Abstract from Luo, Z.-X. and Wible, J. R., 2005. A Late Jurassic digging mammal and early mammalian diversification. Science 308:103-107.

A fossil mammal from the Late Jurassic Morrison Formation, Colorado, has highly specialized teeth similar to those of xenarthran and tubulidentate placental mammals and different from the generalized insectivorous or omnivorous dentitions of other Jurassic mammals. It has many forelimb features specialized for digging, and its lumbar vertebrae show xenarthrous articulations. Parsimony analysis suggests that this fossil represents a separate basal mammalian lineage with some dental and vertebral convergences to those of modern xenarthran placentals, and reveals a previously unknown ecomorph of early mammals.

This specimen (LACM 150948), the holotype, is of an individual represented by lower jaws, an incomplete cranium, and approximately 40% of the postcranial skeleton. It was collected from the Kimmeridgian age (150 MYA) mudstones of the Morrison Formation, Fruita Paleontology Area, Fruita, Colorado. The specimen was made available to The University of Texas High-Resolution X-ray CT Facility for scanning by Drs. Zhe-Xi Luo and John Wible of the Carnegie Museum of Natural History and Dr. Timothy Rowe of The University of Texas at Austin. Funding for image processing was provided by a National Science Foundation Digital Libraries Initiative grant to Dr. Timothy Rowe of The University of Texas at Austin.

The specimen was scanned by Matthew Colbert on 3 September 2005 along the coronal axis for a total of 975 slices. Each slice is 0.060 mm thick, with an interslice spacing of 0.060 mm and a field of reconstruction of 50 mm.

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Click on the thumbnail to the left for a false-color roll animation (1.9 mb) of the specimen with the matrix rendered semi-transparent.

Click on the thumbnail to the left for an unreduced version of the front page image.