Placerias Quarry Panorama

Here is a panorama of the area where the Late Triassic Placerias Quarry is located in the Chinle Formation near St. Johns, Arizona. Sharp eyes can pick out a red car at the quarry just left of center of the photo above the juniper trees. Historically this quarry is one of the most productive sites in the Chinle Formation, and has produced numerous skeletons of aetosaurs, phytosaurs, "rauisuchians", crocodylomorphs, dinosauriforms, and of course more than 40 individuals of the dicynodont Placerias hesternus. The limited exposures have made stratigraphic correlation of this site to other Chinle localities problematic; however, it is a beautiful field area.

Driving Through Desmatosuchus Country

I just recently had the opportunity to drive through western Texas. This area is known many for its flat plains, the Llano Estacado or'caprock'; however, the rivers of the area remove this resistant layer exposing the Permian and Triassic strata below.

White River badlands

It is from these strata that E. C. Case of the University of Michigan collected the type specimens of many Late Triassic archosaurs including the aetosaur Desmatosuchus spurensis in 1919. This specimen came from the breaks of the White (Blanco) River, more specifically at the crossing of the old mail route between the towns of Spur and Crosbyton.

Holotype specimen of Desmatosuchus spurensis in the University of Michigan Museum of Paleontology

Almost three decades earlier E. D. Cope and his collectors had recovered the partial skeleton of another aetosaur that Cope had named Episcoposaurus haplocerus in 1892. E. haplocerus and D. spurensis remained separate taxa unofficially (several authors including Camp, 1930 had suspected they were synonymous) until 1953, when Joseph Gregory formed the new combination Desmatosuchus haplocerus (the type of Epicoposaurus, E. horridus, = Typothorax). Thus the town of Spur lost their namesake taxon as a junior synonym.


Downtown Spur, Texas

Spur is a small town of just over 1000 people east of Lubbock. Because it is surrounded by the breaks of Dockum Creek to the north and east and the White River to the west it is nesled in low hills and woods and differs from many of the other cities up on the caprock. I've visited Spur twice now, once in 2001 and just recently. Why? Because of this:


This is a mural on the side of the local history museum, which tells the story of the area. Note the prominence of Desmatosuchus in the lower right corner. Here is a close-up.


Let's just say that outdoor murals of aetosaurs are rare, and to someone who has spent over a decade researching these animals and especially this taxon visiting the area where the original specimens were collected, the town D. spurensis was named for, and this spectacular mural, is a thrill (at least for me). I'm also glad that the town of Spur has officially gotten their fossil name back. Desmatosuchus haplocerus is a nomen dubium and thus D. spurensis has been restored as a valid taxon (Parker, 2008). One day I hope to get the opportunity to explore the badlands where Case worked. It would be an ultimate thrill to relocate and document the site where this amazing fossil was collected. If anyone knows where the old mail road crossing was please let me know.

REFERENCE

Parker, W.G. (2008). Description of new material of the aetosaur Desmatosuchus spurensis (Archosauria: Suchia) from the Chinle Formation of Arizona and a revision of the genus Desmatosuchus. PaleoBios 28(1): 1-40.