October 2001
Dates To Remember
October 20, 2001 (Saturday) will be the Mazon Creek Open House at the Elgin Public Museum. This is a chance to see many top private collections of Mazon Creek fossils and to hear speakers talk about them. If you are a member of Burpee Museum and receive their Museum Musings, they have an incorrect date of September 20 (Thursday) listed.
February 22 and 23, 2002 will be the Burpee Museum Out of the Rock Paleofest. The main speaker will be Bob Bakker and they are in the process of lining up others also.
"Evolution" on PBS in September
Mark your calendars. PBS will air a series titled "Evolution" an 8 hour series over September 24-27 (2 hours a night). It will include interviews and discussions of historical figures like Darwin. There will also be a web site and a companion text by Carl Zimmer and an educational outreach program. The web site is www.pbs.org/wgbh/evolution.
Field Museum News
Here is some recent news from research groups at The Field Museum.
One of the zoologists, Steve Goodman has been spending a great deal of his life living in Madagascar (most of the last 14 years). This island is fascinating because of the unusual life forms found nowhere else in the world. Of course, this holds true for its fossil life as well (as we all know). Now early next year Steve hopes to publish a comprehensive book (about 1,000 pages) called "The Natural History of Madagascar" through the University of Chicago Press. It will be a compilation of the work of 400 researchers from 20 countries and will include many graphics and color pictures. There are new species found there every day but many may be lost even before they are found if the island’s forests continue to be destroyed by the growing human population.
Rudiger Bieler, chairman of the zoology department has been spending a lot of time in the Florida Keys picking up seashells (just like some tourists I know – just ask Irene Broede). Back in 1995 there were 582 mollusk species known and they are now up to about 1,400 species known. Many of the new species are snails whose adult size is less than a grain of sand! These include the shells of worm snails that are considered ugly and are usually cemented to rocks. Mollusks are interesting because they have been around for about 500 MY, and they can be studied to better understand evolution and the ecology of the environment when they lived. There are now about 100,000 living species of gastropods (snails and slugs) and 30,000 species of bivalves (clams and oysters). Bieler has been involved in a long-term study with Paula Mikkelsen of the American Museum of Natural History in surveying the Keys to determine a baseline of what animals live where within the Keys.
Earliest Land Plants
An August 10 Science article by Daniel Heckman of Penn State et al pushes the date of land colonization by plants back to at least 700 MYA. Historically, it is thought to have happened about 450- 400 MYA when the first terrestrial plants and fungi appeared. They did this using a molecular approach studying gene sequences from 119 proteins from a variety of fungi, both aquatic and terrestrial. They found that the first land fungi may even have separated from aquatic fungi more than 1.3 BYA ago instead of 370 MYA ago as previously reported. Earlier gene work had placed their origin at about 600 MYA, and the oldest lichen fossils are only 400 MYA. The first fossil spore plants are dated at 520 MYA. However, some feel that these early spores are from higher level plants that would indicate that there were simpler plants out there before that date. The authors feel that this might help explain the sudden rise in oxygen and glaciation that occurred 650 MYA, but not all agree with his theory. And there are others that would still put more weight on the actual fossil record instead of the DNA data.
Dinosaur Noses
The cover of the August 3 Science showed the old and the new interpretation for the placement of the dinosaur nose. The article by Lawrence Witmer of Ohio University moves the nostrils of Diplodocus from the top of its face further down its snout. Historically, the sauropod nostrils were placed higher because they were believed to have browsed in deep water and this would facilitate their breathing under those conditions. That explanation doesn’t make sense now that we know that they stayed on land, but no one changed the position of the nostrils before. Witmer argues that the large nasal cavities can be estimated based on the large and numerous blood and nerve vessel scars and cartilage formation scars that can be found on some of the skulls. A forward nasal opening also would make better use of the large nasal passages that would improve smell and heat exchange (warming the air and cooling the brain). An opening further back on the skull would not make effective use of all the nasal area. In addition, he has studied 45 species of birds, crocodiles and lizards as the dinosaur’s closest living relatives. He found that they almost always have nostrils far forward in the nasal passage. He even shows a forward movement for the nostrils of our favorite – the T rex. He says that this would help them make better use the large bony nostril. Chris Brochu is quoted as saying "He’s looking at something that a lot of us took for granted and applying some common sense to it."
Bacteria inside Bacteria inside Mealybugs
You’ve heard of parasites living within other animals, but now there is a report even more complicated than that living arrangement. The July 26 Nature reports that they have found a bacterium that resides long-term within another bacterium like a capsule. These packages in turn reside within the strange mealybug. The capsules surround the nucleus of the mealybug cells filling most of the cytoplasm area of the cells. They do not know why this arrangement has happened and whether the internal bacterium is a parasite or is there on a mutual benefit situation. They know now that the bacterial capsule invades the egg of the mealybug to assure that it will be passed on to the next generation. This is the first clear documentation of such a living arrangement. This has implications for the evolution of all cells with nuclei. Some believe that the nucleus arose from one bacteria invading another.
New Madagascar Sauropod
A Stony Brook graduate student Kristina Curry Rogers found the new titan while working with David Krause and Cathy Forster. The skeleton is very complete (90%) for the Titanosaur that lived about 70 MYA. Its name is Rapetosaurus krausei (for a mythical giant of Madagascar and expedition leader Krause). The young animal measured about 26 feet long and weighed the same as an elephant. As an adult it might become 50 feet long. It had a long neck, short tail and long narrow snout. They have two skulls (the second is of an adult) that show the nostrils on top of the head. The teeth were pencil-like pegs for raking leaves. They also found bones from two other new dinosaur species not yet reported.
Neanderthals are a Separate Species
The cover of the August 2 Nature reports on a new study by Marcia Ponce de Leon et al that uses a new technique (computerized tomography) to study the fossil bones. They studied 16 partial Neanderthal skulls (from 6 months to several decades of age), 3 partial H. sapiens skulls (from a child, a teen, and adult) and 22 skulls of modern groups at various ages. The growth patterns vary early on in the development of Neanderthals and humans. The skull characteristics of Neanderthals, such as long flat braincase, protruding face and flat skull floor, develop within the first few years of life. To the authors these early variations indicate that they are morphologically separate species. Further validation needs to be obtained by testing the early ontogony stages of other hominid lines.
Other scientists admire the work done in the report but question whether it proves that Neanderthals developed differently from humans. The chief proponent of the opposite theory is Milford Wolpoff at the University of Michigan. He argues that you would need to study the changes in the same individual at different life stages (which is impossible for fossils) and that there are too few juvenile fossils of Neanderthals for a complete study.
New Early Hominid Ancestor from Ethiopia
The bones of 5 of the earliest hominids called Ardipithecus ramidus kadabba have been found in Ethiopia. They are being dated at 5.2 to 5.8 MYA. DNA studies have shown that the lineages leading to humans and chimpanzees diverged about 6.5 to 5.5 MYA, so these are very close to that time. Some dental features are unique to hominids and so these are believed to be on the hominid line. The holotype is a right upper jaw with teeth roots, with associated hand and arm bone pieces. Better known Ardipithecus hominids are dated about 4.4 MYA and include the famous Lucy. The area, that is now desert, was dense forest when Ardipithecus lived there. This raises the question of why they became bipedal. Many have thought that hominids became bipedal when they moved out into the savanna. This discovery questions the recent report of a new hominid species named Orririn from Kenya that is dated at 6 MYA. Its position is uncertain with thick enameled teeth more like apes. However, its leg bones do show it to have been bipedal. And the story of early man gets a new chapter. Stay tuned.
Karen Nordquist, ESCONI Paleontology Study Group
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