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Review: National Forum's Digging Dinosaurs
The National Forum, the journal of the Honor Society of Phi Kappa Phi, publishes four times each year issues that cover a wide range of topics. Some recent issues concentrate on each of the following topics: Poverty in America, Excellence in Education, Gender and Equity, Writing History, and Aging America. The Summer of 1998 issue has the title of "Digging Dinosaurs." The Editor, James P. Kaetz, explains that the title is a pun: "This issue is literally about digging dinosaurs - finding fossils, preparing them, wresting from the bones their secrets. But on another level, it is about digging dinosaurs in time-honored Beat meaning of the word: enjoying all there is to know abut one of the most successful species in earth's long history."
Seven working paleontologists wrote the articles of this issue. Kevin Padian, Professor of Integrative Biology and a curator in the Museum of Paleontology, University of California, Berkeley, explains "How to Collect and Identify a Dinosaur. Jane Mason, a senior preparator at the same Museum in Berkeley, wrote "From Picks and Shovels to Pins and Needles." Karen Chin of the U. S. Geological Survey provides insights "On the Elusive Trail of Fossil Dung." She recognizes that fossilized feces provide a unique record of animal activity, not available from skeletal fossils.
The first article in this issue reveals a new way to interpret dinosaurs in the controversy between those who believe dinosaurs are overgrown "reptiles" and those who find them as the predecessors of birds. John R. Horner, Curator of Paleontology at the Museum of the Rockies in Bozeman, wrote about "Dinosaur Behavior." He is able to conclude that some dinosaurs behaved like modern birds in caring for their young. The evidence comes from nest-like structures discovered near the tiny town of Bynum, Montana. The remains of post-hatchlings nestlings were found in two of the nests. The partial skeleton of a Troodon sitting of a clutch of eggs has been discovered. An artist's reconstruction of this scene is on the cover of this issue of the National Forum.
Most of the articles deal with interesting interpretations that are often controversial. David J. Varricchio , Curator of Paleontology at the Old Trail Museum in Choteau, Montana, contributed an article with the title "Warm or Cold and Green All Over." He observes that over the last twenty years, biologists and paleontologists have largely switched from traditional classification to one based on evolutionary relationships, i.e., to phylogenetic systematics. Recent classification shows dinosaurs are between their cold-blooded crocodilian cousins and their warm-blooded bird descendants. Dinosaurs could have been warm-blooded or cold-blooded or something in between. The recent discoveries of brooding by the dinosaurs Oviraptor and Troodon imply body heat to raise the temperature of the eggs above that of the environment. Several groups of dinosaurs occupied latitudes to possibly as far as 80( away from the equator. The drastic seasonal changes in day length of these high latitudes would present a sever environmental challenge to cold-blooded species. These latitudes exceed the latitudes of cold-blooded contemporaries.
Dale A. Russell is a curator at the North Carolina State Museum of Natural Sciences. He wrote "Dinosaurs and the Concept of Fitness." Fitness describes how well suited is a species to thrive in an environment. Evidence shows that dinosaurs that came later through the 165 million years of their existence, had larger brains, longer legs, larger eggs, more rapid growth shortly after birth, and better teeth. Body size diminished from the near the middle of the dinosaurian era to the end. This pattern would be consistent with higher metabolic rates. The data suggests that dinosaurs were not nearly as fit as modern mammals and birds. Modern organisms would destroy a Jurassic Park. Russell believes that at the middle period in their evolution, dinosaurs were more reptilian than mammalian or avian.
J. David Archibald, Professor of Biology at San Diego State University, summarizes the three best theories of extinction of the dinosaurs in his article "Death, Taxes, and Extinction." Among the eighty dinosaur-extinction theories, only three ultimate causes seem well enough formulated and testable: marine regression, volcanism, and asteroid impact. Marine regression refers to the draining of epicontinental seas with a major loss of low-coastal-plain habitats, establishment of land bridges, and cooling of emerged land masses. Over four million years there were massive eruptions of flood basalts on the Indian subcontinent; the changes caused by this volcanism at the end of the Cretaceous Period (65 million years ago) have not been well studied but may have had an effect similar to marine regression or asteroid impact. The crater Chicxulub near the tip of the Yucatan Peninsula is about 60 miles across and occurred at the time of massive extinctions. But the Popigai Crater in Siberia is the same size and was formed almost 36 million years ago without identified extinctions. Only the marine regression theory supports the present fossil records that show a highly selective extinction of animals at the end of the Cretaceous Period.
All of the articles without question support the theory evolution, i.e., the change of species over time. Many of the articles discuss controversies of interpreting the fossil evidence. For example, what were the cause of the massive extinction of dinosaurs, and whether dinosaurs were warm-blooded or cold-blooded. Creationists assert that such controversies show that scientists do not accept evolution and have serious doubts about the "theory." Teachers and parents need to emphasize that there is total agreement in the scientific community that species have changes over time, i.e., that evolution happened. The excitement of science comes from dealing with puzzling questions that do not attack the basic fact of evolution. Many of these questions about dinosaurs may soon be answered as more fossil discoveries are made.
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