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DirectionsJeffersoniana (ISSN 1061-1878) is an outlet for relatively short studies treating a single subject, allowing for expeditious publication. Currently, all volumes to date are available as free downloads.
Jeffersoniana #1
On the taxonomy of the Milliped Genera Pseudojulus Bollman, 1887, and Georgiulus, Gen. Nov., of Southeastern United States (Julida: Parajulidae)
Richard L. Hoffman
The parajulid genus Pseudojulus (Bollman, 1887), heretofore of uncertain taxonomic position, is referred to the tribe Aniulini following study of material of its type species P. obtectus (Bollman). The closely related new genus Georgiulus is proposed to accommodate two new taxa: G. paynei (the type species) from southern Georgia, and P. hubrichti from northeastern Georgia. These two genera differ from other aniulines by the dramatic enlargement of the eighth sternum in males. The genitalia of all three species are illustrated, and the major elements of parajulid gonopods are discussed in general.
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Jeffersoniana #2
A Striking New Genus and Species of Bryocorine Plant Bug (Heteroptera: Miridae) from Eastern North America
Thomas J. Henry
The new bryocorine genus and species Pycnoderiella virginiana is described from 19 specimens collected in drift-fence pitfall traps at Seashore State Park, Virginia Beach, Virginia. This striking mirid, possibly the smallest known bryocorine, is distinguished by its small size, unusually modified submacropterous hemelytra, and unique male genitalia. Speculation on the host plant and discussion of its relationship to other North American eccritotarsine Bryocorinae are provided.
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Jeffersoniana #3
The American Species of Escaryus, a Genus of Holarctic Centipeds (Geophilomorpha: Schendylidae)
Luis A. Pereira and Richard L Hoffman
Eight North American species of Escaryus are regarded as valid. A historical summary is provided for the genus, as well as observations on the taxonomic significance of various characters heretofore utilized to distinguish genera of schendylids. Known Palearctic taxa are listed. Escaryus ethopus Chamberlin, E. liber Cook & Collins, E. missouriensis Chamberlin, E. monticolens Chamberlin, E. paucipes Chamberlin, and E. urbicus (Meinert) are redescribed and figured from type material and/or additional specimens. Escaryus delus Chamberlin is considered to be a junior synonym of E. ethopus. Escaryus cryptorobius and E. orestes are described as new species, both from Whitetop Mountain, Virginia. Escaryus japonicus is removed from the North American list, the Alaskan specimen upon which Chamberlin’s 1952 record was based having been found to be an individual of E. ethopus.
Examination of type material of species thought possibly referable to Escaryus shows that the nominal genera LionyxChamberlin 1960 and Zygona Chamberlin 1960, originally proposed in the Schendylidae, must be referred instead to the Geophilidae.
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Jeffersoniana #4
A New Species of Puto and a Preliminary Analysis of the Phylogenetic Position of the Puto Group Within the Coccoidea (Homoptera: Pseudococcidae)
Douglass R. Miller and Gary L Miller
Three instars of the female and five instars of the male Puto kosztarabi are described and illustrated. This represents the first described species from eastern North America. A checklist of the known species of Puto, keys to the adult male Puto, North American female Puto, and instars to P. kosztarabi are included. A cladistic analysis utilizing 23 taxa and 38 characters supports the monophyly of the Puto group.
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Jeffersoniana #5
Cambarus (Cambarus) Angularis, a New Crayfish (Decapoda: Cambaridae) from the Tennessee River Basin of Northeastern Tennessee and Virginia
Horton H. Hobbs, Jr., and Raymond W. Bouchard
Cambarus (Cambarus) angularis is described from some 75 localities in the Powell, Clinch, and Holston river systems of northeastern Tennessee and southwestern Virginia. It seems to have its closest affinity with populations of Cambarus (C.) sciotensis in the New River system in southwestern Virginia. Distinguishing it from the latter and other members of the subgenus Cambarus is the following combination of characters: rostral margins thickened and in most adults forming distinct angles at base of acumen; densely punctate areola 3.3 to 5.6 times as long as broad; chelae with single row of usually low tubercles on mesial margin of palm, fingers gaping in larger adults; central projection of first pleopod strongly recurved, almost always reaching level of distal base of mesial process, and with subapical notch; epistome conspicuously punctate.
