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USNM 380869

USNM 380869. Calymene platys Green, Trilobita

Research Training Program 2001


Intern Name Advisor Name(s) Department Project Title
Yolanda J. Chacon Dr. Carla J. Dove Vertebrate Zoology, Birds Microscopic feather character analysis of the cranes, rails and allies (Avian Order: Gruiformes)
Erin N. DiMaggio Dr. Sorena S. Sorensen Mineral Sciences Evidence for Feldspar Replacement in Altered Metamorphic Tuffs in the Duck Lake Volcanic Suite
Matthew S. Friedman Dr. James C. Tyler and Dr. G. David Johnson Vertebrate Zoology, Fishes A putative lampridiform from the Oligocene of Peru
Michael C. Holcomb Dr. John Pandolfi and Dr. Ian Macintyre Paleobiology Use of X-radiographs for coral identification
Laura Holladay Dr. Brian Huber Paleobiology Ontogenetic morphometric comparison of middle-late Eocene pseudohastigerinid planktonic foraminifera using X-radiograph image analysis
Abigail J. Knee Dr. Kristian Fauchald Invertebrate Zoology, Worms A cladistic analysis of the scale worm genus Halosydna
Trevor J. Krabbenhoft Dr. Thomas A. Munroe Vertebrate Zoology, Fishes Species-level systematics of the genus Symphurus (Cynoglossidae: Pleuconectiformes) of the western Pacific
Courtney A. Porreca Dr. J. Daniel Rogers Anthropology Paste Composition and Vessel Function: A Case Study of Caribbean Ceramics 
Anastasia L. Poulos Dr. Melinda Zeder Anthropology The Hunting of Gazella subgutturosa by Early Domesticators in the Fertile Crescent: A Comparison of Wild and Domestic Animal Remains in the Archaeological Record
Yana R. Reid Dr. Ron Heyer Vertebrate Zoology, Amphibians and Reptiles Analysis of advertisement calls in the genetically diverse frog taxon currently known as Leptodactylus fuscus
Alexandre Cunha Ribeiro Dr. Richard P. Vari Vertebrate Zoology, Fishes Phylogeny of the genus Oligosarcus Günther: A preliminary survey
Julianne Rowehl Dr. Carole Baldwin, Dr. Lynne Parenti, and Dr. Victor Springer Vertebrate Zoology, Fishes Identification of Galapagos Entomacrodus (Teleostei: Blennidae) with comments on relationships within the Entomacrodus "nigricans" species group
Jeffery Michael Saarela Dr. Paul M. Peterson and Dr. Robert Soreng Botany The taxonomy of Brachyelytrum (Poaceae)
Shannon S. Schwaller Dr. Richard Thorington Vertebrate Zoology, Mammals Morphometric analysis of hand anatomy in five genera of New World primates
Ainsley E. Seago Dr. Steven Lingafelter Entomology A New Species of Crepidodera (Coleoptera: Chrysomelidae)
Dawn M. Stodden Dr. William Melson Mineral Sciences The Assembly of North America: Using Garnet Zoning to Decipher the Geologic History of the Potomac Terrane
Katarina Topalov Dr. Vicki Funk Botany Evaluation of Plant Diversity on the Guiana Shield
Sharon Wilson Dr. Ed Vicenzi Mineral Sciences Microscopy and microchemistry of low temperature aqueous alteration in the Lafayette meteorite

Research Abstracts

Microscopic feather character analysis of the cranes, rails and allies (Avian Order: Gruiformes)

Yolanda ChaconYolanda J. Chacon

Project Advisor:
Dr. Carla J. Dove
Department of Vertebrate Zoology
Division of Birds

Twenty-six feather characters (both micro- and macroscopic) of 12 species of birds within the avian order Gruiformes (cranes, rails and allies) were described, photographed and then investigated using parsimony analysis to determine if feather characters in this group of birds provide phylogenetic signal.

Feather characters were analyzed separately and in combination with mitochondrial 12S rDNA data (Houde, MS in prep) and resulting trees were compared. Strict consensus of two trees obtained from feather characters (TL= 91, CI= 0.68, RI= 0.59, RC= 0.40) shows that these characters have indices comparable to the tree obtained from molecular characters (TL= 2147, CI= 0.53, RI= 0.38, RC= 0.20). However, the resulting feather and DNA trees agree only in some terminal taxa relationships.

