Scientists have successfully replicated the molecular processes that led from dinosaur snouts to the first bird beaks.
Using the fossil record as a guide, a research team led by Yale paleontologist and developmental biologist Bhart-Anjan S. Bhullar and Harvard developmental biologist Arhat Abzhanov conducted the first successful reversion of a bird's skull features. The scientists replicated ancestral molecular development to transform chicken embryos in a laboratory into specimens with a snout and palate configuration similar to that of small dinosaurs such as Velociraptor and Archaeopteryx.
Just don't call them dino-chickens.
"Our goal here was to understand the molecular underpinnings of an important evolutionary transition, not to create a 'dino-chicken' simply for the sake of it," said Bhullar, lead author of the study, published online May 12 in the journal Evolution.
Finding the mechanism to recreate elements of dinosaur physiology has been a topic of popular interest for some time. It has been featured in everything from molecular biologist Jack Horner's 2009 book, "How to Build a Dinosaur," to the upcoming Hollywood movie "Jurassic World."
In this case, the fascination derives from the importance of the beak to avian anatomy. "The beak is a crucial part of the avian feeding apparatus, and is the component of the avian skeleton that has perhaps diversified most extensively and most radically -- consider flamingos, parrots, hawks, pelicans, and hummingbirds, among others," Bhullar explained. "Yet little work has been done on what exactly a beak is, anatomically, and how it got that way either evolutionarily or developmentally."
In the new study, Bhullar and his colleagues detail a novel approach to finding the molecular mechanism involved in creating the skeleton of the beak. First, they did a quantitative analysis of the anatomy of related fossils and extant animals to generate a hypothesis about the transition; next, they searched for possible shifts in gene expression that correlated with the transition.
The team looked at gene expression in the embryos of emus, alligators, lizards, and turtles. The researchers discovered that both major living lineages of birds (the common neognaths and the rarer paleognaths) differ from the major lineages of non-bird reptiles (crocodiles, turtles, and lizards) and from mammals in having a unique, median gene expression zone of two different facial development genes early in embryonic development. This median gene expression had previously only been observed in chickens.
Using small-molecule inhibitors to eliminate the activity of the proteins produced by the bird-specific, median signaling zone in chicken embryos, the researchers were able to induce the ancestral molecular activity and the ancestral anatomy. Not only did the beak structure revert, but the process also caused the palatine bone on the roof of the mouth to go back to its ancestral state. "This was unexpected and demonstrates the way in which a single, simple developmental mechanism can have wide-ranging and unexpected effects," Bhullar said.
The work took Bhullar from the alligator nests at Rockefeller Wildlife Refuge in southern Louisiana to an emu farm in Massachusetts. He extracted DNA from various species in order to clone fragments of genetic material to look for specific gene expression.
Bhullar said the research has several implications. For example, he said, if a single molecular mechanism was responsible for this transformation, there should be a corresponding, linked transformation in the fossil record. "This is borne out by the fact that Hesperonis -- discovered by Othniel Charles Marsh of the Yale Peabody Museum of Natural History -- which is a near relative of modern birds that still retains teeth and the most primitive stem avian with a modernized beak in the form of fused, elongate premaxillae, also possesses a modern bird palatine bone," he said.
Premaxillae are the small bones at the tip of the upper jaw of most animals, but are enlarged and fused to form the beak of birds.
Bhullar noted that this same approach could be used to investigate the underlying developmental mechanisms of a host of great evolutionary transformations.
The other corresponding authors are Zachary Morris, Elizabeth Sefton, Bumjin Namkoong, and Jasmin Camacho, all of Harvard; Atalay Tok, of Uppsala University; Masayoshi Tokita, of Toho University; and David Burnham, of the University of Kansas.
Jim Shelton | EurekAlert!
Researchers uncover protein-based “cancer signature”
05.12.2016 | Universität Basel
The Nagoya Protocol Creates Disadvantages for Many Countries when Applied to Microorganisms
05.12.2016 | Leibniz-Institut DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
05.12.2016 | Power and Electrical Engineering
05.12.2016 | Materials Sciences
05.12.2016 | Power and Electrical Engineering