Feathers are a primitive trait among pennaraptoran dinosaurs, which today are represented by crown birds (Neornithes), the only clade of dinosaurs to survive the end Cretaceous mass extinction. Feathers are central to many important functions and therefore, maintaining plumage function is of great importance for survival. Thus, molt - by which new feathers are formed to replace old ones, is an essential process. Our limited knowledge regarding molt in early pennaraptoran evolution is based largely on a single Microraptor specimen. A survey of 92 feathered non-avian dinosaur and stem bird fossils did not find additional molting evidence. Due to its longer duration, in ornithological collections evidence of molt is found more frequently in extant bird species with sequential molts compared to those with more rapid simultaneous molts. The low frequency of molt occurrence among fossil specimens resembles collections of bird species with simultaneous molts. The dearth of molt evidence in the forelimbs of pennaraptoran specimens may have interesting implications regarding molt strategy during early avian evolution, and suggests that the yearly molting cycle may have evolved later, among crown birds.
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http://dx.doi.org/10.1038/s42003-023-05048-x | DOI Listing |
Comp Biochem Physiol C Toxicol Pharmacol
January 2025
Henan International Joint Laboratory of Aquatic Ecotoxicology and Health Protection, College of Life Sciences, Henan Normal University, Xinxiang, Henan 453007, China. Electronic address:
The widespread use of climbazole (CBZ) has led to its increased presence in aquatic environments, potentially threatening freshwater ecosystems. However, evidence regarding the harmful effects of CBZ on aquatic organisms remains limited. In this study, Daphnia magna was exposed to CBZ at concentrations of 0, 0.
View Article and Find Full Text PDFG3 (Bethesda)
October 2024
Department of Molecular Biology, College of Agriculture, Life Sciences and Natural Resources, University of Wyoming, Laramie, Wyoming 82071, USA.
The conserved Caenorhabditis elegans protein kinases NEKL-2 and NEKL-3 regulate membrane trafficking and are required for larval molting. Through a forward genetic screen we identified a mutation in catp-1 as a suppressor of molting defects in synthetically lethal nekl-2; nekl-3 double mutants. catp-1 encodes a membrane-associated P4-type ATPase involved in Na+-K+ exchange.
View Article and Find Full Text PDFPeerJ
October 2024
Marine Mammal Laboratory, Alaska Fisheries Science Center, National Marine Fisheries Service, NOAA, Seattle, WA, United States of America.
Am J Vet Res
November 2024
North Carolina Museum of Natural Sciences, Raleigh, NC.
Objective: The objective of this study was to analyze the use of rebound tonometry, as a noninvasive diagnostic tool, in arachnids.
Methods: 5 juvenile (yearling) female and 1 juvenile male curlyhair tarantulas (Tliltocatl albopilosus, previously Brachypelma albopilosum) were used to track estimated ventral opisthosoma pressures over a 9-month period of time. Younger, growing animals were selected as they are more likely than adults to go through multiple molts throughout the 9 months of the study length.
G3 (Bethesda)
November 2024
School of BioSciences, The University of Melbourne, Parkville Campus, Melbourne, Victoria 3010, Australia.
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