Although the rails (Rallus, Laterallus) are sister to each other according to both datasets, the DNA characters place Sungrebe (Heliornis) as the closest relative to rails whereas the feather characters place Mesitornis (roatelo) as the sister to that group. The strict consensus feather trees and the DNA tree are congruent in the relationship of Cariama (seriema) to Choriotis (bustard). Grus (crane) and Aramus (Limpkin) are in the same clade according to both trees; however feather characters place Heliornis within that clade instead of Psophia (trumpeter) as is suggested by DNA characters. The DNA tree does not resolve the status of Mesitornis but rather places this taxon as an outgroup to the main clade. A single tree of all combined characters resulted in a tree with indices of TL= 2086, CI=0.54, RI= 0.42, RC=0.23 and was more similar to the tree obtained from the DNA characters.

Although more research is needed on the feather characters in this group of birds, this study provides evidence that feather characters produce trees that cluster into 'natural groupings' in parsimony analysis and supports the idea that these characters can be useful for feather identification and phylogenetic analysis.

Publication: Chacon, Y.J, and Dove, C.J, In Prep. (To be submitted in summer 2002) Microscopic feather character analysis of the cranes, rails and allies (Order: Gruiformes). Proposed for publication in the Wilson Bulletin.

Evidence for Feldspar Replacement in Altered Metamorphic Tuffs in the Duck Lake Volcanic Suite

Erin DiMaggioErin N. DiMaggio

Project Advisor:
Dr. Sorena S. Sorensen
Department of Mineral Sciences

Metavolcanic rocks can be powerful tools for documenting the complex histories of multiple episodes of fluid-rock interaction in long-lived arc crust. The Duck Lake area of the Mammoth Crest, eastern California, is part of a lithotectonic assemblage exposed along the eastern front of the Sierra Nevada. Meta-rhyolite tuffs at Duck Lake show complex K, Na, and Ca systematics and disequilibrium feldspar phase relations that reflect a superposed history of contrasting metasomatic systems.

Using cathodoluminescence and mineral and whole rock compositions, a reconstruction of the metasomatic system's history was prepared. Cathodoluminescence petrography shows igneous phenocryst and ground mass feldspar completely replaced by near-end-member orthoclase (Or>95 after sanidine) and or albite (Ab>95 after plagioclase).

These textures resemble those of nearby meta-tuffs in the Ritter Range Pendent (on strike, 20 km NW) and of unmetamorphosed Tertiary tuffs (Creede, CO, Socorro, NM) that have undergone low temperature K- or K/Na- metasomatism. In those rocks alkali alteration occurred soon after deposition. These early features are overprinted by Ca-metasomatism that is manifested by calcite veins and grossular + epidote veins with calcic plagioclase (An80-100) vein envelopes. The early pseudomorphs of phenocrysts and groundmass feldspar are replaced by calcic plagioclase in this event. Whole-rock geochemistry shows concomitant gains of Ca and Sr and loss of Na. CaO/Na2O for tuff samples ranges to 13, a value >6 times that of unaltered ashflow tuffs. K/Na values for Duck Lake tuffs are similar to those seen in the Ritter Range, Creede, and Socorro, but display distinct slopes on plots of K/Na versus Rb/Sr.

Textures indicate that Ca was sourced by hydrothermal fluid derived from carbonates, probably locally. The Ca-rich silicate veins cut metamorphic fabrics that Tobisch et al. (2000) regionally attributed to batholith emplacement, indicating Ca-metasomatism occurred during retrograde phases of contact metamorphism. Evidently, as seen in many ore deposits, cooling contact metamorphic systems can be accompanied by large amounts of mass transfer.

A putative lampridiform from the Oligocene of Peru

Matt FriedmanMatthew S. Friedman

Project Advisors:
Dr. James C. Tyler and Dr. G. David Johnson
Department of Vertebrate Zoology
Division of Fishes

A nearly complete fish skull and two associated vertebrae (USNM 494403) from the Mancora Formation (Oligocene) of Peru are tentatively identified as a lampridiform and its osteology is described.

Though no synapomorphic characters are observed that definitively place the specimen within the order Lampridiformes, features of the anterior portions of the skull suggest that a lampridiform synapomorphy may have been present in life. This feature, combined with numerous similarities of uncertain polarity found in both the fossil and recognized lampridiform taxa, suggests that cautious placement of the specimen within the order Lampridiformes is warranted.

