Incorporating spatial datasets into paleontology: Effects on estimates of diversity, origination, & extinction

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Wall, Patrick Daniel
Sedimentary rocks; Extinction; Biodiversity; Stenotopes; Earth Sciences; Geology; Paleontology; Physical Sciences and Mathematics
thesis / dissertation description
One of the great strengths of the field of paleontology is its historical nature. The sedimentary rocks that cover 75% of the continents' surface provide information about vast spans of time at scales far greater than a laboratory experiment. Because of this strength, paleontological research has largely focused on temporal, rather than spatial, patterns. One major exception to this is the study of bias in the fossil record. Many researchers have argued that the differential distribution of sedimentary rocks through time and space may influence our understanding of biodiversity patterns recovered from that record.Chapter one of this dissertation explores the relations between outcrop area of marine sedimentary rocks, diversity of organisms found in those rocks, and the distribution of shallow marine seas through time. I maintain that the observed relation between diversity and outcrop area indicates a pervasive bias in the record. Once removed, there is no evidence for the long-term increase in diversity through time, a centerpiece of paleobiological research for several decades. Diversity correlates with outcrop area not only because large areas sample more individual fossils, but also because they encompass an increasingly diverse array of habitats and/or provinces.The movement of organisms across the landscape adds another spatial dimension to paleontology. Chapters two and three of this dissertation focus on a smaller scale, the Acadian foreland basin represented by the Hamilton Group of central and western New York State, to explore how the migration of facies and organisms in space affect estimates of faunal turnover in time. Sampling a small geographic area will tend to over-estimate turnover rates because taxa that have migrated out of that area may not be sampled and therefore are erroneously counted as extinct. Furthermore, times when taxa had large geographic ranges give more accurate turnover estimates than times when taxa have small geographic ranges. Turnover estimates for stenotopic taxa, which tend to have small geographic ranges, are likely to be higher than those of eurytopes for the same reason. These factors may cause stenotopes to appear more vulnerable to extinction than they truly were.