Staff & Student News
Resident Graduate Student Nate Upham (University of Chicago and Zoology/Mammals) has been in Argentina since mid-September collecting data and interacting with collaborators for his dissertation research, which is supervised by his advisor, MacArthur Curator Bruce Patterson (Zoology/Mammals). From September 21–24, he attended the IV Latin American Conference on Vertebrate Paleontology in San Juan, Argentina, where he presented an invited talk in a symposium on the evolution of Neotropical South America organized by Research Associate Darin Croft (Geology). Nate’s talk aimed to interest the fossil-minded audience in integrative approaches to combining fossils with DNA sequence data for studying the evolutionary diversification of the rodent lineage Octodontoidea, for which there is both an abundant Cenozoic fossil record and rich diversity in modern Neotropical habitats (193 species today). Following a short trip to Parque Nacional Iguazú and trek back to Buenos Aires, he worked in the fossil rodent collections at Museo Argentino de Ciencias Naturales “Bernardino Rivadavia” (MACN) the week of October 3 with the assistance of paleovertebrate curator Alejandro Kramarz. A short 45-minute bus ride to La Plata next landed Nate at the excellent Museo de Ciencias Naturales de La Plata (MLP), where he has been working in the fossil rodent collections since October 12 with the aid of curators Marcelo Reguero, Guiomar Vucetich, and Diego Verzi. These museum visits are focused on photographing fossil rodent mandibles to examine their evolutionary changes through time, and are funded in part by the NSF Doctoral Dissertation Improvement Grant awarded to Bruce and Nate in February: “Fossils and phylogeny: investigating the timing of diversification in a diverse lineage of Neotropical rodents (Caviomorpha: Octodontoidea).”
Research & Publications
In a new study published in the journal PLoS One on October 12, a team of scientists led by Professor John R. Hutchinson of The Royal Veterinary College, London, and Associate Curator and Chair Peter Makovicky (Geology), applied cutting edge technology and computer modeling to “weigh” five Tyrannosaurus rex specimens, including The Field Museum’s iconic SUE skeleton. Their results reveal that T. rex grew more quickly and reached significantly greater masses than previously estimated. In a departure from earlier methods, the new study uses mounted skeletons to generate models for body mass estimation, instead of sculpting scale models or extrapolating from dimensions of living animals with very dissimilar body plans from non-avian dinosaurs.
The team used 3D laser scans of mounted skeletons as a template for generating fleshed-out digital models whose masses could then be computed. Digital body cross-sections were reconstructed along the length of each skeleton using the relationships of the soft tissues to skeletons in birds and crocodiles as a guide. A digital skin was then overlaid to generate a body volume, whose mass was calculated after empty spaces such as lungs and the mouth cavity were modeled and subtracted. In order to appreciate the uncertainty involved in estimating how much flesh would wrap the skeleton of an extinct animal, body sections (e.g. head, neck, torso, legs, tail) were modeled individually at three levels of “fleshiness.” The three versions of each body segment were combined in different ways to generate a range of whole body models with varying masses.
T. rex appears to have been significantly heavier than previously believed. SUE, the largest and most complete T. rex skeleton known, weighed in at over nine tons. The new mass estimates also alter understanding of T. rex biology. The higher mass estimates for the larger specimens and a lower one for the smallest individual indicate even faster growth than was proposed in a landmark study just five years ago which estimated they grew as fast as 3,950 pounds per year (1,790 kg) during the teenage period of growth. The rapid growth to gargantuan size came at the cost of speed and agility, according to the study, which concluded that the locomotion of this giant biped slowed as the animal grew. This is because its torso became longer and heavier while its limbs grew relatively shorter and lighter, shifting its center of balance forward. The total limb musculature of an adult T. rex probably was relatively larger than that of a living elephant, rhinoceros, or giraffe, partly because of its giant tail and hip muscles, but these muscles may have acted to stabilize the shift in the center of gravity away from the hips during growth rather than for increased speed. The story was covered widely by print, web, and TV.
Associate Curator and Chair Thorsten Lumbsch (Botany) published a review article with Postdoctoral Research Scientist Steven Leavitt entitled “Goodbye morphology? A paradigm shift in the delimitation of species in lichenized fungi” in the journal Fungal Diversity. In this manuscript
Thorsten and Steven discuss how difficult it is to circumscribe species in these organisms using morphology and how DNA sequence data have revolutionized our understanding of the diversity of lichenized fungi. Traditionally, a number of species were thought to have worldwide distribution, however, DNA data often shows that different species actually occur in the continents that cannot be distinguished based on morphology and are often referred to as “cryptic species.”