Other characters in the fossil, notably the position of the foramen magnum relative to the exoccipital condyles, presence of a supraoccipital crest, and a well-developed first vertebra, exclude the 5 taeniosomous families of higher lampridiforms as well as the bathysomous Lamprididae, allowing for placement of the specimen within the Veliferoidei, the most basal suborder.

This specimen is the only fossil lampridiform known from South America. Given the pelagic habit of all extant members of the Lampridiformes, as well as a billfish fossil from the same locality, it seems likely that the Mancora formation was deposited in a deep-water, offshore environment.

Use of X-radiographs for coral identification

Mike HolcombMichael C. Holcomb

Project Advisors:
Dr. John Pandolfi and Dr. Ian Macintyre
Department of Paleobiology

Recent work has shown the Montastrea annularis species complex to consist of at least three extant species. These species can be distinguished using several techniques, however, in death assemblages and fossilized material, identification using conventional techniques is problematic. Many of the characteristics commonly used depend upon having whole colonies, or unabraded corallite surfaces.

Characteristics measured using X-radiographs were investigated for their potential to distinguish both modern and fossil members of the M. annularis complex. Characteristics showing significant differences among the species included: maximum corallite growth angle, band intensity, growth rate, fan length, corallite angle along the growth axis, budding angles, and colony curvature. These characteristics are much less prone to loss due to taphonomic processes than are many more conventional ones.

These results suggest that X-radiographs may serve as useful tools for separating members of the M. annularis complex. Considerable geographic and/or temporal variation was noted as well as interspecific variation.

Publication: Holcomb, M., Pandolfi, J.M., Macintyre, I.G., and Budd, A.F. In prep. Potential use of X-radiographs to distinguish members of the Montastraea annularis species complex. Proposed for publication in Coral Reefs.

Ontogenetic morphometric comparison of middle-late Eocene pseudohastigerinid planktonic foraminifera using X-radiograph image analysis

Laura HollidayLaura Holladay

Project Advisor:
Dr. Brian Huber
Department of Paleobiology

Middle to late Eocene species of the planispiral planktonic foraminiferal genus Pseudohastigerina include P. micra and P. naguewichensis, which are widely recognized and easily distinguished species. Less readily distinguished are Pseudohastigerina acutimarginata, which resembles P. micra but has a more pinched peripheral margin, and a previously unrecognized morphotype that resembles P. micra in its early ontogeny but becomes more evolute later in its ontogeny.

To test whether or not these latter forms should be synonymized under P. micra, we obtained high resolution X-radiograph images of specimens mounted in axial and edge views to characterize ontogenetic changes in shell and chamber size and shell coiling. Populations of Pseudohastigerina were selected from a geographic array of sites and from several stratigraphic levels within the middle and upper Eocene. The biometric analyses demonstrate significant differences in chamber growth trajectories, chamber coiling, maximum test size, and roundness of the ultimate chamber face between populations of P. naguewichensis and the other three pseudohastigerinid morphotypes. Populations assigned to P. micra and P. acutimarginata are statistically indistinguishable in all coiling and size measurements and comparison of ultimate chamber roundness shows a continuous range of circular to peripherally elongate shapes. The strongly evolute pseudohastigerinids are similar to P. micra in all measured features except final chamber number and maximum test size.

We conclude that P. micra and P. acutimarginata are synonymous and probably represent ecophenotypes, whereas the evolute pseudohastigerinid forms are closely related to P. micra but may represent a new species. Stable isotope data will also be analyzed in order to infer the depth ecologies of the various morphotypes.


(1): Holladay, L. and Huber, B. In prep. (To be submitted to the Journal of Foraminiferal Research in fall 2001) Ontogenetic morphometric comparison of middle-late Eocene pseudohastigerinid planktonic foraminifera using X-radiograph image analysis.

(2): Results will be incorporated into the Atlas of Eocene Foraminifera (Huber, B. et al., in prep.).

A cladistic analysis of the scale worm genus Halosydna

Abby KneeAbigail J. Knee

Project Advisor:
Dr. Kristian Fauchald
Department of Invertebrate Zoology
Division of Worms

Historically, the annelid class Polychaeta, the bristleworms, has been wrought with misclassifications. The taxon has been presumed polyphyletic. Research focused on monophyly as a defining characteristic of clades has been problematic.

Within the polychaetes, the polynoid family of marine worms has particularly mystified taxonomists as this taxon resulted from the systematic removal of monophyletic groupings of scale worms from the former family encompassing them all.