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Jeffersoniana #6
Three Unusual New Epigean Species of Kleptochthonius (Pseudoscorpionida: Chthoniidae)
William B. Muchmore
Three new epigean species of Kleptochthonius are described: K. sheari (type locality, Preston Co., West Virginia); K. inusitatus (type locality, Belmont Co., Ohio); and K. polycllaetus (type locality, Shenandoah National Park, Virginia).
Each of the three new species is unusual in some aspect of the sensory seta(e) on the fixed finger of the palpal chela. In Kleptochthonius (K.) sheari, the single sensory seta is large and spinelike, and is situated near the base of the finger; in K (K.) inusitatus, the sensory seta is very small, and is located just distad of trichobothrim ist; and in K. (K.) polychaetus, there are 10-15 small sensory setae in an irregular row dorsomediad and distad of ist.
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Jeffersoniana #7
A New Dinosauromorph Ichnogenus from the Triassic of Virginia
Nicholas C. Fraser and Paul E. Olsen
Bamsterobates boisseaui ichnogen. et ichnosp. nov. is described from Triassic (Carnian) sediments of the Danville Basin, Virginia. The type, and only, specimen is represented by three pedal and two manual impressions preserved in part and counterpart. Although four digit imprints are preserved, the pedal print is mesaxonic, with digit I very much reduced. The trackway is remarkable for its very small size (pes 18 mm long) yet finely preserved pad impressions. The evidence strongly supports a dinosauromorph maker of the trackway. Evidence for a more specific referral is inconclusive, but if the trackmaker was a true dinosaurian, on balance an ornithischian is favored over a theropod.
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Jeffersoniana #8
"Double-headed" Ribs in a Miocene Whale
Alton C. Dooley, Jr.
“Double-headed” ribs, which are known to occur in modem baleen whales, are reported from a middle Miocene cetothere. These” double-headed” ribs are actually the result of the fusion of an extra rib with the normal first rib. A comparison of the posterior cervical and anterior thoracic vertebrae indicates that this whale has only six cervical vertebrae. The extra pair of ribs is a result of the development of the seventh vertebra as a thoracic rather than a cervical. This type of development is consistent with genetic controls on segmented development observed in arthropods, and with the lowered constraints on skeletal development in mysticetes.
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Jeffersoniana #9
An Outline of the Pre-Clovis Archeology of SV-2, Saltville, Virginia, with Special Attention to a Bone Tool Dated 14,510 yr BP
Jerry N. McDonald
Saltville Valley is an important source of information about the environmental history of the Middle Appalachian region, especially for the past 15,000 years. The Saltville River coursed the valley until about 13,500-13,000 yrs BP, at which time it was diverted by headstream piracy and replaced, in Saltville Valley, by Lake Totten. At site SV-2 (=44SM37), three horizons dating from 14,510 + 80 yr BP to about 13,500_13,000 yr BP document the presence of pre_Clovis people in Saltville Valley and provide insight into their lifeways. At 14,510 yr BP, pre-Clovis people appear to have butchered and processed hide, meat, bones, and tusks of a mastodon (Mammut americanum) and to have utilized parts of the skeleton of a musk ox (Bootherium bombifrons). Five hundred years later, at 13,950 + 70 yr BP, human presence is suggested by unlikely arrangements, associations, and modifications of lithics, including flakes of chert that resemble biface reduction flakes. A midden dating from about 13,500 to 13,000 yr BP constitutes the youngest of the three pre-Clovis horizons recognized to date at SV-2.
SV-2 is one of the few and most complex pre-Clovis archeological sites in North America, and because it is a wet site, it contains a relatively extensive amount of organic information. Evidence suggests that the pre-Clovis people who visited Saltville Valley in 14,510 yr BP had a diversified ivory, bone, and lithic technology — possibly including a biface technology. These people appear to have been mobile hunters and gatherers who regularly visited and exploited the riparian and littoral zones in Saltville Valley where they utilized diverse faunal resources ranging from large mammals to small mammals, reptiles, amphibians, fish, and mussels.