The Philippine islands support some remarkable groups of mammals found nowhere else, including “giant cloud rats” and “earthworm mice” that have diversified greatly, but no direct information about their fossil histories is known. Curator Larry Heaney (Zoology/Mammals) and two colleagues from the Philippines have taken a small, first step in a paper published in early October in the Proceedings of the Biological Society of Washington. The paper describes three fossils from a cave deposit in northern Luzon island that also contained human bones dated at 67,000 BP. The fossils represent one species of an earthworm mouse that still lives in the area today, and one species of cloud rat that appears to have become extinct. The timing and cause of the extinction is uncertain, but can now be investigated with a second, larger sample of mammal bones from the same cave that Larry recently received from his colleagues. Stay tuned.
MacArthur Field Biologist Steve Goodman (Zoology/Birds and Mammals) together with a colleague from the Association Vahatra and The University of Antananarivo in Madagascar (Marie Jeanne Raherilalao) and two others from the Paris Natural History Museum (Astrid Cruaud and Eric Pasquet) published an article in mid-October in Zoologica Scripta. The paper, entitled “Phylogeography and systematics of the Malagasy rock-thrushes (Muscicapidae, Monticola),” examines the patterns of morphological and genetic variation of this genus on Madagascar, which has been subject to considerable debate. The genetic data presented in the article helps to resolve several issues in a definitive manner. Scientific Illustrator Velizar Simeonovski (Zoology) also graced the paper with a color plate of the birds concerned.
Together with his colleagues, professors Ana Crespo (Madrid) and David Hawksworth (London); Associate Curator and Chair Thorsten Lumbsch (Botany) edited a special issue of the journal Lichenologist entitled “Thematic issue: Parmeliaceae.” The idea of presenting a series of manuscripts on the largest family of lichenized fungi together in one issue was developed at an Encyclopedia of Life (EOL) workshop held in the Museum’s BioSynthesis Center in May 2010 entitled “Parmeliaceae: improving our understanding of taxonomy, classification and biogeography of the largest family of lichen-forming fungi.” The occasion was organized by Thorsten, Collections Manager and Adjunct Curator Robert Lücking (Botany) and Ana Crespo, and was attended by 30 scientists from 12 countries, with the financial support of EOL. The issue includes 11 contributions, including two reviews.
Fieldwork & Collections
Public Education & Media Coverage
In this week’s The Field Revealed video series, Collection Manager Paul Mayer (Geology) and Illinois’ state fossil are featured in The Tully Monster (Tullimonstrum gregarium). Check out the video, filmed and edited by C&R Media Producer Federico Pardo, to get a closer look at The Field Museum’s fossil invertebrate collection and to enjoy the fascinating story of the Tully Monster; including the history of its discovery and ideas about its possible classification.
Negaunee Collection Manager Bill Stanley (Zoology/Mammals) appeared on Chicago Tonight on WTTW on October 13, where he discussed the upcoming symposium hosted by The Field Museum focused on the effect that White Nose Syndrome (WNS) is having on North American bats. Bats with white fungus on their noses were first observed in New York in 2006 and this fungus has killed greater than 90% of some bat populations in individual caves in the northeastern United States. Evidence of WNS has now been found in southeastern Canada, as far south as the Carolinas, and even southern Indiana. While no bats have been observed in Illinois with WNS, the potential for the spread of this devastating epidemic has caused Federal and State authorities to close many caves to visitors. Experts on bats and the fungus associated with WNS will come together Saturday, October 15 to discuss the nature of WNS. The interview with Bill can be viewed here.
Graduate Student Reto Trappitsch and his co-supervisor Robert A. Pritzker Assistant Curator of Meteoritics and Polar Studies Philipp Heck (Geology) participated in The Field Museum’s Educator Open House on October 11. 430 educators attended the Department of Education event, mainly from Illinois. Reto and Philipp presented specimens from the Museum’s meteorite collection. Teachers were very interested in the exhibit, and learned about how to identify meteorites and the research conducted at the Robert A. Pritzker Center for Meteoritics and Polar Studies.