How a Favorite Dinosaur Food Survived Extinction by Carl Bates
November 17, 2023
Introduction:
(Fururity) An ancient lineage of plants called cycads, a favored food of grazing dinosaurs, survived extinction by grabbing nitrogen from the air.
The palm-like plants helped sustain dinosaurs and other prehistoric animals during the Mesozoic Era, starting 252 million years ago, by being plentiful in the forest understory.
Like their lumbering grazers, most cycads have gone extinct. Their disappearance from their prior habitats began during the late Mesozoic and continued into the early Cenozoic Era, punctuated by the cataclysmic asteroid impact and volcanic activity that mark the K-Pg boundary 66 million years ago. However, unlike the dinosaurs, somehow a few groups of cycads survived to the present.
A new study, published in the journal Nature Ecology & Evolution, concludes that the cycad species that survived relied on symbiotic bacteria in their roots, which provide them with nitrogen to grow. Just like modern legumes and other plants that use nitrogen fixation, these cycads trade their sugars with bacteria in their roots in exchange for nitrogen plucked from the atmosphere.
What originally interested lead author Michael Kipp is that the tissues of nitrogen-fixing plants can provide a record of the composition of the atmosphere they grew up in. He combines geochemistry with the fossil record to try to understand the Earth’s climate history.
Deoxygenation Levels Similar To Today’s Played a Major Role In Marine Extinctions During Major Past Climate Change Event November 27, 2023
Introduction:
(Eurekalert) Scientists have made a surprising discovery that sheds new light on the role that oceanic deoxygenation (anoxia) played in one of the most devastating extinction events in Earth’s history. Their finding has implications for current day ecosystems – and serves as a warning that marine environments are likely more fragile than apparent.
New research, published today in leading international journal Nature Geosciences, suggests that oceanic anoxia played an important role in ecosystem disruption and extinctions in marine environments during the Triassic–Jurassic mass extinction, a major extinction event that occurred around 200 million years ago.
Surprisingly however, the study shows that the global extent of euxinia (an extreme form of de-oxygenated conditions) was similar to the present day.
Earth’s history has been marked by a handful of major mass extinctions, during which global ecosystems collapsed and species went extinct. All past extinction events appear to have coincided with global climatic and environmental perturbance that commonly led to ocean deoxygenation. Because of this, oceanic anoxia has been proposed as a likely cause of marine extinctions at those times, with the assumption that the more widespread occurrence of deoxygenation would have led to a larger extinction event.
Using chemical data from ancient mudstone deposits obtained from drill-cores in Northern Ireland and Germany, an international research team led by scientists from Royal Holloway (UK), and including scientists from Trinity College Dublin’s School of Natural Sciences (Ireland) as well as from Utrecht University (Netherlands), was able to link two key aspects associated with the Triassic–Jurassic mass extinction.
What was it like when the Universe was at its hottest?
November 21, 2023
In the earliest stages of the hot Big Bang, the Universe became filled with incredibly energetic quanta, reaching a temperature of somewhere between 10^20 and 10^30 K or so. Even at the Large Hadron Collider and in high-energy astrophysical environments around neutron stars and black holes, energies and temperatures created in the late-time Universe cannot compare. So what was the Universe like in these early, super-hot stages? Here's what science has to say about the answer.
Even Without a Meteorite, The Stage Was Set For Dinosaurs to Go Extinct by Tessa Koumoundouros
November 28, 2023
Introduction:
(Science Alert) The explosive end of non-avian dinosaurs is the most infamous blow to life on Earth. But there's long been hints that the asteroid may not be the main culprit behind this mass extinction, just the most spectacular isolated contribution.
Before this dramatic event, 66 million years ago, toxic winds of change were already brewing in the air.
A new analysis by an international team of researchers has added evidence to claims that the world prior to the asteroid blow was anything but paradise, with measures of sulfur in the atmosphere reaching critical levels.
Together with other studies on levels of mercury, the research provides a signature of volcanic activity strong enough to cause significant climate disruptions.
In 1991, the timing of this volcanic activity had been dismissed as too early to be behind the mass extinction event but more recent studies demonstrate it's possible the timing was close enough to be significant.
A recent study published in the Journal of Geophysical Research: Solid Earth sheds new light on the formation of the East Coast of the United States—a "passive margin," in geologic terms—during the breakup of the supercontinent Pangea and the opening of the Atlantic Ocean around 230 million years ago.
