All Published Posts

For everything that has been published on Time Scavengers. Most recent posts will be displayed at the top.

Characteristics of the front limbs of the flying dinosaur, Microraptor

jenebauerLeave a comment

Forelimb feathering, soft tissues, and skeleton of the flying dromaeosaurid Microraptor

By: Maxime Grosmougin, Xiaoli Wang, Xiaoting Zheng, Thomas G. Kaye, Matthieu Chotard, Luke A. Barlow, T. Alexander Deccechi, Michael B. Habib, Juned Zariwala, Scott A. Hartman, Xing Xu, and Michael Pittman

Summarized by: Summarized by Brooke Sacks, an undergraduate student pursuing a B.S. in Biological Sciences at Binghamton University. Upon graduation this spring, she will be pursuing a master’s program before heading to law school. When she is not studying paleontology, Brooke enjoys playing golf, tennis, and traveling. 

Data being used: Researchers analyzed the front limbs, or forelimbs (including the bone structure, soft tissue, and feathers), of ten new Early Cretaceous Microraptor specimens from northern China, stored in the Shandong Tianyu Museum of Nature. The researchers obtained measurements of the bone structures, observed the preserved soft tissue, and measured the feathers for classification; this data was  compared to that of  previously studied specimens, including early flying dinosaurs (such as Anchiornis, Archaeopteryx, and Confuciusornis), as well as modern birds. 

What was the hypothesis being tested? The purpose of the paper is to investigate the feathering, soft tissues, and bones of the Microraptor forelimb. The researchers aimed to 1) reconstruct an accurate model of Microraptor forewing feathering, specifically including the layering of the different types of feathers, 2) observe skeletal characteristics (the thickness and length of pectoral girdle, humerus, ulna, radius, carpals, metacarpals, and phalanges- the bones from the arm closest to the shoulder to the wings) that may provide a deeper understanding of the organism’s flight capabilities, and 3) perform tests on forelimb soft tissues to uncover the functionality of the Microraptor forewing. Overall, this study provides insight into avian evolution of flight, which has not previously been fully known due to limited understanding of Microraptor anatomy. 

Methods: In this study, the researchers used white light and Laser-Stimulated Fluorescence, which is a procedure used to cause fluorescence around the surface of the body tissues and illuminate the specimen for visual analysis. Specifically, this was used to illuminate areas of interest on the specimens: the soft tissue, bones, and feathers. The use of Laser-Stimulated Fluorescence allowed researchers to discern otherwise hidden details in feathers which aid in the classification of the different feather layers. Thirty-second time-exposed images were taken using a Nikon D810 DSLR camera to ensure high-quality photos to study, and the photos were processed for review using Photoshop CS6 software. Additionally, scientists took  measurements of bone lengths and feather lengths, as well marked the number of preserved feathers broken down by type. Microraptor specimens and similar early flying dinosaurs  (Anchiornis, Archaeopteryx, and Confuciusornis) were studied in this comparative analysis. These measurements were compared across all species by uniform standards. 

Results: This study further organized previously discovered layers of feathering (called coverts; see Fig. 1 for details about the layers)  by distinguishing these into primary greater, secondary greater, median and lesser coverts, all of which have different roles in the process of flying (Fig. 1). As a result of analyzing its wing structure, it is clear that Microraptor exhibits characteristics consistent with modern birds that fly continuously at high-speeds–its V-shaped wings and lack of wingtip slotting (i.e. the separation of outer feathers that lets air pass through when flying) are commonly associated with reduced drag and prolonged flight capabilities. Regarding the soft-tissue analysis, Laser-Stimulated Fluorescence revealed the outline and surface texture of Microraptor, indicating this species had a strong arm with tissue covering. Taken together with its wing morphology and bony/soft tissue anatomy, it may be supported that this species, Microraptor, was likely an aerial hunter that possessed a diet typical of modern falcons. Researchers also found that the claws of Microraptor were more curved than other related species. 

A figure depicting a Microraptor forelimb facing upward with feathers extending from the forewing outward respectively in layered tiers. Each layer (marginal coverts, lesser/median coverts, secondary greater coverts, secondary feathers, primary greater coverts, and primary remiges) is a different color on a blue-purple scale to depict the distinct layers in this anatomical reconstruction. The dark blue layer closest to the forewing bone and just covering the forearm is the longest layer representing the marginal covert. The next layer, the lesser/median coverts, is two tiers stretching the entire length of the forewing - these feathers are longer in length as compared to the marginal coverts. The secondary greater coverts are positioned closer to the talons while the secondary feathers cover an area closer to the elbow joint. The primary grater coverts and the primary regime layers are both on the outermost portion of the forewing with the long primary regime feathers taking a V-shape. The scale bar represents 50 mm, and the anatomical model is approximately 5 of the scale bars (or 250 mm).
Figure 1. Model of Microraptor forewing feathering by layers. The wing has layers as follows, moving outward respectively: marginal coverts, lesser/median coverts, secondary greater coverts, secondary feathers, primary greater coverts, and primary remiges. These terms are classifications of the layers of feathering on this anatomical model of a forewing. The marginal coverts and the lesser/median coverts makeup the portion of the wing closest to the arm. The secondary greater coverts and the secondary feathers make up the middle tier – these layers contain feathers longer than that of the marginal/lesser coverts. The primary greater coverts and primary regimes are the outermost feathers making up the tip of the wing. The primary feathers form a V-shape, while the secondary feathers projecting from the ulna, which is on the pinky side of this anatomical model, are fan-shaped. The V-shape of the outermost layer (primary regimes) indicates that Microraptor was likely a fast-moving bird of prey because this shape is optimal for reducing drag thus allowing for faster flight. This data is an anatomical reconstruction of Microraptor feather layering derived from the analysis of 14 specimens. The black scale bar is 50 mm.

Why is this study important? This study is significant because it draws connections between anatomical features and functional applications. In this study, the V-shaped primary regimes on the outermost feather layer indicate that this species was likely a fast-flying hunter, which had not been previously known. From this, we can draw conclusions about their diet as likely hunters, and this methodology can be applied to learn more about other avian species. Additionally, because the claws of Microraptor were so curved, researchers think that  this species could have been climbing trees during their lifetime. 

Broader implications beyond this study: By comparing this species of flying dinosaur  to both modern and prehistoric organisms, scientists can gain a deeper understanding of avian evolutionary trends, as well as how this particular species once flew and interacted with their environment. Future studies may focus on how Microraptor hindwings, as opposed to their forewings, compare and contrast to the findings discussed in this study. This study adds to how the process of flying evolved in birds over the past ~ hundred million years.

Citation: Grosmougin, M., Wang, X., Zheng, X., Kaye, T. G., Chotard, M., Barlow, L. A., Deccechi, T. A., Habib, M. B., Zariwala, J., Hartman, S. A., Xu, X., & Pittman, M. (2025). Forelimb feathering, soft tissues, and skeleton of the flying dromaeosaurid Microraptor. BMC Ecology and Evolution, 25(1). https://doi.org/10.1186/s12862-025-02397-5

10 Million Year Old bat fossils discovered in Slovakia

jenebauerLeave a comment

The Late Miocene Bats (Chiroptera, Mammalia) from the Pannonian region, Slovakia

by: Florentin Cailleux, Lars van den Hoek Ostende and Peter Joinak

Summarized by: Brieahna Wilson, a current biological sciences major at Binghamton University. She is currently a senior and plans to continue her education by getting a master’s in teaching which she will use to teach science to K – 12. When she is not busy with classes or work, she enjoys baking, painting and going to concerts when possible.