The family Polynoidae consists of scale worms linked by the presence of scales and do not fit with the extracted taxa. Using cladistics and the premise that species represent descent with modification from a common ancestor, this research sought to determine the evolutionary relationships within the polynoid genus Halosydna Kinberg 1855 and in relation to its sister taxa.

The states of 88 morphological characteristics were described for eighteen species: eight species associated either historically or currently with Halosydna and ten species of closely related scale worms. Data was entered using the software DELTA and NDE. With this data, the computer software program PAUP produced 44 branching trees of relatedness revealing the most parsimonous paths of speciation based on the synapomorphies of the species.

Analysis of some cladograms in TREEVIEW revealed a grouping of Halosydna species within a monophlyletic clade, while those species removed to the genus Halosydnella fall out along various lines of descent.

Another notable pattern was the close grouping of Halosydna brevisetosa and H. leucohyba, proposed to be synonymous with each other. The resolution in the ingroup can now be further discussed so as to lead to evolutionary clarifications. In the course of the study, two undescribed species, H. augeneri and H. riojai, also were discovered in the NMNH worm collection, previously isolated by M. Pettibone but unpublished. The descriptions of these two species are to be submitted in the next year for publication in the Proceedings of the Biological Society of Washington.

Publication: Knee, A.J. and K. Fauchald. In Prep. A cladistic analysis of the genus Halosydna (Annelida: Polychaeta: Polynoidae), with a description of two new species: H. augeneri and H. riojai. Proceedings of the Biological Society of Washington.

Species-level systematics of the genus Symphurus (Cynoglossidae: Pleuconectiformes) of the western Pacific

Trevor KrabbenhoftTrevor J. Krabbenhoft

Project Advisor:
Thomas A. Munroe, Ph. D.
Supervising Scientist
Department of Vertebrate Zoology
Division of Fishes

The new species, described from 82 specimens collected during the Albatross expeditions around the Philippine Archipelago in 1909, is characterized by a combination of characters including fin-ray counts, vertebral counts, and pigmentation features.

The new species has a predominant 1-2-2 pattern of interdigitation of dorsal pterygiophores and neural spines and 14 caudal-fin rays.

The new species is most similar to S. woodmasoni, but differs drastically in its pigmentation.

Publication: Krabbenhoft, T. and T. Munroe. In prep. A new Cynoglossid Flatfish (Symphurus: Cynoglossidae: Pleuronectiformes) from Deep-waters of the Philippine Archipelago. Copeia.

Paste Composition and Vessel Function: A Case Study of Caribbean Ceramics

Courtney PorrecaCourtney A. Porreca

Project Advisor:
Dr. J. Daniel Rogers
Department of Anthropology

Archaeological ceramics provide a wealth of information about prehistoric cultures, including their technology. Prehistoric technology can also provide information on cultural traditions, lineages, and interactions, providing a broad picture of past cultures. Often the composition of the clay mixture used to make the pottery reflects technological choices made by the potter.

This study examines the relationship of this mix of ingredients and the intended use of the pottery from a period of almost 2,000 years on the Caribbean island of Nevis. To examine the clay mixture, a microscope was used to view cross sections of cut pottery sherds. The larger particles were identified and counted, and the form or shape of the vessel was used to infer its function. The time period or phase from which the vessels date was also a variable. The data was then analyzed to determine the relationship, if any, between the way the pottery was made and its intended use.

The results of this analysis show substantial continuity in the types and numbers of the inclusions across the different vessel functions as well as time periods. The same pattern emerged when the styles of surface treatments, for example painting or incising, were compared with the intended use of the pottery vessel. From this information, it can be concluded that the clay mixture of the ceramics from Nevis, as determined by counting the inclusions, is not directly related to either the intended function of the vessel or the decorative style. This is significant because it indicates a basic technological continuity on Nevis for almost 2,000 years despite theories of major cultural interaction due to migrations from mainland South America.

Future work that would provide more insight concerning this issue might include comparisons of the clay used to make the pottery to that of raw clay samples from the island, or comparing the overall Nevis ceramic collection to collections from other Caribbean islands.

Publication: Porreca, C. A. and J. D. Rogers. In prep. Paste Composition and Vessel Function: A Case Study of Caribbean Ceramics. Journal of American Archaeology.

The Hunting of Gazella subgutturosa by Early Domesticators in the Fertile Crescent: A Comparison of Wild and Domestic Animal Remains in the Archaeological Record

Stacy PoulosAnastasia L. Poulos

Project Advisor:
Dr. Melinda Zeder
Curator of Zooarchaeology
Department of Anthropology

The method of developing sex-specific age curves for domestic goat and sheep remains from archaeological sites has proved valid in identifying a kill-off profile that is representative of either domestication or hunting practices of people 10,000 years ago.

