A chance discovery of a 350 million-year-old fossil reveals a new type of ray-finned fish
The fossil they found belonged to a fish that had died 350 million years ago, its bony husk spanning nearly a metre on the lake bed. The large fish had lived in waters thick with rival fish, including giants several times its size. It had hooked teeth at the tip of its long jaw that it would use to trap elusive prey and fangs at the back to pierce it and break it down to eat.
For the last eight years, I have been part of a team under the lead of paleontologist Jason Anderson, who has spent decades researching the Blue Beach area of Nova Scotia, northwest of Halifax, in collaboration with Mansky and other colleagues. Much of this work has been on the tetrapods — the group that includes the first vertebrates to move to land and all their descendants — but my research focuses on what Blue Beach fossils can tell us about how the modern vertebrate world formed.
The modern vertebrate world is defined by the dominance of three groups: the cartilaginous fishes or chondrichthyans (including sharks, rays and chimaeras), the lobe-finned fishes or sarcopterygians (including tetrapods and rare lungfishes and coelacanths), and the ray-finned fishes or actinopterygians (including everything from sturgeon to tuna). Only a few jawless fishes round out the picture.
This basic grouping has remained remarkably consistent — at least for the last 350 million years.
Before then, the vertebrate world was a lot more crowded. In the ancient vertebrate world, during the Silurian Period (443.7-419.2 MA) for example, the ancestors of modern vertebrates swam alongside spiny pseudo-sharks (acanthodians), fishy sarcopterygians, placoderms and jawless fishes with bony shells.
Armoured jawless fishes had dwindled by the Late Devonian Period (419.2-358.9 MA), but the rest were still diverse. Actinopterygians were still restricted to a few species with similar body shapes.
By the immediately succeeding early Carboniferous times, everything had changed. The placoderms were gone, the number of species of fishy sarcopterygians and acanthodians had cratered, and actinopterygians and chondrichthyans were flourishing in their place.
The modern vertebrate world was born.
Blue Beach has helped build our understanding of how this happened. Studies describing its tetrapods and actinopterygians have showed the persistence of Devonian-style forms in the Carboniferous Period.
Whereas the abrupt end-Devonian decline of the placoderms, acanthodians and fishy sarcopterygians can be explained by a mass extinction, it now appears that multiple types of actinopterygians and tetrapods survived to be preserved at Blue Beach. This makes a big difference to the overall story: Devonian-style tetrapods and actinopterygians survive and contribute to the evolution of these groups into the Carboniferous Period.
But significant questions remain for paleontologists. One point of debate revolves around how actinopterygians diversified as the modern vertebrate world was born — whether they explored new ways of feeding or swimming first.
The Blue Beach fossil was actinopterygian, and we wondered what it could tell us about this issue. Comparison was difficult. Two actinopterygians with long jaws and large fangs were known from the preceding Devonian Period (Austelliscus ferox and Tegeolepis clarki), but the newly found jaw had more extreme curvature and the arrangement of its teeth. Its largest fangs are at the back of its jaw, but the largest fangs of Austelliscus and Tegeolepis are at the front.
These differences were significant enough that we created a new genus and species: Sphyragnathus tyche. And, in view of the debate on actinopterygian diversification, we made a prediction: that the differences in anatomy between Sphyragnathus and Devonian actinopterygians represented different adaptations for feeding.
To test this prediction, we compared Sphyragnathus, Austelliscus and Tegeolepis to living actinopterygians. In modern actinopterygians, the difference in anatomy reflects a difference in function: front-fangs capture prey with their front teeth and grip it with their back teeth, but back-fangs use their back teeth.
Since we couldn't observe the fossil fish in action, we analyzed the stress their teeth would experience if we applied force. The back teeth of Sphyragnathus handled force with low stress, making them suited for a role in piercing prey, but the back teeth of Austelliscus and Tegeolepis turned low forces into significantly higher stress, making them best suited for gripping.
We concluded that Sphyragnathus was the earliest actinopterygian adapted for breaking down prey by piercing, which also matches the broader predictions of the feeding-first hypothesis.
Substantial work remains — only the jaw of Sphyragnathus is preserved, so the 'locomotion-first' hypothesis was untested. But this represents the challenge and promise of paleontology: get enough tantalizing glimpses into the past and you can begin to unfold a history.
As for the actinopterygians, current research indicates that they first diversified in the Devonian Period and shifted into new roles when the modern vertebrate world was born.
This article is republished from The Conversation, a nonprofit, independent news organisation bringing you facts and trustworthy analysis to help you make sense of our complex world. It was written by: Conrad Daniel Mackenzie Wilson, Carleton University
Read more:
We discovered a new fossil species of prehistoric fish
It's less than 2cm long, but this 400 million year old fossil fish changes our view of vertebrate evolution
A 380-million-year-old fossil 'fish' from Scotland has been discovered in Australia
Conrad Daniel Mackenzie Wilson receives funding from the Natural Sciences and Engineering Research Council of Canada, the Ontario Student Assistance Program, and the Society of Vertebrate Paleontology.
Hashtags
Try Our AI Features
Explore what Daily8 AI can do for you:
Comments
No comments yet...
Related Articles
Yahoo
11 hours ago
- Yahoo
Dino disco: 100-million-year-old giant courtship arena discovered in Colorado
At Dinosaur Ridge, researchers uncovered a remarkable and unusual site where dinosaurs gathered and performed mating dances over 100 million years ago—and it might be the largest 'lekking' area ever found. A team of paleontologists recently published their groundbreaking discovery of possibly one of the most significant mating sites from the dinosaur age. 'Lekking' refers to the elaborate mating dances that male dinosaurs would present to females. Today, some modern birds carry on this ancient tradition as descendants of the dinosaurs. In these displays, males engaged in energetic movements while females observed and selected a partner based on the performance. Researchers had previously noted the existence of five fossilized scrape marks at Dinosaur Ridge. After a closer investigation, however, they discovered much more than a few traces of this ritual. Aerial images revealed 35 marks made by different dinosaurs, making this former wetland home to one of the largest mating destinations in the ancient world. Once upon a time, 100 million years ago, many species walked through this former wetland, such as duck-billed hadrosaurs and ostrich-like herbivores. They left track marks in the soft Earth. Nearby, researchers discovered that they marked solid rock on a slope with a more dynamic set of traces, suggesting they began their mating rituals here. Paleontologists gathered aerial images of the site, which is, in a humorous twist of fate, closed to foot traffic to preserve and protect the track marks. They did not expect to uncover what appeared to be a space more like a dance club where dinosaurs would gather and dance, hoping to secure a mate. Dr. Caldwell Buntin of Old Dominion University, the study's lead author, told IFLScience that Martin Lockley, who first identified the trace fossils, determined they were likely related to mating displays after ruling out other possibilities such as nesting, foraging, territorial marking, or water-seeking behavior. Buntin and his team wanted to evaluate the validity of Lockley's findings that these were, in fact, traces of a mating dance using a data-driven approach. High-resolution drone imagery revealed 35 Ostendichnus, the scientific name for this specific type of claw marks associated with the dance of sex, according to the study. Buntin told Science that he believed Ornithomimids, or ostrichlike herbivores, and Acrocanthosaurus, which looks like a both used this sacred ground to populate their species. These markings—bowl-shaped and long and thin as if the dinosaurs kicked back their feet—were clustered together at different layers of the rock. Researchers understood that the element of time was present. These dinosaurs returned to this site over generations to put themselves out there—to attract a female. 'These traces were generated by backward kicking movements repeated by both the left and right foot,' Buntin said. In interpreting the choreography, researchers understood that the dinosaurs turned clockwise and scraped their claws through the sand. The circular markings suggest that, later, they might have nested here. Scientists have only found three lekking sites worldwide. Already a rare discovery, the site at Dinosaur Ridge might be 'the clearest case yet of a dinosaur display arena,' according to Amy Atwater, the site's director of paleontology. Buntin told Science that future work might require the state of Colorado to allow researchers to visit it, so they can study the traces of mating up close, as they still cannot make any definitive statements as to who these markings belong to. Nonetheless, some of it is open to the public, so dinosaur lovers can visit one of the world's only and most popular hiking sites. This site stands to contribute to the field and provide new insights into the ancient beasts that once ruled the Earth—the dinosaurs. The discovery of 35 scrape sites offers new insight into dinosaur courtship, showing they likely performed display behaviors to attract mates. The study was published in the journal Cretaceous Research.
Yahoo
2 days ago
- Yahoo
A chance discovery of a 350 million-year-old fossil reveals a new type of ray-finned fish
In 2015, two members of the Blue Beach Fossil Museum in Nova Scotia found a long, curved fossil jaw, bristling with teeth. Sonja Wood, the museum's owner, and Chris Mansky, the museum's curator, found the fossil in a creek after Wood had a hunch. The fossil they found belonged to a fish that had died 350 million years ago, its bony husk spanning nearly a metre on the lake bed. The large fish had lived in waters thick with rival fish, including giants several times its size. It had hooked teeth at the tip of its long jaw that it would use to trap elusive prey and fangs at the back to pierce it and break it down to eat. For the last eight years, I have been part of a team under the lead of paleontologist Jason Anderson, who has spent decades researching the Blue Beach area of Nova Scotia, northwest of Halifax, in collaboration with Mansky and other colleagues. Much of this work has been on the tetrapods — the group that includes the first vertebrates to move to land and all their descendants — but my research focuses on what Blue Beach fossils can tell us about how the modern vertebrate world formed. The modern vertebrate world is defined by the dominance of three groups: the cartilaginous fishes or chondrichthyans (including sharks, rays and chimaeras), the lobe-finned fishes or sarcopterygians (including tetrapods and rare lungfishes and coelacanths), and the ray-finned fishes or actinopterygians (including everything from sturgeon to tuna). Only a few jawless fishes round out the picture. This basic grouping has remained remarkably consistent — at least for the last 350 million years. Before then, the vertebrate world was a lot more crowded. In the ancient vertebrate world, during the Silurian Period (443.7-419.2 MA) for example, the ancestors of modern vertebrates swam alongside spiny pseudo-sharks (acanthodians), fishy sarcopterygians, placoderms and jawless fishes with bony shells. Armoured jawless fishes had dwindled by the Late Devonian Period (419.2-358.9 MA), but the rest were still diverse. Actinopterygians were still restricted to a few species with similar body shapes. By the immediately succeeding early Carboniferous times, everything had changed. The placoderms were gone, the number of species of fishy sarcopterygians and acanthodians had cratered, and actinopterygians and chondrichthyans were flourishing in their place. The modern vertebrate world was born. Blue Beach has helped build our understanding of how this happened. Studies describing its tetrapods and actinopterygians have showed the persistence of Devonian-style forms in the Carboniferous Period. Whereas the abrupt end-Devonian decline of the placoderms, acanthodians and fishy sarcopterygians can be explained by a mass extinction, it now appears that multiple types of actinopterygians and tetrapods survived to be preserved at Blue Beach. This makes a big difference to the overall story: Devonian-style tetrapods and actinopterygians survive and contribute to the evolution of these groups into the Carboniferous Period. But significant questions remain for paleontologists. One point of debate revolves around how actinopterygians diversified as the modern vertebrate world was born — whether they explored new ways of feeding or swimming first. The Blue Beach fossil was actinopterygian, and we wondered what it could tell us about this issue. Comparison was difficult. Two actinopterygians with long jaws and large fangs were known from the preceding Devonian Period (Austelliscus ferox and Tegeolepis clarki), but the newly found jaw had more extreme curvature and the arrangement of its teeth. Its largest fangs are at the back of its jaw, but the largest fangs of Austelliscus and Tegeolepis are at the front. These differences were significant enough that we created a new genus and species: Sphyragnathus tyche. And, in view of the debate on actinopterygian diversification, we made a prediction: that the differences in anatomy between Sphyragnathus and Devonian actinopterygians represented different adaptations for feeding. To test this prediction, we compared Sphyragnathus, Austelliscus and Tegeolepis to living actinopterygians. In modern actinopterygians, the difference in anatomy reflects a difference in function: front-fangs capture prey with their front teeth and grip it with their back teeth, but back-fangs use their back teeth. Since we couldn't observe the fossil fish in action, we analyzed the stress their teeth would experience if we applied force. The back teeth of Sphyragnathus handled force with low stress, making them suited for a role in piercing prey, but the back teeth of Austelliscus and Tegeolepis turned low forces into significantly higher stress, making them best suited for gripping. We concluded that Sphyragnathus was the earliest actinopterygian adapted for breaking down prey by piercing, which also matches the broader predictions of the feeding-first hypothesis. Substantial work remains — only the jaw of Sphyragnathus is preserved, so the 'locomotion-first' hypothesis was untested. But this represents the challenge and promise of paleontology: get enough tantalizing glimpses into the past and you can begin to unfold a history. As for the actinopterygians, current research indicates that they first diversified in the Devonian Period and shifted into new roles when the modern vertebrate world was born. This article is republished from The Conversation, a nonprofit, independent news organisation bringing you facts and trustworthy analysis to help you make sense of our complex world. It was written by: Conrad Daniel Mackenzie Wilson, Carleton University Read more: We discovered a new fossil species of prehistoric fish It's less than 2cm long, but this 400 million year old fossil fish changes our view of vertebrate evolution A 380-million-year-old fossil 'fish' from Scotland has been discovered in Australia Conrad Daniel Mackenzie Wilson receives funding from the Natural Sciences and Engineering Research Council of Canada, the Ontario Student Assistance Program, and the Society of Vertebrate Paleontology.
Yahoo
2 days ago
- Yahoo
Personality plays a role in whether you believe in climate change, Dalhousie study finds
Personality plays a role in whether people believe in climate change, a recent study has found — and that could have implications for efforts to combat climate skepticism. The research from Dalhousie University in Halifax found people who are more skeptical about climate change are more likely to rank higher on scales of narcissism, machiavellianism and psychopathy — traits that reflect a tendency to be self-centred, manipulative, callous and socially aversive. People who are less skeptical about climate change are more likely to have pro-social personality traits of openness, agreeableness, honesty, humility and emotionality. Scott Pruysers is an associate professor in the political science department at Dalhousie University and the lead author of the study, published in March in the journal Climatic Change. He says understanding the personality roots of climate skepticism can help develop more effective strategies to encourage environmentally conscious behaviour. "The precursor to developing good policy or understanding why people care about this issue is understanding who doesn't care about it, who remains skeptical," he said. "And so we're going to have to get kind of creative and smarter with the messaging." The researchers analyzed data from a survey of 1,725 Canadians conducted in 2020. The survey respondents were asked to rate how much they agreed or disagreed with the following statements: I am certain that climate change is happening. Claims that human activities are changing the climate are exaggerated. Floods and heat waves are not increasing; there is just more reporting of it in the media these days. Climate change is just a result of natural variation in the climate. Climate change is a scam. Government should do more to address climate change. Pruysers says while researchers have previously looked at the roots of climate skepticism, some of those studies had limitations that the Dalhousie study tried to overcome. While other studies have relied primarily on undergraduates as participants, his study ensured the participants reflected the income, gender and age distribution of the Canadian population. In addition, previous studies have used as few as 10 descriptors (for example, reserved/quiet, or disorganized/careless) to assess personality. Pruysers's study used more robust measures that included more than 160 descriptors. There is worldwide scientific consensus that the Earth's climate is changing, and that human activity has unequivocally caused climate change. The United Nations' Intergovernmental Panel on Climate Change (IPCC), which produces assessments written by hundreds of leading scientists, has found that climate change is a threat to human well-being and planetary health, and that changes must be made to ensure a liveable and sustainable future. The Dalhousie study found that more than 20 per cent of participants believe claims that human activity is changing the climate are exaggerated, 17 per cent believe climate-related events such as floods or heat waves are not increasing, and more than 10 per cent disagree that governments should be doing more to address climate change. More recent data has also found similar levels of skepticism among Canadians and dwindling concern about climate change. Demographic and political factors do affect climate skepticism. For instance, the study found that men and people who are more right wing are more skeptical, while those with higher education levels, income and political knowledge are less skeptical. While the participants' self-placement on the left-right ideology scale was the factor that most accurately predicted climate skepticism, openness was the second most predictive factor, outperforming factors such as age, education, income and political interest and knowledge. The study made it clear to Pruysers that personality does play a role, so in order to convince skeptics to adopt planet-friendly practices, he says different tactics may be needed. For example, Pruysers said, other research has shown that people who score higher in narcissism are more likely to buy environmentally friendly products if they might be seen and admired by others while doing it. Pruysers emphasized that the study is not labelling climate skeptics as narcissists or psychopaths. "When people hear something like narcissism or psychopathy, right, it's jarring. We're not talking about clinical levels of these things," he says. Rather, he says, the traits are measured on a spectrum and most people will exhibit elements of those traits. Matthew Hornsey is a professor in the business school at the University of Queensland in Australia who researches the psychological motivations for rejecting scientific consensus, including climate change skepticism. He said the Dalhousie study is "one of the more authoritative statements" around the role of personality and climate skepticism and its methodology is more sophisticated than other studies on the topic. While the data makes it clear there is a relationship between climate skepticism and darker personality traits, and pro-social traits and acceptance of climate science, those relationships are not particularly strong. "Just because something is there, doesn't mean it's a big, big effect," Hornsey said. "You would have a hard time predicting people's climate change views just from their personality." He said putting the study's findings to use would be challenging. "What do you do with this information? You can't change people's personalities, and so it's not easy to have an intervention around that." Hornsey did note, however, that developments in artificial intelligence have improved the ability to detect personality from the media people consume and how they write on social media. That ability could be harnessed to develop "micro-targeted" messages based on personality. "But, you know, that's a whole can of worms," he said. MORE TOP STORIES
