APRIL 2002
Hutchinson T rex Paper Out
Remember the talk that John Hutchinson from Stanford gave at the Field Symposium on May 12, 2001 about the locomotion of the T rex? Well, it is finally published in Nature with Mariano Garcia of Borg Warner and is causing a stir. They calculated that an adult 13,000 pound T rex would need leg muscles weighing 43% of its body mass in each leg to run fast. They compared it to a running chicken that needs a calculated 4.7% of its body mass in each leg to run fast. It has 8.8% that is more than enough. However, they feel that T rex can move fast enough to catch its slower prey. Evidence from the new theropod trackways in the U.K. show that a large theropod (smaller than T rex) can move at about 29 km/hr. Some paleontologists have suggested that T rex could move at 72 km/hr. and Hutchinson does not feel that is possible without much larger leg muscles. They found that it could have moved at a fast walk of about 11 mph. They applied the same principles to other dinosaurs and found similar results. With their less cursorial legs and feet and less hip mass, they would not be very speedy either. Tom Holtz, a proponent of a speedy T rex, is a supporter of this data at this point (until someone finds a faster trackway for a big animal or a better model), but Greg Paul (author of "Predatory Dinosaurs of the World") has some questions. Most agree that the smaller predatory dinosaurs were indeed built for speed. The question is about the big guys. There will be more on this in the future.
A Juvenile Alamosaurus from Texas
A titanosaurid sauropod Alamosaurus sanjuanensis was found disarticulated just below the K/T border in a floodplain. It is about half the size of the adult type and referred specimens. The bones were scattered and had various amounts of deterioration indicating that some had been buried sooner than others. They suggest that the animal was probably mired in the mud with its left side trapped since those parts are found. After death most of the parts of the right side were washed away. There were no bite marks or shed theropod teeth found. A key characteristic of this animal is its unusual ischium. It also lacks fusion between the centra and neural arches of the cervical and dorsal vertebrae indicating it is still a juvenile. They also have some elements from the limbs, including some that have not been found before. There have not been any other sauropods found at the end of the Cretaceous in southwest North America. It does appear to be most closely related to an unnamed one found in Brazil and to Neuquensaurus australis from Argentina. This is reported in the January 2002 issue of the Journal of Paleontology by Lehman and Coulson.
A New Crustacean Named Shackleton
Antarctica typically has a low diversity of biota, but a new conchostracan, branchiopodan crustacean named Cyzicus (Lioestheria) shackletonensis. It is named after the glacier named after the explorer we all know so well. These are Late Carboniferous/Lower Permian deposits. There are also ostrocodes found and trace burrows and tracks, and an unusual arthropod along with pieces of carbonized wood. The wood indicates that vegetation was nearby and there must have been enough sun and warmth for growth.
Modern conchostracans have a single season life span after hatching from an egg. This is because water is usually seasonal and eggs can be left on the substrate to hatch in water later. This may be helpful in determining the length of the seasons. They also form bands after shedding their shells about every three days. The C. (L.) shackeltonensis fossils have from 9 to 14 bands giving them a lifetime of from 27 to 42 days if it was similar to today’s species. They have about 100 fossils, many with part and counterpart.
K/T Asteroid Wiped Out Plant-Eating Bugs
Kirk Johnson from the Denver Museum and some Smithsonian colleagues have reported on what happened to the insects at the Cretaceous/Tertiary boundary by studying leaf fossils. There is a poor record of fossil insects but a good one of fossil leaves many of which show the damaging effects of plant-eating insects. They estimate a loss of 55 to 60 % of plant-eating bugs. Many of the fossils studied were from quarries in South Dakota from layers above and below the K/t disturbance caused by the asteroid in the Yucatan. They also determined that the generalists usually survived while the specialists dining on certain plants lost 70% of their numbers.
Dinotopia on TV in May
Sunday May 12 will see the debut of a new version of Dinotopia A Land Apart from Time based on a book by James Gurney that is a story of dinosaurs and people together (it is fiction). It will be on ABC and this will be the first of a series. It tells the story of the island of Dinotopia where gentle dinosaurs live successfully with humans.
Sereno in Boston – Furcula and Duck Croc
The BBC reports on fossil discoveries revealed by Paul Sereno at the American Association for the Advancement of Science (AAAS) meeting in Boston. He talked about the significance of the 110 MY old Suchomimus (spinosaur) furcula. Finding the earliest furcula or fused clavicles would help determine how it evolved and for what original purpose. In birds of course it is a flexible spring used in flight. Close to the spinosaur, Paul found a small 2 foot long adult dwarf crocodile with an unusual duck muzzle. It is broad and hangs out over the lower jaw with no interaction between the upper and lower jaw teeth. And its nostrils point forward instead of being on top of the skull indicating that it may have lived on river banks. It lived at the same time as the monster Sarcosuchus that was 40 feet long. There were five other species that were in between these two extremes. The fossils being found now may indicate that Africa and South America may not have separated until 90 million years ago. He also has more predatory dinosaurs from India and Africa from the Cretaceous in the publication pipeline. Paul also talked about his "Mesozoic lawnmower", Nigersaurus with its huge battery of 1,000 teeth. It was 145 feet long and 10 feet high and was there 100 MYA as angiosperms were just evolving and Sarcosuchus was hunting. Much more to come!
Karen Nordquist, ESCONI Paleontology Study Group
Featured Web Sites
Field Museum of Natural History
SVP Society for Vertebrate Paleontology
Return To Home Page | Return To Karens Komments | Go to Karens Komments March 2002
Last Updated 6/6/2002
Number Of Visitors Since 3/23/2005