May 17, 2019 Mary Gates Hall

POSTER SESSION 2 POSTER SESSION 2 MGH 206, Easel 169 MGH 206, Easel 168 1:00 PM to 2:30 PM 1:00 PM to 2:30 PM

Characterizing the Growth Patterns of Thickened A New Drepanosauromorph Species from the Chinle Synapsid Skulls via Osteohistology Formation of Petrified Forest National Park, Arizona Lianna Molas Marilao, Senior, English (Creative Writing), Gabriel Stedman (Gabe) Goncalves, Senior, Earth & Space Biology (Ecology, Evolution & Conservation) Sciences (Biology) Mentor: Christian Sidor, Biology Mentor: Christian Sidor, Biology Mentor: Zoe Kulik, Biology Mentor: Brandon Peecook, Field Museum

Cranial elaboration, in the form of domes, horns, and bony Drepanosauromorpha is an extinct group of bosses, has evolved multiple times in vertebrate history, in- known from the Middle to Late (237–212 MA). cluding in non-mammalian synapsids, the extinct ancestors The clade currently includes seven genera (Avicranium, of mammals. The lack of similarly thickened skulls in living Dolabrosaurus, , Hypuronector, Kyrgzsaurus, has meant that very little can be inferred about how , and Vallesaurus) that are known from fos- these features developed or why they evolved. Here we use sils collected in Europe (Italy, UK), North America (Ari- comparative bone histology to describe the microanatomy of zona, New Mexico, New Jersey), and Asia (Kyrgyzstan). Oudenodon, a 255-million-year-old synapsid with distinctive The first described drepanosauromorph, Drepanosaurus un- nasal bosses. We compared thin-sections from the thickened guicaudatus, was based on a flattened holotype preserv- portions of Oudenodon to the non-thickened skull of its rel- ing most of a complete skeleton. Subsequently described ative, Diictodon, in order to better understand how cranial drepanosauromorphs display the following diagnostic fea- elaboration developed in synapsids. We took thin sections tures: the length of the chevrons (ventral spines below from the thick nasal bosses as well as non-thickened regions the tail vertebrae) is substantially longer than corresponding of Oudenodon to capture changes in tissue microstructure. tail neural spines, the cervical (neck) vertebrae are hetero- Then, we compared these thin-sections to similar regions of coelous (saddle-shaped articular surface), the cervical ribs the skull in Diictodon, which lacks cranial elaboration. In the are absent as distinct ossi???cations, and the chevrons are bone tissue of both Oudenodon and Diictodon, we observed fused to their respective centra. In recent years, both three- a cancellous, spongey interior sandwiched between two lay- dimensionally preserved partial skeletons and isolated ma- ers of compact cortical bone. This pattern of bone is typical terial of drepanosauromorphs have been found across both in many modern skulls but the thickness of the cancellous Europe and North America. These discoveries have helped region in Oudenodon is strikingly thicker, even in regions shape our understanding of the biology and diversity of away from the boss. We hypothesize that increased cranial drepanosauromorphs. However, comparing isolated, three di- thickness in Oudenodon is due to this middle expansion of mensionally preserved specimens to the more complete, yet spongey, cancellous tissue. As a result of the increased bone two dimensionally preserved articulated specimens is diffi- thickness, sutures in Oudenodon are deep, wide, and convo- cult due to differences in preservation. Here, we describe a luted when compared to the relatively simple interdigitated new drepanosauromorph species from the Chinle Formation sutures in Diictodon. These and other histologic comparisons in Petrified Forest National Park, Arizona based on the left with distantly related taxa allow us to interpret the growth second manual ungual (claw) . Some of the characteristics and construction of cranial elaboration in synapsids, adding that distinguish this claw from those of most drepanosauro- to our understanding of how these thickened skulls evolved. morphs is its size. It differs significantly from all known Future work can also explore the possible soft tissue covering Drepanosaurus specimens (like the Italian holotype and the of these bosses and domes, which may have been used for Hayden Quarry Drepanosaurus) because of the ventral place- intraspecific display or combat. ment of the cotyle (articulation surface), the height of the claw, the lack of compression along the pre-axial/post-axial plane, and a furrow along the midline. This new taxon not

Undergraduate Research Program 1 www.uw.edu/undergradresearch only highlights unsuspected morphological variation within if un-iodized table salt may be an alternative to IMI, specifi- Drepanosauromorpha, but also helps sheds light on the evolu- cally targeting juvenile shrimp (recruits) inhabiting the upper tionary history of smaller-bodied reptiles within 10-15 cm of the sediment. Studies in 2018 indicated that a ecosystems. 2-3-fold increase in salinity resulted in 100% mortality when juveniles were exposed in artificial seawater. In 2019, we ex- posed juveniles (3 replicates, 5 shrimp each) within 10 cm POSTER SESSION 4 of native sediment to five different salt solutions to achieve Commons East, Easel 50 sediment pore water salinities of 25 (ambient, control), 35, 4:00 PM to 6:00 PM 50, 70, and 100 ppt. Salt solutions were prepared with na- tive seawater, added on top of the sediment (depth = 2 cm), Is Table Salt a Viable Alternative for the Control of and allowed to percolate through the sediment column for 6 Burrowing Shrimp on Shellfish Beds in Washington h (low tide). At 6 h, 2 cm of ambient seawater (25 ppt) were State? added to simulate tidal inundation and allowed to remain on Kylie Sahota, Junior, Aquatic & Fishery Sciences the surface for 12 h (low-high + high low tide) with two sub- NASA Space Grant Scholar, UW Honors Program sequent drawdowns and tidal inundations at 25 ppt (total test Eric R. Anderson, Junior, Environmental Science & duration = 48 h). The sediment was then sieved to remove the Resource Management shrimp and determine mortality. Average survival of controls William Gaege Baxter, Junior, Environmental Science & (25 ppt) was 73.3% whereas none of the shrimp exposed to Resource Management elevated salinities survived. Additional tests are underway to Rose Ann Denney, Senior, Environmental Science & examine different exposure scenarios. Results to date suggest Resource Management (Wildlife Conservation) table salt may be a viable and greener alternative to IMI. Victoria S (Victoria) Fleck, Junior, Environmental Science & Resource Management (Landscape Ecology & Conservation), History Isabela Sofia Garcia, Senior, Environmental Science & Resource Management (Wildlife Conservation) Raegan E. Jarvis, Junior, Aquatic & Fishery Sciences Claire Louise Johnston, Junior, Environmental Science & Resource Management Claudia R Penney, Sophomore, Aquatic & Fishery Sciences, Marine Biology Allison Phillips, Junior, Environmental Science & Resource Management Iona Mae Rohan, Senior, Environmental Science & Resource Management (Wildlife Conservation) Gushneet Singh Sarna, Senior, Environmental Science & Resource Management Jonathan L. (Jon) Schroeder, Junior, Aquatic & Fishery Sciences Zach Thomas, Junior, Aquatic & Fishery Sciences, Spanish Ariana Winkler, Senior, Environmental Studies, Environmental Science & Resource Management UW Honors Program Mentor: Christian Grue, Aquatic & Fishery Sciences

Imidacloprid (IMI), a neonicotinoid insecticide, is being sought by shellfish growers to control burrowing shrimp (ghost shrimp, Neotropea californiensis) in Willapa Bay and Grays Harbor, Washington. The shrimp destabilize sediments resulting in poor survival and low yields of the commercially harvested Pacific oyster (Crassostrea gigas), threatening the local shellfish industry. A permit for the use of IMI has been denied by the State, Pacific County has declared an economic emergency, and the outcome of an appeal by the growers re- mains uncertain. We have undertaken studies to determine

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