25 June 2011

A major discovery

Posted by Callan Bentley

Visiting Butch Dooley and crew on a dinosaur dig in the Jurassic Morrison Formation on Wednesday morning, I did a lot of wandering around the area, dubbed the Two Sisters site. I noticed something in the sandstone at the top of one hillock, and thought it looked like a sauropod footprint:

(The depression is filled in with modern mud.)

I took a photo, and thought, I need to ask Butch if there have been any trackways reported from this site. I recalled seeing sauropod tracks in the Morrison at its type locality, in Morrison, Colorado, at Dinosaur Ridge. But there were other distractions at Two Sisters, so I strolled on, and then I noticed something else:

That’s three similar looking concave-up disks of sandstone, differentially weathering out from the silty matrix and sliding downhill. If these really are sauropod tracks, then perhaps the compression of the sand and mud under the dinosaur’s weight rendered the footprints more compact and resistant to erosion, so they stand up relatively tough and coherent, while the rest of the rock falls apart and erodes away…

Closeup portraits of all three:

The one at the top of the hill from the top…

…and from the side…

Butch blogged it up here, and though he’s not 100% sure, he seems to think I’m on to something! That would be pretty cool, from the point of view of my ego. Though I’m no paleontologist, I’m thrilled to potentially discover something previously unknown, and potentially significant.