This fearsome 17-foot-long Xiphactinus audax is ready for #FossilFriday!
Alive during the Late Cretaceous (about 85 million years ago), Xiphactinus and its relatives were large predators with strong jaws and many teeth. Xiphactinus swam in the great inland sea that covered most of North America at the end of the Age of Dinosaurs. This specimen was collected in Lane County, Kansas.
The colorful plumes, or tentacles, are used for passive feeding on suspended food particles and plankton in the water. The plumes are also used for respiration. Though the plumes are visible, most of these worms are anchored in their burrows that they bore into live calcareous coral. Christmas tree worms are very sensitive to disturbances and will rapidly retract into their burrows at the slightest touch or passing shadow. They typically re-emerge a minute later, very slowly, to test the water before fully extending their plumes.