Post by creature386 on May 25, 2013 16:31:02 GMT 5
I remember in the old carnivora times (by that I mean the times when I joined), there were many discussions about intervertebral discs in dinosaurs and if they would enlarge the dinosaur. Now, I have found that article:
B. M. Rothschild, R. A. DePalma, D. A. Burnham and L. D. Martin (2012) Anatomy of a Dinosaur – Clarification of Vertebrae in Vertebrate Anatomy
www.sps-ops.sps.co.in/WebDAV/attachments/AHE/12053/SharedPDF/r1_AHE_12053.pdf
I would now like to present the information shown there.
If you don't have enough time to read all, here the summary:
Let's now start with the rest. You know that there was a hadrosaur-mummy. Based on that mummy, intervertebral disks were suggested, who enlarge the animals length by 20%. Here now the problem:
The paper suggests no solid structure connecting the vertebra, rather an open joint space. For the study caudal vertebra (PBMNH.P.09.039) of the dinosaur Edmontosaurus collected in the Hell Creek Formation were used.
Results
What does this mean:
What do you think about that? Do you think intervertebral disks may be still plausible or do you agree with the article?
B. M. Rothschild, R. A. DePalma, D. A. Burnham and L. D. Martin (2012) Anatomy of a Dinosaur – Clarification of Vertebrae in Vertebrate Anatomy
www.sps-ops.sps.co.in/WebDAV/attachments/AHE/12053/SharedPDF/r1_AHE_12053.pdf
I would now like to present the information shown there.
If you don't have enough time to read all, here the summary:
The flat-end surfaces of dinosaur vertebral centra led to the presumption that intervertebral discs occupied the space between their vertebrae. A set of fused hadrosaur vertebrae allowed that hypothesis to be tested. The Tyrannosaurus rex responsible for this pathology did not escape unscathed. It left behind a tooth crown that had fractured. Fragments of that tooth were scattered through the intervertebral space, evidencing that there was no solid structure to impede its movement. That eliminates the possibility of an intervertebral disc and instead proves the presence of an articular space, similar to that in modern reptiles, but at variance with what is noted in birds. While avian cervical verte- bral centra appear to be separated by diarthrodial joints, the preponderance of their thoracic vertebral centra is not separated by synovial joints.
Let's now start with the rest. You know that there was a hadrosaur-mummy. Based on that mummy, intervertebral disks were suggested, who enlarge the animals length by 20%. Here now the problem:
Study of dinosaur mummies has as yet provided only limited glimpses of soft tissue structures (Lull and Wright, 1942; Manning et al., 2009).
The paper suggests no solid structure connecting the vertebra, rather an open joint space. For the study caudal vertebra (PBMNH.P.09.039) of the dinosaur Edmontosaurus collected in the Hell Creek Formation were used.
Results
Bony bridging joined two vertebrae, completely surrounding, but maintaining the interventricular space (Fig. 1). The intervertebral region was completely isolated from the surrounding matrix. The distance between the opposing surfaces of the adjacent vertebrae was 1.3 cm. Embedded in the vertebrae and surrounded by extensive growths of reactive bone was a tooth from the theropod dinosaur Tyrannosaurus rex. The latter was identified on the basis of size of tooth and its serrations (Smith et al., 2005). Healing of the vertebrae and the formation of reactive bone indicate that the hadrosaur survived for an appreciable amount of time after the attack. The tyrannosaur tooth had fractured in the attack, and parts were distributed throughout the space between the vertebral centra (Fig. 1). The end plates of the vertebral centra were unaffected.
What does this mean:
Presence of tooth fragments in the space between the vertebrae (that was completely isolated from the external environment by the reactive surrounding bone) could not occur separate in location from the embedded tooth, if an intervertebral disc were present. This is only explain- able by the presence of a joint space. The bone reaction occurred from the trauma of the tyrannosaur bite. This buried part of the fractured tooth within the surface, while the distal fragments were free to move within the joint space.
What do you think about that? Do you think intervertebral disks may be still plausible or do you agree with the article?
