Sandy Carlson | University of California, Davis (original) (raw)

Papers by Sandy Carlson

The nature and extent of enamel ultrastructural variation in mammals has not been thoroughly inve... more The nature and extent of enamel ultrastructural variation in mammals has not been thoroughly investigated. In this study we attempt t o identify and evaluate the sources of variability in enamel ultrastructural p a t t e r n s a t a number of hierarchic levels within t h e extinct order Multituberculata. These levels include: 1) different positions on a single tooth; 2) different depths and orientations of a prepared enamel surface; 3) different teeth from a single individual; 4) isolated teeth assigned to a single species; 5) between congeneric species; 6) between genera; and 7) within suprageneric taxa. Nearly all of the specimens examined can be unambiguously characterized by one of two major ultrastructural types: large (X diameter = 8.2 pm, N = 32, sd ' Department of Geological Sciences and Museum of Paleontology. ' 1 he l!niversity of M~chigan. Ann Arbor.

PDF table explaining how the identifiers, labels and conditions of the different phylogenetic ana... more PDF table explaining how the identifiers, labels and conditions of the different phylogenetic analyses as given in the main text and in the supplemental data materials relate.

The raw morphological matrix, as used in the Bayesian analyses, as a Nexus-formatted text file.

Minerals

Due to their robust preservation and widespread nature, marine bivalve shells are increasingly us... more Due to their robust preservation and widespread nature, marine bivalve shells are increasingly used as informative, high-resolution records of past environmental conditions. Unfortunately, few studies have investigated variability amongst individuals in a genetic cohort and throughout their ontogeny. We measured several morphological properties and the element patterning of 200-day-old juvenile Leukoma staminea (Conrad, 1837) grown in identical conditions from the same reproductive cohort. We hypothesized that slower shell growth would correspond to the reduced incorporation of trace/minor elements (Sr, Mg, and S) in the aragonite lattice, as has been documented in other biomineralizing marine invertebrates. Microprobe analyses of adult shells revealed higher levels of S, Sr, and Mg in the dark, slower-growing growth lines compared to the light, faster-growing increments, particularly in the inner shell layer, thus refuting our hypothesis. Moreover, elemental count variation within ...

Part H, Brachiopoda (Revised), vol. 2 & 3, 2000

GSA Annual Meeting in Denver, Colorado, USA - 2016, 2016

Brachiopods and their long loops • One of the most diverse and abundant marine invertebrates in t... more Brachiopods and their long loops • One of the most diverse and abundant marine invertebrates in the fossil record. • The loop is a calcareous structure that supports the lophophore. • Important morphological character.-Phylogeny, taxonomy, ontogeny Terebratalia transversa Cardinalia Loop Cardinal process Socket ridges Outer hinge plates Crura + crural processes Descending branch Ascending branch Transverse band Connecting band (horizontal) Septum

Paleobiology

We highlight the historical and contemporary policies that govern paleontological research on fed... more We highlight the historical and contemporary policies that govern paleontological research on federally recognized Native American lands. The United States has a long history of fossil dispossession from Indigenous Peoples, and federal policies surrounding the management of Native American lands (i.e., reservations), and the geological resources therein, have changed through time. These changes reflect shifting popular and political ideologies regarding Native American nations’ sovereignty and self-governance. As of 2022, the United States has a government-to-government relationship with federally recognized Tribal entities, but that has not always been the case. Historians have divided post-contact Native American federal policy into distinct eras: Colonial Times to 1820, Native American Removal and Reservation (1820–1887), Allotments and Attempted Assimilation (1887–1934), Reorganization and Preservation (1934–1953), Termination and Relocation (1953–1968), and Tribal Self-Determin...

Data on the maximum body size of terebratulide genera collected from figured specimens in the Tre... more Data on the maximum body size of terebratulide genera collected from figured specimens in the Treatise on Invertebrate Paleontology (Kaesler 2000). Linear measurements of shell width and length were gathered, as well as shell height wherever possible. For genera comprising two or more species, genus body size was calculated as the geometric mean of the holotype specimen for each species. If the holotype was not figured for a species, the paratype, neotype, or best-resolution illustration was used, in that order. Length: shell length (in mm) - beak to commissure; Width: shell width (in mm) - parallel to hinge; Height: shell height (in mm) - perpendicular to the other two axes; Area: product of shell length and width, in log10 mm^2; Volume: product of shell length, width, and height, in log10 mm^3; Figure: figure number of the measured illustration in the Treatise on Invertebrate Paleontology; Figure_part: figure part in the Treatise (required to get the exact specimen measured); Founder: this is the authority for the species as reported in the Treatise; Year: this is the year in which the measured species was described

Independent molecular and morphological phylogenetic analyses have often produced discordant resu... more Independent molecular and morphological phylogenetic analyses have often produced discordant results for certain groups which, for fossil-rich groups, raises the possibility that morphological data might mislead in those groups for which we depend upon morphology the most. Rhynchonellide brachiopods, with more than 500 extinct genera but only 19 extant genera represented today, provide an opportunity to explore the factors that produce contentious phylogenetic signal across datasets, as previous phylogenetic hypotheses generated from molecular sequence data bear little agreement with those constructed using morphological characters. Using a revised matrix of 66 morphological characters, and published ribosomal DNA sequences, we performed a series of combined phylogenetic analyses to identify conflicting phylogenetic signals. We completed a series of parsimony-based and Bayesian analyses, varying the data used, the taxa included, and the models used in the Bayesian analyses. We also performed simulation-based sensitivity analyses to assess whether the small size of the morphological data partition relative to the molecular data influenced the results of the combined analyses. In order to compare and contrast a large number of phylogenetic analyses and their resulting summary trees, we developed a measure for the incongruence between two topologies, and simultaneously ignore any differences in phylogenetic resolution. Phylogenetic hypotheses generated using only morphological characters differed amongst each other, and with previous analyses, while molecular-only and combined Bayesian analyses produced extremely similar topologies. Characters historically associated with traditional classification in the Rhynchonellida have very low consistency indices on the topology preferred by the combined Bayesian analyses. Overall, this casts doubt on the use of morphological systematics to resolve relationships among the crown rhynchonellide brachiopods. However, expanding our dataset to a larger number of extinct taxa with intermediate morphologies is necessary to exclude the possibility that the morphology of extant taxa is not dominated by convergence along long branches

R script for generating all figures in associated Evolution 2016 from provided R workspace file

Table giving the number of taxa having each character state (or coded as missing) for each morpho... more Table giving the number of taxa having each character state (or coded as missing) for each morphological character in the revised matrix.

The Paleontological Society Special Publications, 1996

List of character changes across reweighted tree (Fig. 4

List of apomorphies across reweighted tree (Fig. 4)

Geological Society of America Abstracts with Programs, 2017