In mammals, embryonic cranial development is modular and step-wise: The individual cranial bones form according to a defined, coordinated schedule. The typical increase in the size of the brain in mammals in the course of evolution ultimately triggered changes in this developmental plan, as a study conducted on embryos of 134 species of animal headed by palaeontologists from the University of Zurich reveals.
Embryonic development in animals – except mice and rats – remains largely unexplored. For a research project at the University of Zurich, the embryos of 134 species of animal were studied non-invasively for the first time using microcomputer imaging, thus yielding globally unique data.
The embryos studied came from museum collections all over the world. The international team of researchers headed by Marcelo Sánchez-Villagra especially studied cranial formation and discovered that the individual cranial bones develop in different phases that are characteristic for the individual species. According to the study, which was published in the journal Nature communications, how the cranial bones develop in mammals also depends on brain size.
Brain size influences the timing of cranial development
The skulls of full-grown animals consist of many individual bones that have fused together. There are two types of bone: dermal and endochondral bones. Endochondral bones form from cartilaginous tissue, which ossifies in the course of the development. Dermal bones, on the other hand, are formed in the dermis. The majority of the skull consists of dermal bones. The bones inside the skull and the petrous bone, part of the temporal bone, however, are endochondral.
As Daisuke Koyabu, now at University of Tokyo, who conducted the studies while he was a post-doc under Sánchez-Villagra, was able to demonstrate, the different bone types do not develop synchronously: Dermal cranial bones form before the endochondrals. According to Sánchez-Villagra, this indicates that the individual bones form based on a precisely defined, coordinated schedule that is characteristic for every species of animal and enables conclusions to be drawn regarding their evolutionary relationships in the tree of animal life.
The researchers also discovered that individual bones in the area around the back of the head have changed their development plan in the course of evolution. “The development of larger brains in mammals triggered the changes observed in the development of bone formation,” Sánchez-Villagra.
Mammals: masticatory apparatus first
With the aid of quantitative methods and evolutionary trees, the researchers ultimately reconstructed the embryonic cranial development of the last common ancestors of all mammals, which lived 180 million years ago during the Jurassic period. As with the majority of mammals, its cranial development began with the formation of the masticatory apparatus bones.
Daisuke Koyabu, Ingmar Werneburg, Naoki Morimoto, Christoph E. Zollikofer, Analia M. Forasiepi, Hideki Endo, Junpei Kimura, Stoshi D. Ohdachi, Son Ngyuen Truong, Marcelo R. Sánchez-Villagra, Mammalian skull heterochrony reveals modular evolution and a link between cranial development and brain size. Nature communications. April 4, 2014, doi: 10.1038/ncomms4625
Prof. Dr. Marcelo R. Sánchez-Villagra
Paläontologisches Institut und Museum
Nathalie Huber | Universität Zürich
Another piece of Ebola virus puzzle identified
17.01.2019 | Texas Biomedical Research Institute
New scale for electronegativity rewrites the chemistry textbook
17.01.2019 | Chalmers University of Technology
World first experiments on sensor that may revolutionise everything from medical devices to unmanned vehicles
The new sensor - capable of detecting vibrations of living cells - may revolutionise everything from medical devices to unmanned vehicles.
Dead and alive at the same time? Researchers at the Max Planck Institute of Quantum Optics have implemented Erwin Schrödinger’s paradoxical gedanken experiment employing an entangled atom-light state.
In 1935 Erwin Schrödinger formulated a thought experiment designed to capture the paradoxical nature of quantum physics. The crucial element of this gedanken...
Cellulose obtained from wood has amazing material properties. Empa researchers are now equipping the biodegradable material with additional functionalities to produce implants for cartilage diseases using 3D printing.
It all starts with an ear. Empa researcher Michael Hausmann removes the object shaped like a human ear from the 3D printer and explains:
The phenomenon of so-called superlubricity is known, but so far the explanation at the atomic level has been missing: for example, how does extremely low friction occur in bearings? Researchers from the Fraunhofer Institutes IWM and IWS jointly deciphered a universal mechanism of superlubricity for certain diamond-like carbon layers in combination with organic lubricants. Based on this knowledge, it is now possible to formulate design rules for supra lubricating layer-lubricant combinations. The results are presented in an article in Nature Communications, volume 10.
One of the most important prerequisites for sustainable and environmentally friendly mobility is minimizing friction. Research and industry have been dedicated...
Just in time for Christmas, a Mars-analogue mission in Morocco, coordinated by the Robotics Innovation Center of the German Research Center for Artificial Intelligence (DFKI) as part of the SRC project FACILITATORS, has been successfully completed. SRC, the Strategic Research Cluster on Space Robotics Technologies, is a program of the European Union to support research and development in space technologies. From mid-November to mid-December 2018, a team of more than 30 scientists from 11 countries tested technologies for future exploration of Mars and Moon in the desert of the Maghreb state.
Close to the border with Algeria, the Erfoud region in Morocco – known to tourists for its impressive sand dunes – offered ideal conditions for the four-week...
16.01.2019 | Event News
14.01.2019 | Event News
12.12.2018 | Event News
17.01.2019 | Physics and Astronomy
17.01.2019 | Materials Sciences
17.01.2019 | Information Technology