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  • Fossil plant revealed as a baby turtle fossil.

    Fossil plant revealed as a baby turtle fossil.

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    Newswise — From the 1950s to the 1970s, a Colombian priest named Padre Gustavo Huertas collected rocks and fossils near a town called Villa de Levya. Two of the specimens he found were small, round rocks patterned with lines that looked like leaves; he classified them as a type of fossil plant. But in a new study, published in the journal Palaeontologia Electronica, researchers re-examined these “plant” fossils and found that they weren’t plants at all: they were the fossilized remains of baby turtles.

    “It was truly surprising to find these fossils,” says Héctor Palma-Castro, a paleobotany student at the Universidad Nacional de Colombia.

    The plants in question had been described by Huertas in 2003 as Sphenophyllum colombianum. The fossils come from Early Cretaceous rocks, between 132 and 113 million years ago, during the dinosaurs’ era. Fossils of Sphenophyllum colombianum were surprising at this time and place— the other known members of the genus Sphenophyllum died out more than 100 million years prior. The plants’a ge and locality piqued the interest of Fabiany Herrera, the Negaunee assistant curator of fossil plants at the Field Museum in Chicago, and his student, Palma-Castro.

    “We went to the fossil collection at the Universidad Nacional de Colombia in Bogotá and started looking at the plants, and as soon as we photographed them, we thought, ‘this is weird,’” says Herrera, who has been collecting Early Cretaceous plants from northwestern South America, an area of the world with little paleobotanical work.

    At first glance, the fossils, about 2 inches in diameter, looked like rounded nodules containing the preserved leaves of the plant Sphenophyllum. But Herrera and Palma-Castro noticed key features that weren’t quite right.

    “We spent days searching through wooden cabinets for fossil plants. When we finally found this fossil, deciphering the shape and margin of the leaf proved challenging,” says Palma-Castro.

    “When you look at it in detail, the lines seen on the fossils don’t look like the veins of a plant— I was positive that it was most likely bone,” says Herrera. So he reached out to an old colleague of his, Edwin-Alberto Cadena.

    “They sent me the photos, and I said, “This definitely looks like a carapace’— the bony upper shell of a turtle,” says Cadena, a paleontologist who focuses on turtles and other vertebrates at the Universidad del Rosario in Bogotá. When he saw the scale of the photos, Cadena recalls, “I said, ‘Well, this is remarkable, because this is not only a turtle, but it’s also a hatchling specimen, it’s very, very small.”

    Cadena and his student, Diego Cómbita-Romero of the Universidad Nacional de Colombia, further examined the specimens, comparing them with the shells of both fossil and modern turtles. “When we saw the specimen for the first time I was astonished, because the fossil was missing the typical marks on the outside of a turtle’s shell,” says Cómbita-Romero. It was a little bit concave, like a bowl. At that moment we realized that the visible part of the fossil was the other side of the carapace, we were looking at the part of the shell that is inside the turtle.”

    Details in the turtle’s bones helped the researchers estimate how old it was at death. “Turtle growth rates and sizes vary,” says Cómbita-Romero, so the team looked at features like the thickness of its carapace and the spots where its ribs were knitting together into solid bone. “This is a feature uncommon in hatchlings but observed in juveniles. All this information suggests that the turtle likely died with a slightly developed carapace, between 0 to 1 years old, in a post-hatchling stage,” he says.

    “This is actually really rare to find hatchlings of fossil turtles in general,” says Cadena. “When the turtles are very young, the bones in their shells are very thin, so they can be easily destroyed.”

    The researchers say that the rarity of fossilized baby turtles makes their discovery an important one. “These turtles were likely relatives of other Cretaceous species that were up to fifteen feet long, but we don’t know much about how they actually grew to such giant sizes,” says Cadena.

    The researchers don’t fault Padre Huertas for his mistake— the preserved shells really do resemble many fossil plants. But the features that Huertas thought were leaves and stems are actually the modified rib bones and vertebrae that make up a turtle’s shell. Cómbita-Romero and Palma-Castro nicknamed the specimens as “Turtwig,” after a Pokémon that’s half-turtle, half-plant.

