FOSSILS
Fossil predator is the oldest known animal with “saber teeth”
“Vaguely dog-like” animal was one of the oldest-known close cousins of modern mammals
Field Museum
image:
A reconstruction of the oldest known gorgonopsian in life.
view moreCredit: Illustration © Henry Sutherland Sharpe.
The first true mammals evolved roughly 200 million years ago, during the early days of the dinosaurs. But mammals are the last surviving members of an older group, called the therapsids. At first glance, many therapsids weren’t obviously mammal-like , but they also had subtle features that we recognize in mammals today, like a hole on the sides of their skull for the jaw muscle to attach and structures on their jaw bones that would eventually evolve into mammals' distinctive middle ear bones. In a new paper in the journal Nature Communications, scientists announce the discovery of a fossil therapsid that’s the oldest of its kind, and maybe the oldest therapsid ever discovered: a vaguely dog-like saber-toothed predator.
The new fossil, which doesn’t have a species name yet, is a member of a group called the gorgonopsians. “Gorgonopsians are more closely related to mammals than they are to any other living animals,” says Ken Angielczyk, the Field Museum’s MacArthur Curator of Paleomammalogy in the Negaunee Integrative Research Center and a co-author of the paper. “They don’t have any modern descendents, and while they're not our direct ancestors, they're related to species that were our direct ancestors.”
Until now, the oldest known gorgonopsians lived roughly 265 million years ago. However, the new fossil is from 270-280 million years ago. “It is most likely the oldest gorgonopsian on the planet,” says Josep Fortuny, senior author of the article and head of the Computational Biomechanics and Evolution of Life History group at the Institut Català de Paleontologia Miquel Crusafont (ICP) in Spain.
The fossils were found in Mallorca (also sometimes spelled Majorca), a Spanish island in the Mediterranean Sea. But in the time of the gorgonopsians, Mallorca was part of the supercontinent of Pangea.
“The large number of bone remains is surprising. We have found everything from fragments of skull, vertebrae, and ribs to a very well-preserved femur. In fact, when we started this excavation, we never thought we would find so many remains of an animal of this type in Mallorca,” explains Rafel Matamales, curator of the Museu Balear de Ciències Naturals (MUCBO | MBCN), research associate at the ICP, and first author of the article.
These bones allowed the researchers to reconstruct what the animal looked like and a little about its life. “If you saw this animal walking down the street, it would look a little bit like a medium-sized dog, maybe about the size of a husky, but it wouldn’t be quite right. It didn’t have any fur, and it wouldn’t have had dog-like ears,” says Angielczyk. “But it’s the oldest animal scientists have ever found with long, blade-like canine teeth.” These saber teeth suggest that this gorgonopsian was a top predator in its day.
The fact that this gorgonopsian predates its closest relatives by tens of millions of years changes scientists’ understanding of when therapsids evolved, an important milestone on the way to the emergence of mammals, and in turn it tells us something about where we come from.
“Before the time of dinosaurs, there was an age of ancient mammal relatives. Most of those ancient mammal relatives looked really different from what we think of mammals looking like today,” says Angielczyk. “But they were really diverse and played lots of different ecological roles. The discovery of this new fossil is another piece of the puzzle for how mammals evolved.”
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Figure from the paper showing the fossil bones that have been found of the new gorgonopsian.
Credit
Matamales-Andreu et al, illustration by Eudald Mujal / SMNS
Journal
Nature Communications
Article Title
Early–middle Permian Mediterranean gorgonopsian suggests an equatorial origin of therapsids.
Article Publication Date
17-Dec-2024
Described in Mallorca the world's oldest ancestor of mammals
video:
Interview to Josep Fortuny (Institut Català de Paleontologia Miquel Crusafont, ICP) and Rafel Matamales (Museu Balear de Ciències Naturals, MUCBO | MBCN) on the oldest gorgonospid specimen described in Mallorca (Spain). Footage resources of the fossil ar also provided.
view moreCredit: Institut Català de Paleontologia Miquel Crusafont (ICP)
Gorgonopsians are an extinct group of synapsids that lived during the Permian, between 270 and 250 million years ago. They belong to the evolutionary lineage that would give rise to the first mammals 50 million years later. They were warm-blooded animals like modern mammals, but, unlike most of them, they laid eggs. They were carnivorous and were the first animals to develop the characteristic saber teeth. They were often the superpredators of the ecosystems in which they lived, and their appearance would be similar to a dog, but without ears or fur.
