Field of Science

Billings Gap Strikes Again! Another New Phytosaur Skull from this Historically Fossiliferous Area of the Petrified Forest

Billings Gap is a small valley on the east side of Petrified National Park between Blue Mesa and an unnamed mesa to the east. Triassic vertebrate paleontologists familiar with the area know that historically Billings Gap contains very fossiliferous beds of the Blue Mesa and lower Sonsela Members. Starting in the 1920s groups from the University of California Museum of Paleontology, the Smithsonian, and the American Museum of Natural History have worked this area and come away with phytosaur skulls for their museum collections. When the National Park Service acquired a portion of Billings Gap in 2007 we explored the area the day the land ownership changed and were rewarded immediately with a partial skull, and a year later with a complete skull.

Hoping to have similar luck this year we headed into the Gap and were rewarded when Susan Drymala recovered the almost completely preserved skull shown below. The specimen is palate-side down and oriented obliquely in this photo with the snout directed to the lower right of the photo. The skull roof is still covered in matrix, but you can see the right side of the skull in this picture. This specimen, from the Camp Butte Beds of the Sonsela Member (sensu Martz and Parker, 2010), probably belongs to the genus Smilosuchus (sensu Stocker, 2010); however, we need to complete the excavation and get this thing prepared to test its taxonomic affinities.



While Susan was finding and uncovering this beauty, I was about a half mile away prospecting lower levels of the Upper Blue Mesa Member. I found a lot of bone, but was especially excited about the recovery of ornamented skull fragments and several vertebrate of what looks suspiciously like Doswellia. If so this would be a first occurrence of this taxon in the Petrified Forest area. Unfortunately I have no photos of the material to post at this time.

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