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Jeffersoniana #10
First Confirmed New World Record of Apocyclops dengizicus (Lepeshkin), with a Key to the Species of Apocyclops in North America and the Caribbean Region (Crustacea: Copepoda: Cyclopidae)
Janet W. Reid, Robert Hamilton IV and Richard M. Duffield
An adult female of the cyclopoid copepod crustacean Apocyclops dengizicus (Lepeshkin) was found in the leaf vase of a northern pitcher plant, Sarracenia purpurea Linnaeus, in a freshwater boggy area on the coastal plain of eastern Virginia, USA. This is the first confirmed record of A. dengizicus, an Old World species, in the Americas. Species of Apocyclopsnormally inhabit brackish coastal lagoons and salt marshes and inland saline lakes, and finds in continental fresh waters are rare. This is only the second record of a member of the genus from a phytotelm (plant cup). We describe this individual, and report a possible second new record of the same species, based on juvenile specimens, from the eastern shore of the Chesapeake Bay in Maryland, USA. Apocyclops dengizicus may have been introduced into the region of the Chesapeake Bay by human agency, and may have established viable populations in the region. We review and update records of the other species of Apocyclops (A. dimorphus, A. panamensis, A. spartinus, and Apocyclops sp.) reported from North America, islands of the Caribbean, and Bermuda, and provide a key for their identification.
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Jeffersoniana #11
A Review of the Eastern North Atlantic American Squalodontidae (Mammalie: Cetacea)
Alton C. Dooley, Jr.
Previous listings of species of the catecean family Squalodontidae give the appearance of a diverse, well-represented group, but nearly all of the named specimens from North America are based on extremely poor material or were improperly proposed. This paper reviews the descriptions of these species and their type specimens to determine their validity.
Of 16 specimens from North America examined in the study, only two are members of the family Squalodontidae, and only one, Squalodon calvertensis Kellogg, 1923, is based on material sufficient for reliable identification. And additional unnamed squalodont species is identified. Thus the diversity of Miocene Squalodontidae in North America was much lower than has been indicated in the literature.
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Jeffersoniana #12
New Record and New Species of the Genus Diacyclops (Crustacea; Copepoda) from Subterranean Habitats in Southern Indiana, USA
Janet W. Reid
Ten species of the cyclopoid copepod crustacean genus Diacyclops were collected by Julian J. Lewis and his associates from caves, wells, and the hyporheic zone of streambeds in karst and non-karst terrain in southern Indiana, USA. These collections included six previously known species: D. crassicaudis brachycercus, D. jeanneli, D. navus, D. nearcticus, D. sororum, and D. yeatmani. Diacyclops jeanneli, which was originally described from Marengo Cave in Crawford County, is redescribed herein. A population of D. jeanneli still exists in Marendo Cave, and other populations were discovered in Floyd, Harrison, and Orange counties. All the sites where D. jeanneli was collected are located in the Blue Ridge faunal basin. Three new species, D. salisae, D. lewisi, and D. indianensis, are described from wells and a cave in Big Oaks National Wildlife Refuge. The refuge lies within the Muscatatuck faunal basin, with was covered by the Illinoian glacier. these three species show few or none of the morphological reductions that are normally associated with the subterranean habitat. They may have invaded subterranean habitats comparatively recently, i.e., after the Illinoian glacier began to retreat about 140,000 years ago. Female cyclopoids that are morphologically identical to D. indianensiswere recently discovered in two caves in east-central Tennessee; therefore the primary habitat of D. indianensis may be groundwater rather than caves. Both Diacyclops jeanneli and D. conversus show several reductions that are typical of subterranean cyclopoids, and may be more ancient subterranean inhabitants than D. salisae, D. lewisi, and D. indianensis.
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Jeffersoniana #13
Acroneuria yuchi (Plecoptera Perlidae) a New Stonefly from Virginia, U.S.A.
Bill P. Stark and B.C. Kondratieff
Acroneuria yuchi, new species, is described from male, female and egg specimens collected in Lee Co., Virginia, U.S.A. It differs from all known Acroneuria in having the egg chorion covered in hexagonal follicle cell impressions.
