Hen cranium evolution slowed after the extinction of the dinosaurs

Bird skull evolution slowed after the extinction of the dinosaurs

From emus to woodpeckers, fashionable birds present exceptional range in cranium form and dimension, typically hypothesized to be the results of a sudden hastening of evolution following the mass extinction that killed their non-avian dinosaur cousins on the finish of the Cretaceous 66 million years in the past. However this isn’t the case based on a research by Ryan Nicholas Felice at College Faculty London, publishing within the open-access journal PLOS Biology. In probably the most detailed research but of chicken cranium morphology, Felice and a world crew of researchers present that the speed of evolution really slowed in birds in comparison with non-avian dinosaurs.

Bird skull evolution slowed after the extinction of the dinosaurs
Phenotypic distinction between every specimen for every landmark within the 11-module dataset
and the imply cranium form.For every specimen, the imply landmark configuration is plotted
with factors colored relative to the Procrustes distance between the place of that time
within the imply form and in that specimen. Hotter colors denote landmarks having
greater displacement from the imply, and cooler colors are extra comparable
to the imply form [Credit: Felice et al, 2020]

The researchers used high-dimensional 3D geometric morphometrics to map the form of 354 dwelling and 37 extinct avian and non-avian dinosaurs in unprecedented element and carried out phylogenetic analyses to check for a shift within the tempo of evolution after the origin of birds. They discovered that each one areas of the cranium developed extra quickly in non-avian dinosaurs than in birds, however sure areas confirmed speedy pulses of evolution specifically lineages.

For instance, in non-avian dinosaurs, speedy evolutionary modifications within the jaw joint had been related to modifications in eating regimen, whereas accelerated evolution of the roof of the cranium occurred in lineages that sported bony ornaments similar to horns or crests. In birds, probably the most quickly evolving a part of the cranium was the beak, which the authors attribute to adaptation to completely different meals sources and feeding methods.


The authors say that general slower tempo of evolution in birds in comparison with non-avian dinosaurs calls into query a long-standing speculation that the range seen in fashionable birds resulted from speedy evolution as a part of an adaptive radiation following the end-Cretaceous extinction occasion.

Supply: Public Library of Science [August 18, 2020]

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