A Short History
The Cedar Mountain Formation was originally described as the Cedar Mountain Shales in 1944 by William Stokes. A few battered dinosaur bone fragments were mentioned, but nothing identifiable. The first major discovery was made in 1964 by Lin Ottinger, who ran a rock and fossil shop in Moab. Lin was aware of the scientific importance of the find and reported the discovery to Jim Jensen of Brigham Young University (BYU). Jensen excavated the site located just west of Arches National Monument. It proved to be a partial ankylosaur skeleton.
The specimen and stratigraphy (study of the rock layers) were described in a Master’s Thesis by Norman Bodily at BYU in 1968, and later published the following year. Bodily called the specimen Hoplitosaurus after an ankylosaur first described from the Lakota Formation of the Black Hills in South Dakota. Bodily noted some similarities between the body armor, called osteoderms, between the two specimens.
At about the same time of Ottinger’s discovery, Carlyle Jones found some dinosaur eggshells in the Cedar Mountain Formation near Castle Dale on the west side of the San Rafael Swell. Jones also brought these specimens to Jensen’s attention, who eventually wrote a brief scientific paper on them in 1970.
A few years after Ottinger found the ankylosaur, he found another site high on the edge of a cliff north of Moab, Utah. The specimen consisted of only a jaw fragment with two teeth, but again Lin donated it to Jensen, who later named the specimen with Peter Galton as Iguanodon ottingeri, in honor of its discoverer. Jensen visited the site and discovered a lot of bone there. As a result, he had a narrow road bulldozed up to the site to make access easier. He called the site Dalton Well after the nearby former Civil Conservation Corps (CCC) camp and Japanese Concentration Camp. The quarry was worked for a year, then left until 1994 when it was re-opened jointly by Brigham Young University and the Museum of Western Colorado. It has been worked almost yearly since.
Ottinger also found a large, partial thigh bone, the femur, a few kilometers (a few miles) north of where he found the jaws. The bone was split down the middle and part was lost. However, what remained was eventually turned over to Jensen. He and Peter Galton included a description of the bone, as a hadrosaur, in the same publication naming Iguanodon ottingeri. Although I have long been skeptical of this identification, a new discovery north of Arches National Monument suggests that they may have been correct (see Dinosaurs of the Cedar Mountain Formation).
Another site containing dinosaur eggshell fragments was found by Steve Robison of the National Forest Service. The site was found in 1982, a few kilometers (few miles) from where Carlyle Jones had made his discovery. News of the discovery, as well as the eggshells found by Jones made their way to Karl Hirsch. Karl was a recognized expert of fossil eggs and he realized the importance of the discoveries. He told of these discoveries to Jeffrey Eaton, then a graduate student at the University of Colorado. In 1983, Jeff began to search the Cedar Mountain Formation along the west side of the San Rafael Swell. He found several sites of microvertebrate fossils. Such sites are accumulations rich in small bones and teeth ranging in size from one to 25 millimeters (an inch or less).
Microvertebrate sites are especially important producers of fossil teeth and tiny bones. When potential sites are found by crawling on hands and knees, the rock is shoveled into bags, then taken to a river or back to the lab. There, the rock is broken down in water and flushed through screening (window-screening or smaller) stretched across the bottom of wooden boxes. The sand, silt and mud is flushed through with water, leaving behind a residue of gravel and fossils. The fossils can then be picked out with tweezers.
All of Jeff’s sites were in the Mussentuchit Member and in the Dakota Formation. Although Eaton was primarily interested in the fossil mammal teeth, numerous dinosaur teeth were also recovered and these provided important clues about the types of dinosaurs present. Jeff published on the fossil mammals in a series of scientific articles.
A year after Jeff started prospecting in 1983, Mike Nelson from Kansas State University led a small crew to prospect the Cedar Mountain Formation along the west side of the Swell as well. He discovered additional microvertebrate sites and published on these with Eaton. Also during the mid- to late 1980s, Rich Cifelli, from the Oklahoma Museum of Natural History, began hunting for microvertebrate sites as well. Rich found numerous localities in the Mussentuchit Member south of the San Rafael Swell. These sites also produced numerous dinosaur teeth.
One of Rich Cifelli's microvertebrate localities west of the San Rafael Swell.
One important site found by Cifelli's crews is a Eolambia bone bed. The site has produced numerous bones of juveniles and subadults, many of which are lacking their joints suggesting that they were gnawed off by scavengers. The abundance of individuals of one species suggests that a herd had perished and the carcasses lay on the ground decomposing before burial.
In 1986, Caryle Jones, who had previously discovered dinosaur eggshell, reported dinosaur bones southeast of Castledale. The site was named the Long Walk Quarry and was worked by Frank DeCourten, then of the University of Utah. The site produced several partial sauropod skeletons in a cement-hard limestone. Work on extracting these specimens is still ongoing.