The remains recovered in Mallorca belong to a small to medium-sized animal, approximately one meter in length, and come from a site located in the municipality of Banyalbufar (Serra de Tramuntana, Mallorca, Spain). Excavations were carried out in three different campaigns during which a large quantity of material was recovered. “The large number of bone remains is surprising. We have found everything from fragments of skull, vertebrae, and ribs to a very well-preserved femur. In fact, when we started this excavation, we never thought we would find so many remains of an animal of this type in Mallorca,” explains Rafel Matamales, curator of the Museu Balear de Ciències Naturals (MUCBO | MBCN) and research associate at the Institut Català de Paleontologia Miquel Crusafont (ICP), and first author of the article.
Its location of the specimen in the Balearic Islands is an unusual fact in itself. The known remains of gorgonopsians prior to this discovery belonged to very high latitudes such as Russia or South Africa. Its age has also surprised the researchers who conducted the study. “It is probably the oldest gorgonopsian on the planet. The one we found in Mallorca is at least 270 million years old, and the other records of this group worldwide are, at the very least, slightly younger,” points Josep Fortuny, senior author of the article and leader of the Computational Biomechanics and Evolution of Life History research group at the ICP.
Among the excavated fossil remains, a nearly complete leg stands out, which has allowed researchers to study how the animal moved. Unlike reptiles, which have a more ancestral locomotion with their legs more spread out, gorgonopsians had their legs positioned more vertically and, therefore, moved in a way that was intermediate between reptiles and mammals. This system is more efficient for walking and especially for running. The recovered saber teeth confirm its diet. “We know that this is a carnivorous animal, a characteristic shared by all gorgonopsians worldwide. The saber teeth are a common feature in large predators of ecosystems, and what we have found was likely one in the environment in which it lived,” emphasizes Àngel Galobart, researcher at the ICP and director of the Museu de la Conca Dellà.
When Mallorca Was Not an Island
During the Permian, approximately 270 million years ago, Mallorca was not an island but was part of the supercontinent Pangaea. It was located at an equatorial latitude, where countries like Congo or Guinea can be found today. The climate was monsoonal, alternating between wet and very dry seasons. It has been found that the site where the fossils were found was a floodplain with temporary ponds where gorgonopsians and other fauna drank. Among the animals that cohabited in this ecosystem were moradisaurine captorhinids, an ancient group of herbivorous reptiles to which the Tramuntanasaurus tiai belongs, which may have been part of the gorgonopsians' diet.
Despite the small area that occupy, the Balearic Islands have an exceptional fossil record. The most studied and well-known fossils are from the Pleistocene and Holocene. However, the fossil record from other periods is considerably less known. Nonetheless, remarkable fossils have been found, such as the world's oldest mosquito, nearly a thousand species of ammonoids (cephalopods related to squids), ancestors of horses and hippos, giant sharks, and large coral reefs.
In addition to Matamales, Fortuny, and Galobart, the study also involved Eudald Mujal, researcher at the Staatliches Museum für Naturkunde Stuttgart (Germany), Tiago Simões, from the Princeton University (USA), Christian Kammerer from the North Carolina Museum of Natural Sciences (USA), and Kenneth Angielczyk from the Field Museum of Natural History (USA). The study has been supported by the project "Mallorca abans dels dinosaures: estudi dels ecosistemes continentals del Permià i Triàsic amb especial èmfasi en les restes de vertebrats" from the Institut Català de Paleontologia Miquel Crusafont (ICP) and funded by the Departament de Cultura i Patrimoni (Consell Insular de Mallorca) and the CERCA program of the Generalitat de Catalunya.
