Dan Peppe, Ph.D.

For decades, many scientists believed dinosaurs were already dwindling in number and variety long before an asteroid strike sealed their fate 66 million years ago. But new research in the journal Science from Baylor University, New Mexico State University, the Smithsonian Institution and an international team is rewriting that story. The dinosaurs, it turns out, were not fading away. They were flourishing. A final flourish in the San Juan Basin In northwestern New Mexico, layers of rock preserve a hidden chapter of Earth’s history. In the Naashoibito Member of the Kirtland Formation, researchers uncovered evidence of vibrant dinosaur ecosystems that thrived until just before the asteroid impact. High-precision dating techniques revealed that fossils from these rocks are between 66.4 and 66 million years old – placing them in the catastrophic Cretaceous-Paleogene boundary. “The Naashoibito dinosaurs lived at the same time as the famous Hell Creek species in Montana and the Dakotas... They were not in decline – these were vibrant, diverse communities.” – Daniel Peppe, Ph.D. “The Naashoibito dinosaurs lived at the same time as the famous Hell Creek species in Montana and the Dakotas,” said Daniel Peppe, Ph.D., associate professor of geosciences at Baylor University. “They were not in decline – these were vibrant, diverse communities.” Dinosaurs in their prime The New Mexico fossils tell a different story than originally thought. Far from being uniform and weakened, dinosaur communities across North America were regionally distinct and thriving. Using ecological and biogeographic analyses, the researchers discovered that dinosaurs in western North America lived in separate “bioprovinces,” divided not by mountains or rivers, but by temperature differences across regions. “What our new research shows is that dinosaurs are not on their way out going into the mass extinction,” said first author Andrew Flynn, Ph.D., ‘20, assistant professor of geological sciences at New Mexico State University. “They're doing great, they're thriving and that the asteroid impact seems to knock them out. This counters a long-held idea that there was this long-term decline in dinosaur diversity leading up to the mass extinction making them more prone to extinction.” Life after impact The asteroid impact ended the age of dinosaurs in an instant – but the ecosystems they left behind set the stage for what came next, the researchers said. Within 300,000 years of their extinction, mammals began to diversify rapidly, exploring new diets, body sizes and ecological roles. The same temperature-driven patterns that shaped dinosaur communities continued into the Paleocene, showing how climate guided life’s rebound after catastrophe. “The surviving mammals still retain the same north and south bio provinces,” Flynn said. “Mammals in the north and the south are very different from each other, which is different than other mass extinctions where it seems to be much more uniform.” Why the discovery matters today The discovery is more than a window into the past – it’s a reminder of the resilience and vulnerability of life on Earth. Conducted on public lands managed by the U.S. Bureau of Land Management, the research highlights how carefully protected landscapes can yield profound insights into how ecosystems respond to sudden global change. With a clearer understanding of the timeline of the dinosaurs’ final days, the study reveals not a slow fade into extinction but a dramatic ending to a story of flourishing diversity cut short by cosmic chance.

