نتایج جستجو برای: early cretaceous
تعداد نتایج: 692756 فیلتر نتایج به سال:
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...
Debate on the magnitude of Cretaceous extinctions and timing of modern bird origins has sharply coalesced over the past two decades into contested models, gradualistic or explosive. Molecular clocks, bolstered by phylogenetic, biogeographic, and vicariance models, support an Early Cretaceous origin for birds and mammals over 100 million years ago. Yet, although numerous new Chinese fossils of a...
The orb web is a spectacular evolutionary innovation that enables spiders to catch flying prey. This elegant, geometric structure is woven with silk fibers that are renowned for their superior mechanical properties. We used silk gland expression libraries to address a long-standing controversy concerning the evolution of the orb-web architecture. Contrary to the view that the orb-web design evo...
Blood-feeding insects, as vectors of disease for humans and livestock alike, have garnered significant interest, but our understanding of their early evolution is hindered by the scarcity of available material and the difficulty in distinguishing early hematophages from non-blood-feeding relatives. Here, we report a new family of true bugs including two new genera and species from the Early Cre...
A short review of the state of the art of research on insects from the Cretaceous period is given. The recent achievements and priorities for future efforts are indicated. © 2014 Elsevier Ltd. All rights reserved. The Cretaceous, the geologic period from circa 145 to 66 million years (Ma) ago is a complex time period in Earth's history (Gale, 2000; Keller, 2008; Cohen et al., 2013). Generally s...
A new genus and species of ornithomimosaur, Afromimus tenerensis, is described based on a fragmentary skeleton from the Lower Cretaceous (Aptian–Albian) El Rhaz Formation of Niger. The holotype and only known individual preserves caudal vertebrae, chevrons and portions of the right hind limb. Derived ornithomimosaurian features include the broad, peanut-shaped articular surfaces of mid caudal c...
Early Cretaceous vertebrate assemblages from East Asia and particularly the Jehol Biota of northeastern China flourished during a period of highly debated climatic history. While the unique characters of these continental faunas have been the subject of various speculations about their biogeographic history, little attention has been paid to their possible climatic causes. Here we address this ...
An ornithurine bird, Hongshanornis longicresta gen. et sp. nov., represented by a nearly complete and articulated skeleton in full plumage, has been recovered from the lacustrine deposits of the Lower Cretaceous Jehol Group in Inner Mongolia, northeast China. The bird had completely reduced teeth and possessed a beak in both the upper and lower jaws, representing the earliest known beaked ornit...
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