Navigation Links
The life histories of the earliest land animals

The fossil record usually shows what adult animals looked like. But the appearance and lifestyle of juvenile animals often differ dramatically from those of the adults. 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.


Contact: Per Ahlberg
Uppsala University

Related biology news :

1. Scientists confirm that parts of earliest genetic material may have come from the stars
2. More acidic ocean could spell trouble for marine lifes earliest stages
3. Researchers devise means to create blood by identifying earliest stem cells
4. Earliest animal footprints ever found -- discovered in Nevada
5. Engineering technology pinpoints earliest signs of animal life
6. Evidence of earliest known domestic horses found in Kazakhstan
7. Researchers find the earliest evidence of domesticated maize
8. New research reveals the earliest evidence for corn in the New World
9. Report: African, Asian, Latin American farm animals face extinction
10. UT researcher sheds new light on hybrid animals
11. Penn Veterinary Medicine report new strategy to create genetically-modified animals
Post Your Comments:
(Date:3/23/2016)... , March 23, 2016 ... Interesse erhöhter Sicherheit Gesichts- und Stimmerkennung mit ... Inc. (NASDAQ: MESG ), ein ... dass das Unternehmen mit SpeechPro zusammenarbeitet, um ... der Finanzdienstleistungsbranche, wird die Möglichkeit angeboten, im ...
(Date:3/22/2016)... and SANDY, Utah , ... which operates the highest sample volume laboratory in ... Genomics and UNIConnect, leaders in clinical sequencing informatics and ... launch of a project to establish the informatics infrastructure ... NSO has been contracted by the Ontario ...
(Date:3/18/2016)... -- --> --> Competitive ... Unmanned Vehicles, Physical infrastructure and Perimeter Surveillance & Detection Systems ... security market and the continuing migration crisis in the ... has led visiongain to publish this unique report, which ... defence & security companies in the border security market ...
Breaking Biology News(10 mins):
(Date:6/24/2016)... ... ... Researchers at the Universita Politecnica delle Marche in Ancona combed medical journal ... Their findings are the subject of a new article on the Surviving Mesothelioma website. ... the blood, lung fluid or tissue of mesothelioma patients that can help point doctors ...
(Date:6/23/2016)... , June 23, 2016   Boston Biomedical ... novel compounds designed to target cancer stemness pathways, ... been granted Orphan Drug Designation from the U.S. ... of gastric cancer, including gastroesophageal junction (GEJ) cancer. ... designed to inhibit cancer stemness pathways by targeting ...
(Date:6/23/2016)... , June 23, 2016 Houston Methodist ... the Cy-Fair Sports Association to serve as their ... agreement, Houston Methodist Willowbrook will provide sponsorship support, ... connectivity with association coaches, volunteers, athletes and families. ... the Cy-Fair Sports Association and to bring Houston ...
(Date:6/23/2016)... June, 23, 2016  The Biodesign Challenge (BDC), a ... ways to harness living systems and biotechnology, announced its ... in New York City . ... students, showcased projects at MoMA,s Celeste Bartos Theater during ... , MoMA,s senior curator of architecture and design, and ...
Breaking Biology Technology: