Eggciting News

Regular readers will know that I like to add a little variety to the blog but never stray too far from birds. After all, birds are not just for looking at and it's doubtful that curiosity ever really killed a cat, least of all an enquiring mind, amateur or professional. 

Birds feature in many branches of science, history, art, and in recent years, studies of evolution, and the origin of birds via dinosaurs. Research in the past few decades has shown many traits once thought to define modern birds, including feathers, wishbones, brooding behaviours, avian-style lungs, and hollow skeletons evolved first in their dinosaur forebears. 

Bird eggs have been admired since ancient times for their many hues and patterns, from the turquoise-blue of the Common Starling to the blotchy browns of the Curlew. And now, a study shows the colours and markings on birds’ eggs are even older than thought. They may have graced dinosaur eggs some 150 million years ago. 

Curlew eggs 

Mini dinosaur hatching

Starling nest

Yale University. "Dinosaurs put all coloured birds' eggs in one basket, evolutionarily speaking." 

ScienceDaily. 31 October 2018. 

"According to researchers at Yale, the American Museum of Natural History, and the University of Bonn, birds inherited their egg colour from non-avian dinosaur ancestors that laid eggs in fully or partially open nests. 

Last year, molecular paleo biologist Jasmina Wiemann of Yale University published the first evidence of dinosaur egg colouration, using chemical analysis to detect two pigments—blue-green biliverdin and red-brown protoporphyrin—in the eggs of a 70-million-year-old parrot-beaked oviraptorosaur called Heyuannia from China. 

"This completely changes our understanding of how egg colours evolved," said author, Jasmina Wiemann. "For two centuries, ornithologists assumed that egg colour appeared in modern birds' eggs multiple times, independently." 

The egg colours of birds reflect characteristic preferences in nesting environments and brooding behaviours. Modern birds use only two pigments, red and blue, to create all of the various egg colours, spots, and speckles. 

Wiemann and her colleagues analysed 18 fossil dinosaur eggshell samples from around the world, using non-destructive laser micro spectroscopy to test for the presence of the two eggshell pigments. They found them in eggshells belonging to Eumaniraptoran dinosaurs, which include small, carnivorous dinosaurs such as Velociraptor. 

"We infer that egg colour co-evolved with open nesting habits in dinosaurs," Wiemann said. "Once dinosaurs started to build open nests, exposure of the eggs to visually hunting predators and even nesting parasites favoured the evolution of camouflaging egg colours, and individually recognizable patterns of spots and speckles." 

Co-author Mark Norell, the Macaulay Curator of Palaeontology at the American Museum of Natural History, noted that "Coloured eggs have been considered a unique bird characteristic for over a century. Like feathers and wishbones, we now know that egg colour evolved in their dinosaur predecessors long before birds appeared."  

Eggs of British Birds - Seebohm - 1896

Now never let it be said that Another Bird Blog doesn't offer its readers food for thought.

Back soon with more birds and things.

In the meantime, linking with Stewart's World Bird Wednesday.