Nothing more symbolizes dinosaurs than the long necked sauropods, and for these creatures, the largest animals ever to walk on land, gigantism is their evolutionary claim to fame. Indeed, among the many dinosaurs exhibited in museums, none are more spectacular and dominating. They display exaggerated proportions from towering necks to whip lashing tails held together on colossal body supported by massive limbs. On exhibit, thunder lizards capture the imagination of the visitor in a way that is both humbling and thrilling.
This Diplodocus skeleton is visually the most spectacular dinosaur in our quarry. Its discovery is particularly exciting because it preserves the bones of the front limbs together with the mostly articulated skeleton. Diplodocus skeletons more than 50% complete are rare, and there exists only 6 adult skeletons known on exhibit all without associated forelimbs. Even the well-known Carnegie skeleton has reproduction forelimbs taken from the Houston skeleton (type of D. hayi). Our Sleeping Beauty is more than 90% complete - see osteographic reconstruction. Moreover, it is marvelously preserved without distortion, indicating that it was buried rapidly after death and before scavengers could tear it apart. This also represents the rare and more primitive species Diplodocus longus.
Therefore, the research potential of our specimen is excellent. The species of Diplodocus can now be reviewed in a comparative study.
NEW DINOSAUR DISCOVERY (download pdf)
The Dana Quarry has yielded magnificent dinosaur discoveries. One specimen, nicknamed “Twinky”, is particularly endearing due to its small size and exquisite state of preservation. Discovered in the spring of 2009, this new diplodocid is both the first complete specimen belonging to a young individual, and the only one to have preserved a nearly complete axial skeleton. There are no comparable specimens housed in museum collections quite like “Twinky”. In complete paleontological context, this outstanding specimen offers unique opportunities to study ontogenetic development in sauropods, as it is part of a rare population sample.
The bones of the skeleton are currently in the process of being jacketed in plaster and carefully removed from the quarry. Field observations taken from exposed bones indicate that the skeleton is approximately 80-90% complete, and if mounted free standing may reach an estimated 40-45 feet in length. The standing area the feet occupy may be less than 16 feet long, hence “Twinky” measures about half the length of an adult specimen from the same quarry.
The skull is preserved and probably the lower jaws, as well, but a more accurate description must await lab preparation of these very delicate cranial elements, which were not disturbed while in the ground. Several tiny teeth were uncovered besides a mass of thin bone about 8 inches long located beneath a section of caudal vertebrae, which provides a high degree of probability that the cranium is preserved.
Virtually complete sets of foot bones down to the claws, where also uncovered. The pelvic elements are also preserved semi-articulated. The limbs are preserved in near correct anatomical position. For example, the right hind limb (femur, tibia, fibula, and foot) is preserved in articulation folded immediately under the pelvis, in kind of squat position. The other limbs, including the complete scapulocoracoid and sternum sets, are similarly preserved in situ very close to the body, suggesting rapid burial after death.
The complete series of cervical, dorsal, sacral, and caudal vertebrae were found articulated without interruption. This important find allows, with certainty, identification of the exact number of elements in each vertebral group, thereby providing a template from which to compare other diplodocid fossils. This new information may also help to distinguish sexual dimorphism in Diplodocidae, possibly, by comparing the number of cervical vertebrae against the relative lengths and robustness in different individuals. Speculation, resulting from Dana Quarry recent finds, suggests the differences in cervical vertebrae may be gender related and not phylogenetic.
Interestingly, in the skeleton's death pose, the cervical vertebrae are flexed upward from the base where they meet the dorsals, however, the big, elongated neck elements are positioned in straight alignment. In contrast, the preserved position of the caudal bones are arched over and around the upper part of the body, suggesting that the tail, in life, can bend up and move much more freely than the neck. Comparisons from two other skeleton examples with articulated cervicals (“Probrontodiplodocus” and “Sleeping Beauty”) also from Dana Quarry, we can see that the anterior cervicals are more flexible, presumably to enable the head to look about independently, despite the restricted movement that exists in the rest of the neck. In this manner, the head and neck may have functioned similarly as in living giraffes, in increasing the ability to see completely around the body. In “Probrontodiplodocus” the cervical vertebrae from 1-9, the neural arches are undivided, which provides evidence supporting the functional forward movement of the neck. This condition is unique for Dana sauropods, and marks the most primitive condition known for Diplodocidae.
The caudal vertebrae preserves a virtually continuous chevron series exhibiting exact placement together with a diversity of shapes along the tail not seen before. The most interesting are the transitional chevrons located between the single club-shaped ones in front and the characteristic double beam types behind. In these chevrons, the anteroposteriorly expanded distal processes are formed downward creating distinctive arches. This assortment of chevron shapes along the tail length is reminiscent of the condition seen in some mammalian groups that have powerful prehensile tails, as in anteaters for example. Another noteworthy feature lies in the presence of four fused mid caudal vertebrae, possibly numbers C16-20. Fused caudal vertebrae are a characteristic Diplodocid feature found in many but not all specimens. The fusion of the mid caudal vertebrae may have acted the same way a bullwhip employed from a man’s arm responds by helping to transmit power and speed through the unique combination of rigidity and looseness of the tail. As far as the back as the turn of the last century, speculation concerning the fused caudal elements suggests that they may have acted to strengthen the tail when rearing into a tripod stance.
The partial axial skeleton of Diplodocus longus from Como Bluff, housed at the American Museum (Osborn1899), and the only other comparable example, is in most details different by comparison, despite the similar overall appearance. In the AMNH specimen, there are no fused vertebrae, and transitional chevrons are not deeply arched. The whiplash section of the tail is not preserved and cannot be compared.
Towards the end of the "Twinky" tail, after the 32nd caudal, the neural spines in the whiplash section of vertebrae suddenly change into simple, but robust, freestanding processes with a distinctive backward hook. These spines are without zygapophyses, and seem to have developed to provide added weight and strength to better control the free action in the whiptail. These hooked shaped neural spines may have helped to create a serrated edged along the tail, enhancing the flesh cutting ability of the tail during its use. In their sandstone matrix, these whiplash vertebrae are noticeably preserved spaced apart, indicating, that these elongated elements may have been held together by a tough but flexible tissue. The ends of these vertebrae seem be biconvex but matrix surrounding them prevents positive proof of this condition. Over a dozen whiptail vertebrae are present past the 32nd , but the exact number cannot be determined until complete preparation is completed. Thus, this extraordinary functional morphology in the tail region of these dinosaurs supports the presence of a capability more sophisticated than the side swiping tail defensive behavior of a monitor lizard or crocodile. In life, "Twinky", with a tail designed to slash flesh, may have had the capability to strike at a target with deadly accuracy.