Hypothesis/purpose of paper: Bat (scientific name: Chiroptera) fossils are relatively rare compared to the amount of fossilized rock that we have. Bats tend to live in hot and high humidity areas, which lead to faster decomposition. Additionally, they have very small and fragile bones which oftentimes may get destroyed or scavenged before fossilization can occur.  Karstic sites are areas such as caves that are typically created by dissolved limestone. They have been very important in paleontology for the discovery of fossils, however, this study found that fluviolacustrine deposits (rock formations formed at the bottom of lakes and stream waters created by sediments running from rivers into lakes) also held a wide array of fossils that were useful in determining the diversity of the bat population from the late Miocene, roughly five to ten million years ago. Scientists describe the diversity of bats in this article.  

Data: Scientists use newly discovered fossils of numerous upper Miocene fluviolacustrine (created from rivers running into lakes) deposits from Slovakia from three locations (called Borský Svätý Jur, Studienka A, and Krásno). All of the small mammals found (in this case, bats) were not new species. These fossils were studied and their preserved features, particularly their teeth, were measured. 

Methods: The dental fossils of the bats were measured and compared to one another in order to determine how many species of  bats were present in these areas. A digital measuring microscope was used to measure different dental features such as canines, incisors, molars, mandibles (jaws) using their height, length and width. See Figure 1 below.

Three gray fossils on a black background and an outline of a missing fossil. The first is slightly round with many indented or jagged edges, roughly 750 μm wide and 1000 μm tall. The second is rounded, smoother than the first, roughly 600 μm in width and 750 μm in height with a bump at the top roughly 300μm in diameter and 100 μm in height. The third is elongated, 1500μm in length and also slightly rounded, 600 μm in height with a short, stubby protrusion in the middle of the bottom, 100μm wide and tall. The outline looks like the third image, 1500μm in length and 600μm tall, but the protrusion is on the top in the middle, 300 μm tall and 200 μm wide and there are two longer protrusions on the bottom near each side, 500 μm in height and 100μm in width.
Figure 1. Scanning electron photomicrographs of the molar teeth of one of the bat species, named Rhinolophus cf. R. grivensis. This shows an example of some of the fossils that were found in these deposits. The first three are images of the actual bat molar fossils while the third is an outline of what it would look like because not all of the fossils were fully preserved. 

Results: Seven different taxa, or groups, were identified by comparing the differences in the teeth and jaws of the bat fossils. Differences in the sizes of teeth and the complexities of their shapes helped to identify and compare the fossils. The first small Miocene bat had high dental complexity, so there were many grooves and cusps along the teeth which helped to identify them as a species that was already established. The second group lacked larger upper canines.For other groups, the size and shape of molars were used to identify the species. There were also specimens with larger grooves or smoother areas on the teeth than other fossils. While many of the fossils were incomplete, the available details There helped scientists decide what group they belonged to. 

Significance: High diversity in areas such as this one are typically found in karst (cave) environments, not fluviolacustrine.  This is because karstic sites have more stable conditions and offer more protection for the preservation of fossils compared to fluviolacustrine which can be found in areas with more movement that could disrupt fossilization, especially in more delicate fossils, like bats. Discovering this level of diversity in a different material than usual showcases the importance of studying a broader scope of geologic areas. This could lead to more breakthroughs with more fossils in the future, allowing a clearer understanding of what animals existed and how they may have changed over time.

Broader Impact: The fossil record of bats is not very extensive because their bones are fragile and have a lower chance of getting fossilized. Because of this lack of fossilization, there has not been a very thorough understanding of bat diversity. This study helps to improve the understanding of bat diversity in this area from ten million years ago which can increase diversity estimates. This could also mean more information for understanding how other organisms existed during this time period and how bats may have interacted with them. 

Citation: Cailleux, F., van den Hoek Ostende, L., & Joniak, P. (2025). The late Miocene Bats (Chiroptera,  Mammalia) from the Pannonian region, Slovakia. Journal of Paleontology, 99(4),    975–991. doi:10.1017/jpa.2025.10136

The Significance of Cherishing BIPOC Perspectives

AdrianeLeave a comment

A picture of me at my favorite stop during the experience; the Rancho La Brea tar pits museum in LA. A black woman with blue braids wearing a black and white shirt and black pants stands in front of a fence, some sedges, and some buildings.

I recently attended a field trip and some presentations with the ADI Geo-History program at the University of Missouri. During those presentations, we learned many things about geoheritage, which is defined simply as the intersection of geology with human experiences and values. How these things overlap is crucial to being a responsible geoscientist and preserving and furthering diversity in the geosciences.

Most importantly, we discussed the experiences and struggles of those most marginalized by the colonialist history of the geosciences, those being BIPOC individuals across the planet. BIPOC people have been cruelly subjected to the theft of their land and people, while being forced to share space with the people who committed these atrocities in the first place. As part of this, their voices have historically been, and still are, devalued and overlooked, which inhibits the extent to which BIPOC individuals may participate in and contribute to the geosciences. Being Black myself, I can personally attest to how demeaning and frustrating it is to work in a field where few people look like you, and fewer still seem to have any interest in listening to your lived experiences or even giving you the space to discuss them in the first place. This creates the imperative to amplify these voices, ensuring that BIPOC people are given the space to share their perspectives and weigh in on practices that directly affect them. Too often, BIPOC people are spoken for and about rather than being the ones to tell their own stories. Attending presentations about Indigenous knowledge and perspectives and the importance of listening to and valuing these perspectives gave me hope that the discipline is making progress toward making this practice more commonplace.

A picture of some of the fossil collections in the museum that we were allowed to look at. Various fossil boxes, a picture of mammoth skeletons, a mammoth tooth, and a saber-tooth cat skull are depicted.

I heard from people who are actively working to make a difference in the state of diversity and inclusion in the geosciences. Teachers presented their work on creating databases and accessible learning resources about geoheritage sites that students themselves could edit and improve. This allows students with personal or cultural connections to sites to add their voices to the things people could learn about them, reinforcing the importance of responsible environmental stewardship and respect for the land they inhabit. Others discussed a thought process of seeing the world with two eyes, those of a scientist, and those of a person with feelings for the world around them and valuing both perspectives differently depending on the situation to create a more holistic view of the world instead of seeing things unemotionally. Scientists often see the world overly rationally, discounting personal thoughts and emotions of those affected by science and only giving weight to the scientific value of their work. We also discussed specific geoheritage sites and their significance to different kinds of people, not only focusing on the significance white people assigned to them after stripping them of their true, original value. This was very nice to see as somebody who is far too accustomed to watching these kinds of things be ignored by the greater geoscience community.

While all of this was heartwarming to see and gave me hope for the future of the geosciences, it also inspired me to want to do more work on improving the state of diversity, equity, and inclusion in my field. Moreover, I gained some new ideas on how to proceed in that work. I now have some specific objectives I want to put effort into, such as helping to contribute to communal learning resources like the ones I learned about in the program and incorporating them and elements of them into the courses I teach in the future. Furthermore, I want to impart on my students the importance of geoheritage: how to value it and the voices that shape it. Ultimately, what I took away from my time with the program was the imperative to continue working on amplifying BIPOC voices and perspectives, and the knowledge that many others are doing the same. Especially today more than ever, in these times where diversity itself is being challenged as a valid concept, and people of diverse backgrounds are being made to feel unsafe and insecure in their jobs and place of learning, I believe it is more crucial than ever to fight to protect diversity and to remember its importance to our field.

https://msstate.co1.qualtrics.com/jfe/form/SV_8vonPetQQ5IJHcG
Please consider providing feedback about your thoughts on geohistory and this post using the link or QR code above!

The Mysterious Dunkleosteus: Bigger Mouths do not Equal Bigger Bodies

jenebauerLeave a comment

Giant, swimming mouths: oral dimensions of extant sharks do not accurately predict body size in Dunkleosteus terrelli (Placodermi: Arthrodira) 

by: Russel Engelman 

Summarized by Marcella Funes is currently a biological science major at Binghamton University. She is currently a senior and plans to extend her academic studies at Binghamton University for her masters in biological sciences. Once concluded with her degrees, she hopes to do behavior research on animals. In her free time, Marcella enjoys checking out the animals at local aquariums and zoos! 

What data were used? This study primarily focused on the extinct fish Dunkleosteus terrelli, a giant armored fish from the Late Devonian Period. This extinct fish is part of a class of fish known as placoderms,  meaning “plate skin” fish. Along with their armored skin, these fish had a jointed neck, putting them in the extinct order, called “arthrodires”. Scientists focused on the measurements of the upper jaw perimeter, mouth width, mouth length, and head length of D. terrelli. These specific measurements were collected from the four Dunkleosteus terrelli specimens held at the Cleveland Museum of Natural History (Ohio, USA). These measurements  were then compared to the measurements of 985 existing fish species, 180 of which were sharks. Comparative measurement data was also collected from multiple smaller taxa of fossil arthrodires. 

What was the hypothesis being tested? Scientists sought out to provide evidence that the previous proposed body lengths for the Dunkleosteus terrelli were inaccurate. The current predicted body length measurements were established by using the relationship between the upper jaw perimeter of the D.terrelli and body length of existing sharks. However, scientists believed that this method is unreliable, and they sought to test the accuracy of this method. 

Methods: Researchers collected measurements from skeletons of the extinct D. terrelli. These measurements were then compared to measurements of existing shark species. Using this comparative analysis, researchers were able to tell how reliable the body size predictions of D. terrelli are. Since there are only skeletons of D. terrelli, the measurements of existing sharks are often used to fill in the gaps and predict the possible body size of the armored giant. To conclude that their findings were statistically significant, researchers also ran statistical tests. These tests showed the validity of using shark mouth and body length dimensions to predict body size in D. terelli. 

Results: Scientists found that the current body length estimates of D. terrelli are not accurate for many reasons. The first reason being stated that extinct arthrodires, such as the D. terrelli, have proportionally larger mouths for their body size. Sharks, on the other hand, typically have a proportionate mouth to body size. The shark-based model also caused extreme overestimates of D. terrelli body size. The shark-based model estimated the body length of D. terrelli to be 5.3-8.8 meters– this is now known to be an overestimation. These overestimated body sizes can be observed in Figure 1. Based on the head lengths of D. terrelli found in this study, the body length was more accurately predicted to be around 2.69 meters. 

This graph shows the relationship between mouth size and body length seen in extinct arthrodires and existing sharks. The x-axis of this graph displays total length in centimeters, while the y-axis shows the mouth width in centimeters. The middle of the graph includes a blue trendline in a positive direction showing the overall pattern of the dataset. The arthrodire placoderm groups being measured include Plourdosteus, Coccosteus, and Incisoscutum noted by black stars. These points are above the blue trendline in the approximate total length between 30-100 cm and a mouth width between 3–10 cm. D.terrelli is noted as a yellow star. Being below the trendline, these arthrodire placoderms have larger mouth sizes compared to their bodies. Their total length ranges at about 900 cm with a mouth length of about 90cm. The modern-day sharks measured were the Alopias, along with the extinct shark Cladoselache. The data of these sharks are along the blue trendline.
Figure 1. This graph shows a comparison between mouth width and total body length in sharks and arthrodires. This figure shows that arthrodires have larger mouth to body proportions than sharks. Other arthrodire placoderms being compared include Plourdosteus, Coccosteus, and Incisoscutum. Sharks being compared to placoderms are Alopias, the extinct Cladoselache, and other chondrichthyes.  Noted by the yellow star, shark-based models of the D.terrelli predict them to have a larger body size. This can be compared to the black stars, which are the body size of other arthrodire placoderms stated earlier.

Why is this study important? Previously, there had been many debates on the accurate body length of arthrodires such as the Dunkleosteus terrelli. Being a staple of the Devonian Period, having accurate measurements gives better insight into how this apex predator species hunted. Since D. terrelli did not have any teeth, they utilized their jaws to shear their prey. Accurate measurements of their jaws can display how these apex predators utilized their powerful jaws. With these measurements, future research can be done about their jaw force as well how they used their mouths as a vacuum for prey.

Broader Implications beyond this study: This study can cause scientists to revisit previous size estimates and hopefully better understand the marine ecosystem of the Devonian Period. D. terrelli were at the top of the food chain during the Devonian Period. These apex predators would eat through other thick shelled placoderms, suggesting possible cannibalism. Along with placoderms, soft- bodied prey was also a part of their diet. With better full body measurements further research can be done into the eating habits, as well into changes to the jaws through growth of D. terrelli. 

Citation: Engelman, Russel. 2023. Giant, swimming mouths: Oral dimensions of extant sharks do not accurately predict body size in Dunkleosteus terrelli (Placodermi: Arthrodia). PeerJ. https://peerj.com/articles/15131/ 

From One Cell to Millions: How Multicellular Life Took Over the World

jenebauerLeave a comment

Lost world of complex life and the late rise of the eukaryotic crown

By: Jochen J. Brocks, Benjamin J. Nettersheim, Pierre Adam, Philippe Schaeffer, Amber J. M. Jarrett, Nur Güneli, Tharika Liyanage, Lennart M. van Maldegem, Christian Hallmann & Janet M. Hope 

Summarized by: Neha Tengshe is a junior studying biological sciences at Binghamton University. She loves video games and hanging out with her friends. She’s super interested in phylogeny (the study of how living things are related), communication systems in animals and plants, and biology as a whole!! She loves her family and working on wikis for her interests, though she finds code frustrating at times. She’s excited to be able to share this article about one of her passions with the readers!!

What was the hypothesis being tested? The point of the paper was to examine and potentially explain the contrast between the theoretical timeline for the emergence of multicellular organisms (eukaryotes) versus the tangible evidence of their appearance in the fossil record. The theoretical timeline was produced by using a molecular clock model. Molecular clocks are a mathematical model that count how many genetic mutations have accumulated between organisms and estimate a rate at which the mutations appeared, which can provide an estimate of when different organisms first evolved. Molecular clock models suggest that eukaryotes emerged earlier than fossil remains can be found, so the researchers decided to try a different approach: they looked for biomarkers, or chemical markers, that proto-eukaryotes might have left behind in the rock record to figure out when they began their reign. The chemicals they chose to investigate are called sterols. Sterols in eukaryotes are used to regulate cell membranes, so they’re both vital to survival and generally abundant, as long as the eukaryotes that synthesize them are also abundant. Meanwhile, bacteria (which are prokaryotes, not eukaryotes) use a different chemical for the same purpose as sterols. The chemicals bacteria produce are called hopanepolyols, and the change from the simpler hopanepolyols to the sterols the crown group uses are an important indicator of the evolutionary timeline of eukaryotes. Specifically, the researchers decided to compare the number of fossilized hopanepolyols (which would be preserved as hopanes) to the number of fossilized sterols (which preserve as steranes). 

