Jun 2022
Thwaites Glacier is losing ice more quickly than at any other time in the last 5,500 years
Ancient penguin bones reveal unprecedented shrinkage in key Antarctic glaciers
Mar 2019
The offspring may have been the cause of its mother’s demise, scientists suspect
In a first, a fossilized egg is found preserved inside an ancient bird
Jul 2020
The first fossilized signs of sequential molting support the idea that Microraptor was a flyer
This dinosaur may have shed its feathers like modern songbirds
Mar 2020
Life on Earth has been punctuated by a number of catastrophic mass extinctions throughout history. During these events, diverse taxonomic groups collapsed from the relatively rapid and widespread extinction of large numbers of species. Precipitated by a massive asteroid impact on Earth that occurred more than 65 million years ago, the end-Cretaceous mass extinction led to the obliteration of forests around the world and caused the disappearance of approximately three-fourths of all plant and animal life on Earth. Most notably, all nonavian dinosaurs went extinct at that time. Included in that extinction event were many species of prehistoric birds (avians), which are considered by taxonomists to be members of the dinosaur family. Larger avian species that were dependent on trees for nesting or food comprised the majority of extinctions. However, smaller ancestral forms of ground-dwelling birds survived. See also: Aves; Chicxulub impact crater; Cretaceous; Dinosauria; Extinction; Extinction (paleontology); Forest; Mass extinctions; Tree
Ground-dwelling birds survived the end-Cretaceous mass extinction
May 2018
The evolutionary transition of certain dinosaurs into modern birds has long been an active area of paleontological research. Because the members of the class Aves are living representatives of theropod dinosaurs, paleontologists have sought fossil evidence to support this evolutionary line of descent. One very critical fossil example is Ichthyornis dispar. This extinct flying bird, which resembled a modern-day seagull, is known exclusively from the latest stages of the Cretaceous (approximately 100–65 million years ago) in North America. The initial discovery of this fossil bird in the 1870s was so notable in providing skeletal evidence of the transitional period between dinosaurs and modern birds that Charles Darwin highlighted the jaw of Ichthyornis as support for the theory of evolution. Now, using the latest fossil finds of this ancient bird in Kansas, along with more precise analyses of fossil specimens previously discovered in the late 1800s, researchers have generated a three-dimensional computer tomography image of this animal's skull, showing that it possessed a beak and other skeletal structures similar to those of modern birds. See also: Animal evolution; Aves; Avian evolution; Computerized tomography; Cretaceous; Cretaceous bird radiation; Dino-Birds; Dinosauria; Evolution of theropod dinosaurs; Extinction; Extinction (paleontology); Ichthyornithiformes; Neornithes; Paleontology
Ichthyornis provides clues for avian evolution
May 2020
Scientists have identified the earliest known fossil of a modern bird. The fossil remains—comprising an almost-complete skull and a few limb bones embedded in rock—were discovered in a limestone quarry in Belgium. Estimated to be approximately 66.7 million years old and named Asteriornis maastrichtensis (subclass Neornithes, class Aves), recent analyses of the anatomical features of this diminutive fossil avian (which weighed about 400 g, or about the weight of a very small teal or quail) led investigators to declare it to be the oldest known common ancestor of today's land fowl (chickens and chickenlike birds, order Galliformes) and waterfowl (ducks and ducklike birds, order Anseriformes). Because of the anatomical resemblance of the fossil bird to various fowl, particularly chickens, investigators have assigned the nickname of Wonderchicken to this species. See also: Anseriformes; Aves; Fossil; Galliformes; Neornithes
Oldest common ancestor of chickens and ducks