1O257LF

More documents

Recommendations

Info

© 2010 Dinosauria International Ten Sleep Report Series No. 1 “Einstein” received its nickname when it was discovered that the braincase was preserved along with the rest of the skeleton. “Einstein” is also one of the three skeletons in the Dana sample found in direct association with its skull representing a typical Apatosaurus morphology. In addition to the braincase, several other cranial elements comprising “Einstein’s” skull include both quadrates, a left maxilla displaying unerupted dentition in their respective alveoli, isolated teeth, and several indeterminate bone fragments. Although the skeleton was not entirely articulated, it was isolated, and its bones were distributed short distances from one another (Fig 17). A summary list of DQ-EN bones recovered is as follows: brain case, both quadrates, a section of the left maxilla, 14 teeth; twelve cervical and ten dorsal vertebrae; ten cervical and sixteen thoracic ribs; five sacral vertebrae; caudal vertebrae C 1– 30; nine anterior chevrons; both ilia, pubes, and ischia. Appendicular skeleton include: both scapulae, coracoids, right sternum, six partial sternal ribs and right humerus; right and left femora, tibiae, fibulae and astragalii; left pes preserving metatarsals 1 and 3 - 5, one isolated phalanx, and 1 st & 2 nd claws. The plaster jacket (A147) containing the cranial elements weighed more than 5,000 pounds – contained in that block were the pelvis, left hind leg, seven cervical vertebrae, dorsal vertebrae D2 and D3, three caudal vertebrae, chevrons, and a complete dorsal rib. Thus, the association of the skull with the skeleton is indisputable; its discovery was made in the lab, in this large block, within the main mass of the skeleton, tangled between the bones of the hindquarters (Fig 17 D) . The postcranial skeleton is approximately 70-80% complete. In its overall size, 21.64 m. (71 feet), DQ-EN is approximately 10 -15% smaller by comparison with the mounted specimen at the AMNH, but is exceedingly more complete. DQ-EN is especially intriguing, because we can interpret many of the differences between it and the other Dana specimens as part of observable sexual dimorphism in Amphicoelias “brontodiplodocus”. Except for the overall skeletal robustness and development of massive laterally expanded cervical ribs, there exist few features not associated with ontogenetic or individual variation separating DQ-EN from the other Dana Quarry individuals. In other words, there is little reason to suspect that DQ-EN is a different species from the rest of the sample preserved. Reasons to suspect the presence of another species is greatly diminished by the DQ-PC skeleton, which has a complete skull and a better articulated postcranial skeleton. The most critical dimorphic feature in DQ-EN is the hypertrophic development of the cervical ribs, which expand the neck skeleton outward in a unique fashion. We speculate that this immensely broad neck was used in life, for the purpose of bearing down on the female’s neck, using its stronger construction together with the greater body weight for the purpose of subduing its mate during copulation. Reinforcing this idea are the low neural spines and narrow overall width of the cervical ribs in specimens we consider female (DQ-BS and DQ-SB), which appear to be designed specifically to under-fit with those of male neck vertebrae like the ones we see in DQ-EN and DQ-PC. The limbs in DQ-EN are typically apatosauroid in morphology. In order to bear the added weight, the limbs assume massive proportions. The humerus is distinctly broad at both ends, while the femur is also broadened transversely. “Einstein” is the first Dana Quarry dinosaur that has been reconstructed and mounted in a freestanding lifelike pose. In the summer of 2008, “Einstein” made his public debut at the Abu-Dhabi International Airport where his spectacular skeleton went on exhibit (Fig 17 B). The unveiling caused a media event and, for several months, DQ-EN was a major attraction that amazed and thrilled thousands of visitors at the airport; many had never seen an actual dinosaur skeleton before in their lives. Today, “Einstein” has a good home in Mexico, where it will be the centerpiece in a forthcoming museum planned to celebrate the first National Museum of Natural History of Mexico. DQ-PE = “Prince”, Fig 18, and 28B During the preparation of this manuscript in 2010, another remarkable skeleton was discovered immediately next to Sleeping Beauty (DQ-SB), hence “Prince Charming”. The skeleton representing DQ-PE is complete with an exceptionally well-preserved skull and lower jaw. This skull was found at the end of the anterior cervical series. The exact number of cervicals will remain unknown until the large blocks can be prepared. This skull is massive and much larger than that of “Einstein”. It is nearly 20% greater in overall proportion, e.g., the transverse width of the occipital condyle is 46 mm and in DQ-EN it is 37 mm, thereby providing another large male for comparison. The skull is buried with its rostrum pointing downward and a series of articulated anterior cervicals can be seen immediately behind the braincase. Numerous displaced teeth (Fig 18 b) can be seen concentrated on one side of the skull. Due to their proximity, these may belong to the lower jaws. The posterior cervical vertebrae, tentatively identified as C 13-15 with dorsals 1 & 2 attached, are massive elements rivaling the largest known specimens from the Morrison. On these cervicals, the ribs display primitive features, massive and long prominent anterior processes. The posterior cervicals are well preserved and mostly articulated, so we have, for the first time, the opportunity to study this osteological aspect in what we consider to be a male example. Numerous long bones are preserved without distortion and are dimensionally comparable to the type of Apatosaurus louisae, 26
