نتایج جستجو برای: early cretaceous

تعداد نتایج: 692756  

2014
Michael P. Donovan Peter Wilf Conrad C. Labandeira Kirk R. Johnson Daniel J. Peppe

Plant and associated insect-damage diversity in the western U.S.A. decreased significantly at the Cretaceous-Paleogene (K-Pg) boundary and remained low until the late Paleocene. However, the Mexican Hat locality (ca. 65 Ma) in southeastern Montana, with a typical, low-diversity flora, uniquely exhibits high damage diversity on nearly all its host plants, when compared to all known local and reg...

Journal: :Science 2007
G V R Prasad O Verma A Sahni V Parmar A Khosla

The sedimentary record documenting the northward drift of India (Late Cretaceous to late Early Eocene) has recently provided important clues to the evolution, radiation, and dispersal of mammals. Here, we report a definitive Late Cretaceous (Maastrichtian) archaic ungulate (Kharmerungulatum vanvaleni genus et species nova) from the Deccan volcano-sedimentary sequences exposed near Kisalpuri vil...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2011
Xiaoting Zheng Larry D Martin Zhonghe Zhou David A Burnham Fucheng Zhang Desui Miao

The crop is characteristic of seed-eating birds today, yet little is known about its early history despite remarkable discoveries of many Mesozoic seed-eating birds in the past decade. Here we report the discovery of some early fossil evidence for the presence of a crop in birds. Two Early Cretaceous birds, the basal ornithurine Hongshanornis and a basal avian Sapeornis, demonstrate that an ess...

Journal: :Trends in ecology & evolution 1999
Archibald

In a perspectives article, Bromham et al.1 raise some important concerns about the use of both molecular and paleontological data in assessing the timing of diversification of extant mammalian orders. In Box 1, they describe well the need to differentiate crown (or more generally, nodebased) taxa from stem-based taxa. Unfortunately, their Fig. 2 is not clearly explained and thus confuses these ...

Journal: :Proceedings. Biological sciences 2014
Sebastián Apesteguía Raúl O Gómez Guillermo W Rougier

Rhynchocephalian lepidosaurs, though once widespread worldwide, are represented today only by the tuatara (Sphenodon) of New Zealand. After their apparent early Cretaceous extinction in Laurasia, they survived in southern continents. In South America, they are represented by different lineages of Late Cretaceous eupropalinal forms until their disappearance by the Cretaceous/Palaeogene (K/Pg) bo...

2010
Phil Senter James I. Kirkland John Bird Jeff A. Bartlett

BACKGROUND The theropod dinosaur family Troodontidae is known from the Upper Jurassic, Lower Cretaceous, and Upper Cretaceous of Asia and from the Upper Jurassic and Upper Cretaceous of North America. Before now no undisputed troodontids from North America have been reported from the Early Cretaceous. METHODOLOGY/PRINCIPAL FINDINGS Herein we describe a theropod maxilla from the Lower Cretaceo...

Journal: :International Geology Review 2023

The classic Neotethyan Ankara Melange formed within the Triassic-Eocene İzmir-Ankara-Erzincan ocean (‘N Neotethys’), bordered in central Anatolia by Kırşehir and Tauride-Anatolide continental units to south discontinuous Sakarya continent northwest. Farther north, separate Intra-Pontide probably remained partly open until early Cenozoic. developed via phases of intra-oceanic accretion (mainly p...

Journal: :Cretaceous Research 2022

The synlestid damselfly, Cretaphylolestes cretacicus gen. et sp. nov., is described from the Lower Cretaceous Shouchang Formation (lower Aptian) of Zhejiang Province, Eastern China. It oldest Synlestidae, as we exclude Late Jurassic–Early genus Gaurimacia this family. clade Lestiformia currently represented in Mesozoic by two Early genera its stem group, a Perilestidae mid-Cretaceous Burmese am...

2011
Denver W. Fowler Holly N. Woodward Elizabeth A. Freedman Peter L. Larson John R. Horner

The carnivorous Tyrannosauridae are among the most iconic dinosaurs: typified by large body size, tiny forelimbs, and massive robust skulls with laterally thickened teeth. The recently described small-bodied tyrannosaurid Raptorex kreigsteini is exceptional as its discovery proposes that many of the distinctive anatomical traits of derived tyrannosaurids were acquired in the Early Cretaceous, b...

Journal: :Molecular biology and evolution 2013
J Romiguier V Ranwez E J P Douzery N Galtier

It is widely assumed that our mammalian ancestors, which lived in the Cretaceous era, were tiny animals that survived massive asteroid impacts in shelters and evolved into modern forms after dinosaurs went extinct, 65 Ma. The small size of most Mesozoic mammalian fossils essentially supports this view. Paleontology, however, is not conclusive regarding the ancestry of extant mammals, because Cr...

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