In geology, passive margins are "quiet" areas, locations with minimal faulting or magmatism, where land meets the ocean. Understanding their formation is crucial for many reasons, including that they are stable regions where hydrocarbon resources are extracted and that their sedimentary archive preserves our planet's climate history as far back as millions of years.
Startling new insights into the catastrophic impact of one of the most devastating events in Earth's history have been revealed by a team led by researchers with the USC Dornsife College of Letters, Arts and Sciences. More than deepening our understanding of the end-Triassic mass extinction, their findings offer critical lessons for today's environmental challenges.
About 200 million years ago, Earth experienced its fourth major mass extinction event. Triggered by a dramatic rise in greenhouse gases due to volcanic activity, the event led to rapid global warming and a significant shift in the planet's biosphere, ending the Triassic period and launching the Jurassic. Many scientists now believe Earth is in the midst of another mass extinction, driven in large part by similar climate changes.
Earth scientists at USC Dornsife took a unique approach to analyzing the impact of this extinction event on both ocean and land ecosystems, using a novel "ecospace framework" method that categorizes animals beyond just their species. It accounts for ecological roles and behaviors—from flying or swimming predators to grazing herbivores and from ocean seafloor invertebrates to soil-dwelling animals on land.
'Appetite for drumsticks': First prey found in a tyrannosaur stomach
by Daniel Lawler
The Gorgosaurus is a member of the tyrannosaurid family that also includes the T-Rex.
Prey has been discovered inside the stomach of a tyrannosaur skeleton for the first time, scientists said Friday, revealing that the mighty dinosaurs had an "appetite for drumsticks" when they were young.
The skeleton of the Gorgosaurus, a member of the tyrannosaurid family that also includes the T-Rex, sheds light on how these dinosaurs grew from fairly slender juveniles into gigantic, bone-crushing, apex-predator adults, they added.
The Gorgosaurus—which means "dreadful lizard"—was around six years old when it died more than 75 million years ago, according to a new study in the journal Science Advances.
The fossil was discovered in 2009 at the Dinosaur Provincial Park, east of the Canadian city of Calgary. But when they got the skeleton back to the lab, the scientists noticed something strange.
The study's lead author, Francois Therrien of the Royal Tyrrell Museum, told AFP they were amazed to "discover the remains of the last meal of this young tyrannosaur still preserved in place".
What was most surprising, he added, was that the small leg bones sticking out of the tyrannosaur's ribcage belonged to two young, bird-like dinosaurs called Citipes.
Citipes are thought to have had feathers, wings and a beak and walk on two feet, somewhat resembling modern-day cassowaries, Therrien said.
72 Million Years Ago, A Monstrous "Blue Dragon" Roamed The Pacific Ocean Holly Large
December 16, 2023
Introduction:
(IFL Science) If the idea of time traveling to the oceans of the Cretaceous has ever sounded like an appealing idea to you, you might be about to change your mind. Researchers have described a brand-new, 72-million-year-old species of mosasaur, that’s thought to have terrorized the ancient Pacific Ocean.
The study describing the mosasaur came as a result of co-author Akihiro Misaki uncovering a near-complete fossil specimen of the species – named Megapterygius wakayamaensis – whilst hunting for ammonites in Japan’s Wakayama Prefecture. In fact, it’s thought to be the most complete mosasaur skeleton ever found in Japan or the northwestern Pacific.
It took researchers five years to remove the sandstone surrounding the fossil, and they also had to make a cast whilst it was still in situ, in order to provide an accurate record of how all the bones were positioned in the skeleton.
The result of that painstaking work, however, was the discovery of a species unique among mosasaurs, with rear flippers longer than its front ones and a rudder-like tail. “We lack any modern analog that has this kind of body morphology — from fish to penguins to sea turtles,” said co-author Takuya Konishi in a statement. “None has four large flippers they use in conjunction with a tail fin.”
The authors have theorized that the large front fins may have helped the mosasaur with rapid maneuvering, the rear fins with pitch to dive or surface, and the tail for acceleration. “It’s a question just how all five of these hydrodynamic surfaces were used. Which were for steering? Which for propulsion?” Konishi explained. “It opens a whole can of worms that challenges our understanding of how mosasaurs swim.”