The application of this technique to the study of wild, hunted gazelle remains has further reinforced the potential for this kind of metric study, which is based on sexual dimorphism and fusion rates. Modern gazelle specimens were measured as a means of calibrating the degree of sexual dimorphism of the gazelle. Sexual dimorphism proved to be a dominant factor in the size of various bones. Regional variation was also strongly prevalent in the specimens; however, the ratio of male to female remained consistent and replicated the ratio of sexual dimorphism found in studies of modern goat and sheep.

This regional variation was found to be present in the archaeological record as well. Thousands of gazelle specimens were analyzed from archaeological sites throughout the highland and lowland regions of the Zagros in Iran û Ali Kosh, Asiab, Sarab, Guran, Palegawra, M'lefaat, and Jarmo. A comparison of the sex-specific survivorship curves derived from the archaeological data of hunted gazelle with that of domestic remains was a startling contrast. Domestic goats and sheep replicated a similar pattern of domestication practice to that of the previously studied site of domestication, Ganj Dareh, whereas the gazelle specimens gave strong evidence of a less specific selection in their hunt. The hunters focused more haphazardly, although there does seem to be a trend for the selection of bigger and older males, interspersed with female and young, which contrasts with the focused selection of young males for kill by the domesticators.

Analysis of advertisement calls in the genetically diverse frog taxon currently known as Leptodactylus fuscus

Yana ReidYana R. Reid

Project Advisor:
Dr. Ron Heyer, Curator
Department of Vertebrate Zoology
Division of Amphibians and Reptiles

The focus of this project was to analyze the advertisement calls of the Leptodactylus fuscus.

Although morphologically very similar, previous electrophoretic analysis demonstrated the likelihood that this taxon contains more than one species. Using call analysis with Canary software along with the statistical application of SYSTAT, the call variation was quantified throughout the geographic range of L. fuscus.

Previous study of genetic differentiation in L. fuscus demonstrated that there was genetic partitioning among population units consistent with multiple species, rather than a single species, characterizing the unit currently understood as L. fuscus. Data were analyzed for 32 individual frogs from 24 localities throughout the distributional range of Leptodactylus fuscus. Data was taken on 10 calls for each frog (for those recordings with 10 or more calls). The data taken were call rate, call duration, carrier frequency, beginning frequency, ending frequency, frequency sweep, and temporal characterization of the waveform. Call rate, call duration, carrier frequency, ending frequency, and frequency sweep demonstrated a correlation with temperature and these parameters were standardized to 25C for further analysis.

Beginning frequency did not demonstrate a correlation with temperature. Multidimensional scaling analysis of our data indicated that frogs from the same locality showed the same kind of variation as frogs from different localities. The advertisement call data support the single species hypothesis in Leptodactylus fuscus. Our study demonstrates that speciation in frogs is not always accompanied by differentiation of advertisement calls.

Phylogeny of the genus Oligosarcus Günther: A preliminary survey

Alexandre Cunha Ribeiro
Universidade de São Paulo
Ribeirão Preto

Project Advisor:
Richard P. Vari, Ph.D.
Supervising Scientist
Department of Vertebrate Zoology
Division of Fishes

"It was a great experience working in my favorite field, Phylogenetic Biogeography, in one of the best museums."

The genus Oligosarcus comprises 16 species that occur in most of the major drainages of the south central portions of South America. Members of the genus are small to mid-sized fishes (about 40 to 200 mm) occurring mainly in streams. With the exception of O. schindleri, collected from a tributary of Río Charape which flows into the Rio Madeira of the Amazon basin, all Oligosarcus species occur outside the Rio Amazonas basin and no species of the genus have been collected north of 15º S (Menezes, 1988). Little ecological information on Oligosarcus is available although life history studies of a few species report that they range from omnivores to fish predators. Information on intrageneric relationships for Oligosarcus was effectively nonexistent and biogeographic hypotheses as a consequence were not grounded on phylogenetic information. Data from a series of osteological systems examined demonstrates that the genus is monophyletic, provides insight into likely sister groups to Oligosarcus, and partially resolves the interrelationships within the genus. The results of this study indicate that the fragmentation of the genus Oligosarcus into mostly allopatric species is congruent with a hypothesis of speciation associated with somewhat recent vicariant events as evidenced by the lack of sympatry between sister groups, a situation contrary to that in many other fish species in that region. The sister-group relationship between O. pintoi and O. planaltinae suggested by the results is consistent with the idea that the High-Paraná is a endemic area. However, the recognition of "lowland species" and "plateau species" groups as postulated by Menezes (1988) is not supported by the phylogeny, since some of the "plateau species" are more closely related to a subunit, but not all of the "lowland species."

