Story by Debra Holtz
The work of Judd Case, Saint Mary's Dean of Science, continues to expand our understanding about what life on earth was like during the age of dinosaurs. His newest contribution identifies a new species of marsupial living alongside the dinosaurs that provides fresh evidence of a land bridge connecting North America and Europe 66 million years ago.
The new species - a herpetotheriid marsupial, an extinct group closely related to our own opossum - was discovered through a tiny tooth (pictured above) found in the Maastricht ENCI quarry in the Netherlands, according to a paper co-authored by Case in the December 2005 edition of the Journal of Mammalian Evolution. Case, a paleontologist and marsupial expert, originally identified the specimen when he was shown a picture of the upper right molar by fellow co-author, James Martin of the South Dakota School of Mines and Technology.
The finding represents the first time a marsupial has been identified as living in Europe alongside dinosaurs during the last period of the Mesozoic Era. The 66-million-year-old fossil suggests that temporary trans-Atlantic land bridges existed during this period, known as the Cretaceous. Until now, paleontologists assumed that these marsupials had not made the crossing from North America to Europe until some 10 million years after the extinction of dinosaurs.
Case, who made headlines around the world in 2004 with the discovery in Antarctica of a new dinosaur species, previously published a paper in the January 2005 issue of the Journal of Mammalian Evolution that identified this same group of marsupials living in North America some 75 million years ago. Previously, these marsupials were thought to have originated in South America after the fall of dinosaurs and then rapidly appeared in North America 55 to 37 million years ago.
Case and Martin collaborated on the paper with colleagues from the Natural History Museum in Maastricht (Natuurhistorisch Museum Maastricht), Netherlands, where the tooth, less than 2 millimeters in size, is on exhibit (under magnification), next to a life-size model of this new species.