Gondwanatherians

DESCRIBER    Luo and Wible, 2005
TIME    Jurassic Late
Kimmeridgian Tithonian
CLASS    Mammalia
FOSSILSITE    Morrison Formation, Colorado, US
INFO

Luo, Z.-X. and Wible, J.R. (2005). A Late Jurassic digging mammal and early mammalian diversification. Science 308 (57180): 103-107.

Abstract: \"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.\"

The authors describe the new genus and species Fruitafossor windscheffeli, a small mammal known from a relatively complete specimen (lower jaws, incomplete cranium, and nearly 40% of the postcranium, including a complete forelimb and manus, elements of the hindlimb and pes, and many vertebrae).Fruitafossor was a fossorial mammal, with the forelimbs and hands specialized for scratch digging. The authors propose that it fed on termites and other insects, as well as plants. The teeth are rather aardvark-like and the lumbar vertebrae are xenarthrous (to help the vertebral column resist torsion produced by digging), but the authors are at pains to point out that both features are convergent upon tubulidentates and true xenarthrans. The phylogenetic analysis shows Fruitafossor to represent a unique lineage of basal mammals, a long way from eutherians, and positioned between the monotreme and triconodont lineages.

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