This research was supported by the Alice Eve Kennington Endowment.

Identification of Galapagos Entomacrodus (Teleostei: Blennidae) with comments on relationships within the Entomacrodus "nigricans" species group

Julianne RowehlJulianne Rowehl

Project Advisors:
Dr. Carole Baldwin, Dr. Lynne Parenti, and Dr. Victor Springer
Department of Vertebrate Zoology
Division of Fishes

Documenting biodiversity is important for understanding the complexity of ecosystems, as a foundation for future conservation decisions, and for understanding evolution in a historical context. Comparative morphological studies provide the basis for recognizing biological diversity. These studies involve careful comparisons of the anatomy of organisms, including superficial features and internal structures such as bones and cartilage. When a population of animals belonging to a known genus is discovered in a geographical area in which the genus has not been recorded previously, morphological comparisons with other known species of the genus are needed to identify the new population. In this study, fish of the tropical blenny genus Entomacrodus were collected from the Galapagos Islands in the eastern Pacific Ocean. This fish has never been reported from Galapagos. A comparative morphological study was performed, and the fish was identified as Entomacrodus chiostictus, a widespread species in the eastern Pacific. A study was then performed to examine relationships of 10 fish species within this genus. The main differences between the species in the genus are the coloration patterns, and detailed comparisons of numerous external and internal features in this study revealed few other differences. Color patterns are usually extremely important in fish because the females and males often recognize each other on the basis of these patterns. It has been hypothesized that Entomacrodus originated in the central Pacific Ocean and moved eastward to the eastern Pacific and Atlantic. Results of this study support a Pacific origin of the genus and suggest a close relationship among Atlantic members of the genus and E. chiostictus. Because the 10 species studied are so similar to one another anatomically, hypotheses of relationships within the group (based on morphology) are not well supported. Molecular data may provide more insight into the evolution of this fish genus.

Publication: None

The taxonomy of Brachyelytrum (Poaceae)

Jeff SaarelaJeffery Michael Saarela

Project Advisors:
Dr. Paul M. Peterson, Curator of Grasses
Dr. Robert Soreng, Research Associate
Department of Botany

The Taxonomy of Brachyelytrum (Poaceae). Brachyelytrum, commonly known as long-awned wood grass, is a small native grass genus occurring in eastern North America and eastern Asia that grows in deciduous and mixed-coniferous forests. Workers in the past have recognized variation in the genus at the species, subspecies and varietal levels. Macromorphological and phytogeographical data support the recognition of three distinct species in Brachyelytrum. Brachyelytrum japonicum, distributed throughout southern Japan and eastern Korea, is characterized by narrow leaves [(0.5 0.7(0.8) mm], long first glumes [(0.2) (0.4-1.6) (2.0) mm] and long rachillas [((6.8)7.2-8.4(8.8) mm]. Brachyelytrum erectum is distributed throughout the eastern United States from northwestern Minnesota south to central Louisiana, east to northern Florida and north to northeastern New York. It tends to be a larger plant in many characters with respect to B. aristosum, and is characterized by longer hispid hairs on the lemma [(0.2)0.4-0.8(0.9) mm] and wide lemmas [(0.8)1.1-1.5(1.8) mm]. Brachyelytrum aristosum has a more northerly distribution, occurring in southern Canada from southern Ontario east to Newfoundland, the northern adjacent United States and south through the Appalachian Mountains to northwestern North Carolina. It is characterized by short scaberulous hairs on the lemma [(0.06)0.08-0.14(0.2) mm] and narrow lemmas [(0.7)0.8-1.2(1.4) mm]. We include a key to the taxa, synonymies, representative specimens and descriptions.

Publication: Saarela, J.M., P.M. Peterson and R.J. Soreng. In Prep. (To be submitted fall 2001) The taxonomy of Brachyelytrum (Poaceae). Proposed for publication in the botanical journal Sida.

