E.S.C.O.N.I.

It’s time to talk about dinosaurs again! There is a lot going on now and this is some of it. The new issue of the Journal of Vertebrate Paleontology (April 17, 2000) has a lot of dino articles that I will summarize here.

Chris Brochu of the Field Museum writes about the CT (high resolution computed tomographic analysis) scan done on SUE’s skull. Previous T rex skull studies had involved sawing the skull causing irreparable damage. This technique does not damage the fossil. It revealed details of the inner ear, and nerve and vascular pathways within the skull. It also assisted the preparators in their work as it revealed the presence of fossil material still hidden in the matrix. They found an endocranial volume to be 28.2 cm long with olfactory bulbs that were about 20 cm long. The large olfactory bulbs indicate a very good sense of smell. The 12 cranial nerves and two optic nerves are visible. The right stapes was the first ear bone ever found in a T rex. The real SUE skull is now on display at the Field Museum as it was found.

A new troodontid theropod based on two adult specimens from the Cretaceous in Mongolia is described by Mark Norell et al. It has been named Byronosaurus jaffei after a supporter of the expeditions that found the bones. These dinosaurs are thought by many to be the closest relatives to birds. Seven of eight species of this animal come from Asia. Two characters in the skull of this animal are shared with birds and not with other theropod dinosaurs. These are the fact that their teeth are not serrated and the fact that they have a secondary palate. This new species adds to the information about these little known theropods.

Finally, there is the report on the biggest sauropod found to date, which has been called Sauroposeidon proteles. This is based upon four articulated neck vertebrae found by Richard Cifelli et al from the early Cretaceous of Oklahoma. Comparing these bones to those of the known Brachiasaurus skeletons shows that this new animal was much larger. The detailed study of these four bones showed distinct differences between them and Brachiasaurus justifying the new species and genus name. Both animals did show the tendency for a slight S curve shape between the 6^th and 7^th vertebrae. The cervical ribs were also preserved and were quite remarkable in that they extend under the two following centra with some spaces where there are three ribs on top of each other. These appear to be the last of the giant North American sauropods and represent the longest and lightest of their necks.

Jack Horner et al have completed a detailed study on representative bones of many Maiasaur bones. Because so many skeletons of all ages of this duckbilled dinosaur have been found, it was a good animal to use for a growth study. The bones were sampled both crosswise and longwise. They identify 6 stages of growth based on changes seen in the bone structure; small nestling, large nestling, small juvenile, large juvenile, subadult, adult. The patterns showed that nestlings grew at a very high rate, juvenile and sub-adults grew at moderate rates and adults grew at low to very low rates. They estimate that nestlings would have lasted for one to two months, late juvenile age would be reached in one or two years, and adult size would be reached in six to eight years. The bone patterns show similarities to other dinosaurs, pterosaurs and extant birds and mammals. They are unlike those of living non-avian reptiles. LAGs or lines of arrested growth do not appear until the later sub-adult and adult stages, and do not appear to be a reliable way to determine age. In addition, bones from different parts of the body show some variation in the LAGs found. They conclude that looking at the bones of living reptiles is not a valid way of interpreting the growth patterns of dinosaurs. Jack also uses this information to propose that some dinosaurs took care of their young at least for a while.

Australian researchers have found evidence of the gut contents (cololites) from an early Cretaceous ankylosaur called Minmi. Of course for years coprolites have been studied to help determine the diets of dinosaurs. However, there can be a question as to which dinosaur it came from. The cololites are still within the animal so there isn’t the question of possession. The articulated skeleton was found within a nodule indicating little disturbance except some flattening. There are plant remains over about 10% of the surface with seed material found as well. There were no gastroliths found. It was found in a marine environment that lowers the possibility of introduction after death. Stomach contents from mummified hadrosaurs in Canada have been questioned for that reason. If real, this would verify that some ankylosaurs were herbivorous and that they were cutting off the leaves with a sharp beak or teeth rather than breaking them down with gastroliths. They may also have had cheeks so that they could cut them down in the mouth to the small size pieces found in the cololite.

And the really hot news in the dino world is the discovery of a dinosaur heart that was reported in the April 21 issue of Science by Dale Russell et al. This has shaken the paleo world and some think that it proves that at least some dinosaurs had high metabolic rates. Many paleontologists are skeptical that this is indeed a heart and are reserving judgement without seeing the actual specimen. The heart was found in the chest of a Thescelosaurus specimen (an ornithischian not believed to be ancestral to birds) discovered in the Hell Creek Formation (late Cretaceous) in South Dakota. It indicated a four-chamber organ with one major aorta. They say that this heart is like a bird’s and that it further supports the theory that dinosaurs had an advanced heart. However, they could not say when the heart developed in the dinosaur line and whether it arose once or more than once. This will be debated for a while to come. In the meantime, this dinosaur named Willo has his own website at www.dinoheart.org.

Finally, after over two years of work, the largest and most complete T rex ever found was unveiled ceremoniously at the Field Museum. I was very fortunate to be there and found it to be thrilling to see her in her glory. Because the skull is so heavy and is deformed, it was decided to mount it separately on the second floor. Now people can see it very closely at eye level. It is easier to see the bones, teeth and damage done when it was buried. The reconstructed skull cast on the skeleton looks more like the animal when it was alive. In addition, there are copies of the furcula (the controversial wishbone), the right arm and part of the tail that can be seen closely and touched. Another part of the exhibit displays the gastralia which were not mounted. These are the stomach ribs that would have been embedded in muscle. Since they were not directly attached to the skeleton it is not known exactly how to add them to the mount. Therefore, the decision was made not to mount them at this time. There are also displays discussing the theories about SUE and what we have learned about her so far. Another new exhibit at the Museum displays part of the dinosaur art collection of John Lanzendorf. It includes many of his sculptures and paintings from well known paleoartists and is set up like a comfortable living room. Many of these pieces are to be found in his new book "Dinosaur Images", which is a must for those interested in Dinoart.

      Karen Nordquist, ESCONI Paleontology Study Group

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