With over 30,000 species worldwide, the ray fins are currently the largest group of fish. These bony fish were not always as numerous, however. Losses of other fish species, such as cartilaginous fish, helped them to spread successfully. As paleontologists from the University of Zurich together with international researchers reveal, a series of serious extinction events between 300 to 200 million years ago played a central role in the development of today’s fish fauna.
Today, ray-finned fish, which belong to the bony fish, are by far the most biodiverse fish group in both salt- and freshwater. Their spectacular variety of forms ranges from eels, tuna, flounders and angler fish all the way to seahorses.
after severe losses among cartilaginous fishes during the Middle Permian extinction, bony fishes experienced a massive diversification in the subsequent Trias period.
Picture: University of Zurich
With around 1,100 species, the second most biodiverse group is the cartilaginous fish, which are almost exclusively marine and include sharks, rays and chimaeras. Exactly why bony fish managed to prevail in different habitats is the subject of debate: Do they have a better body plan, which is suited to more ecological niches than that of the cartilaginous fish? Or are other factors involved in their successful distribution? Paleontologists from the University of Zurich now reveal that climate catastrophes in the past played a crucial role in the dominance of ray-finned fish today.
Cartilaginous fish greatly depleted by extinction events
The scientists studied the changes in biodiversity among cartilaginous and bony fish during the Permian and Triassic periods around 300 to 200 million years ago – an interval marked by several serious extinction events. They evaluated the global scientific literature on bony and cartilaginous fish from the last 200 years and collected data on diversity and body size, the latter providing an indication of the fish’s position in the food chains in the seas and freshwater.
Based on the data evaluated, the researchers demonstrate that cartilaginous fish, the most biodiverse fish group at the time, especially suffered heavily during an extinction event in the Middle Permian epoch while the Permian ray-finned fish escaped relatively unscathed. After an even bigger mass extinction close to the Permian-Triassic boundary, which wiped out 96 percent of all sea organisms, these bony fish diversified heavily.
Of the ray-finned fish, the so-called Neopterygii (“new fins”) became particular biodiverse during the Triassic and, with over 30,000 species, today constitute the largest vertebrate group. Triassic Neopterygii primarily developed small species while the majority of the more basal ray-fins produced large predatory fish. Moreover, many bony fish developed morphological specializations in the Triassic, such as in the jaw apparatus, dentition or fins. This enabled new ways of locomotion, including gliding over the surface of the water, much like flying fish do today. Moreover, there is also evidence for viviparity in Triassic bony fish, for the first time ever.
Extinction events correlate with climate changes
Unlike bony fish, cartilaginous fish, which had already been heavily decimated by the end of the Permian, did not really recover. Many groups that were still biodiverse in the Permian disappeared completely or became extremely rare during the extinction events of the Permian and the Triassic. “Our results indicate that repeated extinction events played a key role in the development of today’s fish fauna,” explains Carlo Romano, a postdoc at the University of Zurich’s Paleontological Institute and Museum. Most of these severe crises are linked to massive volcanic activity, global climate changes and sea level lowstands.
C. Romano, M. B. Koot, I. Kogan, A. Brayard, A. V. Minikh, W. Brinkmann, H. Bucher, J. Kriwet, Permian-Triassic Osteichthyes (bony fishes). Diversity dynamics and body size evolution. Biological Reviews, November 28, 2014. S. 1-44. doi: 10.1111/brv.12161.
Dr. Carlo Romano
Paleontological Institute and Museum
University of Zurich
Tel: +41 634 23 47
Nathalie Huber | Universität Zürich
'Y' a protein unicorn might matter in glaucoma
23.10.2017 | Georgia Institute of Technology
Microfluidics probe 'cholesterol' of the oil industry
23.10.2017 | Rice University
Salmonellae are dangerous pathogens that enter the body via contaminated food and can cause severe infections. But these bacteria are also known to target...
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
23.10.2017 | Event News
17.10.2017 | Event News
10.10.2017 | Event News
23.10.2017 | Life Sciences
23.10.2017 | Physics and Astronomy
23.10.2017 | Health and Medicine