional K–Ar isotopic dates for the Carmacks Group (Upper Cretaceous), west central Yukon

1986 ◽  
Vol 23 (11) ◽  
pp. 1857-1859 ◽  
Author(s):  
G. W. Lowey ◽  
W. D. Sinclair ◽  
L. V. Hills
Keyword(s):  
Late Cretaceous ◽  
Upper Cretaceous ◽  
The Other ◽  
West Central ◽  
Indian River

Three whole-rock K–Ar analyses on andesites from the Indian River area, west central Yukon, yielded dates of 69.0 ± 1.7, 65.2 ± 1.7, and 64.8 ± 1.7 Ma. These confirm earlier dates indicating the Carmacks Group is Late Cretaceous in age. A single date of 51.4 ± 3.9 Ma was obtained from a tuff in the Sixty Mile River area, west central Yukon, suggesting an Eocene age for these deposits. However, this date is considered equivocal because it is anomalous when compared with the other dates from the area.

Multi-Aged Small Pterosaur Track Assemblage from the Upper Cretaceous of Korea

2021 ◽  
Author(s):  
Jongyun Jung ◽  
Min Huh ◽  
Koo-Geun Hwang ◽  
Hyun-Joo Kim ◽  
Byung-Do Choi ◽  
...  
Keyword(s):  
Late Cretaceous ◽  
Korean Peninsula ◽  
Upper Cretaceous ◽  
Global Distribution ◽  
The Other

Abstract The pterosaur is the earliest and largest powered flying vertebrate, even earlier and larger than the other extant archosaurian group, birds. However, evidence for this flying reptile, including the diversity of the small-sized pterosaur after the mid-Cretaceous, and their ecology, has remained elusive. Here we present numerous and dense pterosaur track assemblages from the Hwasun Seoyuri tracksite in the Upper Cretaceous Jangdong Formation of the Neungju Basin in Korea. The pterosaur track assemblage, assigned to Pteraichnus isp., consists of various sized, randomly oriented manus-dominated tracks with several pes claw marks. These features commonly indicate the semi-aquatic behavior and multi-age gregariousness of pterosaurs. The supposed trackmaker of pterosaur tracks would be the small-sized pterodactyloid that inhibited the Late Cretaceous Korean Peninsula, but that has not previously been reported. This ichnological evidence for the global distribution of small-sized pterosaurs could be interpreted to mean that the pterosaur fauna in the Late Cretaceous was more distributed and diverse than was previously known.

A new species of late Cretaceous crab (Brachyura: Carcineretidae) from Albion Island, Belize

1997 ◽  
Vol 71 (4) ◽  
pp. 615-620 ◽  
Author(s):  
Francisco J. Vega ◽  
Rodney M. Feldmann ◽  
Adriana C. Ocampo ◽  
Kevin O. Pope
Keyword(s):  
New Species ◽  
Late Cretaceous ◽  
Upper Cretaceous ◽  
The Other ◽  
Congeneric Species ◽  
Lower Maastrichtian ◽  
Chicxulub Impact ◽  
A New Species ◽  
Stratigraphic Range ◽  
Barton Creek

A new species of carcineretid crab, Carcineretesplanetarius, is described from the Upper Cretaceous (lower Maastrichtian) Barton Creek Dolomite at Albion Island, Belize. The age is based on the stratigraphic range of associated nerineid gastropods and correlation with nannoplankton, benthic foraminifera, and the other known congeneric species of crab found in Jamaica. Confirmation of this age aids in constraining the timing of ejecta deposits of the Chicxulub impact found at the top of Barton Creek Dolomite exposed on Albion Island. Paleoenvironmental and paleoecological analyses suggest that these crabs were swimmers in lagoonal settings, capable of burrowing a few centimeters into the mud for protection.

