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| Title | Maastrich Mammal |
| Identifier | UPR pdf\Maastrich Mammal.pdf |
| Digitaization Specification | Master file format: 62309 bytes, application/pdf; Uncompressed, PDF, ; Checksum: 85cddbe79cfe9fa200f015af459e6269; Adobe Photoshop CS3
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| Transcript | South Dakota School of Mines News FOR IMMEDIATE RELEASE December 29, 2005 Contact: Breanna Bishop, 394-6082 NEW FOSSIL MAMMAL FROM EUROPE RELATED TO THOSE IN SOUTH DAKOTA INDICATES NEW TRANSATLANTIC DISPERSAL ROUTE DURING THE AGE OF DINOSAURS A mammal whose origins are in South Dakota has been identified in Europe in the type Maastricht of the Netherlands. Dr. James E. Martin, Museum of Geology, South Dakota School of Mines and Technology, identified the mammals as a relative of living opossums while conducting research funded by the National Science Foundation. The marsupial tooth represents a mammal new to science, is 66 million years old, and is most similar to those found in the Late Cretaceous time (~70 million years) in western South Dakota. The European relative indicates these mammals were able to disperse across a heretofore unknown, northern high-latitude trans-Atlantic route. Such teeth had not been found before because the Netherlands was under salt water at the end of the Age of Dinosaurs. Evidently, remains of this small pouched mammal had floated out to sea, sunk, and was preserved against all odds. Until now, paleontologists had assumed that these marsupials had not made the crossing from North America until the Eocene, some 10 million years after the extinction of dinosaurs. The new fossil suggests that already during the end of the Cretaceous (end of the Age of Dinosaurs) that temporary trans-Atlantic land bridges existed. The new find thus fundamentally changes our views on the distribution of animals at the end of the Age of Dinosaurs. Two amateur collectors, Roland Meuris and Frans Smet, from the Netherlands discovered the tooth, and when paleontologists at the Natural History Museum of Maastricht showed a photograph to Martin, he recognized its significance. The find of this new marsupial species has just been published in the scientific journal, Journal of Mammalian Evolution. The new species is named after the - more - South Dakota School of Mines and Technology 501 E. Saint Joseph Street Rapid City, SD 57701-3995 Phone: (605) 394-6082/2554 Fax: (605) 394-6177 amateurs and is termed Maastrichtidelphys meurismeti, which means the "Maastricht opossum of Meuris and Smet." The South Dakota School of Mines Museum of Geology that sponsored much of this research is a major center for the study of fossils, both in the Northern Great Plains and worldwide. Although the Museum possesses vertebrate fossils from around the world, specimens from South Dakota comprise a majority of the collections, and based upon this library of specimens, Martin was able to recognize the uniqueness of the Maastricht mammal. In addition to the extensive research collections, the museum is also a major contributor to the South Dakota School of Mines and Technology's Paleontology Program which is widely recognized for its Paleontology graduate degree and research expertise in paleontology. - - - - - - - - - - - - - - - Background information on the new Cretaceous mammal Maastrichtidelphys On the discovery In 2002, amateur collector Roland Meuris took a rock sample at the ENCI cement quarry near Maastricht, Netherlands, to analyze this for small shark teeth. Fellow collector Frans Smet subsequently recognized a mammal tooth in that same sample – the first mammal tooth from the Maastricht Cretaceous – upon which he contacted staff of the Natuurhistorisch Museum Maastricht. Study Only in scanning electron microscopy does the small tooth, measuring 1.36 x 1.85 mm, reveal its true identity, because it is the details that count in describing and identifying mammal teeth. The placement of the various cusps, protuberances on the chewing surface, their height and differences therein, as well as the structure and position of ‘troughs' between the cusps are all characteristic features, allowing the identification of a species on the basis of a single tooth. The first mammal from the Maastricht Cretaceous Never before had mammal teeth been recorded from the Maastricht Cretaceous. Maybe that does not come as a surprise because the Maastricht is composed of rocks laid down in a seabed, not laid down in terrestrial enviornments where marsupials are normally found. Also, the ��Age of Dinosaurs' is a term used for a time period, the Mesozoic. Although correct, the name ‘Age of Dinosaurs' is slightly misleading: even in those days mammals were already around, although they played a far more modest role and were far less impressive than dinosaurs which often grew to gigantic size. Terrestrial animals During the Cretaceous, all mammals were land-based. Therefore, all remains of terrestrial animals in the Maastricht Cretaceous rocks come from dead bodies transported by rivers into the sea. - more - Age The new find is about 66.1 million years old. Mammals in the Age of Dinosaurs During the Cretaceous, mammals did not grow larger than the average household pet (i.e. a small dog or cat); most species did not even reach that size, as they were mostly mouse- to rat-size. Smaller mammals have diminutive bones, delicate and fragile. Only under special conditions does any mammal skeleton stand a chance of being fossilized. Of necessity, our current knowledge of primitive mammals is primarily derived from the study of teeth. Teeth are small, but very durable thanks to their enamel covering. Therefore, they are often the sole remains to be found of Cretaceous mammal species. The Maastricht marsupial is no exception. New species, formal publication In the newest issue