New Material from the Type Specimen of Megalneusaurus Rex (Reptilia: Sauropterygia) from the Jurassic Sundance Formation, Wyoming
Abstract: In 2008, an articulated distal forelimb of the type specimen of the large pliosauromorph Megalneusaurus rex (UW 4602) was discovered adjacent to the original excavation pit from which two hindlimbs had been collected in 1895.
The molding and casting facility at the Wyoming Dinosaur Center allows staff to readily create detailed reproductions of fossils. These casts are both lighter and more stable than the original bone. In many cases, especially for the largest dinosaurs (the sauropods), the bones are so huge and heavy that they cannot be placed on display safely. Thus, copies of those bones must be created in order to display these massive animals in all of their glory.
Within the Wyoming Dinosaur Center museum, we have our very own preparation lab, specifically designed to accommodate as many as 13 people at a time. Once bones are moved to the lab, preparators are tasked with choosing the best tools to remove unwanted matrix.
Projects start with micro jackhammers, air chisels, and dental tools, while more detailed work can be accomplished under the microscope using drills so small they can remove only a single grain of sand at a time. Cleaning a fossil requires great patience and skill as this is an extremely slow and tedious process. These bones have never before been seen by any other living being. To make sure they survive to be seen by as many people as possible, we must pay the utmost attention to detail. Sometimes, the bones are too fragile to be worked on as is and glue must be used on the surface and in cracks to further stabilize the bone before the matrix can be removed.
The second step in the Wyoming Dinosaur Center discovery process is digging and unearthing dinosaurs. The techniques used today have not changed since the late 1800s. Technologic advances have made mapping and record keeping at the site much easier, but the shovel and pickaxe can’t be beaten.
Shovels are used to remove the soft overburden and pickaxes are good for breaking through the hard sandstone layers. When the first bone is spotted, further work becomes much more tedious. Small hand tools like oyster knives, dental picks, and paint brushes to remove matrix from around the bone. With everything that we do, we are constantly watching for new bone fragments, using glue to make sure nothing is moved out of place prematurely. Once a bone is exposed enough to be removed, it is covered with a thick layer of plaster-soaked burlap strips. This creates what is known as a field jacket which allows the bone to be removed without fear of it falling apart while being removed from the site. After it is removed the bone is taken to the museum where it will be cataloged and placed in storage.
Each field season we regularly excavate at 5 or 6 dig sites, removing more than 100 bones every summer. WDC quarries have produced Allosaurus, Camarasaurus, Diplodocus, and Apatosaurus bones. In addition to our dinosaur sites, the Warm Springs Ranch, also possess marine deposits full of Belemnites, Oysters, Clams, and even the occasional marine reptile. Staff have even found what could possibly be a coprolite site. That’s right, fossilized dinosaur poop!
165 million years ago, Thermopolis, Wyoming was covered in a shallow ocean called the Sundance Sea. This was a shallow, inland sea that extended across parts of the North American Continent during the Middle to Late Jurassic Period. Evidence suggests that this deposit was created by a series of events that caused the ocean to progress and regress repeatedly across the continent.
Above the Sundance Formation lies the Morrison Formation, deposited roughly 150 million years ago. This distinctive sequence of sedimentary rocks has been among the most fertile sources of dinosaur fossils in the entire world. It is within this formation that the Wyoming Dinosaur Center staff focuses their search for fossils. Finding new places to dig is the first step in the paleontological process and it takes both keen observational skills and patience. One thing out there to help us is erosion which exposes new material every year. Over the past 24 years, WDC field technicians have found and identified over 130 dig sites on the Warm Spring Ranch.
“The “Thermopolis Specimen” was discovered in Bavaria, Germany, and has the best-preserved skull and feet of the twelve Archaeopteryx specimens found to date. However, most of the neck and lower jaw have not been preserved.
The “Thermopolis Specimen” was described by Mayr, Pohl, and Peters in the December 2, 2005 Science Journal. The description shows that the Archaeopteryx lacked a reversed toe, a universal feature of birds, limiting its ability to perch on branches and implying a terrestrial or trunk-climbing lifestyle. This has been interpreted as evidence of theropod ancestry. In 1988, Gregory S. Paul claimed to have found evidence of a hyper-extensible second toe, but this was not verified or accepted by other scientists until the “Thermopolis Specimen” was described and published. Until recently, the feature was thought to belong only to the species’ close relatives, the Deinonychosaurs.
The “Thermopolis Specimen” was assigned to Archaeopteryx Siemensii in 2007. The specimen is considered to represent the most complete and best-preserved Archaeopteryx remains yet. Most of the twelve specimens discovered and scientifically described include impressions of feathers, which make Archaeopteryx a clear candidate for a transitional fossil between birds and dinosaurs. Because these feathers are of an advanced form (flight feathers), these fossils are evidence that the evolution of feathers began before the Late Jurassic.”
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