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Re: Cretaceous marsupial from Netherlands
Is it even possible to conclusively distinguish a "true" marsupial from a
closely related non-marsupial metatherian based on one tooth? Which
marsupial molar synapomorphies are the key?
On Fri, 30 Dec 2005 12:39:01 -0500 "email@example.com" <firstname.lastname@example.org>
> From: Ben Creisler email@example.com
> In case this news item has not been mentioned yet:
> Marsupial tooth find bolsters land bridge
> By Jackie Burrell CONTRA COSTA TIMES
> MORAGA - The recent discovery of a 66-million-year-old marsupial
> tooth in
> the Netherlands provides fresh proof that a land bridge connected
> the North
> American and European continents during the age of dinosaurs.
> St. Mary's College dean of science Judd Case and his colleague James
> say the 2-millimeter fossil, which belongs to a newly discovered,
> species similar to an opossum, suggests that dinosaurs and small
> not only lived in Europe at the same time, but also traveled the
> trans-Atlantic migration route from South Dakota to the
> "Wow," said Case. "It changes what we know."
> Taken together with other, recent finds of North American-type
> dinosaurs and certain types of snakes in Northern Europe, it appears
> animals used temporary land bridges to travel across the high polar
> latitudes 10 million years earlier than paleontologists had thought.
> tooth may be tiny, said Case, but it will have a major impact on
> scientists' views of Cretaceous climate, geography and life.
> Amateur collectors Roland Meuris and Frans Smet were looking for
> tooth fossils in a quarry near Maastricht, Netherlands, in 2002 when
> came across an intriguing rock sample from the Cretaceous period.
> When Smet
> spotted what he thought were mammal teeth, he contacted the nearby
> Natuurhistorisch Museum Maastricht, which specializes in fossils.
> His timing was perfect. James Martin was researching marine reptiles
> Maastricht when the museum's fossil experts asked his opinion of the
> odd tooth.
> The South Dakota paleontologist had collaborated frequently with
> Case on
> dig projects. The pair made headlines last year with a spectacular
> Antarctic dinosaur find. And last January, Case published a paper on
> startling new North American find -- 75-million-year-old
> marsupial fossils that were 20 million years older than expected.
> Martin knew exactly what he was looking at in Maastricht.
> "He said, 'Wow!'" Case remembered. "He told me where it's from and
> it's from, and I said, 'Wow!'"
> The Netherlands discovery -- dubbed Maastrichtidelphys meurismeti to
> collectors Meuris and Smet -- fills an intriguing gap in the fossil
> Scientists have long known that dinosaurs and small mammals
> during the so-called Dinosaur Age, but fossilized mammal skeletons
> rare. Most primitive mammal studies rely on teeth. Using scanning
> microscopy to examine surface details, scientists can identify
> species with
> a single tooth.
> In this case, the upper molar belonged to the new marsupial species
> in Canada, Montana, Wyoming and South Dakota -- and now, the
> But how did a mouse-sized creature cross the Atlantic Ocean?
> Earth's geography was very different back then, said Case. The
> Atlantic was
> only half as wide. Sea levels were lower -- and significantly lower
> at two
> points, around 71 and 67 million years ago. And continents were
> Case and Martin believe animals hopped from land mass to land mass
> the 70-degree latitude line.
> "Eastern Canada was attached to Greenland," said Case. "The Faroes
> stuck on top of Great Britain and Great Britain was connected to the
> of Europe. It had been felt that North American dinosaurs had made
> one-time only entry into Europe -- but no."
> The discovery of a North American marsupial and duck-billed
> dinosaurs in
> Maastricht indicates that the polar crossing was no chilly
> experiment, but
> a temperate migration path in a world filled with new, flowering
> "While the dinosaurs were munching on leaves, these little guys
> probably eating insects and these new flowers," said Case. "It's
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