New fossil fish species scales up evidence of Earth’s evolutionary march
Are the world's oldest 'living fossil' coelacanths still evolving?
Peer-Reviewed Publicationimage:
A live recreation of the Ngamugawi wirngarri coelacanth in
its natural habitat. P3D graphic credit: Katrina Kenny
Credit: Illustration Katrina Kenny (courtesy Flinders University)
Access VIDEO, photos and captions here
Climate change and asteroids are linked with animal origin and extinction – and plate tectonics also seems to play a key evolutionary role, ‘groundbreaking’ new fossil research reveals.
The discovery of an exceptionally well preserved ancient primitive Devonian coelacanth fish in remote Western Australia has been linked to a period of heightened tectonic activity, or movement in the Earth’s crust, according to the new study in Nature Communications. (Open access when published)
Led by Flinders University and experts from Canada, Australia and Europe, the new fossil from the Gogo Formation in WA, named Ngamugawi wirngarri, also helps to fill in an important transition period in coelacanth history, between the most primitive forms and other more ‘anatomically-modern’ forms.
“We are thrilled to work with people of the Mimbi community to grace this beautiful new fish with the first name taken from the Gooniyandi language,” says first author Dr Alice Clement, an evolutionary biologist and palaeontologist from Flinders University.
“Our analyses found that tectonic plate activity had a profound influence on rates of coelacanth evolution. Namely that new species of coelacanth were more likely to evolve during periods of heightened tectonic activity as new habitats were divided and created,” she says.
The study confirms the Late Devonian Gogo Formation as one of the richest and best-preserved assemblages of fossil fishes and invertebrates on Earth.
Flinders University Strategic Professor of Palaeontology John Long says the fossil, dating from the Devonian Period (359-419 million years ago), “provides us with some great insight into the early anatomy of this lineage that eventually led to humans”.
“For more than 35 years, we have found several perfectly preserved 3D fish fossils from Gogo sites which have yielded many significant discoveries, including mineralised soft tissues and the origins of complex sexual reproduction in vertebrates,” says Professor Long.
“Our study of this new species led us to analyse the evolutionary history of all known coelacanths.”
Many parts of human anatomy originated in the Early Palaeozoic (540-350 million years ago). This was when jaws, teeth, paired appendages, ossified brain-cases, intromittent genital organs, chambered hearts and paired lungs all appeared in early fishes.
“While now covered in dry rocky outcrops, the Gogo Formation on Gooniyandi Country in the Kimberley region of northern Western Australia was part of an ancient tropical reef teeming with more than 50 species of fish about 380 million years ago.
“We calculated the rates of evolution across their 410 million-year history. This revealed that coelacanth evolution has slowed down drastically since the time of the dinosaurs, but with a few intriguing exceptions.”
Today, the coelacanth is a fascinating deep-sea fish that lives off the coasts of eastern Africa and Indonesia and can reach up to 2m in length. They are "lobe-finned" fish, which means they have robust bones in their fins not too dissimilar to the bones in our own arms, and are thus considered to be more closely related to lungfish and tetrapods (the back-boned animals with arms and legs such as frogs, emus and mice) than most other fishes.
Over the past 410 million years, more than more than 175 species of coelacanths have been discovered across the globe. During the Mesozoic Era, the age of dinosaurs, coelacanths diversified significantly, with some species developing unusual body shapes. However, at the end of the Cretaceous Period, around 66 million years ago, they mysteriously disappeared from the fossil record.
The end Cretaceous extinction, sparked by the impact from a massive asteroid, wiped out approximately 75% of all life on Earth, including all of the non-avian (bird-like) dinosaurs. Thus, it was presumed that the coelacanth fishes had been swept up as a casualty of the same mass extinction event.
But in 1938, people fishing off South Africa pulled up a large mysterious looking fish from the ocean depths, with the ‘lazarus’ fish going on to gain cult status in the world of biological evolution.
Another senior co-author, vertebrate palaeontologist Professor Richard Cloutier, from the University of Quebec in Rimouski (UQAR), says the new Nature Communications study challenges the idea that surviving coelacanths are the oldest ‘living fossils’.
“They first appear in the geological record more than 410 million years ago, with fragmentary fossils known from places like China and Australia. However, most of the early forms remain poorly known, making Ngamugawi wirngarri the best known Devonian coealacanth.
“As we slowly fill in the gaps, we can start to understand how living coelacanth species of Latimeria, which commonly are considered to be ‘living fossils,’ actually are continuing to evolve and might not deserve such an enigmatic title,” says Professor Cloutier, a previous honorary visiting scholar at Flinders University.
The study’s coauthors have affiliations with Mahasarakham University in Thailand, the South Australian Museum, Max Planck Institute for Evolutionary Anthropology in Germany, University of Bristol, Curtin University in Western Australia and the WA Museum.