What data was used? The data used are rocks from the Proterozoic Eon, specifically around the Tonian Period (around 1 billion to 720 million years ago). The researchers were looking for traces of sterol groups that predated the types of sterol groups that modern-day eukaryotes (like humans) use. In this paper, modern day eukaryotes’ sterol groups are called “Crown-Sterols” (which include mushrooms to bananas to humans to dragonflies, anything with more than one cell alive today is a Crown-Sterol!), since they are the crown group of the eukaryotic line. A crown group is all living relatives and descendants of an ancestor, so for this study, all living eukaryotes act as the “crown group.” 

Methods: The researchers used rocks from before the Tonian Period, ground them down into powder, and used various solvents to clean them of potential contaminants. They used this powder to perform mass spectrometry. They heated up the powder until it vaporized and put the gaseous form in a spectrometer, which produced a graph with peaks that are unique to certain substances. Essentially, different chemicals have specific signatures that they leave when being analyzed with a mass spectrometer. They then matched the peaks to known formulas to identify the target compounds (i.e. the steranes and the hopanes). 

Results: Researchers found that there was another group of eukaryotes that functioned on simple sterols (Ursterols), due to traces of these simpler sterols (the traces are called Ursteroids) being preserved in the researched rocks. Researcher Konrad Bloch, who deciphered the cholesterol pathway, suggested that the full pathway for cholesterol emerged from other pathways for complete but simpler sterols (which he called Ursterols), and the synthesis yielded more and more complicated products (Cholesterol) over time because they performed better than their simpler predecessors (Ursterols). The discovery of the ursterol-using eukaryotes (Ur-Eukaryotes) helps realign the timings inferred by theoretical models like the molecular clock with what living groups can be observed today. The researchers argued that Crown-group eukaryotes co-existed with this group of Ur-Eukaryotes, until the Tonian when the Crown group’s more complex sterol eventually won out. 

Figure 1 has three sets of graphics. The leftmost one depicts a rectangle, labeled with four words on the left side one after another: Paleoproterozoic, Mesoproterozoic, Neoproterozoic, and Phanerozoic. After Paleoproterozoic, there is the label 1.6, which stands for 1,600 million years ago, or 1.6 billion years. After Mesoproterozoic, there is the label 1.0, which stands for 1,000 million years ago, or 1 billion years. In the Neoproterozoic section, there are 3 labels. 0.72, which stands for 720 million years ago, 0.63, which stands for 630 million years ago, and 0.54, which stands for 540 million years ago. Then, at the end of the Phanerozoic section, there is a 0, which means it represents the present day. On the right side of the rectangle, there is another, smaller rectangle. It is purple in the Paleoproterozoic and Mesoproterozoic sections, red in the Neoproterozoic section, and green in the first half of the Phanerozoic section and blue in the second half. Where the smaller rectangle is purple, it is labeled “Protosteroids,” where it is red, blue, and green, it is labeled “Cholosteroid biota”. Now, the large rectangle. Purple on the large rectangle represents Protosteroids, dark gray represents that nothing has fossilized, blue represents ursteroids, red represents cholosteroids, green represents stigmasteroids and dark blue represents ergosteroids. The rectangle is dark gray for the majority of the Paleoproterozoic section; it turns purple a little before the 1.6 label. The purple remains until halfway through the Mesoproterozoic section. There is a small patch of light blue towards the end of the purple section. There is a row of dark gray, then purple again, with no blue. The purple ends at the 1.0 label. There is dark gray, until 40% of the way through the Neoproterozoic section, then it is slightly purple, majority red, and some dark blue. Then in the Phanerozoic section, there is very little purple, 20% red, 30% dark blue, and 45% green.
Figure 1: The graphic on the left illustrates the stratigraphy (the layers) of the rocks the samples were taken from, specifically showing the concentrations of different sterol groups within the rocks over time. This comparison is a visual representation of the changing ratios of the eukaryotes that produced each kind of sterol. Many protosteroids illustrate just how abundant early eukaryotic life was, as well as how sudden the Crown Group’s change to cholesterol during the Tonian caused it to become the dominant type of sterane. Next, the graphic in the middle shows a family tree, depicting the group that descended from the Last Eukaryotic Common Ancestor. Finally, the images on the right are examples of these fossilized eukaryotes look like.

Figure 2 is a family tree diagram. There are seven branches that end in nothing. One branch is labeled LECA, which then splits into 8 branches. The first is labeled Alveolates, the second is labeled Rhizaria, the third is labeled Haptophytes, the fourth is labeled Chlorophytes and is green, the fifth is labeled Rhodophytes and is red, the sixth is labeled Holozoa, the seventh is labeled fungi, and the last is Amebozoa. There is a circle at the start of the Rhizaria split, which connects to an image of the oldest known Rhizaria in Figure 3. There is a green circle that connects to an image of the oldest known chlorophyte in Figure 3, and a green triangle on the chlorophyte line, labeled “Rise of Chlorophytes”. There is a red circle on the Rhodophyte line, which connects to an image of the oldest Rhodophytes, and a triangle labeled “Rise of Rhodophytes”. On the Holozoa line, there is a circle and triangle one after another. The circle is labeled “Ediacaran biota”, and the triangle is labeled “Cambrian Explosion”. There is a circle on the Fungi line, which connects to an image of the “Oldest fungus”. There is a circle on the Amoebozoa line at the exact same plane as the circle on the Rhizaria line, and the circle on the Amoebozoa line is labeled “oldest Amebozoan”.

Figure 3 is pictures of various fossils, connected to Figure 2. The oldest known Rhizaria looks like a sponge. The oldest known chlorophyte looks like a bunch of noodles. The oldest known rhodophyte looks like a lavender flower, but brown. The oldest known fungi looks like a circle with a worm coming out of it. The oldest known amoebozoa looks like a human stomach, or a minecraft squid ink sac. 

Why is this study important? Having a tighter range on when eukaryotes emerged gives researchers a better understanding of the timeline for how complex life on earth evolved. Knowing this gives researchers a guideline of what age of rocks they should investigate for more clues. It also gives them a reliable way to measure how far the shifts of diversity and abundance between prokaryotes and eukaryotes has come, just by measuring the ratio of hopanes to steranes. This paper opens the door to tracking one of paleontology’s biggest challenges (due to lack of preserved fossils, as these earliest fossils didn’t have bones or teeth, just soft tisue), the rise of eukaryotic life. It also finds evidence of another, previously theorized but undetected group of eukaryotes, the multicellular organisms that rule the Earth today.

Broader Implications beyond this study: One of the fundamentals of biology is cell theory, which posits that all cells came from other cells. That means that everything is related, and if you go back far enough, you will find an organism that all eukaryotes descended from, what scientists call “the Last Eukaryotic Common Ancestor” (LECA, for short). Discovering details about LECA helps to explain the origin of many modern eukaryotic systems and complex life as a whole. 

Citation: Brocks, J.J., Nettersheim, B.J., Adam, P., Schaeffer, P., Jarrett, A.J.M., Güneli, N., Liyanage, T., van Maldegem, L.M., Hallmann, C., Hope, J.M. Lost world of complex life and the late rise of the eukaryotic crown. Nature 618, 767–773 (2023). https://doi.org/10.1038/s41586-023-06170-w

The Importance of Endocasting Techniques When Studying Extinct Hominins

jenebauerLeave a comment

 “From Fossils to Mind” by de Sousa, Beaudet, et al.

Biography: Summarized by Jacob Davidson: Jacob is a student at Binghamton University currently working towards a bachelor of biological sciences. He enjoys playing guitar and piano, playing sports like baseball, basketball, and volleyball, and spending time either outdoors or with his pet cat, snake, and turtle.

What is the point of this paper? The point of this paper was to analyze the importance of endocasting techniques (i.e. creating casts of the inside of a fossilized skull’s cranial cavity; Figure 1), along with its limitations. This paper also emphasizes the importance of data sharing when trying to understand and compare extinct hominins’ (primates from which humans are very closely related to) brains to modern humans.

Methods: Prior to the application of endocasting techniques, studying ancient hominin neurology was very limited. The brain’s soft tissue rarely fossilizes, making it difficult to study. The brain does, however, leave imprints indicating its size, shape, and more on the cranial bone, revealing many different factors that can help interpret brain function. While relative brain size is believed to be loosely correlated with intelligence, many other factors that can be analyzed through endocasts reveal a lot about ancient hominins’ brains.

Results: One telling detail that can be analyzed in endocasts is the overall vasculature of the brain. This vascularity indicates cerebral blood flow, which demonstrates brain activity in both cognitive and functional processes. Blood flow can be estimated from small depressions that blood vessels made on the inner surface of the endocast. Another aspect of neurology that is revealed in endocasts is brain shape. Mammalian brains display a cerebrum (the upper part of the brain) that is positioned relatively higher, due to the development of the neocortex (the center of the brain). Modern human brains have a disproportionately large and superiorly positioned (i.e. higher) cerebrum. This leads to a key distinction between Homo sapiens and Neanderthals (our closest extinct relative): Homo sapiens has a “globular” endocranial shape. This distinction could be a key factor in modern human’s greater intelligence. In conjunction with modern day genetics testing, this shape could be linked to an important genotype expression, that also could play a role in interpreting differences in brain function and overall intelligence between Neanderthals and Homo sapiens. 

While endocasts are revealing for the brain anatomy of extinct hominin species, they can only reveal so much information. In order to fully understand how extinct hominin species’ brains worked, many other things need to be accounted for. Everything from behavioral patterns to genetics need to be assessed when trying to paint a full picture of extinct hominin species. This is where the importance of scientific communication and data sharing is reflected. Most of the data on this topic is not currently shared, making research harder than necessary. Histological (i.e. tissue and cells) collections and databases contain a wide variety of data that can be used to help better understand many different extinct species’ brains. Through sharing this information, researchers can collaborate to learn even more, while also communicating their findings with museums, institutions, and other researchers.

The image demonstrates an endocast of an Australopithecus africanus and compares it to the digital 3d modeling of other mammalian brains. The endocast is a full, solid cast of the fossil’s cranial cavity, aiding researchers in understanding the brain’s size, vasculature, shape, cerebral sulci, and lateralization for the species to which the fossil belongs (these words are the text in the image next to the endocast). The digital 3d imaging of mammalian brains demonstrates the complexity of each brain, while showing how much data can be observed from an endocast. The endocast of the Australopithecus africanus was made by creating an internal mold of an Australopithecus africanus’ fossilized skull. When compared to different digital images of brains shown in this image, human brains are shown to be larger while containing more folds than the Australopithecus africanus, Eastern lowland gorilla, Rhesus macaque, and Grey mouse lemur. Scale bar is 5 cm, so the average human brain is about 15 cm in width and the brains in the previous sentence get progressively smaller in their respective order.
Figure 1. An image of the endocast of an early relative of humans, Australopithecus africanus, along with digital imaging of different mammalian brains on the right. 

Why is this important? Human history can be traced back millions of years. Modern humans (Homo sapiens) only appeared relatively recently in the fossil record, while the extinct evolutionary relatives of humans, such as the genera Paranthropus and Australopithecus, first appeared millions of years ago. Through analysis of fossil endocasts, along with comparisons to modern humans and other mammals, paleontologists can now better understand past hominin brain function, specialization, and plasticity (i.e. the ability to learn and create new pathways). This field of research is known as paleoneurology, and research in this field is key to understanding both ancient and modern hominin brain function and disease.

Broader implications: Biology helps us understand the world around us, but, arguably, it also serves a more important role. Biology has long helped us improve human life. From understanding human anatomy to sequencing the first human genome, biology and all of its subcategories have aided in the pursuit to improve human life. Paleoneurology serves a huge role in this pursuit. Through understanding hominin brains throughout time and comparing them to modern Homo sapiens brains, we can understand the evolutionary steps we took, along with the aspects of our brains particular to humans and how they may shine a light on subjects like mental health, disease, and neurodegeneration.

Citation: de Sousa, A. A., Beaudet, A., Calvey, T., Bardo, A., Benoit, J., Charvet, C. J., Dehay, C., Gómez-Robles, A., Gunz, P., Heuer, K., van den Heuvel, M. P., Hurst, S., Lauters, P., Reed, D., Salagnon, M., Sherwood, C. C., Ströckens, F., Tawane, M., Todorov, O. S., … Wei, Y. (2023, June 13). From fossils to mind. Nature News. https://www.nature.com/articles/s42003-023-04803-4 

Bone eating “Osedax worms” variation and spread geographically

jenebauerLeave a comment

New occurrences of the bone-eating worm Osedax from Late Cretaceous marine reptiles and implications for its biogeography and diversification 

By: Sarah Jamison-Todd, Philip D. Mannion, Adrian G. Glover and Paul Upchurch  

Summarized by: Yasamin Taqwai is a biology major student at Binghamton University. She transferred this semester as a junior, after graduating with associates from Suny Broome University. Her lifelong dream and goal have been to be a doctor, especially an OBGYN. She hopes to attend Langone medical school after getting her bachelors. When she is not busy with school, she takes turns volunteering for health services and practicing self-care. She loves family time and baking as her therapy and peaceful time.  

What data were used?  Osedax are worms known for eating the bones of dead marine animals, such as whales or reptiles. They do not eat the whole bone, but by burrowing into it, they can break down the organic material, like the collagen and fat inside. The worms have a root-like structure that helps them penetrate the bone and release enzymes that dissolve the organic parts and absorb nutrients. This eating process creates holes and tunnels in the bone which makes up the fossil record of these worms (these are called trace fossils). The Osedax trace fossils used in this study were found on different marine reptiles from the Late Cretaceous Period, around 100 to 66 million years ago. There were 13 collections of these reptile fossils taken from in the United Kingdom, mainland Europe, and the United States. In these fossils, the researchers specifically looked for degradation or burrow structures that showed an Osedax worm had been present on them. The researchers also looked at CT scans of 20 specimens of Osedax with unique patterns. These patterns refer to the holes and tunnels created as the worms fed on the bones of the extremely well-preserved fossils of marine reptiles, such as plesiosaurs and mosasaurs.   

What was the hypothesis being tested?  Scientists wanted to research how Osedax worms have evolved over time: specifically, how their diversification into different species has been shaped by environmental factors and geographic differences. The researchers hypothesized that there was a greater species variation in Osedax than what previous studies had recognized. The researchers also hypothesized that Osedax fossils were found across a broader geographical range than previously thought, suggesting they spread to more areas than earlier studies had recognized. This was important for understanding not just the worms themselves but also for examining how they interacted and contributed to the health of marine ecosystems, such as how ecosystem maintained its balance during the Cretaceous. 

Methods:  Scientists examined fossil reptiles by analyzing the physical characteristics left by Osedax worms. They specifically studied the size and shape of boreholes and tunnels made by the worms as they fed on the bones (Fig. 1). These differences in borehole size provided information on variations in the worms’ eating habits. These size variations also potentially reflected different species of Osedax, as each species might create boreholes of distinct dimensions or patterns.  The fossils with Osedax pattern on them were scanned using different CT scanners to get a detailed examination of the pattern. After visualizing characteristics of the trace fossils, the researchers looked at the geographical locations of where the fossils were discovered. They compared the variations they found across different geographical locations. They were looking for trends, whether certain species of Osedax worms were more common in specific regions or the size of boreholes varied based on location. These trends could help identify differences in their feeding behaviors, showing how environmental factors may have influenced their range and adaptation. 

The figure consists of five images, each labeled with a letter a, b, c, d, or e. Each image shows a fossil that have unique holes left by the Osedax. Picture a (Type 4) has a light brown-yellowish fossil with a rectangular shape. The holes on this fossil are scattered and shallow. It ranges in size from a small coin to a pencil eraser. Picture b (Type 5) has a gray-brown rib fossil and looks like two wooden chopsticks in a container. It has a shallow, scoop like holes near the surface that’s about the size of a fingertip. Picture c (Type 1,2,3) also has a light brown-yellowish fossilized tooth root with a rectangular shape. It shows two small borings toward the bottom left, one circular and one slightly elongated, each about the size of a small bead. Picture d (Type 5) has placed horizontally a cylindrical jaw piece fossil. It has a hole through it horizontally near the top. The holes are small and narrow, similar to a ballpoint pen tip. Picture e (Type 5) has a gray-brown trapezoid-rectangular jaw fossil with a smooth surface in the middle and rough pits near the top and bottom. The pits are deep and lobate, ranging from the size of a pea to a marble.
This figure analyzes the different shapes and depth of the erosion by bone eating worm Osedax. These morphotypes suggest variations in Osedax feeding behaviors and ecological adaptations (Figure 1). Five different types of bone eating patterns were found. Type 1 (C): Thick, radial branches form the main part of the chamber. Type 2 (C): Deep lobate chambers, showing a different feeding way. Type 3 (C): Filamentous branches off a central chamber, showing adaptation. Type 4 (A): Larger, shallow chambers with radial branches that show different ecological resources. Type 5 (D,E,B): Smaller central chambers that show small bites or feeding behavior.

Results:  The results of the study supported the hypothesis that Osedax worms had a greater species diversity and a broader geographic range than previously known. After analyzing different patterns left by Osedax the researchers were able to identify five different hole morphotypes, which suggests the presence of different species of Osedax worms that likely fed on marine reptiles. One significant finding came from a fossil connected with the Cenomanian Stage of the Late Cretaceous (~100–93 million years ago), which showed three different morphotypes within a single tooth, indicating the worms may have coexisted on the same organism. The study also found that Osedax had a greater geographic distribution, expanding their previously known range from the eastern side of the northern Atlantic Ocean to include the western side as well. They also believe that Osedax speciation occurred earlier than the timeline they had thought. This is based on the discovery of high diversity in fossils from older marine reptiles compared to the previously studied fossils of whale bones. The presence of multiple Osedax species in these earlier fossils suggests that the worms had diversified significantly before the Cenozoic Era (the past 65 million years), a time they are commonly associated with. Finally, the study also discusses a bias in Osedax speciation. Since these worms need well-oxygenated environments to thrive, fossils from low oxygen or deep ocean habitats may not show Osedax feeding traces. This means that the record of Osedax trace might be incomplete, further influencing our perception of their diversity and distribution over time and need to be researched further.   

Why is this study important?   This study helps us understand the interactions between Osedax worms and marine reptiles during the Late Cretaceous. It shows how these bone-eating worms did not function as parasites, but as decomposers, feeding on the bones of dead marine animals, such as plesiosaurs and mosasaurs. By burrowing and breaking down collagen and fat, it left distinct trace fossils which are valuable for identifying Osedax trace and knowing their ecological role. It also shows how Osedax can affect the preservation of fossils. Their feeding activity could mean that some marine reptile fossils collected today are incomplete as it could have impacted how well these organisms were preserved. These potential gaps in the fossil record could change our interpretation of past ecosystems. Additionally, the researchers believe that Osedax worms diversified earlier than previously thought, pushing back the timeline for their evolution. These findings mean we might not have a complete picture of the ecosystem and can reevaluate the timeline more precisely based on the new information and see the ecological significance of Osedax worms.   

Broader Implications beyond this study:   By studying Osedax worms, we can learn more about how marine ecosystems function and how different species interact. For example, when Osedax worms decomposes the bones of dead marine animals, they release nutrients for other organisms to consume and benefit from. This shows the interconnectedness of marine life and the importance of decomposers in maintaining a balanced ecosystem. Although Osedax worms and the marine reptiles they fed on are extinct, other organisms today, such as marine fungi, play a similar role. These organisms can be important for maintaining the balance of marine ecosystems and ensuring that nutrients from dead organisms are returned to the food web to support the thrive of other marine life. If these similar decomposers are threatened by pollution or climate change the nutrient cycle could be disrupted. Understanding the role of Osedax could help form strategies to protect or restore these organisms. Through Osedax, scientists can better understand how these processes worked in the past and apply that knowledge to modern ecosystems.

Citation: Jamison-Todd, S., Mannion, P. D., Glover, A. G., & Upchurch, P. (2024). New occurrences of the bone-eating worm Osedax from Late Cretaceous marine reptiles and implications for its biogeography and diversification. Proceedings of the Royal Society B  Biological Sciences, 291(2020). https://doi.org/10.1098/rspb.2023.2830  

A Study of the Evolutionary Causes of Spherical Shell Formation in Marine Microorganisms

jenebauerLeave a comment

Convergent evolution of spherical shells in Miocene planktonic foraminifera documents the parallel emergence of a complex character in response to environmental forcing 

Peter Kiss, Natália Hudáčková, Jürgen Titschack, Michael G. R. Siccha, Zuzana Heřmanová, Lóránd Silye, Andrej Ruman, Samuel Rybár, and Michal Kučera

Summarized by Sofia Corsico-Sánchez, a junior double majoring in biology and environmental science with a minor in geology at Binghamton University. Her future plans include becoming an independent researcher whose work combines her interests in species conservation and the fossil record. When she is not studying, Sofia can be found reading, knitting, practicing ballet, or getting tackled in rugby. 

What was the hypothesis being tested?: The hypothesis being tested in this paper was the potential evolutionary cause of spherical shells found in certain species of planktic foraminifera, which are marine zooplankton that float near the surface of the water. Researchers have been unsure of the specific factors that led to their fully spherical shell shape, which differs from the incrementally increasing chamber size shell shape seen in most other species of foraminifera. The scientists behind this study compared three foraminiferal genera: Praeorbulina, Orbulina, and Velapertina; Velapertina was endemic to, or only found in, the Paratethys, an ancient inland body of water that spanned across western Europe into central Asia. Praeorbulina is believed to be the ancestor of Orbulina. Even though Orbulina and Velapertina evolved at different times, they are both found with this unique spherical outer shell shape. The researchers wanted to determine if this shape is due to homoplasy, or a trait that develops in two species without a common ancestor, which could indicate similar environmental pressures that favored this shell shape. These scientists first needed to look at if Velapertina and Orbulina were different genera entirely or were just morphological variations of each other. 

What data were used?: Scientists used specimens from three species: Praeorbulina glomerosa circularis (an extinct ancestor of Orbulina from the early Miocene), Orbulina suturalis, and Velapertina indigena. Because Velapertina was endemic to the Paratethys and the researchers were looking into the relationship between it and Orbulina, they used Velapertina and Orbulina specimens from this area. The Praeorbulina specimens were from the Pacific, and were compared to the Orbulina from the Paratethys to ensure that the Orbulina samples from Paratethys were morphologically similar to their ancestor, and were not diverging from the Orbulina lineage due to their location.