    “In the Pokémon universe, you encounter the concept of combining two or more elements, such as animals, machines, plants, etc. So, when you have a fossil initially classified as a plant that turns out to be a baby turtle, a few Pokémon immediately come to mind. In this case, Turtwig, a baby turtle with a leaf attached to its head,” says Palma-Castro.” In paleontology, your imagination and capacity to be amazed are always put to the test. Discoveries like these are truly special because they not only expand our knowledge about the past but also open a window to the diverse possibilities of what we can uncover.”

    The scientists also note the importance of these fossils in the larger scheme of Colombian paleontology. “We resolved a small paleobotanical mystery, but more importantly, this study shows the need to re-study historical collections in Colombia. The Early Cretaceous is a critical time in land plant evolution, particularly for flowering plants and gymnosperms. Our future job is to discover the forests that grew in this part of the world,” says Herrera.

    This project was supported by the National Geographic Society, grant (EC-96755R-22) Discovering Early Cretaceous Floras from Northern South America & the Negaunee Integrative Research Center, Field Museum.

     

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  • Florida Keys’ new “margarita snails” are bright yellow

    Florida Keys’ new “margarita snails” are bright yellow

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    Newswise — The “Margaritaville” in Jimmy Buffett’s famous song isn’t a real place, but it’s long been associated with the Florida Keys. This string of tropical islands is home to the only living coral barrier reef in the continental US, along with many animals found nowhere else in the world. One of them is a newly-discovered, bright yellow snail, named in honor of Margaritaville. The lemon- (or, key-lime-) colored snail, along with its lime-green cousin from Belize, is the subject of a study published in the journal PeerJ.

    These marine snails are distant relatives of the land-dwelling gastropods you might find leaving slimy trails in your garden. Nicknamed “worm snails,” they spend most of their lives in one place. “I find them particularly cool because they are related to regular free-living snails, but when the juveniles find a suitable spot to live, they hunker down, cement their shell to the substrate, and never move again,” says Rüdiger Bieler, curator of invertebrates at the Field Museum in Chicago and the study’s lead author. “Their shell continues to grow as an irregular tube around the snail’s body, and the animal hunts by laying out a mucus web to trap plankton and bits of detritus.”

    Bieler has spent the past four decades studying invertebrate animals living in the Western Atlantic, but these particular snails “are so small and so well-hidden that we’ve not encountered them before during our scuba diving surveys. We had to look very closely,” he says. The new species belong to the same family of marine snails as the invasive “Spider-Man” snail that the same team described from the Vandenberg shipwreck off the Florida Keys in 2017.  

    He and his colleagues, including fellow Field Museum curator Petra Sierwald, came across the lemon-yellow snails in the Florida Keys National Marine Sanctuary, and they found a similar, lime-colored snail in Belize. “Many snails are polychromatic– within the same species, you get different colors,” says Bieler. “In a single population, even a single little cluster, one might be orange, one might be gray. I think they do it to confuse fish and not give them a clear target, and some have warning coloration.”

    “Initially, when I saw the lime-green one and the lemon-yellow one, I figured they were the same species,” says Bieler. “But when we sequenced their DNA, they were very different.”

    Based on these molecular data, Bieler, Sierwald, and their co-authors Timothy Collins, Rosemary Golding, Camila Granados-Cifuentes, John Healy and Timothy Rawlings, placed the snails in a new genus, Cayo, after the Spanish word for a small, low island. The yellow snail was named Cayo margarita after the citrusy drinks in Jimmy Buffet’s “Margaritaville.” The lime snail’s name, Cayo galbinus, means “greenish-yellow.” 

    The Cayo snails have a key trait in common with another worm snail genus, Thylacodes, for which the team described a new species from Bermuda and named Thylacodes bermudensis. While only distantly related, these snails all have brightly colored heads poking out of their tubular shells. “Our thought is this is a warning color,” says Bieler. “They have some nasty metabolites in their mucus. That also might help explain why they’re able to have exposed heads– on the reef, everybody is out to eat you, and if you don’t have any defensive mechanism, you will be overgrown by the corals and sea anemones and all the stuff around you. It seems like the mucus might help deter the neighbors from getting too close.”

    Bieler says that the study is important because it helps illuminate the biodiversity of coral reefs, which are under severe threat due to climate change. “There have been increases in global water temperatures, and some species can handle them much better than others,” says Bieler. The Cayo snails have a tendency to live on pieces of dead coral, and as more coral is killed off, the snails might spread. 