Marine reptiles from the Nanaimo Group (Upper Cretaceous) of Vancouver Island

2002 ◽  
Vol 39 (11) ◽  
pp. 1591-1603 ◽  
Author(s):  
Elizabeth L Nicholls ◽  
Dirk Meckert
Keyword(s):  
British Columbia ◽  
Late Cretaceous ◽  
Upper Cretaceous ◽  
New Genus ◽  
Pacific Coast ◽  
Vancouver Island ◽  
The Other ◽  
Western Interior Seaway ◽  
Marine Reptiles ◽  
The Pacific

A new fauna of fossil marine reptiles is described from the Late Cretaceous Nanaimo Group of Vancouver Island. The fossils are from the Haslam and Pender formations (upper Santonian) near Courtenay, British Columbia, and include elasmosaurid plesiosaurs, turtles, and mosasaurs. This is only the second fauna of Late Cretaceous marine reptiles known from the Pacific Coast, the other being from the Moreno Formation of California (Maastrichtian). The new Nanaimo Group fossils are some 15 million years older than those from the Moreno Formation. However, like the California fauna, there are no polycotylid plesiosaurs, and one of the mosasaurs is a new genus. This reinforces the provinciality of the Pacific faunas and their isolation from contemporaneous faunas in the Western Interior Seaway.

scholarly journals The phylogenetic affinities and morphological peculiarities of the bird-like dinosaur Borogovia gracilicrus from the Upper Cretaceous of Mongolia

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e12640
Author(s):  
Andrea Cau ◽  
Daniel Madzia
Keyword(s):  
Late Cretaceous ◽  
Upper Cretaceous ◽  
Distal Part ◽  
The Other ◽  
Theropod Dinosaur ◽  
Distinctive Morphology ◽  
Valid Taxon ◽  
Phylogenetic Affinities ◽  
Second Toe

Borogovia gracilicrus is a small-bodied theropod dinosaur from the Maastrichtian (Upper Cretaceous) Nemegt Formation of southern Mongolia. The taxon is based on a single fragmentary specimen preserving only the distal part of the hindlimbs. The morphology of Borogovia shows a peculiar combination of features, some of which are traditionally considered troodontid synapomorphies and others which are unusual for Troodontidae but are shared with other maniraptoran clades. In particular, the second toe of B. gracilicrus differs from other troodontids in lacking some of the features which contribute to the specialized ‘sickle-clawed’ second toe, here termed the ‘falciphoran condition’, shared with dromaeosaurids and some other paravians, such as the strongly compressed and falciform ungual. Phylogeny reconstructions intended to explore the affinities of Borogovia consistently support its referral within a subclade of troodontids including all Late Cretaceous taxa. The placement of Borogovia is not significantly affected by its unusual combinations of hindlimb features or by the homoplasy of the elements forming the falciphoran condition. Borogovia is supported as a valid taxon and is distinct from the other Nemegt troodontids, Tochisaurus and Zanabazar. The lack of a falciform ungual, and the distinctive morphology of the second toe in B. gracilicrus are interpreted as a derived specialization among Troodontidae and not as retention of the plesiomorphic condition of non-paravian theropods.

A large pteranodontid pterosaur from the Late Cretaceous of Eastern Europe

2020 ◽  
pp. 1-13
Author(s):  
Alexander O Averianov ◽  
Maxim S Arkhangelsky
Keyword(s):  
North America ◽  
Eastern Europe ◽  
Late Cretaceous ◽  
Upper Cretaceous ◽  
The Other

Abstract The Campanian Beloe Ozero locality within the Rybushka Formation in Saratov Province, Russia, is one of the richest and most diverse Upper Cretaceous pterosaur localities in Europe. It produces identifiable remains of Pteranodontidae indet. and Azhdarchidae indet., as well as bones which can be attributed to either of these groups. The pteranodontid specimens from the Beloe Ozero locality described in this paper include a cervical III, distal scapula, humerus deltopectoral crest, proximal syncarpal, preaxial carpal and complete femur. Based on the femur and proximal syncarpal, the wingspan estimate for the Beloe Ozero pteranodontid varies from 5.2 to 6.5 m. Volgadraco bogolubovi, known from the neighbouring Shyrokii Karamysh locality of the same formation and attributed previously to the Azhdarchidae, is more likely pteranodontid than azhdarchid. The other putative records of the Pteranodontidae in the Late Cretaceous of North America, Europe and Asia are discussed. Pteranodontid pterosaurs had a much wider distribution on the northern continents in the Late Cretaceous than previously thought.