Morphometric analysis of hand anatomy in five genera of New World primates

Shannon SchwallerShannon S. Schwaller

Project Advisor:
Richard Thorington, Ph. D.
Supervising Scientist
Department of Vertebrate Zoology
Division of Mammals

A morphometric analysis of hand and wrist bones in three genera of New World primates was conducted.

Specimens in sub-family Atelinae: Alouatta (species A. palliata and A. seniculus), Lagothrix (L. lagotricha) and Ateles (Ateles spp.) were compared with an out-group consisting of two genera of the sub-family Cebinae: Cebus (C. albifrons and C. capucinus) and Saimiri (S. sciureus). The closely related Atelinae have specialized hand morphology, such as elongated fingers and reduced thumbs. The Cebinae have a more generalized hand morphology. Comparing the Atelinae with an out group demonstrating less derived hand morphology tested the hypothesis that similar anatomical change in hand anatomy, such as finger length and thumb reduction, occurs in the same manner in closely related taxa.

The results from this study demonstrated that anatomical changes in proportions and growth allometry occur very differently in Ateles spp. relative to the other Atelinae species. Ateles spp. showed significantly longer metacarpal lengths relative to phalangeal lengths in the other Atelinae species. Also different in Ateles spp. was the reduction of thumb length through losses of both phalanges and in mid-shaft robustness through the loss of bony material in height and diameter. Ateles spp. demonstrated significantly different proportional and growth patterns of metacarpal length relative to phalangeal lengths from both species of Alouatta and the species L. lagotricha. Growth allometry in the long bones of the hand of Ateles differed significantly from the Atelinae. These results suggest that the genetic processes underlying the growth patterns have undergone significant changes among closely related species of the Atelinae sub-family.

A New Species of Crepidodera (Coleoptera: Chrysomelidae)

Ainsley SeagoAinsley E. Seago

Project Advisor:
Dr. Steven Lingafelter
Department of Entomology

An unusual, seemingly polymorphic species of beetle was investigated and determined to represent an undescribed, cryptic species. Working with a generous series of suspiciously variable Crepidodera browni, we discovered a correlation between male genitalia shape and elytral color.

Through extensive dissection, examination, illustration, and analysis of these traits, we present a previously unknown species of flea beetle. We have named this minute, iridescent, coppery-bronze beetle Crepidodera praestigiator. C. praestigiator resides in the very backyard of the Smithsonian; the type specimens were found feeding on willow trees in the McKee-Beshers Wildlife Area in Montgomery County, Maryland.

108 beetles were dissected and their genitalia examined and illustrated. Crepidodera browni is described as a new species, found in Maryland and the Northeastern United States.

Publication: Seago, A. and S. Lingafelter. In Prep. A New Species of Crepidodera (Coleoptera: Chrysomelidae) from Maryland. Coleopterists Bulletin.

The Assembly of North America: Using Garnet Zoning to Decipher the Geologic History of the Potomac Terrane

Dawn StoddenDawn M. Stodden

Project Advisor:
Dr. William Melson
Department of Mineral Sciences

This study examined the Sykesville Formation in the easternmost Potomac Terrane between Roosevelt Island and Chain Bridge in the Potomac River Gorge on the Virginia side. The Liberty Complex of the Potomac terrane is an accretionary prism (composed of the Sykesville Formation and the Morgan Run Formation) that was accreted on to Eastern North America probably over 400 million years ago by collision between a westward advancing magmatic arc and the accretionary prism.

This study of the Sykesville formation included structural mapping, precursory rock analysis, and chemical analyses of garnets and other minerals, all indicators of the geologic history of the rocks. The structural mapping the study area has shown a depositional trend that follows that of the surrounding terrain. In the Sykesville Formation, there are many quartz structures. These structures appear to be beds or veins. To decipher the protolith, thin section of quartz were analyzed using cathodoluminescence revealing relict sand grains preserved in the quartz thin section, giving evidence supporting that the quartz is depositional in nature. Garnets were also examined using electron microprobe analysis, a method in which the x-rays generated by a minute, 2-micron electron beam impinging on a mineral grain are analyzed for the elements that produced them. Chemical zoning in garnets acts as a record of the growth history of the garnet, as well as, the surrounding rocks. With the microprobe, several X-ray maps of some garnets in the Sykesville formation were constructed.

The research revealed that the Sykesville Formation, after deposition, has undergone one episode of metamorphism. Future analysis of the chemical composition of these garnets will unveil more about the pressures and temperatures at which the garnets were formed as well as the peak pressures and temperatures reached during the ancient collision, which added the Potomac Terrane to Eastern North America. With the data compiled in this study, more work to decipher the exact history of the Sykesville Formation will be possible.