    Moreover, says Bieler, “it’s another indication that right under our noses, we have undescribed species. This is in snorkeling depth in a heavily touristed area, and we’re still finding new things  all around us.”

    This study was contributed to by scientists at the Field Museum, Florida International University, Queensland Museum, and Cape Breton University. 

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  • Archaeological study of 24 ancient Mexican cities reveals that collective forms of governance, infrastructural investments, and collaboration all help societies last longer

    Archaeological study of 24 ancient Mexican cities reveals that collective forms of governance, infrastructural investments, and collaboration all help societies last longer

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    Newswise — Some cities only last a century or two, while others last for a thousand years or more. Often, there aren’t clear records left behind to explain why. Instead, archaeologists piece together clues from the cities’ remains to search for patterns that help account for why certain places retained their importance longer than others. In a new study published in the journal Frontiers in Ecology and Evolution, researchers examined 24 ancient cities in what’s now Mexico and found that the cities that lasted the longest showed indications of collective forms of governance, infrastructural investments, and cooperation between households.

    “For years, my colleagues and I have investigated why and how certain cities maintain their importance or collapse,” says Gary Feinman, the study’s lead author and MacArthur Curator of Anthropology at the Field Museum in Chicago.

    In previous studies, Feinman and his colleagues cast a wide net in terms of the cities they looked at, ranging across Mesoamerica over thousands of years. They found a broad pattern of societies with good governance that fostered the well-being of their people lasting longer than ones with autocratic leaders and big disparities in wealth. This new study tightens the focus on cities from similar places and times: all 24 of the cities analyzed were in the western half of Mesoamerica and were founded between 1000 and 300 BCE.

    To a non-archaeologist, looking at ancient ruins and trying to extrapolate what its government was like might seem like an impossible task. But remnants of the cities’ buildings, ground plans, plazas, and monuments contain clues.

    “We looked at public architecture, we looked at the nature of the economy and what sustained the cities. We looked at the signs of rulership, whether they seem to be heavily personalized or not,” said Feinman. Art and architecture celebrating larger-than-life rulers point to more autocratic or despotic societies, whereas the depiction of leaders in groups, often masked, is more indicative of shared power arrangements.

    Feinman and his co-authors, David Carballo of Boston University, Linda Nicholas of the Field Museum, and Stephen Kowalewski of the University of Georgia, found that among the 24 ancient cities they analyzed, the ones with more collective forms of governance tended to remain in power longer than the autocratically ruled cities, sometimes by a thousand years. However, even among places that likely had good governance, some cities outlasted others.

    To get at why these similarly governed cities fared differently, the researchers examined other aspects of their makeup including infrastructure and indications of household interdependence. “We looked for evidence of path dependence, which basically means the actions or investments that people make that later end up constraining or fostering how they respond to subsequent hazards or challenges,” says Feinman.

    Early efforts to construct dense, interconnected residential spaces and the construction of large, central, open plazas were two of the factors that the authors found contributed to greater sustainability and importance of the early cities.

    To examine sustainability in the past, most research looks for correlations between specific climatic or environmental events and the human responses. This approach may make sense, but it is hard to know whether the timing is reliable. Such studies often emphasize a correlation between environmental crisis and collapse without also considering how other cities successfully navigated the challenges and continued as major population centers.

    The authors use a different tack. Knowing residents faced hazards, including drought, earthquakes, periodic hurricanes/heavy rains, challenges from competing centers and groups, they examined the durational history of the 24 centers and what factors fostered their sustainability. The finding that governance had an important role in sustainability shows that “responses to crises and disasters are to a degree political,” says Linda Nicholas, an adjunct curator at the Field Museum and co-author of the study.

    The cities that lasted the longest had a combination of infrastructural investments and collective governance. It’s a lesson still relevant today. “You cannot evaluate responses to catastrophes like earthquakes, or threats like climatic change, without considering governance,” says Feinman. “The past is an incredible resource to understand how to address contemporary issues.”