Reconstruction of the appearance in life of a gorgonopsian in a floodplain of the Permian of Mallorca
Credit
Henry Sutherland Sharpe ©
The silhouette of the described animal showing the different anatomical elements recovered during the excavation
Credit
Eudald Mujal / SMNS
Replica of the saber tooth fossil
Replica of some of the postcranial elements of the gorgonopsian from Mallorca
Replica of the left femur of the gorgonopsian from Mallorca
Credit
Anna Solé / Institut Català de Paleontologia Miquel Crusafont
Journal
Nature Communications
Method of Research
Observational study
Subject of Research
Animals
Article Title
Early–middle Permian Mediterranean gorgonopsian suggests an equatorial origin of therapsids
Article Publication Date
17-Dec-2024
This mysterious plant fossil belongs to a family that no longer exists
The find suggests there’s more diversity in the fossil record of flowering plants than previously recognized
Florida Museum of Natural History
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An strange, extinct plant once thought to be related to modern ginseng is now considered the lone representative of an unknown family.
view moreCredit: Florida Museum of Natural History photo by Jeff Gage
In 1969, fossilized leaves of the species Othniophyton elongatum — which translates to “alien plant” — were identified in eastern Utah. Initially, scientists theorized the extinct species may have belonged to the ginseng family (Araliaceae). However, a case once closed is now being revisited. New fossil specimens show that Othniophyton elongatum is even stranger than scientists first thought.
Steven Manchester, curator of paleobotany at the Florida Museum of Natural History, has studied 47-million-year-old fossils from Utah for several years. While visiting the University of California, Berkeley, paleobotany collection, he came across an unidentified and unusually well-preserved plant fossil collected from the same area as the leaves of Othniophyton elongatum.
Manchester is the co-author of a new study in which he and his colleagues showed that the leaves in question belonged to a unique plant, with unusual flowers and fruits. Close observation revealed that the 1969 fossils and those later studied by Manchester at UC Berkeley were from the same plant species. But the leaves, fruits and flowers attached to the woody stem of the Berkeley fossils were nothing like those of the other plants in the ginseng family, to which that species had been originally assigned.
“This fossil is rare in having the twig with attached fruits and leaves. Usually those are found separately,” Manchester said.
The authors extensively analyzed physical features of the old and new fossils, then methodically searched for any living plant family to which they could belong. There are over 400 diverse families of flowering plants alive today, but the authors couldn’t match the fossils’ strange assortment of features with any of them.
Resisting the urge to tidily lump the obscure specimen in with a living group, the team then searched for extinct families it might have belonged to but came up empty-handed once again.
The authors say their results underscore what may be a pervasive problem in paleobotany. In many cases, extinct plants that existed less than 65 million years ago are placed within modern families, or genera — the taxonomic groups directly above the level of individual species. This can create a skewed estimate of biodiversity in ancient ecosystems.
“There are many things for which we have good evidence to put in a modern family or genus, but you can’t always shoehorn these things,” Manchester said.
The species does not belong to any living family or genus
The fossils were discovered in the Green River Formation near the ghost town of Rainbow in eastern Utah. Roughly 47 million years ago, the area was a tectonically active, massive inland lake system that provided the perfect conditions for fossil preservation. Low-oxygen lake sediments and showers of volcanic ash slowed the decomposition of many fish, reptiles, birds, invertebrates and plants, allowing some of them to be preserved in amazing detail.
Researchers who had studied the original leaf fossils of this species had very little to work with. Without flowers, fruits or branches, they were limited to analyzing the shape and vein patterns of the leaves. Based on the arrangement, researchers thought it might be a single leaf made up of multiple smaller leaflets. This type of compound leaf is a defining feature of several plants in the ginseng family.
But the new fossils had leaves that were directly attached to stems, which painted a very different picture of what the plant once looked like.
“The two twigs we found show the same kind of leaf attached, but they're not compound. They’re simple, which eliminates the possibility of it being anything in that family,” Manchester said.
The fossil’s berries ruled out families like the grasses and magnolias. The flowers did resemble some modern groups, but other features ruled those out, too. Even with such a pristine fossil in their repertoire, researchers were left with more questions than before.
Researchers could now see the fossil in a new light
Stumped, the team set the fossil aside for several years. Then the Florida Museum hired a curator of artificial intelligence who established a new microscopy workstation. When viewed through the digital microscope’s powerful lens and computer-enhanced shadow effect illumination, the authors could see subtle peculiarities they’d missed during prior observations.
