نتایج جستجو برای: cretaceous

تعداد نتایج: 9055  

2016
Thomas John Dixon Halliday Paul Upchurch Anjali Goswami

The effect of the Cretaceous-Palaeogene (K-Pg) mass extinction on the evolution of many groups, including placental mammals, has been hotly debated. The fossil record suggests a sudden adaptive radiation of placentals immediately after the event, but several recent quantitative analyses have reconstructed no significant increase in either clade origination rates or rates of character evolution ...

2005
Jeffrey A. Wilson Philip D. Gingerich

Recent geological and paleontological exploration in the Pab Formation (Upper Cretaceous) of Balochistan Province has uncovered new terrestrial vertebrate remains. Together with Cretaceous vertebrates from India, the Pab vertebrates provide information about the paleobiogeographic history of Indo-Pakistan during its northward migration towards Asia. Vertebrate remains collected from several loc...

Journal: :Royal Society open science 2015
Valentin Fischer Maxim S Arkhangelsky Ilya M Stenshin Gleb N Uspensky Nikolay G Zverkov Roger B J Benson

During the Middle and Late Jurassic, pliosaurid plesiosaurs evolved gigantic body size and a series of craniodental adaptations that have been linked to the occupation of an apex predator niche. Cretaceous pliosaurids (i.e. Brachaucheninae) depart from this morphology, being slightly smaller and lacking the macrophagous adaptations seen in earlier forms. However, the fossil record of Early Cret...

2014
Friðgeir Grímsson Reinhard Zetter Heidemarie Halbritter Guido W. Grimm

The fossil record of Aponogeton (Aponogetonaceae) is scarce and the few reported macrofossil findings are in need of taxonomic revision. Aponogeton pollen is highly diagnostic and when studied with light microscopy (LM) and scanning electron microscopy (SEM) it cannot be confused with any other pollen types. The fossil Aponogeton pollen described here represent the first reliable Cretaceous and...

Journal: :Molecular phylogenetics and evolution 2015
R Will Stein Joseph W Brown Arne Ø Mooers

The phylogeny of Galliformes (landfowl) has been studied extensively; however, the associated chronologies have been criticized recently due to misplaced or misidentified fossil calibrations. As a consequence, it is unclear whether any crown-group lineages arose in the Cretaceous and survived the Cretaceous-Paleogene (K-Pg; 65.5 Ma) mass extinction. Using Bayesian phylogenetic inference on an a...

2017
Chase Doran Brownstein

The fossil record of dinosaurs from the Early Cretaceous of Eastern North America is scant, especially since a few stratigraphic units from the east are fossiliferous. Among these stratigraphic units, the Arundel Clay of the eastern seaboard has produced the best-characterized dinosaur faunas known from the Early Cretaceous of Eastern North America. The diverse dinosaur fauna of the Arundel Cla...

2014
Thomas E. Williamson Stephen L. Brusatte

Studying the evolution and biogeographic distribution of dinosaurs during the latest Cretaceous is critical for better understanding the end-Cretaceous extinction event that killed off all non-avian dinosaurs. Western North America contains among the best records of Late Cretaceous terrestrial vertebrates in the world, but is biased against small-bodied dinosaurs. Isolated teeth are the primary...

Journal: :Current Biology 2016
Michael S. Engel Phillip Barden Mark L. Riccio David A. Grimaldi

A hallmark of animals that are eusocial, or those with advanced sociality, is reproductive specialization into worker and queen castes. In the most derived societies, these divisions are essentially fixed and in some arthropods, include further specialization--a tripartite system with a soldier caste that defends the colony. Eusociality has originated numerous times among insects but is believe...

2018
Ryoko Matsumoto Susan E Evans

Albanerpetontids are an enigmatic fossil amphibian group known from deposits of Middle Jurassic to Pliocene age. The oldest and youngest records are from Europe, but the group appeared in North America in the late Early Cretaceous and radiated there during the Late Cretaceous. Until now, the Asian record has been limited to fragmentary specimens from the Late Cretaceous of Uzbekistan. This led ...

2014
L. Colli I. Stotz H.-P. Bunge M. Smethurst S. Clark G. Iaffaldano A. Tassara F. Guillocheau

The South Atlantic region displays (1) a topographic gradient across the basin, with Africa elevated relative to South America, (2) a bimodal spreading history with fast spreading rates in Late Cretaceous and Eo-Oligocene, and (3) episodic regional uplift events in the adjacent continents concentrated in Late Cretaceous and Oligocene. Here we show that these observations can be linked by dynami...

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