Closing the gap between fish and land animalsJune 26, 2008New exquisitely preserved fossils from Latvia cast light on a key event in our own evolutionary history, when our ancestors left the water and ventured onto land. Swedish researchers Per Ahlberg and Henning Blom from Uppsala University have reconstructed parts of the animal and explain the transformation in the new issue of Nature. It has long been known that the first backboned land animals or "tetrapods" - the ancestors of amphibians, reptiles, birds and mammals, including ourselves - evolved from a group of fishes about 370 million years ago during the Devonian period. However, even though scientists had discovered fossils of tetrapod-like fishes and fish-like tetrapods from this period, these were still rather different from each other and did not give a complete picture of the intermediate steps in the transition. In 2006 the situation changed dramatically with the discovery of an almost perfectly intermediate fish-tetrapod, Tiktaalik, but even so a gap remained between this animal and the earliest true tetrapods (animals with limbs rather than paired fins). Now, new fossils of the extremely primitive tetrapod Ventastega from the Devonian of Latvia cast light on this key phase of the transition. "Ventastega was first described from fragmentary material in 1994; since then, excavations have produced lots of new superbly preserved fossils, allowing us to reconstruct the whole head, shoulder girdle and part of the pelvis", says Professor Per Ahlberg at the Department of Physiology and Developmental Biology, Uppsala University. The recontructions made by Professor Ahlberg and Assistant Professor Henning Blom together with British and Latvian colleagues show that Ventastega was more fish-like than any of its contemporaries, such as Acanthostega. The shape of its skull, and the pattern of teeth in its jaws, are neatly intermediate between those of Tiktaalik and Acanthostega. "However, the shoulder girdle and pelvis are almost identical to those of Acanthostega, and the shoulder girdle is quite different from that of Tiktaalik (the pelvis of Tiktaalik is unknown), suggesting that the transformation from paired fins to limbs had already occurred. It appears that different parts of the body evolved at different speeds during the transition from water to land", says Per Ahlberg. Uppsala University |
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| Related Tetrapods Current Events and Tetrapods News Articles Ancient fossils shed light on anatomical changes accompanying evolution of first land vertebrates Cartoon depictions of the first animals to emerge from the ocean and walk on land often show a simple fish with feet, venturing from water to land. Fossils suggest earlier land-water transition of tetrapod New evidence gleaned from CT scans of fossils locked inside rocks may flip the order in which two kinds of four-limbed animals with backbones were known to have moved from fish to landlubber. Details of Evolutionary Transition from Fish to Land Animals Revealed New research has provided the first detailed look at the internal head skeleton of Tiktaalik roseae, the 375-million-year-old fossil animal that represents an important intermediate step in the evolutionary transition from fish to animals that walked on land. Extreme nature helps scientists design nano materials Scientists are using designs in nature from extreme environments to overcome the challenges of producing materials on the nanometre scale. Primordial fish had rudimentary fingers Tetrapods, the first four-legged land animals, are regarded as the first organisms that had fingers and toes. Now researchers at Uppsala University can show that this is wrong. Using medical x-rays, they found rudiments of fingers in the fins in fossil Panderichthys, the "transitional animal," which indicates that rudimentary fingers developed considerably earlier than was previously thought. Unheard of life history for a vertebrate There is a newly discovered life history among the 28,300 species of known tetrapods, or four-legged animals with backbones. Found: First lungless frog Researchers have confirmed the first case of complete lunglessness in a frog, according to a report in the April 8th issue of Current Biology, a publication of Cell Press. The aquatic frog Barbourula kalimantanensis apparently gets all the oxygen it needs through its skin. Recovering from a mass extinction The full recovery of ecological systems, following the most devastating extinction event of all time, took at least 30 million years, according to new research from the University of Bristol. Coelacanth fossil sheds light on fin-to-limb evolution A 400 million-year-old fossil of a coelacanth fin, the first finding of its kind, fills a shrinking evolutionary gap between fins and limbs. Quantum dot recipe may lead to cheaper solar panels Rice University scientists today revealed a breakthrough method for producing molecular specks of semiconductors called quantum dots, a discovery that could clear the way for better, cheaper solar energy panels. More Tetrapods Current Events and Tetrapods News Articles |
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