Date of Completion

8-21-2014

Embargo Period

8-21-2014

Keywords

trace fossils, Paleozoic, Mesozoic, behavior, archaeognathan, dinosaurs

Major Advisor

Andrew Bush

Associate Advisor

Pieter Visscher

Associate Advisor

David Wagner

Field of Study

Geological Sciences

Degree

Doctor of Philosophy

Open Access

Open Access

Abstract

Ichnology is the study of trace fossils, which are important because they provide direct evidence of animal behavior and because, as sedimentary structures, they are often preserved in environments devoid of body fossils. This study examines why skeletons are rare in New England and uses ichnology to evaluate the behaviors of its Carboniferous and Jurassic inhabitants.

The first chapter addresses taphonomic processes that preserved dinosaur bones from Connecticut as molds. The animal’s body decomposed above ground, where its skeleton disarticulated and was transported fluvially. The bones were buried and dissolved underground due to acidic groundwater. Their preservation as molds provides a rare glimpse into taphonomic processes limiting body fossil preservation in New England.

The second chapter presents a new study of Dinosaur Footprint Reservation in Massachusetts to test whether gregarious behavior existed in large, Early Jurassic theropods. Track orientations were compared to the paleoshoreline direction, as indicated by oscillation ripples. Analysis indicates that large carnivores paralleled the shore, suggesting an alternative to the herding hypothesis.

The third chapter uses experimental ichnology to determine the maker of unusual Carboniferous arthropod trackways. Modern jumping bristletails and silverfish were used as analogues for the track makers; experiments show that different orientations of the tail appendages explain the differences in the fossil trackways.

The fourth chapter presents a new reconstruction of continental occurrences of the well-known fossil fly burrow called Treptichnus based on specimens from the Jurassic of Massachusetts. Thin sections indicate that the burrows were largely horizontal, in contrast to previous reconstructions.

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