Methods: Using the specimens from the three species, scientists imaged their development using an X-ray (Fig. 1). Foraminifera grow by sequentially adding chambers. In the case of these species, their final chamber envelops their entire shell, which makes it difficult to see the growth pattern of the previous chambers. It is also difficult to determine the morphological differences among the three species, as differentiating features lie within the outer chamber. Thus, the usage of an X-ray is crucial to identify these differences.

Structural scans of three different foraminifera species used in this study: Praeorbulina glomerosa circularis, Orbulina suturalis, and Velapertina indigena. Four angles of each species are shown (total of twelve images); the first angle for each is a general scan of the species, and the remaining three highlight the different chambers of each specimen with different colors. In the Praeorbulina and Orbulina samples, the drastic changes in subsequent chamber size is apparent– the smallest chamber (highlighted in red) is barely seen in comparison to the next few chambers. The final, engulfing chamber is clearly much larger than the previous chamber. In the Velapertina sample, the chamber growth is shown to be more gradual; while each subsequent chamber is larger than the previous one, the change is not as drastic. The final, engulfing chamber pictured here is much bigger than the previous one, but not nearly as different in size as the Praeorbulina and Orbulina samples. There are labels that highlight shared shell features, like the areal and sutural apertures.
Figure 1: This is an X-ray tomography scan of the shell structures of the three different species looked at in this study: Praeorbulina glomerosa circularis, Orbulina suturalis, and Velapertina indigena. Praeorbulina is the likely ancestor of Orbulina, and the morphological similarities can be seen clearly, especially in terms of the sutural aperture (the area of the shell with an opening). The X-ray shows the morphological similarities between O. suturalis and V. indigena; however, the different views show the morphological differences, such as the sizes of the inner chambers. Despite evolving at different times, this spherical shell phenotype was expressed, suggesting a similar environmental pressure.

Results: X-ray scans revealed the inner differences between the Orbulina and Velapertina specimens, indicating that they are, in fact, different species. These inner differences include a difference in growth patterns: both Praeorbulina and Orbulina chamber formation increased in size rapidly (showing their close evolutionary relationship), while Velapertina chambers were similarly sized throughout formation. Previous studies have shown that this spherical formation was evolutionarily advantageous because of its minimum surface-to-volume ratio, which is ideal for gas exchange mechanisms within the foraminifera. This spherical shape is indicative of an environment where oxygen did not deplete, which can tell researchers more about different environmental aspects of the habitats the organism lived in. 

Why is this study important?: This study built on previous suggestions of foraminiferal genera differences between Orbulina and Velapertina by using technology to show their inner morphological differences. This shows that the development of certain traits between species that may not be directly related is possible under similar environmental conditions, as seen in the similar shell structure of these two genera. By looking at the evolutionary advantages of this structure, scientists can better understand how the environment of the past impacted the development of species, and what that might mean for the future. 

Broader implications beyond this study: In a world where anthropogenic climate change is rapidly changing our environment, it feels as though we are stepping into the unknown. However, our geologic history preserved by our rock record shows periods of environmental similarities. Because these genera were found to be different (from the comparison of specimens from different species), scientists can better understand how the environmental pressures of the past impacted the developmental response of these species, and how modern-day species may react to similar (or even different!) environmental changes. By looking into the past, we can have a better understanding of our potential future. 

Citation: Kiss, P., Hudáčková, N., Titschack, J., Siccha, M. G. R., Heřmanová, Z., Silye, L., Ruman, A., Rybár, S., & Kučera, M. (2023). Convergent evolution of spherical shells in Miocene planktonic foraminifera documents the parallel emergence of a complex character in response to environmental forcing. Paleobiology, 49(3), 454–470. https://doi.org/10.1017/pab.2022.48

Utilizing Stromatolites Fossils and Lake Paleo Shorelines Analysis to Understand the Transition from Paleolake Lisan to Dead Sea

jenebauerLeave a comment

Unveiling the Transition From Paleolake Lisan to Dead Sea Through the  Analysis of Lake Paleo Shorelines and Radiometric Dating of Fossil Stromatolites

By: Julius Jara‐Muñoz, Amotz Agnon, Jens Fohlmeister, Sara Tomás, Jürgen Mey, Norbert Frank,  Birgit Schröder, Andrea Schröder‐Ritzrau, Yannick Garcin, Yaniv Darvasi, Daniel Melnick, Maria Mutti, and Manfred R. Strecker

Summarized by: Summarized by Megha Goswami, a senior at Binghamton University. She is currently working towards a B.S. in geology: geophysics and will graduate in Fall 2024. She plans to take a gap year and gain experience in the geology field, then return for a Master’s program. Outside of college, she likes to hike, paint, and garden.

What data were used? In this study, the researchers collected fossil stromatolites, once-living microbe organisms or blue-green algae, from the eastern and western coasts of the Dead Sea. Fossil stromatolites are great for tracking changes in ancient coastlines, as these blue-green algae form around the shorelines of lakes and seas (called paleo shorelines). The researchers used multiple photos of these geologic features to create 3D photogrammetric models of the shorelines of the paleo lake Lisan.

What is the goal of this paper? To gain a deeper understanding of the climate during the most recent cold period (the Last Glacial Maximum, approximately 120,000 to 11,500 years ago), scientists conducted radiometric dating on stromatolite fossils (see Figure 1). They reconstructed the paleo shorelines to establish the approximate timeline of when paleo Lake Lisan transitioned into what is now the Dead Sea. This data was then compared with previous studies, which indicated that during the last glacial period, the depression that once contained paleo Lake Lisan remained filled for roughly 10,000 years. As the lake dried up, the remnants of the paleo shorelines were left behind.

Fossil Stromatolites are rock formations in which microbial organisms are layered on top of each other, creating dark and light color layer patterns. In figure 1, there are six specimens, A through F, of the stromatolites with various textures and forms. Image A showcases a specimen of stromatolite about 7cm long and 3cm in height. Lines are running horizontally, one light in color and the other much darker, like layers in a cake. In Image B, the stromatolite has different textures than the specimen in Image A; the texture looks like crushed-up Rice Krispies, almost one foot long, and one color. Image C is looking at fossil stromatolite under the microscope; the image can be described as looking like three mini lakes filled with clear water and land surrounding it. I is covered in snow-white color; however, there is one area on the image where there is a blob (less than 1mm in size) with a distinct color, which represents uncommon material that is not usually found in stromatolite fossil (quartz). Image D displays fossil stromatolites in the bedrock or stuck onto the land, about 80cm long. Like in Image A, darker color lines run across the specimen, and the lines are close together in a nice wavy pattern. In image E, the size of the stromatolite is quite large, about 1 to 2 meters; the color is much darker compared to other specimens, and the texture is a bit spongy-like, but now the stromatolite is encrusted on the gaps/cracks of bedrock. Image F, this image is located on the now slope gradient of a hill, which probably represents the past shorelines more over the stromatolite embedded in the bedrock, and it is about 1m to 1.5m long. The specimen is all one color, with thin layers running horizontally along the specimen, and the texture is a bit coarse, like sand grains, but with pebbles in them.
Figure 1. The different forms of fossil stromatolites used in this study. (A)Well-layered stromatolite specimen, (B) Sponge-like textured stromatolite, (C) Stromatolite specimen partly filled with minerals after the death of the stromatolite (quartz), (D) Well-layered stromatolite with vertical growth, (E) Here, stromatolites are present in the fracture of the bedrock, (F) A very large stromatolite specimen with vertical growth 

Methods: Stromatolite samples were collected from the western to eastern coast of the Dead Sea to explore the transition from Paleolake Lisan to the current Dead Sea. Scientific analyses were conducted in the laboratory on the fossil stromatolites and the ancient shorelines of the paleo-lake. The samples were dated using both radiocarbon and uranium-series dating methods. Radiocarbon dating estimates a sample’s age by measuring the amount of carbon-14 it contains. In contrast, the uranium-series dating method assesses uranium isotopes, such as U234, U238, and thorium-230, to estimate the ages of the stromatolite specimens. Additionally, temporal corrections were applied to the U-series ages to account for the presence of other materials or impurities in the samples that could influence the age determination of the stromatolite specimens. Scientists also implemented further corrections to the data to address changes in altitude, water levels, and tectonic activity that occurred since the time when these fossils were formed. After completing these tests and analyses, the researchers successfully determined the ages of the samples, reconstructed the shoreline levels of Paleolake Lisan, and compared their findings with those of previous studies.

