Sunday, June 3, 2012

Summer at Petrified Forest National Park

I have once again arrived at Petrified Forest National Park (PEFO) for the summer, doing paleontological field work with Bill Parker and several others. This year, we will be prospecting the new tract of land that was added to the park as well as reopening the Revueltosaurus quarry.

Shortly after leaving the park last year, it expanded by 26,000 acres through the purchase of the Hatch Ranch. This area encompasses a large area to the east and northeast of Blue Mesa (including Ninemile Wash) as well as a smaller area to the west (view park map). Most importantly, it includes strata of the Chinle Formation that are not exposed in the rest of the park, increasing the potential for important finds in the park. I got to spend some time in the expansion area last summer and it is definitely a great resource for paleontologists. This summer, we will start to explore these lands for vertebrate fossils.

Hatch Ranch - Expansion Area (2011)

Bill Parker was quoted as saying the following in the NPS news article about the expansion of the park:

Revueltosaurus quarry 2012
Historically the park has been expanded south to north, while the main resource rich exposures run east to west. Acquisition of these lands by the park brings some of the most fossil rich areas into the park for protection and future paleontological research. The fossils on these lands will add greatly to our understanding of life on earth during the Late Triassic and provide research opportunities for years to come.-Bill Parker, paleontologist, 2011.
The Revueltosaurus quarry was discovered in 2004 in the north end of the park, not far from Lacey Point. Bill Parker and crew found several bones weathering out of the side of a hill, which upon further investigation, revealed multiple in situ individuals of what they later discovered to be Revueltosaurus callenderi. Revueltosaurus was originally described by Hunt (1989) based on several isolated teeth from New Mexico. It has long been thought to be an ornithiscian dinosaur, but the skeletons found by Parker et al (initially discussed by Parker et al 2005) places these animals squarely in the pseudosuchian side of the archosaur tree. Furthermore, Nesbitt (2011) was able to place Revueltosaurus as the sister taxon to aetosaurs.

Reconstruction of R. callenderi by Jeff Martz, winner of the 2011 Lanzendorf PaleoArt Prize in Scientific Illustration

The quarry was closed in 2006 after recovering material from at least 8 individuals, but there was evidence that more bone was still there to be found. This year, Bill Parker, Bruce Bailey, and we interns are reopening the quarry. Overburden has already been removed and we have just begun excavating. Things are looking promising already; as of yesterday, we have begun to uncover bone in 3 different areas of the quarry. Bill Parker found the first bone - an osteoderm and vertebra (pictured to the left, top) - while Franceska (a.k.a. Frankie) found several elements fused together while slowly removing overburden towards the middle of the quarry (pictures to the left, bottom). I started trying to remove rock from the quarry floor to get down to the level where Frankie found her bones and ended up running into several vertebrae and a rib. 

This should be a pretty great field season.

Parker, W. G., R. B. Irmis, S. J. Nesbitt, J. W. Martz, and L. S. Browne. 2005. "The Late Triassic pseudosuchian Revueltosaurus callenderi and its implications for the diversity of early ornithischian dinosaurs." Proceedings of the Roayal Society B 272: 963-969

Hunt, A. P. 1989 A new ornithischian dinosaur from the Bull Canyon Formation (Upper Triassic) of east-central New Mexico. In Dawn of the age of dinosaurs in the American Southwest (ed. S. G. Lucas & A. P. Hunt), pp. 355–358. Albuquerque, NM: New Mexico Museum of Natural History.

Nesbitt, S. J. 2011. "The Early Evolution of Archosaurs: Relationships and the Origin of Major Clades." Bulletin of the American Museum of Natural History, Number 352