• Bone Histology and Geochemical Taphonomy of Arctic Centrosaurine Ceratopsids from the Kikak-Tegoseak Quarry (North Slope, Alaska)

      Tumarkin-Deratzian, Allison; Chemtob, Steven M.; Grandstaff, David E.; Fiorillo, Anthony R. (Temple University. Libraries, 2018)
      Pachyrhinosaurus perotorum, a paleo-Arctic centrosaurine ceratopsid from the Kikak-Tegoseak Quarry (North Slope, Alaska) represents a unique opportunity to add to the understanding of ceratopsian bone histology, which is poorly understood due to the minimal preservation of growth markers (e.g. lines of arrested growth) and limited histological sampling across the ceratopsian lineage. Histological analyses of eight rib fragments from P. perotorum were conducted to add to the understanding of ceratopsian growth dynamics. Cyclical growth is preserved within ribs from P. perotorum allowing for the assignment of relative ontogenetic ages. One juvenile (DMNH 23891), 4 sub-adults (DMNH 21574, DMNH 24384, DMNH 24228, and DMNH 23888), and one adult (DMNH 24237) were identified. Radial and reticular fibrolamellar bone is prevalent in juvenile and sub-adult individuals indicating P. perotorum grew rapidly during ontogeny. Dense secondary bone is widespread in adult and three sub-adult individuals, which obscures most primary bone tissue and lines of arrested growth (LAGs). The degree of remodeling is higher than that previously reported in dinosaur rib histology, and may be attributable to differences in element-specific growth rate, environmental or biomechanical stresses. However, more histological studies of P. perotorum comparing growth between different postcranial long bones are needed to constrain the controls of secondary bone within this paleo-Arctic species. Although previous studies have interpreted taphonomy of the Kikak-Tegoseak Quarry (KTQ) using sedimentological and paleontological data, less is known about the geochemical taphonomy of this assemblage. P. perotorum bone has been altered from carbonate-hydroxyapatite to carbonate fluorapatite. XRD full width half maximum (FWHM) values display narrower peak widths (0.29-0.35°) than modern bone indicating a more crystalline apatite lattice structure. ATR-FTIR infrared splitting factor (IR-SF) values in P. perotorum specimens are greater (3.3-3.6) than in modern bone indicating that apatite crystallite sizes are larger than what is typically found in non-fossil bone. Higher crystallinity is a common result in fossil bone due the growth of authigenic apatite. ATR-FTIR spectra reveal elevated carbonate due to the addition of B-type carbonate into the apatite lattice. Relative amounts of carbonate correlates with ontogeny which could reflect a biological signal, although the effect of diagenetic alteration cannot be ruled out. Based on the elevated carbonate within bones of P. perotorum, there is potentially significant diagenetic alteration of the δ18Ocarbonate signal, therefore future stable isotope studies from the KTQ P. perotorum specimens should be cautious. Determining the potential chemical alteration of the δ18Ophosphate is more difficult since crystallinity data cannot differentiate between biogenic and secondary phosphate in bone. However, depleted carbonate: phosphate ratios can indicate the addition of more phosphate and thus, potential diagenetic alteration of the δ18Ophosphate. REE spider patterns yield different patterns between P. perotorum bones, which indicates taphonomic reworking (spatial and/or temporal) due to the preservation of different redox conditions and diffusion periods between bones. This observation is surprising due to the lack of significant/variable bone weathering or abrasion.

      Terry, Dennis O., 1965-; Grandstaff, David E.; Tumarkin-Deratzian, Allison; Ullmann, Paul V. (Temple University. Libraries, 2020)
      Previous studies on microtaphonomy have identified multiple different organic microstructures in fossil vertebrates from a variety of time periods and environmental settings. This study seeks to investigate the potential taphonomic, paleoclimatic, and geochemical controls on soft tissue and cellular microstructure preservation. To this end, fifteen vertebrate fossils were studied: eight fossils collected from the Oligocene Sharps Formation of the Arikaree Group in Badlands National Park, South Dakota, and seven fossils from formations in the underlying White River Group, including the the (Oligocene) Brule Formation of Badlands National Park, and the (Eocene) Chadron Formation of Flagstaff Rim, Wyoming; Toadstool Geologic Park, Nebraska; and Badlands National Park, South Dakota. A portion of each fossil was demineralized to identify any organic microstructures preserved within the fossils. I investigated several potential soft tissue preservation factors, including taxonomy, paleoclimate, depositional environment, and diagenetic history as shown through bone apatite crystallinity and trace element alteration. Soft tissue microstructures were preserved in all fossil samples, and cellular material was recovered from most fossil specimens. Soft tissue and cellular preservation was found to occur independent of taxonomy, paleoclimate regime, depositional environment, and apatite crystallinity. The period of fossilization and diagenetic trace element addition, as shown through rare earth element (Lanthanum) diffusion profiles, may be connected to organic microstructure preservation, as longer estimated diffusion periods were correlated with poorer preservation of bone histology and greater cellular degradation in some of the fossil samples.
    • Craniofacial Ontogeny In Centrosaurus apertus

      Tumarkin-Deratzian, Allison; Carr, Thomas D. (Paleontologist); Terry, Dennis O., 1965-; Davatzes, Nicholas (Temple University. Libraries, 2013)
      Centrosaurus apertus, a large bodied ceratopsid from the Late Cretaceous of North America, is one of the most common fossils recovered from the Belly River Group of Canada. This fossil record shows a wide diversity in morphology and size, with specimens ranging from putative juveniles to fully-grown individuals. The goal of this study was to reconstruct the ontogenetic changes that occur in the craniofacial skeleton of C. apertus through a quantitative cladistic analysis. Forty-seven cranial specimens were independently coded in separate data matrices for 80 hypothetical multistate growth characters and 130 binary growth characters. Analyses were executed under heuristic searches with all characters unordered and equally weighted. Both analyses yielded the max-limit of 100,000 most parsimonious saved trees and the strict consensus collapsed into large polytomies, so a 50% majority rule consensus was obtained to recover structure in the data. In order to reduce conflict resulting from missing data, fragmentary individuals were removed from the data matrices and the analyses were rerun under a branch and bound search for both multistate and binary data sets. The multistate analysis yielded a single most parsimonious tree, while the binary analysis yielded thirteen equally most parsimonious trees. A strict consensus of the thirteen trees collapsed into a polytomy in the most mature individuals, but the resolved portion is consistent with the tree recovered in the multistate analysis. Among both the complete and the reduced data sets the multistate analyses recovered a shorter tree with a higher consistency index (CI) than the additive binary data sets. The arrangement within the trees show a progression of specimens with a recurved nasal horn in the least mature individuals, followed by specimens with straight nasal horns in relatively more mature individuals, and finally specimens with procurved nasal horns in the most mature individuals. The supraorbital unit, however, shows no consistent pattern of development. The parietal horns develop relatively early, becoming long and curved in some of the least mature skulls. In relatively mature individuals these structures resorb, leaving the horns with a withered appearance. This resorption continues in the most mature individuals until much of the horn is gone. The development of the parietal and nasal horns may represent a heterochronic process (i.e. peramorphosis) in centrosaurine evolution, where juvenile morphology is similar to that of basal neoceratopsians, whereas the adult condition is comparable to that of derived centrosaurines. Bone textural changes were found to be sufficient proxies for relative maturity in individuals that have not reached adult size. Additionally, frill size is congruent with relative maturity status and makes an acceptable proxy for ontogenetic status, especially in smaller individuals. In adult-sized individuals, the fusion of the epoccipitals and the orientation of the nasal horn are the best indicators of relative maturity. There is no clear evidence for sexually specific characters or sexual size dimorphism in C. apertus.

      Tumarkin-Deratzian, Allison; Terry, Dennis O., 1965-; Grandstaff, David E. (Temple University. Libraries, 2010)
      In modern organisms the structure and arrangement of bone apatite crystals is dependent on the arrangement of the organic collagen fibers. This is reflected in the formation of different types of bone tissue, such as woven (immature) or lamellar (mature), in pathological versus normal bone, or fast-growing (woven) versus slow-growing (lamellar) tissue. Because the basic physiological processes of fracture healing are similar in extant vertebrates, similar patterns may exist in fossil taxa. The three questions of interest for this study were the following: 1) Do differences exist in modern bone apatite crystallinity between normal and pathologic bone? 2) Are differences between normal and pathologic tissue consistent in both modern and fossil bone? 3) Does the type of bone tissue affect fossilization? In this study, we use histological and x-ray diffraction (XRD) analyses to examine fracture pathologies in pedal phalanges from the theropod dinosaur Allosaurus fragilis, and two modern bird species, Branta canadensis (Canada goose) and Cathartes aura (turkey vulture). Raman spectroscopy analysis was performed on modern birds, but not fossil material. Stable isotope and rare earth elements (REE) analyses were performed on fossil material to determine if there are differences in how pathologic bone fossilizes compared to normal bone. Results from Raman spectroscopy and XRD confirm that pathologic bone is more crystalline than normal bone in both fossil and modern taxa. Stable isotope and REE analyses do not show any difference in fossilization between pathologic and normal bone, suggesting that these techniques are more suitable for examining taphonomic rather than physiological differences.

      Buynevich, Ilya V. (Ilya Val); Terry, Dennis O., 1965-; Grandstaff, David E. (Temple University. Libraries, 2014)
      Most major Phanerozoic mass extinctions induced permanent or transient changes in ecological and anatomical characteristics of surviving benthic communities. Many infaunal marine organisms produced distinct suites of biogenic structures in a variety of depositional settings, thereby leaving an ichnological record preceding and following each extinction. This study documents a decrease in burrow size in Thalassinoides-dominated ichnoassemblages across the Cretaceous-Paleogene (K-Pg) boundary in shallow-marine sections along the Atlantic Coastal Plain (Walnridge Farm, Rancocas Creek, and Inversand Quarry, New Jersey) and the Gulf Coastal Plain (Braggs, Alabama and Brazos River and Cottonmouth Creek, Texas). At New Jersey sites, within a regionally extensive ichnoassemblage, Thalassinoides ichnospecies (isp.) burrow diameters (DTh) decrease abruptly by 26-29% (mean K=15.2 mm, mean Pg=11.2 mm; n=1767) at the base of the Main Fossiliferous Layer (MFL) or laterally equivalent horizons. The MFL has been previously interpreted as the K-Pg boundary based on last occurrence of Cretaceous marine reptiles, birds, and ammonites, as well as iridium anomalies and associated shocked quartz. Across the same event boundary at Braggs, Alabama, DTh of simple maze Thalassinoides structures from recurring depositional facies decrease sharply by 22% (mean K=13.1 mm, mean Pg=10.2 mm; n=26). Similarly, at the Cottonmouth Creek site, Texas, Thalassinoides isp. occurring above the previously reported negative £_13C shift and the first occurrence of Danian planktonic foraminifera are 17% smaller in diameter (mean K=21.5 mm, mean Pg=17.9 mm; n=53) than those excavated and filled prior to deposition of a cross-bedded, ejecta-bearing sandstone complex commonly interpreted as the Chicxulub ¡¥event deposit¡¦. At both of these impact-proximal regions, the Cretaceous and Paleogene burrows were preserved in similar lithologies, suggesting that a reduction in size cannot be attributed to sedimentological factors. At all localities, up-section trends in DTh are statistically significant (fÑfnf¬0.05; non-parametric Kruskal-Wallis test). Using the burrow diameter as a proxy for tracemaker body size, a reduction in DTh above the K-Pg boundary likely reflects dwarfing within the post-extinction community of decapod crustaceans. Dwarfing during the early recovery stages of the end-Cretaceous mass extinction, as recorded by ichnofossils, occurred within glauconite-producing (New Jersey), carbonate (Alabama), and siliciclastic (Texas) depositional environments and appears to be widespread. Because this ichnological signal appears to be a general phenomenon across the crisis interval, trace-fossil analysis provides a potential in-situ field method for constraining and correlating the stratigraphic position of the K-Pg and other extinction events, particularly in the absence of other macroscopic, microscopic, and geochemical indicators. Whereas overprinting of the original marine ichnofabric by morphologically similar continental traces is not a concern in lithified sections of Alabama and Texas, such an occurrence must be considered within unconsolidated sections. Within the Hornerstown Formation of New Jersey, a pervasive Thalassinoides framework contains traces of burrowing bees and wasps. Due to their penetration of up to 1 m, excavations just beyond the weathering front are insufficient for exposing the original marine ichnofabric. Insect burrow diameters (7-25 mm) are within the range of Thalassinoides traces (4-31 mm), exhibit occasional branching, and lack of ornamentation (bioglyphs) on the burrow walls. Therefore neither size nor gross morphology are adequate for distinguishing these widely diachronous and unrelated ichnites, especially when the insect burrows have been filled. However, the presence of backfill menisci and a beige clay halo help distinguish the ancient marine burrows, whereas highly oxidized fill and the occurrence of a terminal brooding chamber are diagnostic of modern insect burrows.

      Terry, Dennis O., 1965-; Tumarkin-Deratzian, Allison; Grandstaff, David E. (Temple University. Libraries, 2016)
      Climate change across the terrestrial Eocene-Oligocene boundary of the Great Plains is recorded by shifts in sediments, facies, paleosols, and isotopic records, and is interpreted as a shift to overall cooler and drier conditions. As an independent test of paleoenvironmental shifts caused by climatic change, I compared microwear on M2 molars of Leptomeryx from the White River Group (WR) at Toadstool Park, Nebraska (n = 9) and Flagstaff Rim, Wyoming (n = 11). Comparisons of microwear were made through time at each section. Various measurements of microwear were quantified on original, uncoated specimens using environmental scanning electron microscopy and Microware 4.0 software, and evaluated with ANOVA and Kruskal-Wallis statistical tests. Values of the scratch:pit ratio, scratch number, feature major:minor axis ratio, feature vector length, major axis standard deviation, major:minor axis standard deviation, and feature orientation standard deviation for Leptomeryx M2 molars are significantly different (p<0.05) between Wyoming and Nebraska. Microwear patterns suggest paleoecological differences between the two locations, possibly related to differences in Leptomeryx diet or in amount or character of sediment adhering to ingested vegetation. Little fossil evidence of vegetation type is preserved at either locality, other than clay-filled root traces or occasional rhizoliths or silicified fragments. However, sediments of the WR are a mixture of volcaniclastic enriched mudstone, siltstone, and sandstone, with generally coarser overall particle sizes in Wyoming that reflect proximity to siliciclastic sources. The degree of overall volcaniclastic enrichment and number of airfall tuffs is also higher at Flagstaff Rim. Paleosols suggest a shift from closed canopy forest to progressively open conditions at each locality and, although microwear differences could result from differences in vegetation or particle sizes of adhered sediments on plants, no or very low correlations between microwear features and stratigraphic level were detected at either locality, indicating that any changes in paleoecology over time did not significantly alter the diets of Leptomeryx, although diet may have been geographically different.