Lake Victoria, the largest lake on the African continent and the largest tropical lake in the world, has the potential to dry up more quickly than researchers previously realized, and the White Nile tributary (the only outlet for Lake Victoria) could disappear within a decade, according to a new study published in Earth and Planetary Science Letters. The drying up of these bodies of water, which the project’s researchers say is driven by climate change, could be devastating to large swaths of East Africa and millions of people, according to the study, “Rapid Pleistocene desiccation and the future of Africa's Lake Victoria.” Baylor University faculty members Daniel J. Peppe, Ph.D., associate professor of geosciences, and Joseph D. White, Ph.D., professor of biology in Baylor University’s College of Arts & Sciences, were part of a team of researchers led by Emily Beverly, Ph.D., assistant professor of sedimentary geology at the University of Houston. Beverly earned her doctoral degree in geology at Baylor in 2015. The research team developed a model for Lake Victoria to help understand how changes in rainfall and temperature, due to climate change, would affect the future of the lake. They discovered that relatively small changes in climate could cause lake levels to drop rapidly. “Using future climate projections, our model also predicts that at current rates of temperature change and previous rates of lake level fall, Lake Victoria could have no outlet to the White Nile within 10 years, and Kenya could lose access to the lake in less than 400 years, which would significantly affect the economic resources supplied by Lake Victoria to the East African community,” the researchers wrote. Water Budget Model Peppe said he and his colleagues developed a water budget model for Lake Victoria in Kenya that examines how changes in rainfall and temperature cause changes in water levels in the lake. “Modeling indicates Lake Victoria can transition back and forth between modern lake levels and being completely dried up in centuries to a few millennia,” Peppe said.  The water budget model used information related to: The lake’s size The catchment area, which drains into the lake How much water enters the lake The flow out of the lake Modern climate to estimate lake evaporation Discharge out of the lake and the size of lake The model showed the desiccation and refilling of Lake Victoria can happen over short periods and is directly tied to the mean annual precipitation levels and associated runoff. The research team was also able to use the model to predict the effects of future climate change on Lake Victoria. “We input different climate parameters in the model based on past reconstructions and future projections to see what happened to lake levels in the past and what will happen in the future,” Peppe said. Combined observations from this new modeling and estimates of ancient precipitation indicate that Lake Victoria was likely dried up between 36,000 to 100,000 years ago, Peppe said. “As Lake Victoria dried up, this affected the dispersal patterns of early modern humans and other mammals as grasslands expanded with the retreat of the lake,” he said. Repercussions of Disappearance Peppe said the disappearance of the White Nile could have broad repercussions, including depriving Uganda of its primary source of electricity via hydropower and the water that sustains the Nile during non-flood stages. “In addition, every major port city around Lake Victoria could become landlocked in as little as 100 years. In 400 years, Kenya would have no access to the lake while Uganda and Tanzania would gain huge areas of potential farmland setting up a potentially dangerous dynamic between countries that currently fight over the lucrative fishing rights to the lake,” Peppe said. The researchers wrote that additional regional climate modeling is urgently needed to understand the effects of climate change on the region. ABOUT THE STUDY The new study, “Rapid Pleistocene desiccation and the future of Africa's Lake Victoria,” is published in the journal Earth and Planetary Science Letters. The research team was led by Emily J. Beverly, Ph.D., assistant professor of sedimentary geology at the University of Houston; Joseph D. White, Ph.D., professor of biology in Baylor University’s College of Arts & Sciences; Daniel J. Peppe, Ph.D., associate professor of geosciences in Baylor University’s College of Arts & Sciences; J. Tyler Faith, Ph.D., assistant professor of anthropology, at University of Utah; Nick Blegen, Ph.D., Royal Society Eric Shooter International Fellow, Department of Geography, University of Cambridge; and Christian A. Tryon, Ph.D., professor of anthropology, University of Connecticut. ABOUT BAYLOR UNIVERSITY Baylor University is a private Christian University and a nationally ranked research institution. The University provides a vibrant campus community for more than 17,000 students by blending interdisciplinary research with an international reputation for educational excellence and a faculty commitment to teaching and scholarship. Chartered in 1845 by the Republic of Texas through the efforts of Baptist pioneers, Baylor is the oldest continually operating University in Texas. Located in Waco, Baylor welcomes students from all 50 states and more than 90 countries to study a broad range of degrees among its 12 nationally recognized academic divisions. ABOUT THE COLLEGE OF ARTS & SCIENCES AT BAYLOR UNIVERSITY The College of Arts & Sciences is Baylor University’s oldest and largest academic division, consisting of 25 academic departments and seven academic centers and institutes. The more than 5,000 courses taught in the College span topics from art and theatre to religion, philosophy, sociology and the natural sciences. Faculty conduct research around the world, and research on the undergraduate and graduate level is prevalent throughout all disciplines. Visit www.baylor.edu/artsandsciences.

These days, it doesn’t take much to turn a civil conversation into a full-blown catastrophe. Just mention the words “climate change” and feathers can start to ruffle. But it doesn’t have to be that way, says Dan Peppe, Ph.D., climate change expert and associate professor of geosciences at Baylor University. His research focuses on understanding how plant and animal communities have responded to changes in climate throughout Earth’s history. “Climate change is a fundamentally important issue to our society and is vital for us to have open and honest discussions about it and its potential impacts,” Peppe said. He said the best place to start such a dialogue is with scientific observation. Have a discussion about increases in temperature, he said. Understand what scientists are saying about those temperature changes and their effects. The trick to keeping this cordial? Keep politics out. “All of this conversation is a scientific one based on observation, and as such, shouldn't be a political one,” he said. “Once that baseline is established, we can then begin a conversation of the many possible ways to address those risks.” Peppe said there is often more than one solution to issues of climate change, but people need to listen to each other. “Hopefully there can be a respectful and civil conversation around those potential solutions,” he said. As part of Earth Science Week, Peppe is taking part in the Earth Science Symposium at The Mayborn Museum in Waco, Texas, where he will moderate a panel discussion on climate change. Panelists will discuss the science of climate change, the risks associated with it, and some of the potential solutions. “We hope that this will be a really productive discussion, and one in which the audience can participate,” Peppe said. Source: