© Richard Gilder Graduate School, All Rights Reserved. · Richard Gilder Graduate School · Central Park West at 79th Street, New York, NY 10024
Photography Credits | Design and Development: Wall-to-Wall Studios
Few aspects of the mammalian skull rival the auditory ossicles in dramatically revealing the divergence of mammals from the typical amniote plan. Indeed the discovery that the mammalian malleus and incus are actually homologues of visceral elements of the jaw articulation in amniote relatives of mammals ranks as a milestone in the history of comparative vertebrate anatomy. The mammalian ossicular chain, comprising the malleus, incus, and stapes, acts as an impedance transformer for external sounds reaching the tympanic membrane and ultimately reaching the fluid-filled cochlea of the inner ear. Sensitivity to certain frequencies will therefore relate to the mass, stiffness and friction of the ossicle chain. The great variation in these parameters seen in mammals relates to the great range of hearing adaptations found in echolocators, burrowers, swimmers, and species exhibiting other modes of life. This variation also has a phylogenetic signal and this character system has contributed to some important studies of mammalian relationships. Nonetheless, improvement of the comparative database for the mammalian auditory ossicles is greatly needed. The most comprehensive illustrated study was published in the 19th century (Doran, 1878), and more refined studies of recent decades are usually restricted to a subset of taxa. This project calls for specimen comparisons of a broad sampling of mammals, with particular focus on insectivorans and a selection of other placental mammals taxa, including aardvarks, elephant shrews, hyraxes, elephants, and sirenians. Data with figures will be entered, stored, and analyzed with the help of a powerful, interactive web application MorphoBank. The use of CT scans for these small elements will also be explored. The comparative matrix should allow examination of several theories concerning the varying function of the ossicles in mammalian hearing. The comparative data should also facilitate comparisons of phylogenetic patterns suggested by ossicle variation with those based on molecular data as well as other phenotypic characters.
Neil Landman Curator-in-Charge, Fossil Invertebrates and Professor, Paleontology
The project involves an overview of the nearshore marine community off the Atlantic and Gulf Coastal Plain at the end of the Cretaceous Period and how this community fared during the catastrophic events that culminated this time interval. It will require participation in collecting trips to fossil sites in New Jersey, Maryland, and Missouri to make an inventory of the species composition of the communities before and after the Cretaceous-Tertiary boundary. A background in invertebrate paleontology is recommended.
Nancy Simmons, Division Chair, Curator and Professor, Vertebrate Zoology, Mammalogy
Bats (Order Chiroptera) represent one of the remarkable success stories of mammalian evolution. Nearly worldwide in distribution, there are >1100 extant species and >390 extinct species of bats; among mammals they are second only to rodents in diversity. Although much is known about relationships of major extant lineages and a few of the better-preserved fossil genera, large numbers of fossil taxa cannot yet be placed into context in existing bat phylogenies for one simple reason: they are known only or mostly from dental remains scattered in museums around the world, and no character set exists for evaluating their relationships. As a result, our understanding of the "when," "what" and "where" of early bat evolution remains woefully incomplete. One of the most interesting radiations within the bat lineage is that of New World Leaf-nosed Bats (Family Phyllostomidae), a group that includes insectivores, frugivores, nectarivores, carnivores, and even vampire bats. Detailed phylogenies based on DNA sequence data are being developed, but we cannot yet date the divergence points in the phylogenetic tree accurately because fossils have not yet been integrated into studies of the group. A long-term project is being developed to address these problems through creation of a Virtual Museum of bat fossils and dental exemplars of extant bat families that will be openly accessible to researchers all over the world via MorphoBank (http://morphobank.geongrid.org/), a web-based platform for morphological systematics. A new dataset of >270 dental characters for bats has been developed in that platform that will facilitate placement of fossil bat species into more comprehensive phylogenies based on morphology and gene sequence data. This summer, work will focus on gathering images and data from extant phyllostomid species, identifying new characters in dentitions highly modified for different feeding strategies (e.g., frugivory, nectarivory, blood feeding), and continuing development of the dental character set for all bat families that forms the basis of this project. Work will also include our first efforts to place Miocene fossils attributed to insectivorous, carnivorous, and nectarivorous phyllostomids into the phylogenetic tree.