     

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  • What caused the holes in SUE the T. rex’s jaw? Probably not an infection

    What caused the holes in SUE the T. rex’s jaw? Probably not an infection

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    Newswise — SUE the T. rex is one of the most complete, best-preserved Tyrannosaurus rex specimens ever found. That level of preservation helps reveal details about SUE’s life. For instance, SUE lived to a ripe old age of about thirty-three, and in those years, suffered their fair share of injuries. SUE’s most mysterious ailment might be the holes in their jawbone. These holes, some the diameter of a golf ball, dot the back half of the left lower jaw. It’s not clear what caused them, but similar injuries have been found in other T. rex fossils. In a new study published in Cretaceous Research, scientists showed that one of the popular theories– that SUE had suffered an infection from a protozoan parasite– couldn’t be true.

    “These holes in SUE’s jaw have been a mystery for decades,” says Jingmai O’Connor, the associate curator of fossil reptiles at Chicago’s Field Museum and a co-author of the study. “Nobody knows how they formed, and there have been lots of guesses.”

    One early hypothesis was that SUE suffered from a fungus-like bacterial infection, but that was later shown to be unlikely. It was re-hypothesized that SUE had a protozoan infection. Protozoans are microbes with more complex cell structures than bacteria. There are lots of protozoan-caused maladies out there; one common such disease is called trichomoniasis, caused by a microbe called Trichomonas vaginalis. Humans can get infected with trichomoniasis as an STD, but other animals can catch it too.

    “Trichomoniasis is found in birds, and there’s a falcon specimen with damage to its jaw, so some paleontologists thought that a Trichomonas-like protozoan might have caused similar damage to SUE,” says O’Connor. “So for this study, we wanted to compare the damage in SUE’s jaw with Trichomonas damage in other animals to see if the hypothesis fit.”

    Bruce Rothschild, a medical doctor whose application of scientific medical approaches to paleontology earned him a role as a research associate at the Carnegie Museum, enlisted O’Connor’s assistance in analyzing SUE’s injuries. In March of 2021, O’Connor took high-resolution photos of the holes in SUE’s jaw, and the researchers analyzed them for signs of bone regrowth.

    “This was the first time I’ve worked on a T. rex. I usually work on smaller fossil birds, and I have to admit, I was pretty excited,” says O’Connor. “It really is an incredible animal.”

    The researchers compared the holes in SUE’s jaw to healed breaks in other fossil skeletons. In collaboration with Field Museum bioarcheologist Stacy Drake and co-author anthropologist María Cecilia Lozada from the University of Chicago, O’Connor and Rothschild also examined the healed bones around trepanation holes made in skulls by Inca surgeons and healers in ancient Peru.

    “We found that SUE’s injuries were consistent with these other examples of bone injury and healing. There are similar little spurs of bone reforming,” says O’Connor. “Whatever caused these holes didn’t kill SUE, and the animal survived long enough for the bones to begin repairing themselves.”

    O’Connor then worked with Field Museum assistant collections manager of birds Mary Hennen to find a bird skeleton in the Field’s collections with history of trichomoniasis. “She found me one, and you don’t see jaw holes,” says O’Connor. “You do see signs of infection, and they are in the back of the throat, but there aren’t holes bored through the jaw like we see in SUE.” Trichomonas, or a similar protozoan, doesn’t seem to fit.

    So what did cause these holes, if not an infection? “We still don’t know. My co-author Bruce Rothschild thinks they’re bite or more likely claw marks, but I don’t think that makes sense,” says O’Connor. “The holes are only found in the back of the jaw. So if they are bite marks, why are there not also holes at the front of the jaw? And you don’t see rows of holes, or indentations, like you’d see from a row of teeth, even a row where the teeth are different heights. They’re just random, all over the place.”

    Rothschild’s hypothesis suggests that the claw marks are the result of courtship behavior, possibly even between two male T. rex specimens. Scientists don’t know SUE’s sex, but the fossil’s size makes some paleontologists think SUE was male, and there are lots of examples of homosexual activity in nature. “The ‘gay T. rex’ hypothesis is fun, but I don’t think there’s enough evidence to support it one way or the other,” says O’Connor.

    But if bite or claw marks (love bites or otherwise) are off the table, O’Connor says there are lots of possibilities remaining to explain the holes– some of which we maybe haven’t thought of yet. But she’s keen to help figure it out.

    “The more I started learning about these jaw holes, the more I was like, ‘This is really weird,’” says O’Connor. “What I love about paleontology is trying to solve mysteries, so my interest is definitely piqued.”

     

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