Amphicoelias “brontodiplodocus” Galiano and Albersdörfer e.g., the humerus length in A. louisae is 114.80 cm (45.19 inches) and in DQ-PE it is 106.68 cm (42 inches). DISCUSSION Our initial attempts to identify the new Dana skeletons were frustratingly difficult, largely and ironically, due to their extraordinary completeness. The Dana Quarry specimens represent a sizeable collection of nearly complete skeletons many with associated crania of which there are few published skeletons of equal completeness to compare to. However, it should be noted that the skeletons of Apatosaurus louisae (Holland 1915) and Diplodocus hayi (Holland 1924) are by far the most complete and comparable published examples. Both these specimen are unfortunately freestanding mounts on public exhibition making examination difficult. There are, however, a few disappointing features in the Apatosaurus louisae specimen worth mentioning. The most notable are the damaged posterior cervicals, which prevent relative size comparisons to be made in the sequence of those vertebrae. The post-cranial skeleton belonging to Diplodocus hayi is in need of a detailed description as it is uncertain the extent of reconstruction that was performed for the purpose of completing the mount, and whether the cranium and whiptail section of vertebrae described by Holland (1906 and 1924) were discovered in direct association with the skeleton. Past informal reports by Dinosauria International had originally, for the sake of convenience, referred the present material to the “established” genera Diplodocus and Apatosaurus. This was done in an attempt to avoid adding further confusion to the current taxonomic state of affairs. However, the traditional method of using previously described and accepted material as a guideline for comparison had the opposite effect - it produced numerous inconsistencies and more confusion. The traditional approach in the interpretation of this new fossil evidence would have provided us with two new species to add to the Morrison list of sauropods. Instead, we employed a novel approach by attempting to fit previously reported Morrison fossils within the context of the A. “brontodiplodocus” sample. The results are astoundingly radical compared with previous studies, but not surprising when considering the historical rate of invalid dinosaur taxa, which exceeds 50% due to the poor quality of materials (Benton 2008). Comparisons show that most characters used to distinguish various diplodocid taxa were found within the Dana sample, allowing an excellent opportunity for taxonomic re-evaluation. Hidden by the complexities of taxonomic over splitting, sexual dimorphism, ontogeny, and variation in sauropods have largely gone unrecognized. Over seventeen diplodocid species have been proposed from the Morrison since the bitter feuding days between Edward Drinker Cope and Othniel Charles Marsh. Unfortunately, many of the type specimens are based on fragmentary material, and many of the exhibited skeletons representing these species are unassociated composites. At present, roughly twelve species dispersed within six genera are recognized as valid. Considering the remarkably close morphology uniting these taxa, the number seems unrealistically high for such huge animals restricted to a relatively small time period. Amazingly, most of these recognized genera occur together, and studies exploring the possibility that sexual dimorphism or ontogeny may explain the differences, have not been attempted. Given that the paleontological assessment of the Morrison Formation is over 120 years old, a re-evaluation is well overdue. A census of significant specimens is listed in Table 2 to demonstrate the paucity of diplodocid skeletons that are more than 50% complete. Amphicoelias (Cope 1877) The holotype material of Amphicoelias altus, AMNH 5764, consists of two dorsal vertebrae, an incomplete pubis and one femur (Fig 19). These bones were collected at a high level in the Morrison Formation in Quarry 12 at the Garden Park area in Colorado. The tall neural spine and other features are diagnostic, and together identify, without question, the dorsal vertebrae as belonging to the Diplodocidae (Osborn and Mook 1921, McIntosh 2005, Carpenter, 2006). The type femur is also a diagnostic element displaying typical diplodocid features - elongation, reduced trochanter and a rounded mid shaft cross section. This elongated femur morphology is a shared derived character present in many specimens including the types of D. hayi, D. carnegii, and the USNM D. longus. The dorsal identified as D 6 and pubes belonging to the type are unfortunately fragmented and do not help establish additional characters of taxonomic value beyond diplodocid level. However, reexamination of the posterior dorsal reveals critical determining characters. Fig 11 F View of sacral spines and ribs belonging to DQ-TY Resolving the correct position of the type vertebra is crucial in extending comparisons with other specimens. 27
Page 1 and 2: Amphicoelias "brontodiplodocus" A N
Page 3: Amphicoelias "brontodiplodocus" A N
Page 7 and 8: Amphicoelias “brontodiplodocus”
Page 31: Amphicoelias “brontodiplodocus”
Page 57: Amphicoelias “brontodiplodocus”
Page 60: © 2010 Dinosauria International Te

1O257LF

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?