When they focused on the fossil’s minute fruits, they could see micro-impressions left behind by their internal anatomy, including features of the small, developing seeds.
“Normally we don't expect to see that preserved in these types of fossils, but maybe we've been overlooking it because our equipment didn’t pick up that kind of topographic relief,” Manchester said.
One of the plant’s strangest newly seen features was its stamens, the male reproductive organs of the flower. In most plant species, once the flower is fertilized, the stamens detach along with petals and the rest of the flower parts, which are no longer needed for reproduction.
“Usually, stamens will fall away as the fruit develops. And this thing seems unusual in that it's retaining the stamens at the time it has mature fruits with seeds ready to disperse. We haven't seen that in anything modern,” Manchester said.
With all modern families ruled out, they compared the traits to extinct families. Once again, there was no match to be found.
Julian Correa-Narvaez, the lead author of the study and a doctoral student at the University of Florida, played a major role in gathering information to identify the fossils. “It's important because it gives us a little bit of a clue about how these organisms were evolving and adapting in different places,” he said.
Plant families can contain astonishing amounts of diversity. Seemingly disparate plants like poison ivy, cashews and mangoes are all in the same family, along with over 800 other species. It’s unclear how much diversity in this mysterious extinct group has been lost to time.
This isn’t the only enigmatic species that has come out of the Green River Formation. Similar situations have unfolded when plant fossils from the locality surprised researchers, leading to the discovery of other extinct groups. “The book published in 1969 has all these interesting mysteries that remain,” Manchester said.
With digital access to museum specimens through tools like iDigBio, researchers can continue to study and understand the natural history of plant evolution.
The article was published in the journal Annals of Botany.
Walter Judd of the Florida Museum of Natural History is also a co-author of the study.
Journal
Annals of Botany
DOI
Prehistoric rock in Japan reveals clues to major ocean anoxic event
New analysis pinpoints timing and duration of Ocean Anoxic Event 1a
image:
Northwestern University Ph.D. student, Luca Podrecca takes a break from research in the field near Mount Ashibetsu in Japan.
view moreCredit: Luca Podrecca/Northwestern University
By studying prehistoric rocks and fossils emerging from the side of Mount Ashibetsu in Japan, researchers have precisely refined the timing and duration of Ocean Anoxic Event 1a (OAE 1a), an extreme environmental disruption that choked oxygen from Earth’s oceans to cause significant extinction, especially among plankton.
Researchers have long suspected that massive volcanic eruptions undersea caused carbon dioxide (CO2) increases, global warming and depleted oxygen (called anoxia) in the ocean during the Mesozoic Period. Now, an international team of researchers, including Northwestern University Earth scientists, determined the precise timing of the volcanic eruption and OAE1a, which started 119.5 million years ago. The work adds to a growing volume of evidence that volcanic CO2 emissions directly triggered the anoxic event.
The new study also determined that OAE 1a lasted for just over 1.1 million years. This new information helps scientists better understand how the Earth’s climate and ocean system operates and responds to stress — especially as it relates to current warming.
The study was published late last month in the journal Science Advances. It marks the most detailed and highly resolved dating of an ocean anoxic event ever achieved.
“Ocean anoxic events occur in part as a consequence of climatic warming in a greenhouse world,” said Northwestern’s Brad Sageman, a senior author of the study. “If we want to make accurate predictions about what we will see in the decades ahead with human-caused warming, this information is invaluable. The best way to understand the future is to look at data from the past.”
An expert on ancient climates, Sageman is a professor of Earth, Environmental and Planetary Sciences at Northwestern’s Weinberg College of Arts and Sciences and a co-director of the Paula M. Trienens Institute for Sustainability and Energy.
A Northwestern connection
The Cretaceous Period experienced two major and several minor ocean anoxic events, with OAE 1a as one of the two largest. The most likely cause: volcanic eruptions rapidly injected massive amounts of CO2 into the ocean and atmosphere. These aren’t ordinary volcanoes but large igneous provinces that erupt up to a million cubic kilometers of basalt over several millions of years. When CO2 reacts with seawater, it forms a weak carbonic acid, which literally dissolves sea creatures’ shells. The acid, combined with low oxygen levels, has significant consequences for sea life.