(1) Stodden, D. and W.G. Melson. In Prep. The Assembly of North America: Using Garnet Zoning to Decipher the Geologic History of the Potomac Terrane.

(2) Stodden, D. and W.G. Melson. 2002. Research Abstract, Southeastern Section, Geological Society of America, April 2002.

Evaluation of Plant Diversity on the Guiana Shield

Katarina TopalovKatarina Topalov

Project Advisor:
Dr. Vicki Funk
Department of Botany

The Guiana Shield is located in the northeastern part of South America and includes the countries Venezuela, Guyana, Surinam, French Guiana, and the north part of Brazil. It hosts a unique assemblage of plants and animals that is extremely rich, but not well explored. Since this area is now threatened by resource extraction, it is important that we gain an understanding of its biodiversity so that decisions about its conservation can be made. In the past, areas proposed for conservation have been difficult to evaluate because of incomplete data. There were few areas that have been collected well enough and the collections were lacking locality and other data partially or completely. In order to better understand the biodiversity the first goal of this project was to gather the data from a variety of sources and the second one was to evaluate the collecting bias such as time of year or intensity of collecting. For instance, one of the most commonly made mistakes in floristic analyses is the collecting and determining of only easily reached plant species (not far away from roads, tracks and rivers, etc.). However, even data like this can provide valuable information if analyzed properly, because they can be used as proxies in comparisons of two or more sites. The analyses included plant species checklist data from five areas: Puerto Ayacucho (Venezuela), Iwokrama Forest, Mabura Hill, Kaieteur Falls National Park (Guyana), Saül, Central French Guiana and Reserva Ducke, Brazil. The total of 5645 species records was standardized and imported into a database table. Finally, the ways of overcoming the collecting bias have been tested by using various kinds of statistical analyses in order to provide a more objective application of the already existing data and, therefore, more precise insight into the flora of northeastern South America. The gathered results were used to estimate plant diversity in western Venezuela (the Puerto Ayacucho area) and examine how this diversity compares to similar areas in French Guiana, Guyana and Brazil. The results of the study revealed that the flora of the Puerto Ayacucho area is the most different from those found on other five sites, but in order to bring more specific conclusions, more plant collecting expeditions have to be undertaken.


(1): H. D. Clarke, K. Topalov, V.A. Funk and T. Hollowell. In prep. (To be submitted in fall 2001) Evaluation of Plant Diversity on the Guiana Shield.

(2): Proposed for publication in the Biodiversity and Conservation.

Microscopy and microchemistry of low temperature aqueous alteration in the Lafayette meteorite

Sharon WilsonSharon Wilson

Project Advisor:
Dr. Ed Vicenzi
Department of Mineral Sciences

Out of the 7500 meteorites that have been found on the surface of earth, only fifteen have been identified as Martian. The Lafayette meteorite is an achondrite that is almost certainly from Mars and was found in Lafayette, Indiana in 1931. The 800-gram stone has a crystallization age of 1.3 billion years and contains abundant hydrous secondary alteration veinlets that are 200-700 million years old. Although the age of the alteration is poorly constrained, it is clearly younger than the bulk rock. Since the underlying precept is that a Martian fluid created the low-temperature aqueous alteration, their physical and chemical characteristics provide crucial information in determining whether the Martian subsurface was once suitable to sustain microbial life forms. Hosted by iron-rich olivine and occurring along pyroxene grain boundaries, the veinlets possess a delicate microtexture consisting of silica-rich and iron-rich amorphous phases, smectite and carbonate. A detailed characterization of the textural and microchemical features of the alteration veinlets in Lafayette was undertaken. The olivine and pyroxene veinlets were analyzed by a sensitive X-ray microanalyzer (wavelength dispersive spectroscopy) to quantify the concentration of sulfur, sodium and chlorine in the secondary phases. The presence of sulfate is important regarding the search for life on Mars because it can be present in a form that allows microbial life forms to use it as an energy source. The presence of chloride in the alteration suggests that the water at or near the surface of Mars was slightly saline. The saline component would decrease the freezing temperature of liquid water, extending the conditions suitable for life on Mars.


(1). Wilson, S.A. and E. Vicenzi. In Prep. (To be submitted December, 2001)

(2). Abstract proposed for publication at the Lunar and Planetary Science Conference, March 2002.

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