New dinosaur species from Utah lived at a time of major transition: Iani smithi provides insights into how dinosaurs weather mid-Cretaceous ecological change.

Iani smithi from Utah lived at a time of major transition — Location of holotype locality for Iani smithi. (A) Global map showing location of Mussentuchit Member outcrop in central Utah, western North America, and a stratigraphic section at the quarry with dated ash horizons; and (B) graphical representation of preserved skeletal elements of the holotype specimen. Preserved elements are colored on the left facing skeletal whether they derive from the right or left side of the body. Exact positions of chevrons and ribs unknown due to poor preservation. Credits: Zanno et al., 2023, PLoS ONE, CC-BY 4.0

A new species of dinosaur from Utah sheds light on major North American ecological changes around 100 million years ago, according to a study published June 7, 2023 in the open-access journal PLoS ONE by Lindsay Zanno of the North Carolina Museum of Natural Sciences and colleagues.

The boundary between the Early and Late Cretaceous Period saw major reassembly of global ecosystems associated with a peak in global temperatures. In the fossil record of western North America, this ecological shift has been well-documented for marine habitats, but less study has been done regarding terrestrial life. In this study, Zanno and colleagues identify a new dinosaur from the early Late Cretaceous Cedar Mountain Formation of Utah.

The new dinosaur, named Iani smithi, lived around 100 million years ago and is known from a single fossil specimen including a well-preserved skull and parts of the spine and limbs. The name derives from Ianus, a Roman deity who presided over transitions, referencing the changing world of the mid-Cretaceous.

Iani is a member of an early branch of the ornithopod dinosaurs, a group of mostly bipedal herbivores that also includes famous examples like Iguanodon and Tenontosaurus. Iani is the first early-diverging ornithopod known from the Late Cretaceous of North America.

This discovery, along with other recent reports from the same geologic formation, indicates that several major groups of dinosaurs survived into the early Late Cretaceous despite the ecological changes of the time, but exactly what these survivors were doing and how long they lasted is still unclear. Since Iani and its closest cousins are typically found in ancient coastal habitats along the shores of the now-vanished Western Interior Seaway, the authors suggest that more investigation into coastal deposits of similar age might yield further evidence to address these lingering questions.

The authors add: “Early ornithopods were once a common part of North American ecosystems, but we did not know they survived into the Late Cretaceous. The discovery of Iani helps us link their extinction on the continent with a major interval of global warming, one with striking similarities to our current climate crisis.”

Bibliographic information:

Zanno LE, Gates TA, Avrahami HM, Tucker RT, Makovicky PJ (2023) An early-diverging iguanodontian (Dinosauria: Rhabdodontomorpha) from the Late Cretaceous of North America, PLoS ONE 18(6): e0286042. https://doi.org/10.1371/journal.pone.0286042

Press release from the Public Library of Science.

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Scientists identify a temperature tipping point for tropical forests

point tropical forests — An aerial view of a tropical forest along the eastern Pacific Ocean shoreline of Barro Colorado Island, Panama. Credit: Smithsonian Tropical Research Institute photo

A study in Science by 225 researchers working with data from 590 forest sites around the world concludes that tropical forests release much more carbon into the atmosphere at high temperatures.

All living things have tipping points: points of no return, beyond which they cannot thrive. A new report in Science shows that maximum daily temperatures above 32.2 degrees Celsius (about 90 degrees Fahrenheit) cause tropical forests to lose stored carbon more quickly. To prevent this escape of carbon into the atmosphere, the authors, including three scientists affiliated with the Smithsonian Tropical Research Institute in Panama, recommend immediate steps to conserve tropical forests and stabilize the climate.

Carbon dioxide is an important greenhouse gas, released as we burn fossil fuels. It is absorbed by trees as they grow and stored as wood. When trees get too hot and dry they may close the pores in their leaves to save water, but that also prevents them from taking in more carbon. And when trees die, they release stored carbon back into the atmosphere.

Tropical forests hold about 40 percent of all the carbon stored by land plants. For this study, researchers measured the ability of tropical forests in different sites to store carbon.

“Tropical forests grow across a wide range of climate conditions,” said Stuart Davies, director of Smithsonian ForestGEO, a worldwide network of 70 forest study sites in 27 countries. “By examining forests across the tropics, we can assess their resilience and responses to changes in global temperatures. Many other studies explored how individual forests respond to short-term climatic fluctuations. This study takes a novel approach by exploring the implications of thermal conditions currently experienced by all tropical forests.”

By comparing carbon storage in trees at almost 600 sites around the world that are part of several different forest monitoring initiatives: RAINFOR, AfriTRON, T-FORCES and the Smithsonian’s ForestGEO, the huge research team led by Martin Sullivan from the University of Leeds and Manchester Metropolitan University found major differences in the amount of carbon stored by tropical forests in South America, Africa, Asia and Australia. South American forests store less carbon than forests in the Old World, perhaps due to evolutionary differences in which tree species are growing there.

They also found that the two most important factors predicting how much carbon is lost by forests are the maximum daily temperature and the amount of precipitation during the driest times of the year.

As temperatures reach 32.2 degrees Celsius, carbon is released much faster. Trees can deal with increases in the minimum nighttime temperature (a global warming phenomenon observed at some sites), but not with increases in maximum daytime temperature.

They predict that South American forests will be the most affected by global warming because temperatures there are already higher than on other continents and the projections for future warming are also highest for this region. Increasing carbon in the atmosphere may counterbalance some of this loss but would also exacerbate warming.

Forests can adapt to warming temperatures, but it takes time. Tree species that cannot take the heat die and are gradually replaced by more heat-tolerant species. But that may take several human generations.

“This study highlights the importance of protecting tropical forests and stabilizing the Earth’s climate,” said Jefferson Hall, co-author and director of the Smithsonian’s Agua Salud Project in Panama. “One important tool will be to find novel ways to restore degraded land, like planting tree species that help make tropical forests more resilient to the realities of the 21st century.” The Agua Salud project asks how native tree species adapted to an area can be used to manage water, store carbon and promote biodiversity conservation at a critical point where North and South America connect.

An aerial view of a tropical forest on the eastern Pacific Ocean shoreline of Barro Colorado Island, Panama. Credit: Smithsonian Tropical Research Institute photo

A relevant note:

One of the oldest permanent tropical forest study sites, located on Barro Colorado Island in Panama, is not being monitored for the first time in 40 years as a result of the COVID-19 pandemic, giving scientists less of a handle on any climate change effects that may be taking place.

Steve Paton, director of STRI’s physical monitoring program notes that in 2019 there were 32 days with maximum temperatures over 32 degrees Celsius at a weather station in the forest canopy on the Island and a first glance at his data indicates that these exceptionally hot days are becoming more common.

The Smithsonian Tropical Research Institute, headquartered in Panama City, Panama, is a unit of the Smithsonian Institution. The Institute furthers the understanding of tropical biodiversity and its importance to human welfare, trains students to conduct research in the tropics and promotes conservation by increasing public awareness of the beauty and importance of tropical ecosystems.

The paper Long-term thermal sensitivity of Earth’s tropical forests is published in Science 22 May 2020 (DOI: 10.1126/science.aaw7578)

Press release from the Smithsonian Tropical Research Institute

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