Investigators have re-created the beginnings of the process that enabled scales of dinosaur-era birds to evolve into feathers. Scientists have figured out a way to transform alligator scales into feathers in a laboratory, which could provide vital clues in how dinosaurs evolved into birds. It’s one of the most significant developments in the history of evolution, and scientists are trying to figure out the massive biological shift that gave us the birds we know today.
Scientists were able to figure out what the feather developing genes are in birds, and then they stimulated those genes in alligator embryos, causing the scales to turn into feathers. Their findings were proclaimed in the journal Molecular Biology and Evolution. Experts believe that some dinosaurs evolved into birds that still had scales, while other dinosaurs developed feathers. However, there remains a lot of mystery in exactly how this evolution happened. The full statement from Molecular Biology and Evolution from Oxford University Press follows below.
In first glimpse, most people wouldn’t consider alligators or birds were evolutionary relatives. But indeed, reptiles are the closest living siblings of birds, and all descended from the archosaurs, the ruling reptiles which once commanded ages ago.
Archosaurs provided rise to the age of the dinosaurs and, ultimately, birds and reptiles as their only living descendants. Lately, many transitionary dinosaur fossils with full or partial plumages have been revealed. Scientists speculate these primitive “proto-feathers” of feathered dinosaurs may have evolved to help endothermy, attract mates, gave them an ability to outrun predators better, and eventually glide and fly.
But exactly how the outer skin and underlying tissues specify feathers versus scales and ultimately the evolution of flight has remained a puzzle. Though, this rich evolutionary heritage should be still implanted within all existing reptile and bird DNA. They have also displayed the ability to turn scales into feathers, by turning on and off-key molecular circuits at crucial stages of scale growth and development.
For the research study, the team conducted a whole RNA transcriptome and DNA genomic examination of growing chicks and alligators to recognize their gene expression differences and the critical genes in scale or feather development. Following, they placed these unique chicken feather genes inside alligator eggs, carefully turning them on or off beneath their growing skin to reawaken an ancient programming that can transform scales into feathers.
Dr Cheng Ming Choung, a professor of pathology at the Keck School of Medicine of USC said that our analyses led to the classification of five morpho-regulatory modules that are essential for new feather formation. We suggest that these modules may initially evolve as various strategies for better adaptation. Ultimately, the integrative combination of five morpho-regulatory modules achieves the highly favourable feather architecture today, provides the Ave class to challenge most of the open sky as their ecological niche.
These essential circuits head to the budding and elongation of appendages, follicle with stem cells and dermal papilla to support cyclic redemption, barb ridge formation with different branching forms, and particular feather keratin differentiation. Some molecules could only produce one of the five criteria, eg.; the Sox2 gene can turn on feather budding and entirely inhibits scale production, while Grem1 can produce barb-like branching.
“Additional molecules, such as retinoic acid or Sox18, have a greater ability to produce scutate scales to make feather-like skin appendages,” said Chuong. “These feather-like appendages present all five criteria defining feathers, advising that they operate at a higher hierarchical level in this evolutionary pathway.”
These master regulators may have been the original genes to adapt during early archosaur evolution and gain a newfound strength toward the making of today’s complex feathers. “Intriguingly, some of these phenotypes are related to the unusual filamentous appendages found in the specimens of feathered dinosaurs.”
Motivated by the “flying dragon,” Ping Wu wants to question alligator scales to form feathers. By forced expression of sprouty and beta-catenin, genes they found to help convert chicken scales to feathers, they can cause the formation of elongated scales in alligator embryonic skin. The research significantly adds to the growing list of genes and molecules known to induce feather-like structures in birds and has established a robust new system in alligators to test and further explore the evolution of flight.