Fall 1994

Was Tyranosaurus Rex warm-blooded?
   Recent results from a study performed at North Carolina State University have added further fuel to one of the most heated debates in paeleon-tology: was Tyrannosaurus Rex, and possibly other dinosaurs, warm-blooded? The study measured the ratio of oxygen-16 and oxygen-18 isotopes found in the bones of a well-preserved T. Rex specimen; the more oxygen-18 present, the colder the temperature at which the bones formed. Not only did the study find that the temperature varied very little throughout the T. Rexıs skeleton, but there was little long-term variation as well. These facts were inconsistent with a cold-blooded animal, which generally cannot maintain a constant internal temperature either within its body or across seasons. The point of contention lies in the method of the study itself; opponents point out that there could have been many chemical changes in the bones over 65 million years that render the tests useless. However, the NCSU team counters that the specimens used were much better preserved than previous ones. If T. Rex was in fact warm blooded, it would have been the most voracious predator on Earth, constantly on the prowl for prey and considerably more active than current theories suggest.

Standard Model vindicated: the Top quark found
   The long search for the ultimate constituents of matter has passed a major milestone: the Top quark, the last of the proposed 12 particles that make up all matter in the universe, has been detected at the Fermilab particle accelerator, University of Chicago. Quarks, which come in the six whimsically named forms Up, Down, Charm, Strange, Bottom and Top, always combine in triplets to make up Hadrons, a large class of particles that include the familiar proton (two Up and one Down quark) and neutron as well as many other exotic particles. Quarks and Leptons (the other broad category of particles that include the ubiquitous electron and the elusive neutrino) together are thought to make up all matter in the universe, as described by the standard model of particle interactions. The Top quark eluded detection by physicists for over 17 years due to its relatively high mass, which translates into high energies out of the range for most particle accelerator labs. At Fermilab, Top quark generation is estimated to occur once every few billion collisions; thus the evidence for its existence has been slow in coming.

Nature's Great(est) Wall
   Astronomers are finding ever larger structures in the furthest reaches of outer space: in recent years, surveys of tens of thousands of galaxies have revealed unexpected irregularities and orders, not the expected even distribution. Observations of the universe spanning more than half a billion light-years across (our own Milky Way, which comprises a 100 billion stars, is a mere 100,000 light years across) reveal enormous, irregular collections of galaxies, dubbed the Great Wall and the Southern Wall as seen in the northern and southern hemispheres, respectively. The most intriguing discovery, revealed by a statistical analysis of the patterns in the two Walls, is that some differences exist between their distributions, indicative perhaps of an even greater structure which awaits a larger sampling size to confirm. Such evidence of large scale structures in the cosmos remain an enigma. In the estimated 15 billion years since the Big Bang, itıs not understood how gravity alone could cause the formation of such immense order in such a relatively short time.

Hairy tales
   For many years, primatologists determined kinship, family hierarchy, and social organization among chimpanzees by carefully following particular groups, tracing their developing lineages, and observing the mating patterns of dominant males. Previously, scientists abstained from collecting blood samples, but now genetic analysis of DNA in chimpanzee hairs is breaking new ground in behavioral ecology and evolutionary biology. Unlike blood samples that necessitated tranquilizing the subject, hair can be obtained in great quantities without injury to the chimpanzee. Along with clarifying many points and hypotheses in primatology and the better tracing of chimp family lineages important to behavioral studies, the possible classification of an entirely new species of chimpanzee was also one important outcome of this new research technique. From examining the mitonchondrial DNA of chimps from all over Africa, David Woodruff and Philip Morin of the University of Calfornia, San Diego and Davis respectively, may have distinguished Pan troglodytes verus, the West African subspecies of Pan troglodytes as a separate species. Woodruffıs and Morinıs research found the DNA of West African chimps contained sequence differences particular to their populations. Evolutionary biologists have yet to determine whether these distinctions warrant a new branch in the phylogenetic heritage of the primate family.

A Jovian rendez-vous: the Shoemaker-Levy 9 comet
   This summer, a rare and spectacular collision between the SL-9 comet and Jupiter drew world-wide attention. Beginning July 16 and continuing for six days, fragments of the Shoemaker-Levy comet, pulled apart 2 years before by Jupiter's gravity, struck the gas giant causing havoc within the vast Jovian atmosphere. Enormous plumes from the collisions rose thousands of kilometers above the surface of the planet. Other aspects of this event perplexed astronomers - dark ejections and subsequent dark scars the size of the Great Red Spot (larger than the Earth), emerged in the wake of the comet fragments' numerous collisions. Astronomers expected much lighter plumes consisting of condensed water ice and ammonia, since Jupiter would have ejected water if the fragments had descended into the middle layers of the Jovian atmosphere. Through ultraviolet spectral analysis, ammonia and sulfur compounds (probably "dirt" from the comet) were detected, but water was not. Astronomers believe that either the comet fragments failed to penetrate deeply into Jupiter or that our current understanding of Jupiter's atmosphere needs rethinking.