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
Transport of molecular motors into cilia
28.03.2017 | Aarhus University
Asian dust providing key nutrients for California's giant sequoias
28.03.2017 | University of California - Riverside
The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.
To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
28.03.2017 | Life Sciences
28.03.2017 | Information Technology
28.03.2017 | Physics and Astronomy