Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Four-legged fish an evolutionary mistake

02.09.2005


The ”four-legged fish” Ichthyostega is not the ”missing link” between marine and land animals, but rather one of several short-lived ”experiments”. This is what scientists from Uppsala and Cambridge universities maintain in an article in the latest issue of the scientific journal Nature.



The ”four-legged fish” Ichthyostega lived in Greenland during the Devon Period, some 355 million years ago, and is one of the very oldest land vertebrates. Since it was discovered back in the 1930s, and nearly the entire skeleton has been preserved, it quickly acquired iconic status as the ”missing link” between fish and land animals. Now a Swedish-British research team is presenting a new reconstruction of this classic animal that paints a radically different picture of its body shape and life style.

It isn´t easy to interpret the fossil of Ichthyostega. Even though almost the whole skeleton is represented, there is no single fossil that shows the whole animal. Instead it is necessary to assemble a puzzle from information found in several different fossils. This was first done in the 1950s by Professor Erik Jarvik at the Museum of Natural History in Stockholm, who reconstructed the animal with a crocodile-like body standing on four sturdy legs, with a large torso and a simple backbone made up of identical vertebrae. However, for the last five years a research team from Uppsala and Cambridge has been piecing together another interpretation.


- We discovered that the vertebrae are not at all identical, but differ depending on where in the body they were located. Moreover, the torso is differently shaped than Jarvik thought, and the hind legs look more like the flippers of a seal, says Professor Per Ahlberg of Uppsala University.

The new reconstruction assigns Ichthyostega a backbone that resembles that of a mammal-surprising for such an early land animal. This means that Ichthyostega had an unusual pattern of locomotion. Both fish and primitive now-living land animals, such as salamanders and lizards, move by slithering their bodies sideways. This also seems to be the case for Acanthostega, the other (and more primitive) four-legged fish from Greenland in the Devon Period. But Ichthyostega‚s large torso, with ribs that overlap like roofing tiles, made its upper body completely stiff, and the hind quarters seem rather to be adapted to flexing vertically, as in mammals.

- Ichthyostega probably moved rather clumsily on land by lifting its upper body and ”walking” on its front legs while simultaneously floundering along on its hind flippers. Its also possible that it combined with this a vertical bending of the spine to slide forward something like a giant inchworm, says Per Ahlberg, who maintains that Ichthyostega is not the ”missing link” but rather one of several short-lived evolutionary experiments with various bodily shapes and patterns of locomotion during the transitional period from marine to land life.

Anneli Waara | alfa
Further information:
http://www.uu.se
http://www.nature.com

More articles from Life Sciences:

nachricht A novel socio-ecological approach helps identifying suitable wolf habitats
17.02.2017 | Universität Zürich

nachricht New, ultra-flexible probes form reliable, scar-free integration with the brain
16.02.2017 | University of Texas at Austin

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Switched-on DNA

20.02.2017 | Materials Sciences

Second cause of hidden hearing loss identified

20.02.2017 | Health and Medicine

Prospect for more effective treatment of nerve pain

20.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>