In the winter of 1990, Rob Gaston discovered a trail of bone debris down a cliff face just north of Arches National Monument. He followed the trail up to where bone was weathering out. The College of Eastern Utah began excavating there and soon uncovered a mass grave yard of different dinosaurs. Several thousand bones were eventually uncovered. The carnivorous dinosaur Utahraptor and the armor-plated Gastonia were later named by Jim Kirkland from some of the material.
A few years after Rob’s discovery, Ramon and Carol Jones discovered a site in1992 northwest of the San Rafael Swell. The site was worked by the College of Eastern Utah and produced a partial skull and skeleton of a large iguanodontid that was later named Eolambia caroljonesi by Jim Kirkland. The bones of the specimen were widely scattered, so Ramon, a radiological technician at the University of Utah, used an instrument that measures radiation, called a scintillometer, to try to locate more of the specimen hidden below ground. He found several "hot" spots that did produce more of the iguanodontid, but also the scattered remains of a new nodosaurid that was later named Animantarx ramaljonesi. Fossil bones commonly have low levels of radiation, which gets leached out of volcanic ash.
In 1995, Jim Kirkland, then of Dinamations International in Fruita, Colorado, asked me to tour the Cedar Mountain Formation with him. He had been helping Don Burge and John Bird of the Prehistoric Museum at the College of Eastern Utah. I had just finished a five year project in the Morrison Formation near Canon City, Colorado, and was seeking a new research project. The results of that tour convinced me that there was much work to be done with the Cedar Mountain Formation. I brought a small crew that September for a one week reconnaissance trip. I have been back with my volunteers about twice every year since. Jim turned over an ankylosaur site he found in the Poison Strip Sandstone, which we named Jim’s Ankylosaur. It is probably the same species that Bodily described in 1969, but is a few kilometers (few miles) north.
In our work in the Cedar Mountain, rather than rely upon the chance discoveries of rock hounds and fossil hobbyists, I used the same approach as I did in Canon City. We began a systematic search beginning near the Colorado-Utah border and have over the years followed the Cedar Mountain outcrop westwards. In the process, numerous new dinosaurs were found and many of these were described and named by my volunteers. Our work is on-going (see Canteen and Boots: Digging for Dinosaurs) and will continue for many more years. The Cedar Mountain outcrop belt extends for 370 kilometers (230 miles) and to date we have prospected about a third of that.
One of our first discoveries in 1996, was Billy’s Sauropod, found by Billy Kinneer about in the middle of the Yellow Cat Member. The specimen, a partial skeleton, was later named Cedarosaurus weiskopfae meaning "[Carol] Weiskopf’s Cedar [Mountain] reptile"; Carol was one of my volunteers who had worked at Billy’s Sauropod, and was later tragically killed.
My volunteers working at Billy's Sauropod (that is Billy at the far left).
This sauropod discovery was followed two years later by the discovery of Tony’s Bone Bed in the Poison Strip Sandstone by Tony DiCroce. This site produced another new sauropod that we named Venenosaurus dicroce, or "DiCroce’s Poison [Strip] reptile", as well as a new iguanodontid we named Planicoxa venenica, or "flat-hipped reptile from the Poison [Strip]."
One of our largest sites, Lorrie’s Site found by Lorrie McWhinney, is a mass grave yard primarily of a single species of dinosaur. Such mono-species bone beds as they are called, are important indicators of herding by some species. The dinosaur is of a new species of the ankylosaur Gastonia. It has not yet been named because we are still working the site, which is located near the base of the Ruby Ranch Member. Thus far almost three-thousand bones have been excavated representing perhaps 20 individuals. The site is huge, covering over 600 square meters (2000 square feet). Thus far only a part of that has been excavated (see Canteens & Field Boots for pictures of the work). Allen Shaw, formerly of Brigham Young University, studied the site to try to solve the mystery as to why so many individuals of Gastonia died here.
One of our most fortuitous discoveries was a partial skeleton found near our camp. David Gilpin found what may be the oldest hadrosaur, or duck-billed dinosaur, in North America. A scientific description was published in 2007.
Several smaller sites have been discovered by my crews farther west, near Green River, Utah, including the first sauropod skeleton in the Naturita Sandstone. One important new site was discovered around 1998 by amateur fossil collector, Larry Walker, at the base of the Yellow Cat Member. The site is currently being excavated by the University of Utah and Jim Kirkland. At least two different dinosaurs occur at the site, including a new species of a small carnivorous dinosaur known as a therizinosaurid (see Dinosaurs of the Cedar Mountain).
Although dinosaurs from the Cedar Mountain Formation have been known for almost two decades, only since 1990 has serious attention been paid to them. This research by numerous individuals and institutions is still in its early stages, but some preliminary results have already shed some light on the Dinosaurs of the Cedar Mountain Formation.
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