Christian Kammerer (Postdoctoral Fellow) and John J. Flynn (Frick Curator), Division of Paleontology
Although the evolution of mammals from “reptilian”-grade amniotes in the Permo-Triassic periods (~300-200 million years ago) is one of the most thoroughly studied major morphological transitions in the fossil record, several aspects of the origins of the mammalian body plan remain obscure. In particular, the morphology of the braincase, an area that has been well detailed in early mammals, is poorly understood in the early therapsid relatives of mammals. Existing braincase data provide contradictory phylogenetic positions for different Triassic subgroups of the Cynodontia, the therapsid clade that includes mammals and outside of Cynodontia the picture is even less clear. This lack of resolution represents a major impediment to our understanding of cynodont (and with them, mammalian) origins. To address some of these problems, we are currently engaged in a broad-scale analysis of non-mammalian cynodont phylogeny incorporating endocranial and basicranial characters derived from computed tomographic (CT) data of skulls. Select cynodont outgroups are being included in our research program to establish character polarity, but these outgroups (Gorgonopsia and Therocephalia) represent diverse, species-rich taxa in their own right that are of uncertain monophyly and desperately in need of more thorough basic anatomical study. The proposed research project for an REU student will both allow for expansion of our current phylogenetic research program and for the student to produce an important contribution to theriodont descriptive anatomy. CT methods are increasingly being used in paleontology as a means of visualizing previously inaccessible morphological information (e.g., bones too delicate to be prepared out of the host rock, internal structures in the skull), but the ability to produce and interpret CT data is of general utility in biological and medical research. The REU student will be trained in the assembly, interpretation, and manipulation of CT data, which will be utilized to clarify the morphology of one of the poorly known theriodonts, and placed within a phylogenetic context. The AMNH paleontology collections contain numerous theriodont specimens that would be amenable to this project, the addition of which would be extremely beneficial to reconstructing ancestral states for cynodont cranial characters. Applicants must be very comfortable with computers, familiar with Adobe Photoshop and preferably other imaging programs; some knowledge of vertebrate cranial osteology will be helpful but not required.
Melanie Stiassny, Herbert R. and Evelyn Axelrod Research Curator and Professor, Vertebrate Zoology, Ichthyology
Lorenzo Prendini, Associate Curator and Associate Professor, Invertebrate Zoology
The medical importance, fearsome appearance, and great age of their lineage (400 Mya), contribute to a fascination that has always surrounded scorpions and continues to. During the summer, students will undertake projects assessing the taxonomy and phylogeny of particular groups of scorpions involving (1) sorting, databasing and morphological examination of scorpion specimens and associated data, (2) isolation, PCR and sequencing of scorpion DNA, and (3) mapping and GIS analysis of scorpion distributions.
George Amato, Director and Affiliated Professor, Sackler Institute of Comparative Genomics and Samuel Crane, PhD Candidate at CUNY
In this project, students will be able to learn about DNA barcoding which has been proposed as an important advance in molecular biology for rapidly and cost-efficiently using a short reference sequence of DNA to help catalog and inventory DNA. Participants will be able to work both with AMNH collections of endangered animals as well as agricultural pest species using specimens from the USDA JFK Plant Inspection Station that are current quarantine targets for the USDA in New York City.
Mark Siddall, Curator and Professor, Invertebrate Zoology and Mark Weckel, Director of Research and Land Management Mianus River Gorge Preserve
Superabundant populations of white-tailed deer cause broad declines in native biodiversity and woody regeneration. The problem is especially pronounced in suburban nature preserves of the Northeast where a combination of high-quality deer habitat, few natural predators, and declines in human hunting have resulted in deer densities three to five times greater than is sustainable for forest regeneration. Deer superabundance is most often addressed as a regional problem requiring a regional solution; however, the rose-petal hypothesis of deer population structure offers the possibility for fine-scale (4-20 sq km) deer reductions. The RPH suggests that female deer exist in multi-generational social units whose members' exhibit high fidelity to their natal range. Therefore deer can be removed locally by removing social units without adjacent social groups immediately filling the reduction area. Many nature preserves in Westchester County, NY have adopted localized management programs characterized by a low-catch-per-unit effort. If the RPH is does not hold true for suburban herds, and immigration is high into the reduction area, this will be found to be an insufficient management tool. The RPH is very difficult to test directly; however, tight female philopatry would suggest small-scale genetic structuring evident at the level of both individuals and social-units. Therefore I am looking for an intern to help with the first objective: to examine whether genetic structuring supports or refutes the RPH. Interns will genotype deer collected from Westchester County, NY and neighboring Fairfield County, CT to examine the correlation between genetic relatedness and distance.
Interns will also be exposed to other techniques being used to answer the question: Can archery bring about population reduction in suburbia? www.urbanwhitetail.com
© Richard Gilder Graduate School, All Rights Reserved. · Richard Gilder Graduate School · Central Park West at 79th Street, New York, NY 10024
Photography Credits | Design and Development: Wall-to-Wall Studios
