A classic example is provided by frogs and salamanders. New discoveries from Uppsala, Cambridge and Duke Universities, published in Science, show that some of the earliest backboned land animals also underwent such changes of lifestyle as they grew up.
Professor Per Ahlberg at the Department of Physiology and Developmental Biology, Uppsala University, together with Jennifer Clack, Cambridge University, and Viviane Callier, Duke University, have studied fossil upper arm bones from the two so-called "four-legged fishes", Ichthtyostega and Acanthostega, from Greenland. These animals, which lived during the Devonian period about 365 million years ago, were among the earliest vertebrates (backboned animals) with fore- and hindlimbs rather than paired fins. They belong to the common stem group of all living amphibians, reptiles, mammals and birds.
The researchers have identified several half-grown, as well as fully grown, upper arm bones from Ichthyostega and Acanthostega, allowing them to study how the shape of the bone changed during growth. It turns out that the two animals had different life histories.
"The upper arm bone provides a lot of information about the lifestyle of the animal, because its shape gives clues to the pattern of movement and can tell us for example whether the animal lifted the front part of its body clear of the ground," says Per Ahlberg.
Ichthyostega, which has robust limbs and only a small tail fin, appears to be the more terrestrial of the two. Its forelimb becomes better adapted to supporting weight as the animal grows up. The pattern of muscle attachments on the upper arm bone changes from a "fish-like" to a "land animal-like" configuration, and the shape of the shoulder joint changes so that it becomes possible for the animal to "lock" its forelimb into a weight-bearing position.
Acanthostega has feebler limbs and a large tail fin, and seems to have been more aquatic. In this animal, there are no corresponding changes.
"The explanation is probably that both animals laid their eggs in water just like modern amphibians, which meant that the terrestrial Ichthyostega, but not the aquatic Acanthostega, needed to undergo a lifestyle transformation as it grew from larva to adult," says Per Ahlberg.
Per Ahlberg | EurekAlert!
Scientists discover new 'architecture' in corn
21.01.2019 | Louisiana State University
Nuclear actin filaments determine T helper cell function
21.01.2019 | Universitätsklinikum Heidelberg
The scientific and political community alike stress the importance of German Antarctic research
Joint Press Release from the BMBF and AWI
The Antarctic is a frigid continent south of the Antarctic Circle, where researchers are the only inhabitants. Despite the hostile conditions, here the Alfred...
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...
16.01.2019 | Event News
14.01.2019 | Event News
12.12.2018 | Event News
21.01.2019 | Life Sciences
21.01.2019 | Physics and Astronomy
21.01.2019 | Life Sciences