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Jeffersoniana #14
A New Species of Woodland Salamander of the Plethodon cinereus Group from the Blue Ridge Mountains of Virginia
Richard Highton
Plethodon sherando is described from the Big Levels area of Augusta Co., Virginia. It differs from P. cinereus in details of coloration, in having longer legs and fewer vertebrae, as well as in several allozyme values. A preliminary analysis of allozyme variation indicates it also differs genetically from the other species of the P. cinereus group. It is known to occur at elevations between 579-1091 m in a small area of <100 km="" sup="">2 in the vicinity of Big Levels, Augusta County, Virginia. Within most of its known range, P. sherando is the only eastern small Plethodon present, but at lower elevations it has been taken sympatrically with P. cinereus at five sites. A transect through the overlap zone between the two species near Stony Creek indicates that the altitudinal overlap is at least 46 m. The geographic distance between the highest and lowest sympatric populations in the overlap zone is at least 0.7 km. Since no F1 hybrids were found, apparently the two species do not hybridize frequently, although rare introgression may occur.
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Jeffersoniana #15
Additional Drepanosaur Elements from the Triassic Infills of Cromhall Quarry, England
Nicholas C. Fraser and Silvio Renesto
The Drepanosauride is a group of enigmatic tetrapods represented primarily by articulated material from the Late Triassic of northern Italy and eastern North America. The principal taxa are Drepanosaurus and Megalancosaurus from Italy and Hypuronector from New Jersey. In addition, Dolabrosaurus was erected on the basis of somewhat less complete material from the Chinle Formation of New Mexico. Recently, isolated cervical vertebrae from Norian fissure sediments of the Cromhall Quarry, Avon, England, were referred to the Drepanosauride. Here we report on additional elements from the same fissure infills that can also be assigned to the Drepanodauride. These include several caudal vertebrae and possibly also the claw-like, terminal element of a drepanosaur tail.
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Jeffersoniana #16
A Miocene Cetacean Verebra Showing a Partially Healed Compression Fracture, the Result of Convulsions or Failed Predation by the Giant White Shark, Carcharodon megalodon
Stephan J. Godfrey and Jeremy Altman
CT scans of a pathological whale vertebra (CMM-V-2194) from the Miocene Chesapeake Group of Maryland, show fractures characteristic of a compression fracture with comminution. The etiology of the injury suggests a sudden and intense hyperflexion of at least the posterior thoracic vertebrae. The trauma was sufficiently violent to break the lower third of the centrum, including adjacent sections of both epiphyses, away from the main body of the element. A dislocated fragment of the anterior epiphysis became wedged within the principle fracture precluding “normal” recovery. The trauma was not immediately fatal however as a significant fusion of fragmented elements was well underway at the time of death.
The cause of the vertebral hyperflexion and resulting trauma is unknown. Possibilities range from convulsions to a crushing blow delivered by a giant white shark, Carcharondon megalodon.
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Jeffersoniana #17
A New Crataegus-feeding Plant Bug of the Genus Neolygus from the Eastern United States (Hemiptera: Heteroptera: Miridae)
Thomas J. Henry
The new species Neolygus crataegi is described from two counties in southwestern Virginia where it was collected in June on flowers of hawthorn, Crataegus spp. Dorsal and lateral digital images and a habitus illustration of the adult, scanning electron photomicrographs of selected structures, and illustrations of male genitalia are provided to help distinguish N. crataegi from other species of the genus.
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Jeffersoniana #18
Barstovian (middle Miocene) Land Mammals from the Carmel Church Quarry, Caroline County, Virginia
Alton C. Dooley, Jr.
Excavation of marine sediments of the Calvert Formation at the Carmel Church Quarry has resulted in the collection of remains of several land mammals. These include the first reports from the upper Calvert Formation of the family Dromomerycidae and of the equid Calippus cf. regulus as well as the tayassuid “Prosthennops” xiphidonticus and a tapirid. The presence of Calippus cf. regulus and “Prosthennops” xiphidonticusindicate a late Barstovian age for this deposit, which is consistent with previous assessments based on diatoms.
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Jeffersoniana #19
Unusual Cambrian Thrombolites from the Boxley Blue Ridge Quarry, Bedford County, Virginia
Alton C. Dooley, Jr.
Three unusual thrombolites were collected in June 2008 from the Late Cambrian Conococheague Formation at the Boxley Materials Blue Ridge Quarry in Bedford County, Virginia. These specimens are isolated low domes with a thrombolitic core and a pustulate, stromatolitic outer layer. The two largest domes have a distinctive thickened rim around their margins. There are apparent traces across the upper surfaces of the domes that may indicate grazing by invertebrates.
The overall structure and morphology of the Boxley specimens is reminiscent of modern thrombolites forming in Lake Thetis, a saline lake in southwestern Australia. The low domes and thickened rims in Lake Thetis specimens seem to be a result of growth in a protected setting, with shallowing water levels. Based on the similarities with the Lake Thetis specimens, the Boxley thrombolites may have formed in a protected lagoonal setting with gradually dropping water levels, followed by relatively rapid inundation and burial.
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Jeffersoniana #20
Injuries in a Mysticete Skeleton from the Miocene of Virginia, With a Discussion of Buoyancy and the Primitive Feeding Mode in the Chaeomysticeti
Brian L. Beatty and Alton C. Dooley, Jr.
A mostly complete skeleton of a mysticete from the Carmel Church Quarry displays some injuries, including a fractured and partially-healed left mandible, previously not reported in any fossil mysticete. The mostly healed nature of this non-union impaction fracture indicates that the animal died a significant amount of time after the injury. Additional injuries of the postglenoid process and left premaxilla, as well as the nature of the impaction fracture in the mandible suggest that the cause of this was some impact from the left anterior aspect. Possible scenarios for how this injury could have happened include intraspecific aggression and, more likely, impact with the seafloor during benthic feeding. The ribs of this individual are heavily osteosclerotic from dorsal to ventral ends, which would suggest that this taxon was a benthic feeder. In comparison with a sample of ribs from fossil mysticetes, it appears that Diorocetus may have been one of the last mysticetes with rib osteosclerosis, a feature possibly primitive to Mysticeti. Although this remains speculative, the presence of osteosclerotic ribs in primitive mysticetes suggests that the feeding mode employed by the earliest Chaeomysticeti was one of benthic feeding.
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Jeffersoniana #21
Morphometric and Allozymic Variation in the Southeastern Shrew (Sorex longirostris)
Wm. David Webster, Nancy D. Moncrief, Becky E. Gurshaw, Janet L. Loxterman, Robert K. Rose, John F. Pagels, and Sandra Y. Erdle
Morphometric and allozymic variation was examined in specimens of Sorex longirostristo assess the status of S. l. fisheri, which is thought to be restricted to the Great Dismal Swamp region of southeastern Virginia and northeastern North Carolina. Significant geographic variation was detected in all cranial and external measurements and in body mass. Shrews from southeastern Virginia and throughout eastern North Carolina (S. l. fisheri Merriam 1895) are large overall but they have relatively narrow crania. Shrews from southern Georgia and Florida (S. l. eionis Davis 1957) also are large but they have relatively short tails. Shrews from elsewhere in the range of the species (S. l. longirostris Bachman 1837) are relatively small in all cranial and external dimensions and in body mass. Five of 25 genetic loci examined by starch-gel electrophoresis were variable, with one allele (MPIC) occurring only in shrews from southeastern Virginia and several sites in eastern North Carolina. Allozymic evidence for intergradation was demonstrated through the presence of the MPIC allele in specimens from central North Carolina that morphologically were assigned to S. l. longirostris. Shrews from the Lower Coastal Plain of eastern North Carolina were allozymically more similar to animals from the Great Dismal Swamp, the type locality of S. l. fisheri, than to shrews from western North Carolina and Virginia (S. l. longirostris). Thus, based on morphometric and allozymic information, we conclude that shrews referable to S. l. fisheri are distributed widely in the North Carolina Coastal Plain, well beyond the historic Great Dismal Swamp in southeastern Virginia.
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Jeffersoniana #22
Karyotype Designation and Habitat Description of the Northern Short-tailed Shrew (Blarina brevicauda, Say) from the Type Locality
Cody W. Thompson and Justin D. Hoffman
The karyotype of the northern short-tailed shrew (Blarina brevicauda) has been studied extensively across its range, revealing polymorphisms as a result of Robertsonian fissions/fusions. However, no karyological data have been reported at the type locality due to disagreement on its location. This information is vital given the proximity of a contact zone with the Elliot’s short-tailed shrew (B. hylophaga). Recent evidence has indicated that the type locality of B. brevicauda is situated at the western edge of this species’ distribution in eastern Nebraska. Therefore, it is now possible to establish a karyotype of specimens found at this location. Specimens were collected in 2006 at the type locality and field karyotyped. Chromosome morphology was consistent with previous reports. Two specimens collected from the type locality had a diploid number of 50 and a fundamental number of 48. Further investigation may reveal additional karyotypes at this location.
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Jeffersoniana #23
Diatom Biostratigraphy and Paleoecology of Vertebrate-bearing Miocene Localities in Virginia
Anna R. Trochim and Alton C. Dooley, Jr.
Silicieous microfossil samples were obtained from sediment collected with cetacean remains from three localities in eastern Virginia: the Carmel Church Quarry in Caroline County (CCQ), Westmoreland State Park in Westmoreland County (WSP), and the Rappahannock River in Richmond County (RMC). While the WSP and RMC deposits have been correlated with the upper part of the middle Miocene Calvert Formation based on past studies of diatoms and macroinvertebrates, the assignment of CCQ to the upper Calvert has been based primarily on lithostratigraphy and land mammal biostratigraphy.
Among these samples, CCQ exhibited the greatest diatom diversity with 28 species from 19 genera. At RMC 15 species from 12 genera were identified, while 19 species from 11 genera were found at WSP, which had the greatest abundance of diatoms. In addition, a single silicoflagellate taxon, Dictyocha crux, was identified at each site.
At CCQ, the co-occurrence of Stephanopyxis grunowii and Delphineis biseriataindicates a correlation with Bed 15 of the Calvert Formation. At RMC, the co-occurrence of D. biseriata and D. penelliptica also indicates a correlation with Bed 15. Useful marker diatoms were rare at WSP. Even so, the co-occurrence of D. penellipticaand D. novaecaesaraea combined with the absence of D. biseriata suggests a correlation with Beds 12-15 of the Calvert. Published reports based on mollusks from WSP indicate that this unit correlates with Beds 14-15.
All three sites contained abundant specimens associated with or tolerant of brackish water, including Coscinodiscus rothii at CCQ and WSP, Hyalodiscus laevis at CCQ and RMC, and Paralia sulcata at all three sites. There was a mix of both warm- and coolwater taxa (Actinoptychus senarius, P. sulcata) at all three sites. All three sites also included benthic taxa, suggesting that water depths throughout the area were no greater than 20 meters.
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Jeffersoniana #24
A Middle Miocene Beaked Whale Tooth (Cetacea: Ziphiidae) from the Carmel Church Quarry, Virginia, and Implications for the Evolution of Sexual Dimorphism in Ziphiids
Alton C. Dooley, Jr.
**Please note that the original author has disproved this article since its publishing. More information can be found here.
An apparent right apical mandibular tooth from a beaked whale (Family Ziphiidae) was collected at the Carmel Church Quarry, Caroline County, Virginia in August 2009. The occurrence of this specimen in Bed 15 of the Calvert Formation marks only the second report of a ziphiid from the Calvert Formation. Moreover, this specimen represents, along with the Peruvian Nazcacetus and Messapicetus, the earliest known occurrence of an enlarged mandibular tooth in a ziphiid. The complete closure of the pulp cavity indicates that this tooth derived from a fully mature animal, while the lack of wear on the crown indicates that the tooth had not erupted from the gums, suggesting that the animal was a female. The presence of unerupted mandibular teeth in a fully mature female suggests that, even by the middle Miocene, ziphiids had already evolved modern behavioral patterns in which enlarged mandibular teeth are used exclusively for intraspecific combat between competing males.
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Jeffersoniana #25
Reconnaissance Mineralogy of the Eocene Mole Hill Diatreme, Rockingham County, Virginia
James S. Beard
The Mole Hill diatreme consists of picrobasalt with abundant megacrysts (0.5 mm to 2cm in maximum dimension) of clinopyroxene, Mg-Al-Fe spinel, and (less abundant) olivine. Cognate minerals include microphenocryst and groundmass plagioclase, olivine, clinopyroxene and Fe-Ti-(Cr) spinel. Clinopyroxene is the most abundant megacryst phase. Overall, the clinopyroxene in the megacryst cores is a high-Al, low-Cr augite with Mg# 78-88. Sieve textured rims approach groundmass clinopyroxene compositions. Olivine occurs as megacrysts and also as small (0.1- 0.5 mm) crystals of indeterminate origin. These may be phenocrysts, xenocrysts, or both. All non-groundmass olivine is zoned, becoming Fe- and Ca-rich (and approaching the composition of groundmass olivine) rimward. The most primitive olivine has Fo~90 and NiO as high as 0.75wt.%. More typically, olivine is Fo78-88 with NiO <0.5 wt.%. The megacryst/xenocryst olivine cores have higher Mg# and lower CaO than groundmass olivine. Megacrystic spinels are notably low in Cr, with Cr# <1, and variable Mg# ranging from 52-74. This variation is appears to be continuous, despite the lack of zoning in individual spinel xenocrysts. Plagioclase occurs only as a microphenocryst phase, with uniform An75 cores and rims as sodic as An58. Cognate clinopyroxene (Mg#67-78) is enriched in Ca and Ti relative to the megacrysts. Groundmass olivine has low NiO and high (0.3-0.6 wt.%) CaO. Groundmass spinels have ulvospinel contents near 50%, initially rising with Mg# (in Cr-rich microphenocrysts) then dropping. Although the lack of context for the megacrysts precludes a definitive understanding of their origin, megacryst chemistry (especially the low-Cr spinels and the overall abundance of clinopyroxene) suggests a clinopyroxene-rich source in the upper (e.g. spinel zone) continental lithosphere. This source is likely similar to the Al-augite suite clinopyroxenites and wehrlites that occur as xenoliths and as intrusive veins in composite xenoliths from alkali basalt provinces worldwide. Cognate mineral (groundmass minerals and microphenocrysts) compositions are consistent with crystallization from a slightly evolved alkali basalt melt.
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Jeffersoniana #26
Potential Impacts of the Invasive Herb Garlic Mustard (Alliaria petiolata) on Local Ant (Hymenoptera: Formicidae) Communities in Northern Temperate Forests
Kaloyan Ivanov and Joe Keiper
Garlic mustard, an invasive shade-tolerant species introduced to North America from Eurasia in the late 1860s, now is widely distributed throughout the US and Canada. The presence of garlic mustard results in displacement of understory species and subsequent decline in native plant diversity. By displacing native plants, garlic mustard can affect resource availability and habitat quality, and thereby affect animals across different trophic levels. However, these impacts have been documented infrequently. Our study focused on the small-scale effects of garlic mustard invasion on an abundant and important group of forest-floor arthropods. We evaluated the effects of garlic mustard on forest ant assemblages in invaded and non-invaded areas of two mesophytic forest fragments of northeastern Ohio. Plots invaded by garlic mustard showed reduced leaf litter depth, and an increased abundance of nonnative Amynthas earthworms. Sample-based rarefaction and similarity analyses revealed that the presence of garlic mustard, and the associated decrease in leaf litter depth, had no detectable effect on the observed and expected ant species richness and community composition. Rank-abundance distributions also were largely unchanged in garlic mustard invaded plots. Our results suggest that regional sylvan ant communities are unaffected by the generally presumed negative effects of garlic mustard invasions, or these effects may be more subtle or confounded by other dominating factors.
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Jeffersoniana #27
The Effects of Fire on Lycopodium digitatum strobili
Stephanie I. Vogel, Bryan T. Piatkowski, Alton C. Dooley, Jr., and DorothyBelle Poli
Lycopodium is a commonly ignored plant in the forest understory and in fire ecological studies in spite of the well-documented explosive nature of their spores. Therefore, in order to understand how fire may affect Lycopodium, burn studies were carried out on varying sporophyte life cycle stages. Strobili exhibited varying degrees of sporophyll opening and closing in response to the burning and age was directly correlated to the length of the burn. Spores that were burned and plated on axenic media showed a decrease in germination time, from 9 months to 3 weeks, after being subjected to fire. Beyond providing baseline understanding of the effects of fire on Lycopodium and its reproduction, these studies also provide clues about the possible role of fire in Paleozoic forests.