Results: The scientists discovered that the highest (peak) lake level occurred between 30,000 and 28,600 years ago, with a decline starting around 28,500 and continuing until 18,000 years ago. During the peak period of Lake Lisan, water evaporation rates were also elevated, aligning with other models used for reconstructing past shorelines. Consequently, these findings suggest that the transition from paleo Lake Lisan to the Dead Sea happened 5,000 years earlier than indicated in earlier studies.

Why is this study important? This data offers researchers insights into the regional and local paleoclimate—specifically, the climate during the Last Glacial Maximum, which occurred roughly 120,000 to 11,500 years ago. The findings indicate that following the peak water levels of Lake Lisan, which declined between 28,500 and 18,000 years ago, the rate of water evaporation increased. This suggests that temperatures in the region began to rise during the Last Glacial Maximum, likely showing the transition out of this glacial period.

Broader implications beyond this study? By examining historical geological features, such as lakes and shorelines, scientists can gain insights into the climate conditions during Earth’s last glacial period. This study also enhances their understanding of how lakes reacted to climate change as temperatures increased. By learning about past climates, scientists can better comprehend current climate behavior and make informed predictions about future climate conditions.

Citation: Jara‐Muñoz, J., Agnon, A., Fohlmeister, J., Tomás, S., Mey, J., Frank, N., Schröder, B., Schröder‐Ritzrau, A., Garcin, Y., Darvasi, Y., Melnick, D., Mutti, M., & Strecker, M. R. (2024). Unveiling the transition from Paleolake Lisan to Dead Sea through the analysis of Lake paleo shorelines and radiometric dating of fossil stromatolites. Geochemistry, Geophysics, Geosystems, 25(8). https://doi.org/10.1029/2024gc011541 

How Psittacosaurus dinosaur fossils help connect the evolutionary transition from scales to feathers

jenebauerLeave a comment

Cellular structure of dinosaur scales reveals retention of reptile-type skin during the evolutionary transition to feathers

by: Zixiao Yang, Baoyu Jiang, Jiaxin Xu, & Maria E. McNamara 

Summarized by: Shirley Wang, an undergraduate student at Binghamton University majoring in computer science and minoring in biology. She is interested in learning more about technology and how it can potentially better our relationship with the environment. In her free time, she likes to hike, play video games, and read.

What data were used? The scientists used a preserved juvenile Psittacosaurus specimen from the Early Cretaceous Jehol Biota (approximately 135–120 million years ago) of Nanjing, China to analyze the composition of the preserved skin and skeletal material; fossils are typically only preserved as hard parts (like bones), so soft tissue like skin is rare. The scientists found that the skin seemed to be preserved naturally with silica. What made this data even more significant was the fact that it was preserved three-dimensionally, meaning the silica also preserved the internal cellular structures as well as the epidermal layers (i.e. outermost layers of skin).

What was the hypothesis being tested? The Psittacosaurus was a dinosaur species from the Early Cretaceous Jehol Biota of China that despite not being a bird, had feathers. We currently have little information concerning the soft tissues of organisms in the past, making the silicified Psittacosaurus fossil which preserved these components a rare discovery. Scientists sought to analyze the well-preserved Psittacosaurus fossil to better understand the evolutionary transition from scales to feathers. 

Methods: The scientists used three different analytical methods to collect data: a stereomicroscope with UV light (to easily identify the soft tissue remains from other materials, such as bones and sediment), a Scanning Electron Microscopy (SEM) (to take detailed images of skin samples), and a Micro-attenuated Total Reflection Fourier-Transform Infrared (µATR-FTIR) spectroscopy (to analyze the molecular composition of the skin). In Figure 1, the Psittacosaurus fossil can be seen in both normal and UV light to better examine areas of difference between bones and soft tissues in the specimen.

Results: The soft tissue that the scientists analyzed from the Psittacosaurus fossil had the presence of melanosomes (the cell organelles in charge of color patterns) and corneous beta proteins (proteins that make up the epidermal skin layer in modern birds and reptiles). These features and the morphology of the skin appeared to be closely resembling fossilized archosaurian scales, a common ancestor of today’s crocodilians and avians. Samples from the upper epidermis (outermost layer of skin) of the fossil showed a similar structure to the upper epidermis of modern reptiles. Furthermore, the thickness of the upper epidermis’ structures was compared to those of crocodiles and chickens and was found to be of similar sizes. 

Top Picture (Figure 1. (A)): 664 mm long fossil of a relatively complete dinosaur skeleton preserved in sediment with its four limbs laying flat out in each direction and the underside (belly) facing upwards. The fossil is split in half along the torso, the head side is placed on the left while the tail side is placed on the right. Bottom Picture (Figure 1. (B)): Fossil under UV light coloring the bones blue and soft tissues orange-yellow. There are boxed sections under ultraviolet light highlighting different details of the specimen. Figure 2a-c is next to the split, close to the bottom of the head side of the fossil while Figure 2d-e is above Figure 2a-c, next to the split, closer to the top of the head side of the fossil. Figure 2f-g is next to the split, close to the top of the tail side of the fossil.
Figure 1. (A) showcases the Psittacosaurus fossil in normal light surrounded by sediment. Figure 1. (B) showcases the same fossil but under UV light, highlighting the difference between bones (blue) and preserved soft tissues (orange-yellow) not previously seen under normal light. The boxed areas are regions that resemble features of other known organisms. Figure 2a-c depicts preserved gastroliths (rocks that grind up food inside the animal to help them digest food easier) in the abdomen and ventral skin (skin on the underside of the organism), also shown in Figure 2d-e. Figure 2f-g marks the location of uniquely textured skin, closely resembling archosaurian scales.

Why is this study important? This study is important because it is rare to find fossils of soft tissues as a result of the soft tissue of organisms, such as skin and feathers, decaying too quickly for fossilization to occur. Because of this, the knowledge we currently have about extinct organisms is mainly limited to hard tissues, such as bones and teeth. By studying the Psittacosaurus fossil, we can expand our knowledge of how traits in organisms millions of years ago changed to understand how organisms look now. 

Broader Implications beyond this study: By better understanding the data gathered from the Psittacosaurus fossil, we can in turn better visualize what early relatives of reptiles and birds looked like and could potentially reshape how we view the evolution of feathers. 

Citation: Yang, Z., Jiang, B., Xu, J. et al. Cellular structure of dinosaur scales reveals retention of reptile-type skin during the evolutionary transition to feathers. Nat Commun 15, 4063 (2024). https://doi.org/10.1038/s41467-024-48400-3