Researchers first began pondering ocean anoxic events in the mid-1970s, after a discovery by Northwestern geologist Seymour Schlanger and Oxford professor Hugh Jenkyns. When examining sediment samples from the Pacific Ocean floor, Schlanger and Jenkyns discovered black, organic carbon-rich shales that matched samples — in composition and age — from both the Atlantic Ocean and rock formations in Italy.
Widespread lack of oxygen was the most likely explanation for these deposits. Anoxia prevents the breakdown of organic matter from dead plants and animals, leading to a global pattern of organic enrichment. Instead of decomposing, the settling plankton and other fossils accumulated to form organic carbon-rich strata scattered around the globe.
“How were black shales forming at the same time in the deep oceans and up on land?” Sageman asked. “Schlanger and Jenkyns realized there must have been a massive global event that caused oxygen to decrease from the ocean surface all the way down to the seafloor.”
History solidified in stone
In the new study, researchers looked not to the depths of the oceans but to ancient strata along the northwest edge of a mountain on Japan’s Hokkaido Island. The rocks, or tuffs, formed from volcanic ash that settled and solidified over time. Tectonic activity lifted these layers above sea level during formation of the Japanese islands, leaving them exposed and accessible where streams carve through the temperate rainforest of Hokkaido. By collecting and analyzing the tuffs, Sageman, his Ph.D. student, Luca Podrecca, and their collaborators gained a glimpse into geologic history.
“Magma comes out of a volcano in liquid form and then begins to cool,” Sageman said. “During this process, crystals start to form. By the time the tuff solidifies, the crystals become a tiny closed system. They lock in atoms, and some of those atoms, like uranium, start to decay, meaning they convert from one isotope to another. That provides a tool to date the eruption, and, thus, date a specific layer within a stack of sedimentary rock. While the expertise of team members from Tohuku University in Japan, Durham University in the U.K. and Northwestern focuses on the characterization and global correlation of the strata, our collaborators at the University of Wisconsin-Madison and Boise State University are experts in the geochronological analyses.”
The researchers also used other types of isotopes, such as carbon, which tracks synchronous changes in the carbon cycle, and osmium, which tracks volcanic activity and changes in ocean chemistry.
“These isotope systems provide tools for correlating the OAE1a interval between sites in Hokkaido, southern France and other sites all around the globe,” Sageman said. “They give us markers for instants in geologic time.”
Pinpointing the exact timeline
According to this evidence, an abrupt shift in carbon isotope ratios — caused first by the spike in volcanic CO2added to the carbon cycle (and later by the excess burial of organic matter) — occurred in the early Cretaceous at the beginning of OAE 1a. A concurrent shift in the isotopic ratios of osmium reflects a massive input of volcanic material into ocean waters. The timing of these events corresponds to eruption of the Ontong Java Nui complex, an enormous igneous province about the size of Alaska located in the southwestern Pacific Ocean.
Now that researchers know it took the oceans 1.1 million years to recover from the sharp increase in CO2, they have more insight into how long the effects of CO2-driven warming events might last and what the associated effects, such as ocean anoxia, may be.
“We’re already seeing zones with low oxygen levels in the Gulf of Mexico,” Sageman said. “The main difference is that past events unfolded over tens of thousands to millions of years. We’re driving roughly similar levels of warming (or more) but doing so in less than 200 years.”
The study, “Radioisotopic chronology of Ocean Anoxic Event 1a: Framework for analysis of driving mechanisms,” was supported by the National Science Foundation, the U.K. Natural Environment Research Council and the Japan Science Foundation.
Researchers hike up the side of Mount Ashibetsu in Japan to examine fossilized volanic ash that dates back to the Early Cretaceous.
Researchers bag samples of fossilized volcanic ash, which dates back to the Early Cretaceous.
Credit
Luca Podrecca/Northwestern University
Journal
Science Advances
Method of Research
Experimental study
Article Title
Radioisotopic chronology of Ocean Anoxic Event 1a: Framework for analysis of driving mechanisms
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