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Jeffersoniana #28
Community Structure and Paleoecology of Crocodyliforms from the Upper Hell Creek Formation (Maastrichtian), Eastern Montana, Based on Shed Teeth
George E. Bennett, III
Modern crocodilian populations display a distinct attritional age class frequency distribution, with each age class corresponding roughly to size. Hatchlings constitute the largest age class, with each successive age class containing fewer individuals. This pattern reflects the continuous growth and natural mortality rate in crocodilians.
Screen washing of microvertebrate localities in the upper Hell Creek Formation of eastern Montana has produced several hundred shed crocodyliform teeth. Two dominant species of Hell Creek crocodyliforms, Borealosuchus sternbergii and Brachychampsa montana, possess indistinguishable anterior teeth and have been combined in this study. The sample of shed teeth represents a temporally averaged and spatially constrained assemblage, whereby the effects of stochastic events that affected hatching rates in the original populations during a single season are muted.
Using a modeled population and measured tooth replacement rates through ontogeny of the extant Alligator mississippiensis, it was found that both the extant and extinct crocodyliforms studied shed proportionally similar numbers of teeth in each size category into the environment. Results indicate that: (1) the size and age structures of ancient and extant crocodyliform communities are similar; (2) microvertebrate localities in channel sands are size-sorted and should be used with caution in studies of population demographics; and (3) using unbiased collecting techniques, the community structures of other extinct vertebrates that lack modern analogues can be established.
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Jeffersoniana #29
The First Terrestrial Mammal from the Late Miocene Eastover Formation of Virginia
Brian Lee Beatty and Alton C. Dooley, Jr.
A partial deciduous premolar from a gomphothere is reported from the Late Miocene Eastover Formation in New Kent County, Virginia. This represents the first definitive occurrence of a terrestrial mammal from the Eastover Formation.
Gomphotheres are now known from nearly every marine formation from the Middle Miocene to the Early Pliocene along the middle Atlantic Coastal Plain. Gomphotheres are typically associated with more open habitats, but floral data suggests that the region transitioned from warmer, more forested conditions in the Middle Miocene to heterogeneous conditions in the Late Miocene. The persistence of gomphotheres throughout this interval suggests that substantial open habitats were present along the Coastal Plain from the Middle Miocene to at least the Early Pliocene.
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Jeffersoniana #30
The Incongruent Melting and Crystallization Behavior of Amphibole: A Second Peritectic Reaction in Bowen’s Reaction Series and Its Petrogenetic Consequences
James S. Beard
The reaction of pyroxene plus melt to form amphibole was recognized by Bowen in his earliest depictions of the reaction series. This reaction was included primarily on the basis of observations of amphibole reaction rims about pyroxene. However, the nature of the amphibole-forming reaction was not known to Bowen. Experimental and geochemical work completed since the late 1980s has now identified this reaction,known as dehydration melting, as a peritectic reaction whereby amphibole melts incongruently to form an anhydrous phase assemblage, mostly pyroxene, coexisting with a hydrous, but water-undersaturatedmelt. It is analogous to the incongruent melting of Mg-Fe pyroxene that was first documented by Bowenhimself. Bowen’s reaction series is integral to most introductory geology (and virtually all introductory petrology) curricula. This latterday documentation of a second peritectic reaction in the series is a powerful proof-of-concept that further validates the importance and relevance of the reaction series as a pedagogic tool. The peritectic behavior of amphibole has been shown to have important implications for the genesis, crystallization, hybridization, and fractionation behavior of magmas. These include the genesis of silicic magmas, the behavior of water during crystallization and the chemistry of fractionating systems. Thus, the exploration of the petrological consequences of incongruent melting behavior of amphibole also has a place for discussion in (at least) higher level petrology classes.
