Quantitative Taphonomy of a Triassic Reptile: Tanytrachelos ahynis from the Cow Branch Formation, Dan River Basin, Solite Quarry, Virginia

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dc.contributor.authorCasey, Michelle M.en
dc.contributor.committeechairKowalewski, Michalen
dc.contributor.committeememberFraser, Nicholas C.en
dc.contributor.committeememberXiao, Shuhaien
dc.contributor.departmentGeosciencesen
dc.date.accessioned2014-03-14T20:36:02Zen
dc.date.adate2005-05-18en
dc.date.available2014-03-14T20:36:02Zen
dc.date.issued2005-04-27en
dc.date.rdate2006-05-18en
dc.date.sdate2005-05-10en
dc.description.abstractThe Virginia Solite Quarry assemblage of Tanytrachelos ahynis, with its exceptionally abundant and uniquely preserved specimens, offers an opportunity to quantify multiple aspects of vertebrate taphonomy. The presence or absence of 128 skeletal elements (i.e., bones) as well as the presence or absence of 136 skeletal variables (i.e., morphometric dimensions) were recorded for 100 specimens collected from two distinct layers within the quarry (lake cycles 2 and 16). Anatomical specimen completeness (or the percent of bones/variables present in a specimen) is low (the median specimen preserves 14.5% of bones and 11.8% of measured variables) in spite of protection from high energy currents, predators, and scavengers afforded by anoxic bottom waters. Specimen size, as approximated by femur length, does not significantly impact specimen completeness. Also, post-exhumation weathering, duration of exposure before burial, and morphotype groupings do not appear to have significantly affected anatomical specimen completeness or articulation. Presence or absence of the enigmatic heterotopic bones represents a true biological signal as indicated by the lack of significant difference in anatomical specimen completeness between the two morphotypes as well as qualitative taphonomic evidence. When anatomical specimen completeness has been corrected for post-depositional faulting, lake cycles 2 and 16 differ from one another significantly in terms of articulation and anatomical completeness of specimens. Specimens with soft-bodied preservation are significantly more articulated, but not significantly more complete, than specimens without preserved soft tissues. Preservation frequency of bones/variables (or the percent of specimens in which a bone/variable is present) varies greatly, but is generally low (an average skeletal element is present in 19% of specimens and an average variable can be measured in 12% of specimens), with significant preferential removal of smaller skeletal elements. Hind limbs, specifically femora, are most commonly preserved. Low anatomical specimen completeness and positive correlation between bone size and frequency of preservation both indicate specimen disturbance by minor hydraulic currents. These taphonomic patterns suggest a moderate-depth depositional environment (slightly shallower than previously proposed).en
dc.description.degreeMaster of Scienceen
dc.identifier.otheretd-05102005-200657en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-05102005-200657/en
dc.identifier.urihttp://hdl.handle.net/10919/32503en
dc.publisherVirginia Techen
dc.relation.haspartMCasey.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectLacustrineen
dc.subjectNewark Supergroupen
dc.subjectLagerstattenen
dc.subjectDepositional Environmenten
dc.titleQuantitative Taphonomy of a Triassic Reptile: Tanytrachelos ahynis from the Cow Branch Formation, Dan River Basin, Solite Quarry, Virginiaen
dc.typeThesisen
thesis.degree.disciplineGeosciencesen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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