of the Journal of Mammalian Evolution the new find is formally named, Maastrichtidelphys meurismeti, the ‘Maastricht opossum (didelphid) of Meuris and Smet'. To describe the fossil, the Natuurhistorisch Museum Maastricht sought the help of two American experts of Mesozoic mammals, Professor James E. Martin of the South Dakota School of Mines and Technology (Rapid City), and Professor Judd Case of St Mary's College (Moraga, CA). During Martin's visit to Maastricht in 2003, right after the discovery of the tooth, he recognized it as one of a herpetotheriid marsupial – an unexpected occurrence in the Maastricht Cretaceous. Herpetotheriids are a group of opossum-like marsupials, which came into being in North America during the Cretaceous. The oldest representatives of these marsupials come from Meade County, South Dakota. A detailed comparison with the structure, position and height of cusps, and many other features of the Maastrichtidelphys molar with other Late Cretaceous and Early Paleogene mammals, suggests that Maastrichtidelphys is a close ally of the North American marsupial, Nortedelphys described by Case and others in 2004. Land bridge with North America A North American mammal present in the latest Cretaceous in Europe, suggests that Maastrichtidelphys, or its direct ancestor, had managed to cross the North Atlantic. This sounds dramatic for a small marsupial, but the Atlantic Ocean in those days was half the width (at most) of today's Atlantic Ocean, and further north there may have been a land bridge, via Greenland, during periods of low sea level. Around 71 million years ago, and again four million years later, there were two intervals worldwide where sea level was particularly low. Above 70 degrees N, the ‘Thule' dispersal route may have been dry land; via islands in northern Canada, Baffin Island, Greenland, across the Faroes and Great Britain, Maastrichtidelphys may have reached the European mainland. Greenhouse effect But: were temperatures high enough to allow animals to cross? The best way to lower sea level is by turning water into ice. However, it is widely known that during the Cretaceous climate was much better than today's climate, which makes the existence polar ice caps unlikely. Except for land ice, we can also - more - postulate movements along tectonic plates and activity of mid-ocean volcanic ridges that may have had an impact on sea level. More and more data on climate changes and sea level oscillations during the latest Cretaceous are becoming available; according to recent studies, the mean annual temperature at the poles was ca 6 degrees Celsius during the latest Cretaceous. If that scenario is correct, a crossing during summer months would have posed no problems whatsoever. The find of a few mammal hairs in Siberian amber, which oozed from trees some 70 million years ago, at around 70 degrees N then, make such estimates even more plausible. Other crossings? The discovery of this new mammal sheds more light on other finds of typically North American terrestrial animals in the European Cretaceous. After all, there are hadrosaur (duck-billed) dinosaurs in the Maastricht area, animals otherwise well represented in North America. Some snake remains from the uppermost Creatceous in northwest Europe show similarities to North American boas. And, a single bone fragment of a carnivorous dinosaur from the Maastricht Cretaceous resembles the North American Dryptosaurus to some extent. Seen individually, these finds perhaps were not conclusive evidence to postulate a northerly land bridge during the latest Cretaceous, but taken together with the new mammal these finds become much more meaningful. Martin and Case have already postulated a similar dispersal route across the southern continents to get marsupials from North America to Australia. Their find of a duck-billed dinosaur in Antarctica whose occurrences are common in South Dakota suggest a southern route as well as the northern. Therefore, a world-wide drop in sea level at the end of the Age of Dinosaurs may have allowed greater dispersal throughout the world than previously recognized. Original publication The description of Maastrichtidelphys appears in the scientific journal Journal of Mammalian Evolution. The complete reference is: Martin, J.E., Case, J.A., Jagt, J.W.M., Schulp, A.S. & Mulder, E.W.A. (2005). A New European Marsupial Indicates a Late Cretaceous High-latitude Transatlantic Dispersal Route. Journal of Mammalian Evolution vol. 12, Nos. 3/4, 495-511. # 30# |
| Creator | South Dakota School of Mines and Technology. University Relations; |
| Subject | South Dakota School of Mines and Technology; South Dakota School of Mines and Technology. Museum of Geology; |
| Local Subject | South Dakota School of Mines and Technology
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| Digital Publisher | South Dakota School of Mines and Technology. Devereaux Library
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| Date | 2005-12-29 |
| Type | Text |
| Format | application/pdf |
| Language | eng |
| Relation | Is part of Office of University Relations SDSM&T News Collection |
| Rights | The work from which this copy was made did not include a formal copyright notice. This work may be protected by U. S. copyright law (Title 17, United States Code), which governs reproduction, distribution, public display, and other uses of protected works. Uses may be allowed with permission from the copyright holder, if the copyright on the work has expired, or if the use is fair use or within another legal exemption. The user of this work is responsible for compliance with the law. |
| Submitting Institution | Devereaux Library. South Dakota School of Mines and Technology. |
| Date Digital | 2009 |
| CONTENTdm number | 7193 |
| CONTENTdm file name | 8182.pdf |
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