The late Cenomanian oyster Lopha staufferi () – the oldest ribbed oyster in the Upper Cretaceous of the Western Interior of the United States

2016 ◽  
Vol 66 (4) ◽  
pp. 609-626
Author(s):  
Stephen C. Hook ◽  
William A. Cobban
Keyword(s):  
United States ◽  
New Mexico ◽  
Late Cretaceous ◽  
Upper Cretaceous ◽  
The United States ◽  
The North ◽  
West Central ◽  
Dakota Sandstone ◽  
Western Interior Basin ◽  
Interior Volume

Abstract Lopha staufferi (Bergquist, 1944) is a medium-sized, ribbed, Late Cretaceous oyster with a slightly curved axis and a zigzag commissure; it appears suddenly and conspicuously in upper Cenomanian rocks in the Western Interior Basin of the United States. At maturity, the ribs on both valves thicken into steep flanks that allow the oyster to increase interior volume without increasing its exterior footprint on the seafloor. Lopha staufferi is the first (earliest) ribbed oyster in the Late Cretaceous of the Western Interior, but has no ancestor in the basin. It disappears from the rock record as suddenly as it appeared, leaving no direct descendent in the basin. In the southern part of the basin where it is well constrained, L. staufferi is restricted stratigraphically to the upper Cenomanian Metoicoceras mosbyense Zone (= Dunveganoceras conditum Zone in the north). Lopha staufferi has an unusual paleogeographic distribution, occurring in only two, widely scattered areas in the basin. It has been found at several localities near the western shoreline of the Late Cretaceous Seaway in west-central New Mexico and adjacent Arizona, and in localities 1,900 km (1,200 mi) to the northeast near the eastern shoreline in northeastern Minnesota, but nowhere in between. In west-central New Mexico and adjacent Arizona, L. staufferi is a guide fossil to the Twowells Tongue of the Dakota Sandstone.

The crucial boundaries in the development of the late cretaceous biota of plankton foraminifers in the southern part of the Indian ocean

2019 ◽  
Vol 59 (6) ◽  
pp. 1074-1085
Author(s):  
E. A. Sokolova
Keyword(s):  
Indian Ocean ◽  
Species Composition ◽  
Late Cretaceous ◽  
Upper Cretaceous ◽  
Planktonic Foraminifera ◽  
The Indian Ocean ◽  
Systematic Composition ◽  
Climatic Series

The article analyzes own data on the species composition of shells of planktonic foraminifera from the Upper Cretaceous sediments of the Indian Oceans, as well as from the sections of the offshore seas of Australia. The species of planktonic foraminifera are grouped and arranged in a climatic series. An analysis of the change in the systematic composition of foraminifers made it possible to distinguish periods of extreme and intermediate climatic states in the Late Cretaceous.

CAPTURING A LATE CRETACEOUS PALEOFAUNA: A NEW VERTEBRATE MICROFOSSIL BONEBED IN THE UPPER CRETACEOUS (CAMPANIAN) JUDITH RIVER FORMATION, MONTANA

2019 ◽  
Author(s):  
Gabriela E. Roat ◽  
◽  
Sedalia P. Gomez ◽  
Sun M. Tun ◽  
Katherine I. Irving ◽  
...  
Keyword(s):  
Late Cretaceous ◽  
Upper Cretaceous ◽  
Judith River Formation
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