Navigation Links
480-million-year-old fossil sheds light on 150-year-old paleontological mystery

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
Yale University

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:
Related Image:
480-million-year-old fossil sheds light on 150-year-old paleontological mystery
(Date:10/29/2015)... ANN ARBOR, Mich. , Oct. 29, 2015 ... with Eurofins Genomics for U.S. distribution of its ... DNA-seq kit and Rubicon,s new ThruPLEX Plasma-seq ... DNA to enable the preparation of NGS libraries ... in plasma for diagnostic and prognostic applications in ...
(Date:10/29/2015)... , Oct. 29, 2015 Today, ... a partnership with 2XU, a global leader in ... a smart hat with advanced bio-sensing technology. The ... athletes to monitor key biometrics to improve overall ... partnership, the two companies will bring together the most ...
(Date:10/27/2015)... Oct. 27, 2015 Synaptics Inc. (NASDAQ: SYNA ... that Google has adopted the Synaptics ® ClearPad ... to power its newest flagship smartphones, the Nexus 5X ... --> --> Synaptics ... provide strategic collaboration in the joint development of next ...
Breaking Biology News(10 mins):
(Date:11/25/2015)... 25, 2015 Studies reveal the ... plaque and pave the way for more effective treatment for ...     --> --> ... health problems in cats, yet relatively little was understood about ... studies have been conducted by researchers from the WALTHAM Centre ...
(Date:11/25/2015)... , Nov. 25, 2015 Orexigen® Therapeutics, Inc. ... participate in a fireside chat discussion at the Piper ... York . The discussion is scheduled for Wednesday, ... .  A replay will be available for ... Stilwell  , Julie NormartVP, Corporate Communications and Business ...
(Date:11/24/2015)... , Nov. 24, 2015 Cepheid (NASDAQ: ... be speaking at the following conference, and invited investors ... York, NY      Tuesday, December 1, 2015 at ... York, NY      Tuesday, December 1, 2015 at ... Healthcare Conference, New York, NY ...
(Date:11/24/2015)... CITY , Nov. 24, 2015 /PRNewswire/ - Aeterna ... request of IIROC on behalf of the Toronto Stock ... news release there are no corporate developments that would ... --> --> About ... . --> Aeterna Zentaris is ...
Breaking Biology Technology: