Navigation Links
480-million-year-old fossil sheds light on 150-year-old paleontological mystery
Date:1/9/2008

New Haven, Conn. Discovery of an exceptional fossil specimen in southeastern Morocco that preserves evidence of the animals soft tissues has solved a paleontological puzzle about the origins of an extinct group of bizarre slug-like animals with rows of mineralized armor plates on their backs, according to a paper in Nature.

While evolution has produced great diversity in the body designs of animals, over the course of history several highly distinct groups, such as trilobites and ammonites, have become extinct. The new fossil is of an unusual creature known as a machaeridian, an invertebrate, or animal without a backbone, that existed for about 180 million years from 485 to 305 million years ago.

The new specimen unequivocally identifies machaeridians as annelid worms, an extremely successful and diverse group of animals that includes familiar living animals like the sea mouse, the earthworm and the leech, said Jakob Vinther, graduate student in the Department of Geology & Geophysics at Yale. The specimen was found in an area that had earlier been identified as a rich source of exceptionally preserved fossils including sponges, trilobites, echinoderms and other less-familiar invertebrates.

First described over 150 years ago, armor plates of these strange animals have been found in marine fossil deposits worldwide covering the time span of their existence, and indicating that they were an important component of ancient seafloor ecosystems. Until now there was little information about their body design or how they might be related to other ancient or currently living animals.

These animals disintegrated quickly after death, so complete fossils of their dorsal armor are rare, and their record until now consisted mostly of isolated armor plates scattered in the sediment, said Vinther. The dilemma of studying ancient organisms, he notes, is that the soft body parts, including most internal organs, are unavailable for study because they usually decompose before they can become fossilized.

Previous patchy evidence was insufficient to reveal the relationships of the machaeridians to other animals and there was much speculation about their position in the tree of life. Different authors suggested relationships to groups as varied as mollusks (clams and snails), barnacles (crustaceans including shrimps, crabs and crayfish), echinoderms (starfish and sea urchins) and annelid worms (aquatic bristle worms and garden earthworms).

This inch-long specimen that was recently discovered shows that, below the dorsal armor, the machaeridians had an elongate body with paired, soft, limb-like extensions on each segment, and two bundles of long, stiff bristles on each extension. The segmented nature of the body, and especially the presence of soft limbs carrying bristles, unequivocally identified the machaeridians as annelid worms, say the scientists.

According to the authors, although the exact relationship of machaeridians within the annelid worms is still uncertain, the presence of modified scales suggests that they may even belong to a group of marine bristle worms that are still in existence today.

This exciting discovery has provided important new insights into annelid evolution, showing that some of these worms, which first appeared during the Cambrian radiation, evolved a highly distinctive dorsal, mineralised armor early in their history, said senior author Derek Briggs, the Frederick William Beinecke Professor of Geology and Geophysics at Yale University. It also highlights the great importance of the study of exceptional fossil sites, and of palaeobiology in general, for a better understanding of the evolution of our biosphere. Briggs, the director of the Yale Institute for Biospheric Studies, will assume the directorship of the Yale Peabody Museum of Natural History in July.


'/>"/>

Contact: Janet Rettig Emanuel
janet.emanuel@yale.edu
203-432-2157
Yale University
Source:Eurekalert  

Related biology news :

1. Fossils excavated from Bahamian blue hole may give clues of early life
2. Rodent fossils allows to determine climate of the Iberian Peninsula 6 million years ago
3. 390-million-year-old scorpion fossil -- biggest bug known
4. Can plant-based ethanol save us from our fossil fuel addiction?
5. Fossil record reveals elusive jellyfish more than 500 million years old
6. Fossil record supports evidence of impending mass extinction
7. Fossilized cashew nuts reveal Europe was important route between Africa and South America
8. Living fossils have hot sex
9. Microfossils disclose geologic history of eastern California
10. Fossil data plugs gaps in current knowledge, study shows
11. First orchid fossil puts showy blooms at some 80 million years old
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
480-million-year-old fossil sheds light on 150-year-old paleontological mystery
(Date:4/19/2016)... -- The new GEZE SecuLogic access control ... system solution for all door components. It can be ... interface with integration authorization management system, and thus fulfills ... dimensions of the access control and the optimum integration ... considerable freedom of design with regard to the doors. ...
(Date:4/15/2016)... Research and Markets has announced ... 2016-2020,"  report to their offering.  , ... global gait biometrics market is expected to grow ... 2016-2020. Gait analysis generates multiple variables ... to compute factors that are not or cannot ...
(Date:4/13/2016)... physicians supporting Medicaid patients in Central Florida ... telehealth thanks to a new partnership with higi.   ... can routinely track key health measurements, such as blood ... they opt in, share them with IMPOWER clinicians through ... location at no cost. By leveraging this data, IMPOWER ...
Breaking Biology News(10 mins):
(Date:5/26/2016)... ... May 26, 2016 , ... FireflySci has been manufacturing quartz ... all over the globe. Their cute firefly logo has been spreading to more ... makes spectrophotometer calibration standards that never require recalibration. These revolutionary standards have ...
(Date:5/25/2016)... ... 25, 2016 , ... Thailand’s Board of Investment’s New York ... Francisco. Located at booth number 7301, representatives from the Thai Government, research organizations, ... Thai biotechnology and life sciences sector. , Deputy Secretary General of the ...
(Date:5/25/2016)... ... May 25, 2016 , ... Founder ... double board-certified in surgery and surgery of the hand by the National Board ... stranger to going above and beyond in his pursuit of providing the most ...
(Date:5/25/2016)... ... May 25, 2016 , ... Scientists at the University of Athens say they ... may be hampering the research that could lead to one good one. Surviving Mesothelioma ... it now. , The team evaluated 98 mesothelioma patients who got ...
Breaking Biology Technology: