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NOTE FROM THE EDITOR
SYDNEY GREENE
EDITOR-IN-CHIEF
The Hendrix Scientific represents such a special corner of the Hendrix Community and presents students with the rare opportunity to explore their scientific curiosity free of the threat of academic consequence. This special issue features several personal experiences students had while at undergraduate research programs over the past summer. In their pieces, they discuss the projects they were part of as well as their personal development as a result of these experiences. They explore what it means to conduct research and to embody the effort you put into your work. In every piece, however, students were able to take a scientific question and communicate the personal and global implications of its investigation in a meaningful way. No student’s academic progression occurs in a vacuum: we are all experiencing different things within the context of the broader Hendrix Community and we are all constantly learning from one another’s experiences. At a time when misinformation and miscommunication is prolific, I believe the Hendrix Scientific has, and will continue, to embody this hallmark of the Hendrix Community.
As with each issue of the Hendrix Scientific, this issue showcases Hendrix Students’ diverse interests and different styles of science communication. Part of our mission is to give students a space to pilot different methods of science communication and you will discover them as you read this issue. Hendrix’s liberal arts curriculum gives each student a background in a variety of subjects, and I believe that is reflected in each student’s piece. I am beyond excited to introduce you to the third issue of Hendrix Scientific. We are incredibly thankful for our readers for giving us an audience to share our joys of science with. We hope that you enjoy this issue just as much as we have.
COMBATING IGNORANCE: HOW THE ILLUSION OF UNDERSTANDING AFFECTS AMERICANS VIEW OF
POLITICS
VENESSA HOLTZER
In recent years, the political divide found within the United States of America has grown increasingly precarious. Political polarization, or the act of following an extreme political ideology, is becoming not only common among Americans, but almost expected. When it comes to differing views, rather than agreeing to disagree, friends won’t speak to one another, families won’t spend holidays together, partners spend hours arguing; no one seems to be safe from the effects our recent political climate has caused. When engaging in discussion, many Americans seem to view their political positions as a part of who they are rather than opinions they hold. This has led not only to observing more extreme political views from many Americans, but also a falsely increased sense of understanding around most political decisions. People tend to believe they understand things better than they actually do. This is referred to as the illusion of explanatory depth. In this article, I will review preexisting literature that explores this phenomenon and discuss how it can possibly be reduced.
There are three central studies that have explored the illusion of explanatory depth. The first was Fernbach et al. (2013), which hypothesized that utilizing mechanistic explanations could reduce individuals’ perceived understanding of political policies. The second was Crawford and Ruscio (2021), an attempted replication of Fernbach et al. This study failed to fully replicate Fernbach’s results. The third was Sloman and Vives (2022), which had two main goals. They attempted to replicate Fernbach et al. while simultaneously exploring why Crawford and Ruscio could have failed to replicate. All three of these studies explored the illusion of explanatory depth and how it connects to political policy.Researchers suspected that both mechanistic explanations, or the act of explaining the fundamental mechanics of how something works, and reasoning, or the act of explaining your personal reasoning for your belief, would influence the illusion to varying degrees (Fernbach et al., 2013). On top of these
claims, Sloman and Vives also suspected that the type of value assigned to policies could influence the illusion. They believed that consequentialist and protected value policies would receive two different reactions from participants in terms of their understanding and extremity. Consequentialist policy focuses more on the outcome of the policy, while protected value policy is more connected to personal values and core beliefs.
In Fernbach et al. (2013), researchers conducted three experiments that examined whether people hold unjustified confidence concerning their understanding of complex policies. An individual’s failure to be able to explain how a policy works after claiming to understand it constitutes ‘unjustified confidence.’ Researchers believed making people aware of their lack of knowledge could affect the intensity of their viewpoints and the confidence held in them. Across each of the studies, participants were first asked to rate their political position on six different policies and their understanding of said policies. They were then asked to mechanistically explain their stances. Participants would then re-rate their political position and understanding. In study two, some participants were asked for personal reasons rather than mechanistic explanations. In study three, participants were asked how willing they were to donate to political groups that matched their opinions. Across all studies, researchers observed a significant decrease in perceived understanding and extremity in political position after participants provided mechanistic explanation.
Crawford and Ruscio (2021) aimed to replicate the findings of Fernbach et al. to further understand how an individual’s political moderation can be influenced. Political moderation is the act of rejecting extreme or radical political views. Crawford and Ruscio replicated Fernbach’s second experiment, studying how explanation and reasoning affect political moderation. The replication mirrored the original experiment with minor differences, like bigger samples and instructions showing participants how to measure
their understanding. While the mean level of extremity was the same in both studies’ findings, Crawford and Ruscios’ replications did not produce the same end results: recognition regarding lack of understanding did not lead to political moderation. Crawford and Ruscio also replicated experiment three, called replication two. This again studied whether explanation affected individuals’ willingness to donate to like- minded groups. Results showed that individuals did not donate based on explanation, rather based on their own political extremity. Not only were those who held extreme views more likely to donate, but also reported feeling biased against their ‘outgroups,’ individuals who did not share their position.
As previously mentioned, Sloman and Vives (2022) attempted to replicate and contribute to Fernbach’s research as well as determine why Crawford and Ruscio failed to do so. Researchers hypothesized that the difference in results could be due to the different values assigned to the policies presented. Replicating Fernbachs’ experiment two, they additionally utilized two forms of policy to be judged by participants, consequentialist and protected value. Consequentialist policy focuses more on the outcome of the policy, while protected value policy is more connected to personal values and core beliefs. Researchers found that their results reflected Fernbachs’, and that with consequentialist policies, participants showed a larger reduction in both understanding and extremity. Sloman and Vives’ success in replicating Fernbach et al. further suggests that their findings could be helpful for reducing the illusion of explanatory depth. They showcase that when people hold false confidence in their understanding of extreme politics, having them take the time to truly consider whether they know how it works can reduce perceived levels of understanding and extremity.
References
Crawford, J. T., Ruscio, J. (2021). Asking People to Explain Complex Policies Does Not Increase Political Moderation: Three Preregistered Failures to Closely Replicate Fernbach, Rogers, Fox, and Sloman’s (2013) Findings. Psychological Science, 32(4), 611—621. https://doi.org/10.1177/0956797620972367
Fernbach, P. M., Rogers, T., Fox, C. R., & Sloman, S. A. (2013). Political Extremism is Supported by an Illusion of Understanding. Psychological Science, 24(6), 939—946. https://doi.org/10.1177/0956797612464058
Sloman, S. A., Vives, M.-L. (2022). Is political extremism supported by the illusion of understanding? Cognition, 225, 105146. https://doi. org/10.1016/j.cognition.2022.105146
PARKINSON’S DISEASE
SAMANTHA VACCARELLA
When my grandfather was 43 years old, he was diagnosed with early onset Parkinson’s Disease, and when he was 63, he passed away from the effects. The 20 years he spent battling Parkinson’s were certainly not easy, for him or for our family. I was only seven when he passed so I do not have a lot of memories of him, but from what I do remember he always had a smile on his face. Despite the fact that he was in a wheelchair for most of my life, he always managed to find a way to play with me and my little sister.
Parkinson’s Disease is one of the most common neurodegenerative diseases, affecting roughly six million people worldwide (Tolosa et. al, 2021). In the United States alone, Parkinson’s affects 0.02% of the entire population, around one million people (Hollander & Lawler, 2022).
About 10 to 20 percent of the Parkinson’s Disease cases are early onset. Early onset diagnoses are for anyone under the age of 50, which included my grandfather. While there are several treatments and medications that exist to help ease the symptoms of Parkinson’s, there is no cure for the disease or any way to slow down its progression. Some of the most common treatments include medications, such as Levodopa/Carbidopa, deep brain stimulation, and different types of physical therapy (Parkinson’s Disease: Challenges, Progress, and Promise, 2023). For many years now, researchers have been tirelessly working to find better treatments, preventative measures, and a cure for neurodegenerative diseases, including Parkinson’s, and have faced many challenges during this process.
One challenge this field faces is while there are some medications that exist to help treat and reduce the physical and mental symptoms caused by Parkinson’s Disease, many of these treatments present significant side effects. For example, Levodopa, a medication that helps increase dopamine levels in the brain, is one of the most effective medications in treating Parkinson’s, may reduce motorrelated functions and symptoms for several years, but after prolonged use, can cause uncontrolled muscle movements, also known as dyskinesia, which include spasms, tremors, and sustained muscle contractions (Parkinson’s Disease:
Challenges, Progress, and Promise, 2023).
Because my grandfather was so young when he was diagnosed, he stayed on Levodopa for several years and suffered from this Levodopa-induced dyskinesia. His tremors were getting much worse, and he could no longer walk without help. In an effort to halt the progressing of his tremors, he received an experimental procedure at UAMS about five years after his diagnosis. This procedure is called a bilateral pallidotomy, in which the neurosurgeon went in and damaged a small part of the basal ganglia, a part of the brain that helps control motor movements, in order to hopefully reduce instances of his dyskinesia. This was a very experimental surgery at the time, so there were only three hospitals in the whole country performing it. They used CT imaging during the surgery, so the surgeon had a guide of what was going on in my grandfather’s brain, so he had to stay awake. When the surgery was over, the nurses brought my grandma and mom back to the end of the OR hallway, and my grandfather was able to walk over to them. For a few years after his surgery, his dyskinesia improved and he was able to take an increased dosage of Levodopa to help with his Parkinson’s symptoms.
He was lucky enough to be one of the few success stories from this type of surgery. It was discovered a few years after my grandfather’s surgery that while bilateral pallidotomies did improve the dyskinesia experienced by patients who received this type of surgery, there were many negative side effects, including problems with speech and memory, as well as increased instances of depression (Merello et. al, 2001). It was ruled that the cons far outweighed the pros of the procedure, so it was discontinued nationwide as a treatment for Parkinson’s Disease.
Even though I don’t remember much of it, my grandfather’s battle with Parkinson’s left a lasting impact on me. From following research advancements in the neurodegenerative disease field to exploring different careers in health care, I find myself hoping that someday I’ll get to help treat people like him.
References
Hollander, J., & Lawler, C. (2022, June 9). Neurodegenerative Diseases. National Institute of Environmental Health Sciences. https://www.niehs.nih.gov/research/supported/health/ neurodegenerative Merello, M., Starkstein, S., Nouzeilles, M. I., Kuzis, G., & Leiguarda, R. (2001). Bilateral pallidotomy for treatment of Parkinson’s disease induced corticobulbar syndrome and psychic akinesia avoidable by globus pallidus lesion combined with contralateral stimulation. Journal of neurology, neurosurgery, and psychiatry, 71(5), 611–614. https://doi.org/10.1136/ jnnp.71.5.611
Tolosa, E., Garrido, A., Scholz, S. W., & Poewe, W. (2021). Challenges in the diagnosis of Parkinson’s disease. The Lancet. Neurology, 20(5), 385–397. https://doi. org/10.1016/S1474-4422(21)00030-2
U.S. Department of Health and Human Services. (2023, January 30). Parkinson’s disease: Challenges, progress, and promise. National Institute of Neurological Disorders and Stroke. https://www.ninds.nih.gov/current-research/ focus-disorders/parkinsons-disease- research/parkinsonsdisease-challenges-progress-and-promise#toc-advancingtreatments
PANDEMIC ISOLATION SPEEDS UP BRAIN AGING IN TEEN GIRLS
OLIVIA BARRETT
In 2018, researchers at University of Washington gathered 160 girls and boys with the goal of characterizing typical brain changes, such as prefrontal cortex -- the further development of attention, organizing, planning, emotion, and more--, during teenage years (Barry, 2024; Arain, 2013). Then, on March 20, 2020, the United States began to implement shutdowns and isolation due to the COVID-19 pandemic. After three long years, on May 11, 2023, the researchers then found themselves in a position to gather never before studied information on these adolescents (Corrigan, 2024).
130 of the volunteers returned for testing after the pandemic. The researchers compared MRI scans in 2023 to the scans in 2020 and found something unexpected. The female’s brains experienced faster and more widespread cortical thinning compared to the males. These female’s brains thinned on average 4.2 years ahead of what was expected, whereas boys were 1.4 years ahead. That means that a girl that came in at 13 years old, and returned at 16 years old, now has a brain that resembles a 20-yearold’s (Barry, 2024).
Cortical thinning is the brain rewiring itself as a person matures. The brain prunes redundant neuronal connections and shrinks its outer layer (Barry, 2024). Think of the brain as an oak tree and the bark is the cortex. As the tree ages, the bark can naturally thin a bit. However, if the bark thins too much or too quickly, it can weaken the tree and make it more vulnerable to disease and damage. Similarly, cortical thinning can be a normal part of aging, but excessive thinning can be a sign of underlying health issues and could lead to further health complications. The cortical thinning in the female brain was seen in 30 areas compared to just two in the males. The most pronounced areas for the girls were the Bilateral Fusiform, Left Insula, and Superior Temporal Gyrus (Corrigan, 2024). Together, these areas are involved in recognizing faces and expressions, processing emotions, and comprehending languages, meaning that thinning of
these areas leads to difficulty understanding social cues, processing emotions, being self-aware, and even difficulties recognizing faces in severe cases (Bigler, 2007; Rocha Cabrero, 2023; Tinaz, 2018), In males, the lateral occipital cortexes, responsible for visual processing, were affected. Thinning in these areas can cause recognition and spatial perception difficulties (Grill-Spector, 2001). So, why did this happen? Why were the girls affected so much more?
The COVID-19 pandemic led to significant social isolation, particularly for adolescents who were no longer going to school in person, seeing friends, attending sporting events, etc. For young girls, who heavily rely on social networks for stress relief, this isolation caused immense stress, linked to conditions like depression and anxiety. The “stress acceleration hypothesis” suggests that earlylife stress can prematurely develop the brain’s emotional system. This maturation, often linked to cortical thinning, can be triggered by factors like social isolation, bullying, or parental divorce. Additionally, the body’s stress response, activated by cortisol, can contribute to cortical thinning. While beneficial in short- term stress, prolonged cortisol exposure can damage brain cells and reduce the volume of the hippocampus, a region crucial for emotional regulation, learning, and memory (Tribby, 2024).
The researchers hypothesize that sex differences in brain changes might be due to varying responses to stress. Females, who often depend on social connections, may have experienced heightened stress during the pandemic, leading to more pronounced changes in brain regions (Corrigan, 2024). The COVID-19 pandemic imposed significant lifestyle changes on adolescents, such as remote schooling and isolation, potentially making female adolescents more susceptible to the negative neurobiological consequences of these changes. The accelerated brain maturation observed in this population raises concerns about potential long-term mental health risks including depression, anxiety, trust issues, and cognitive processing for these young women (Belfi, 2015).
Therefore, it is crucial to provide ongoing support to this vulnerable group to mitigate the impact of pandemicrelated stress on their brain development and mental wellbeing, such as mental health support, helping build social connections, encouraging physical activity, and teaching stress management techniques such as meditation.
References
Arain, M., Haque, M., Johal, L., Mathur, P., Nel, W., Rais, A., Sandhu, R., & Sharma, S. (2013). Maturation of the adolescent brain. Neuropsychiatric disease and treatment, 9, 449–461. https://doi.org/10.2147/NDT.S39776
Barry, E. (2024, September 9). Teen girls’ brains aged rapidly during pandemic, study finds. The New York Times. https://www.nytimes.com/2024/09/09/health/teen-brainspandemic-girls.html
Belfi, A. M., Koscik, T. R., & Tranel, D. (2015). Damage to the insula is associated with abnormal interpersonal trust. Neuropsychologia, 71, 165–172. https://doi.org/10.1016/j. neuropsychologia.2015.04.003
Bigler, E. D., Mortensen, S., Neeley, E. S., Ozonoff, S., Krasny, L., Johnson, M., Lu, J., Provencal, S. L., McMahon, W., & Lainhart, J. E. (2007). Superior temporal gyrus, language function, and autism. Developmental neuropsychology, 31(2), 217–238. https://doi. org/10.1080/87565640701190841
Corrigan, N., Rokem, A., & Kuhl, P. (2024, September 9). COVID-19 lockdown effects on adolescent brain structure suggests accelerated maturation that is more pronounced in females than in males. PNAS. https://www.pnas.org/ doi/abs/10.1073/pnas.2403200121?url_ver=Z39.882003&rfr_id=ori%3Arid%3Acrossref.org&rfr_dat=cr_ pub++0pubmed
Grill-Spector, K., Kourtzi, Z., & Kanwisher, N. (2001). The lateral occipital complex and its role in object recognition. Vision research, 41(10-11), 1409–1422. https://doi. org/10.1016/s0042-6989(01)00073-6
Rocha Cabrero F, De Jesus O. Prosopagnosia. (2023, May
Tinaz, S., Para, K., Vives-Rodriguez, A., Martinez-Kaigi, V., Nalamada, K., Sezgin, M., Scheinost, D., Hampson, M., Louis, E. D., & Constable, R. T. (2018, November
26). Insula as the interface between body awareness and movement: A neurofeedback-guided kinesthetic motor imagery study in parkinson’s disease. Frontiers. https://www.frontiersin.org/journals/humanneuroscience/articles/10.3389/fnhum.2018.00496/ full#:~:text=Activation%20in%20th ese%20insula%20 regions,Farrer%20and%20Frith,%202002).
Tribby, A. (2022, November 8). Cortisol and cognition: How the stress hormone affects the brain. Aviv Clinics USA. https://aviv-clinics.com/blog/brain-health/how-cortisolstress-hormone-affects-brain- health/#:~:text=High%20 chronic%20stress%20and%20cortisol,difficult%20 than%20t hey%20should%20be.
THE EFFECTS OF CLIMATE CHANGE ON YELLOWFIN SOLE USING LABORATORY
SCIENCE TO PROMOTE SUSTAINABLE
FISHERIES
KATHRYN YOUN
Yellowfin Sole (Limanda aspera; YFS) composes the largest flatfish fishery in the United States and is especially significant to the Alaskan commercial fishery industry. Despite the economic and ecological importance of YFS, no lab research has been conducted on YFS life stages nor on their responses to climate change. These fish are largely caught in the Bering Sea, which is off the coast of Alaska. Bodies of water closer to the poles experience amplified climate change effects, such as increased rates of ocean warming (OW) and ocean acidification (OA) (Hurst, 2016). The goal of my research was to understand how OW and OA may affect YFS early life stages to further aid fishery management for the sustainability of the species and flourishment of the communities that rely on them.
Prior to the start of the experiment, I learned about the chemical reactions that took place during ocean acidification. Oceans have a natural buffering capacity that allows them to absorb carbon, but only to an extent. Excess carbon will be released into the atmosphere and the ocean pH will decrease. Colder waters have a greater buffering and carbon storage capacity, causing colder oceans to have higher rates of ocean acidification. A deep ocean current is also present that brings O2-rich surface water to the deep, and the deep CO2-rich water to the surface. The waters off the Gulf of Alaska that YFS inhabit experience amplified OW and OA effects due to the natural buffering capacity, the water being colder, and the global ocean circulation.
YFS embryos were reared in-lab and were incubated in one of six combinations of temperature (9°C, 12°C, 15°C) and pH (ambient: ~8.0, low: ~7.35). Incubation took place in a cold room set to 12°C, in which there were three water baths with two aquaria in each, and six beakers of eggs in each of the aquaria. The impermeable glass aquaria maintained pH while the static water bath maintained temperature. As the system was static, water changes were conducted bidaily from the wet lab, where the water was being manipulated with CO2 dosing and air bubbling,
to the experimental cold room. On the side, I collected YFS eggs for pictures to track yolk absorption and growth. This was to further collect information about the species and identify potential batch effects (innate differences between egg batches).
The eggs were checked and photographed every day under a microscope to calculate yolk depletion and growth rates. Upon first heart beats, they went into a microplate respirometer system overnight to record oxygen consumption, a common measure of metabolic rates in physiology studies. The next measurements were taken at hatch and included body length, myotome height (fish width), yolk area, and dry weight. These values were compared to the same metrics at yolk absorption, along with calculating the rate of growth and yolk absorption, to gain knowledge on energy usage and physiological adaptations. 15°C had the greatest effect on the YFS compared to 9°C and 12°C, especially in the at- hatch measurements. The effects of pH were minimal throughout, but greatest when acting with 15°C and at earlier life stages (at-hatch) as well. Both findings supported that earlier life stages were more vulnerable to simultaneous stressors than those later (yolk depletion). Hatch cycle variance, batch effects, and improper equipment/materials/ techniques may have also impaired the data.
The goal of the project was to collect and analyze data to provide free, public information that may be helpful in policy making, which was achieved. While this trial was led by me, this project is in its third year and is now in progress to be published. Such as most experiments, there are ways to improve the research, so looking further into batch effects and YFS reproductive biology with these stressors may be helpful. The Bering Sea is one of the most productive marine ecosystems, which includes the YFS fishery (Fabry et al., 2009). Commercial fisheries provide food security and occupation opportunities, making them fundamental to many human communities and providing reason for continued research in global changes within this field (Doney et al., 2011).
References
Doney, S. C., Ruckelshaus, M., Duffy, J. E., Barry, J. P., Chan, F., English, C. A., Galindo, H. M., Grebmeier, J. M., Hollowed, A. B., Knowlton, N., Polovina, J., Rabalais, N. N., Sydeman, W. J., & Talley, L. D. (2011). Annual Review of Marine Science, 4(1), 11–37. https://doi.org/10.1146/ annurev-marine-041911-111611
Fabry, V., McClintock, J., Mathis, J., & Grebmeier, J. (2009). Ocean Acidification at High Latitudes: The Bellwether. Oceanography, 22. https://doi.org/10.5670/ oceanog.2009.105
Hurst, T. P., Laurel, B. J., Mathis, J. T., & Tobosa, L. R. (2016). Effects of elevated CO2 levels on eggs and larvae of a North Pacific flatfish. ICES Journal of Marine Science, 73(3), 981–990. https://doi.org/10.1093/icesjms/fsv050
THE TINY ANCESTORS OF THE BIGGEST LAND ANIMALS THAT EVER LIVED
JULIE SCHWARTZ
Around 237 million years ago, a small reptilian animal hunted insects in the wet tropics of the supercontinent Pangaea (Jake Hashim-Jones, 2020; Jiang et al., 2019). When it died, its remains were covered with sediment and preserved until its fossils were uncovered in 1998 by a team of researchers (Laura Geggel, 2020). 20 years later, paleontologists determined that this tiny species might be closely related to the ancestors of the largest animals to ever walk or fly (Kammerer et al., 2020).
Kongonaphon kely, or “tiny bug slayer,” was discovered in the Morondava Basin in western Madagascar and dated to the Carnian stage of the late Triassic period (237-227 million years ago). It was identified as a type of archosaur, the group of reptiles that contains dinosaurs (including birds), pterosaurs (flying reptiles), and crocodilians (Kammerer et al., 2020; Justin Tweet, 2021). Specifically, it was determined to be an ornithodiran archosaur.
Ornithodirans are the taxonomic group that includes dinosaurs and pterosaurs. Because K. kely lived in the late Triassic, around the time that dinosaurs and pterosaurs diverged, researchers speculated that the small reptile may be closely related to a common ancestor of these groups (Kammerer et al., 2020).
It is common knowledge that dinosaurs were big animals.
However, it is difficult to imagine the scale of the largest dinosaurs. Theropods, carnivorous dinosaurs that walked on two legs like T. rex, could grow to 40 ft long—longer than a school bus (Hutchinson et al., 2011). Many dinosaurs grew much larger. Sauropods were dinosaurs that sported long necks and tails with legs so giant they may have blended in with tree trunks. The largest sauropods, a group known as Titanosaurs, were the largest animals known to walk the planet. They could grow to over 115 ft long and likely weighed over 50 tons, around as much as nine elephants. These walking giants reached their massive sizes during the Cretaceous period, 140 million years after K. kely lived (Prothero, 2014). One reason that dinosaurs were able to grow to these sizes may have been their digitigrade foot posture—they walked on their tip toes (Kubo, 2016). When foot bones the size of tree trunks are stacked vertically, this provides more stability and maneuverability for massive animals than a plantigrade posture—the way humans and many mammals walk, with the entire foot on the ground. Pterosaurs were the first group of vertebrates that achieved powered flight. Diversifying in the late Triassic, these reptiles formed wings from a lengthened fourth finger (Padian, 1985). There is evidence that the terrestrial ancestors of pterosaurs were small bipedal reptiles that ran digitigrade—on their tip toes (Foffa et al., 2022). Like dinosaurs, pterosaurs grew
Photo by J.D. Gantz
to incredible sizes. Giants like Hatzegopteryx may have grown wingspans of almost 70 feet long--the size of a small airplane (Lawson, 1975). At these sizes, the flying reptiles would have been able to walk on all four limbs in order to hunt small dinosaurs (Naish & Witton, 2017).
The research team studying the K. kely fossils found in Madagascar measured a partial femur to be 38 mm in length, and the total estimated body height was calculated to be 10 cm, or 4 inches. It is the smallest known ornithodiran from the late Triassic, but this specimen is not the only miniature species known from this period. Several close relatives to K. kely were discovered in South America. These specimens were not as tiny as K. kely, but they are notably smaller than their archosaur ancestors and the dinosaurs and pterosaurs that would come after them. Although not much is known about the common ancestor of dinosaurs and pterosaurs, these findings suggest that this reptile fell in with archosaurs experiencing the effects of a miniaturization event (Kammerer et al., 2020).
At the beginning of the Triassic, the planet was recovering from the end-Permian—the worst mass extinction event with the greatest loss in diversity of life Earth has experienced (Marshall, 2023). During and after this extinction, archosaur size generally decreased through a phenomenon known as the Lilliput effect: organisms that are likely to survive a mass extinction are generally smaller than the organisms that die off (Twitchett, 2007). However, this effect does not completely account for the extremely small size of specimens like K. kely. The Permian- Triassic extinction killed off many animals that hunted insects, producing an open position in the early Triassic food web. Insects, which generally reproduce quickly, were able to recover soon after the extinction, providing a widely available food source. The small, lightweight body plan of K. kely, in addition to its smooth, sharp teeth, suggests that these animals would have been well-adapted to hunting insects. By filling the ecological niche left by extinct insectivores, ornithodirans may have experienced a selective pressure to be small (Kammerer et al., 2020).
This miniaturization, strangely, may have been the reason giant dinosaurs and pterosaurs evolved. The agile bipedal anatomy of K. kely is ancestral to all dinosaurs. The success of this evolutionary strategy among dinosaurlike reptiles in the late Triassic enabled dinosaurs to diversify into much larger body plans millions of years later. Furthermore, a lightweight frame is likely necessary for the evolution of powered flight (Lee et al., 2014). The light bodies of small ornithodiran insectivores may have been the ideal precursors to flying pterosaurs (Kammerer et al., 2020).
References
Foffa, D., Dunne, E. M., Nesbitt, S. J., Butler, R. J., Fraser, N. C., Brusatte, S. L., Farnsworth, A., Lunt, D. J., Valdes, P. J., Walsh, S., & Barrett, P. M. (2022). Scleromochlus and the early evolution of Pterosauromorpha. Nature, 610(7931), 313–318. https://doi.org/10.1038/s41586-022-05284-x
Hutchinson, J. R., Bates, K. T., Molnar, J., Allen, V., & Makovicky, P. J. (2011). A Computational Analysis of Limb and Body Dimensions in Tyrannosaurus rex with Implications for Locomotion, Ontogeny, and Growth. PLoS ONE, 6(10), e26037. https://doi.org/10.1371/journal. pone.0026037
Jake Hashim-Jones. (2020). INTERNATIONAL CHRONOSTRATIGRAPHIC CHART [Computer software]. https://stratigraphy.org/timescale/ Jiang, H., Yuan, J., Chen, Y., Ogg, J. G., & Yan, J. (2019). Synchronous onset of the Mid-Carnian Pluvial Episode in the East and West Tethys: Conodont evidence from Hanwang, Sichuan, South China. Palaeogeography, Palaeoclimatology, Palaeoecology, 520, 173– 180. https://doi.org/10.1016/j.palaeo.2019.02.004
Justin Tweet. (2021). Major Groups of Dinosaurs. In Fossils and Paleontology. National Park Service. https://www.nps.gov/subjects/fossils/ major-groups-of-dinosaurs.htm
Kammerer, C. F., Nesbitt, S. J., Flynn, J. J., Ranivoharimanana, L., & Wyss, A. R. (2020). A tiny ornithodiran archosaur from the Triassic of Madagascar and the role of miniaturization in dinosaur and pterosaur ancestry. Proceedings of the National Academy of Sciences, 117(30), 17932–17936. https://doi.org/10.1073/pnas.1916631117
Kevin Padian. (1985). The origins and aerodynamics of flight in extinct vertebrates. Palaeontology, 28, 413–433.
Kubo, T., & Kubo, M. O. (2016). Nonplantigrade Foot Posture: A Constraint on Dinosaur Body Size. PLOS ONE, 11(1), e0145716. https:// doi.org/10.1371/journal.pone.0145716
Laura Geggel. (2020, July 14). ‘Tiny Bug Slayer’ Dinosaur Relative Would Fit in the Palm of a Hand. Live Science. https://www.scientificamerican. com/article/tiny-bug-slayer-dinosaur- relative-would-fit-in-the-palm-of-ahand/
Lawson, D. A. (1975). Pterosaur from the Latest Cretaceous of West Texas: Discovery of the Largest Flying Creature. Science, 187(4180), 947–948. https://doi.org/10.1126/science.187.4180.947
Lee, M. S. Y., Cau, A., Naish, D., & Dyke, G. J. (2014). Sustained miniaturization and anatomical innovation in the dinosaurian ancestors of birds. Science, 345(6196), 562– 566. https://doi.org/10.1126/ science.1252243
Marshall, C. R. (2023). Forty years later: The status of the “Big Five” mass extinctions. Cambridge Prisms: Extinction, 1, e5. Cambridge Core. https:// doi.org/10.1017/ext.2022.4
Naish, D., & Witton, M. P. (2017). Neck biomechanics indicate that giant Transylvanian azhdarchid pterosaurs were short-necked arch predators. PeerJ, 5, e2908. https://doi.org/10.7717/peerj.2908
Prothero, D. R. (2014). The Story of Life in 25 Fossils: Tales of Intrepid Fossil Hunters and the Wonders of Evolution. Columbia University Press. http://ebookcentral.proquest.com/lib/hendrix-ebooks/detail. action?docID=1830701
GLOBAL WARNING: SALT MARSH DEOXYGENATION IN WARMING OCEANS
ANDREW CLARK
When people think of the Atlantic coastlines of the United States, images of beautiful sandy beaches and warm waves often come to mind. However, among the vacation homes and resorts lies a lesser-known habitat with major ecological importance, salt marshes. Salt marsh environments are common ecosystems in estuaries, areas where freshwater and saltwater converge. They are marshy because the soil is composed of deep mud and peat, an organic material made of decomposing plant matter (NOAA, 2024). These unique systems serve as habitats to a wide variety of organisms such as salt-tolerant grasses, shrubs, fish, crustaceans, and migrating birds. The dense canopy of marsh vegetation provides nursery habitats for many species, including juvenile fish and shrimp (Boesch and Turner, 1984). These sheltered waters help young species grow and prepare for life in the open ocean, where they contribute to valuable fishery stocks (Baker et al., 2020). U.S. salt marshes alone provide essential food, refuge, or nursery habitat for more than 75 percent of fisheries species, including shrimp, blue crab, and many finfish (NOAA, 2024). Salt marshes, therefore, play a significant role in providing food and economic security for hundreds of millions of people through fishing industry jobs and food markets, particularly in coastal regions. They also serve roles in protecting against coastal erosion and are key contributors to “blue carbon” sequestration, absorbing carbon dioxide that has dissolved directly into the ocean (zu Ermgassen et al., 2021).
Despite their importance, salt marshes are currently under threat with mounting environmental pressures from coastal development and climate change. Rising global temperatures and nutrient-rich runoff from agricultural and urban areas have led to the growth of hypoxic zones, commonly known as dead zones, in coastal waters where dissolved oxygen (DO) drops to extremely low concentrations (Breitburg et al., 2018). The standard
definition for hypoxia is ≤ 2 mg/L DO, however, many coastal organisms experience negative effects from values well above this threshold. For example, juvenile white shrimp (Penaeus setiferus) show reduced growth at DO levels below 4 mg/L (Rosas et al., 1998). Recent research regarding salt marsh points to the marsh edge as being a particularly critical part of this system with many species appearing to be restricted to the outer few meters of the vegetated marsh (Minello et al., 2008).
Over the summer of 2024, I spent three months doing National Science Foundation (NSF) funded research in the Baker lab at Dauphin Island Sea Lab off the coast of Alabama. As the current status of DO in the flooded salt marsh and its impact on habitat quality in the northern Gulf of Mexico is unknown, our aim was to understand how DO could limit suitability of salt marsh as habitat. We hypothesized that low DO could be driving fish from the flooded marsh.
To assess oxygen levels in various parts of the salt marsh, we deployed DO loggers along gradients from open water to the flooded marsh surface at 10 sites in Mississippi Sound, AL. The sites spanned from sheltered tidal creeks to more exposed, open shorelines of Mississippi Sound. This method was employed to encompass varying levels of wave exposure because mixing due to wave action could modify patterns of DO on the flooded marsh surface. We deployed sensors to log DO every 15 minutes along the gradients at ten, five, and one meters into open water and one, five, and ten meters into flooded marsh for two days or more at each site (Figure 1). After collecting data, we analyzed the proportion of time each area experienced stressful or hypoxic conditions (below 4 mg/L and 2 mg/L DO, respectively) and compared DO levels across marsh and open-water zones.
Our findings reveal that DO levels within flooded marshes frequently fall below what many aquatic species can
tolerate. Hypoxic conditions were recorded at six out of ten study sites. The stressful conditions observed in the DO data suggest that much of the flooded marsh may be a physiologically stressful environment for many aquatic species. W ith hypoxia predicted to worsen due to global warming, decreasing DO in the salt marsh could further limit the distribution and occupation of salt marshes by many aquatic species (Breitburg et al., 2018). The animals that rely on these habitats as critical nurseries and foraging grounds would see declines in population, sending devastating impacts for fisheries as well as for the biodiversity of our oceans. Though much of the focus of this project was on the value of fish and marine life in economic terms, the true worth of salt marshes and oceans transcends monetary value. These habitats are symbols of beauty to many, a reminder of our connection to nature. To preserve the health of our oceans and coasts, research should drive informed policies that address the many factors impacting our ocean, including the complex, long-term impacts of climate change, rising sea levels, and human activity. Only by taking an approach that values both preservation and restoration can we sustain the health and future of our salt marshes and oceans.
Staver, L.W. (2020). Fisheries rely on threatened salt marshes. Science, 370(6517), 670671. https://doi.org/10.1126/science.abe9332
Boesch, D.F. & Turner, R.E. (1984). Dependence of fishery species on salt marshes: the role of food and refuge. Estuaries, 7(4), 460-468. https://doi. org/10.2307/1351627
Breitburg, D., Levin, L.A., Oschlies, A., Grégoire, M., Chavez, F.P., Conley, D.J., Garçon, V., Gilbert, D., Gutiérrez, D., Isensee, K., & Jacinto, G.S. (2018). Declining oxygen in the global ocean and coastal waters. Science, 359, p.eaam7240. https://doi.org/10.1126/science. aam7240
Minello, T.J., Matthews, G.A., Caldwell, P.A., & Rozas, L.P. (2008). Population and production estimates for decapod crustaceans in wetlands of Galveston Bay, Texas. Trans. Am. Fish. Soc., 137(1), 129-146. https://doi.org/10.1577/T06276.1
NOAA. (2024, June 16). What is a salt marsh? National Ocean Service. https://uat.oceanservice.noaa.gov/facts/saltmarsh. html
Rosas, C., Martinez, E., Gaxiola, G., Brito, R., Diaz-Iglesia, E., & Soto, L.A. (1998). Effect of dissolved oxygen on the energy balance and survival of Penaeus setiferus juveniles. Mar. Ecol. Prog. Ser.,174, 67-75. https://doi.org/10.3354/meps174067 zu Ermgassen, P.S.E., Baker, R., Beck, M.W., Dodds, K., zu Ermgassen, S.O.S.E., Mallick, D., Taylor, M.D., & Turner R.E. (2021). Ecosystem services: Delivering decision making for salt marshes. Estuar. Coast., 44(6), 1691-1698. https://doi. org/10.1007/s12237-021- 00952-z
Photo Andrew Clark
1600 Washington Avenue Conway, AR 72032
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