The article, ‘A Late Devonian coelacanth reconfigures actinistian phylogeny, disparity, and evolutionary dynamics' (2024) by Alice M Clement, Richard Cloutier, Michael SY Lee, Benedict King, Olivia Vanhaesebroucke, Corey JA Bradshaw, Hugo Dutel, Kate Trinajstic and John A Long has been published in Nature Communications. DOI: 10.1038/s41467-024-51238-4.
https://doi.org/10.1038/s41467-024-51238-4
VISUAL CONTENT: go to https://drive.google.com/drive/folders/1-MVOxwOvHoZERYHNT3j7Y29gT6Bz27uq?usp=sharing
VIDEO: Youtube link to come (goes live after embargo lifts).
also Devonian coelacanth, Ngamugawi wirngarri, 3D model of skull from CT data (created by Alice Clement) https://www.youtube.com/watch?v=j-0wLY6Scjc
Acknowledgements: The fieldwork was funded by Australian Research Council DP grants. Prof Cloutier also received funding from the NERC and Natural Sciences and Engineering Research Council of Canada. Thanks to the Gooniyandi people, including Rosemary Nuggett, Elder from the Mimbi Caves Community, and other landholders on which the Gogo fish sites are located.
Professor John Long holding a fossil specimen. Photo courtesy: Flinders University
Credit
Flinders University
Ngamugawi wirngarri coelacanth skull bones after they were
acid etched out of rock at Museum Victoria, 2009.
Credit
J Long (Flinders University)
Flinders University vertebrate palaeontologist Dr Alice Clement looking at a model of a modern-day coelacanth and a 3D printed skull of the Ngamugawi wirngarri coelacanth.
Credit
Photo Flinders University
Journal
Nature Communications
Method of Research
Imaging analysis
Subject of Research
Animals
Article Title
A Late Devonian coelacanth reconfigures actinistian phylogeny, disparity, and evolutionary dynamics'
Article Publication Date
12-Sep-2024
Trilobite fossils from upstate New York reveal “extra” set of legs
Discovery of fifth pair of head appendages helps researchers solve trilobite segmentation puzzle
American Museum of Natural History
image:
A photograph of an extremely well-preserved fossil of Triarthrus eatoni from upstate New York
view moreCredit: © M. Hopkins and J-B Hou
A new study finds that a trilobite species with exceptionally well-preserved fossils from upstate New York has an additional set of legs underneath its head. The research, led by the American Museum of Natural History and Nanjing University in China, suggests that having a fifth pair of head appendages might be more widespread among trilobites than once thought. Published today in the journal Palaeontology, the study helps researchers better understand how trilobite heads are segmented.
Trilobites are a group of extinct arthropods whose living relatives include lobsters and spiders. Like other arthropods, the bodies of trilobites are made up of many segments, with the head region comprised of several fused segments. As with other parts of the trilobite body (the thorax and tail), these segments were associated with appendages, which ranged in function from sensing to feeding to locomotion.
“The number of these segments and how they are associated with other important traits, like eyes and legs, is important for understanding how arthropods are related to one another, and therefore, how they evolved,” said Melanie Hopkins, curator and chair of the Museum’s Division of Paleontology.
The segments in the trilobite head can be counted in two different ways: by looking at the grooves (called furrows) on the upper side of the trilobite fossil’s hard exoskeleton, or by counting the pairs of preserved antennae and legs on the underside of the fossil. The soft appendages of trilobites are rarely preserved, though, and when looking at the segments in the trilobite head, researchers regularly find a mismatch between these two methods.
In the new study, Hopkins and colleague Jin-Bo Hou from Nanjing University examined newly recovered specimens of the exceptionally preserved trilobite Triarthrus eatoni from upstate New York. These fossils, known for the gold shine of the pyrite replacement preserving them, show an additional, previously undescribed leg underneath the head.
“This fantastic preservation style allows us to observe 3D appendages in hundreds of specimens directly from the ventral side of the animals, just like looking at the appendages of horseshoe crabs on a beach by grabbing them and turning them upside down,” said Hou.
By making comparisons with another trilobite species, the exceptionally preserved Olenoides serratus from the Burgess Shale in British Columbia, Hopkins and Hou propose a model for how appendages were attached to the head in relation to the grooves in the exoskeleton. This model resolves the apparent mismatch and indicates that the trilobite head included six segments: an anterior segment associated with the developmental origin of the eyes and five additional segments, associated with one pair of antennae and four pairs of walking legs, respectively.
This study expands on the analysis that Hou and Hopkins have done on Triarthrus eatoni, which showed that the walking legs carry micron-sized respiratory structures (gills) and that the function of some of the spines on the walking legs was to keep these gills clean.
Paper DOI: 10.1111/pala.12723
Coauthor Melanie Hopkins with a well-preserved fossil of Triarthrus eatoni from upstate New York.
An extremely well-preserved fossil of Triarthrus eatoni from upstate New York (on right)
Credit
Daniel Kim/ ©AMNH
ABOUT THE AMERICAN MUSEUM OF NATURAL HISTORY (AMNH)
The American Museum of Natural History, founded in 1869 with a dual mission of scientific research and science education, is one of the world’s preeminent scientific, educational, and cultural institutions. The Museum encompasses more than 40 permanent exhibition halls, galleries for temporary exhibitions, the Rose Center for Earth and Space including the Hayden Planetarium, and the Richard Gilder Center for Science, Education, and Innovation. The Museum’s scientists draw on a world-class permanent collection of more than 30 million specimens and artifacts, some of which are billions of years old, and on one of the largest natural history libraries in the world. Through its Richard Gilder Graduate School, the Museum offers two of the only free-standing, degree-granting programs of their kind at any museum in the U.S.: the Ph.D. program in Comparative Biology and the Master of Arts in Teaching (MAT) Earth Science residency program. Visit amnh.org for more information.
Journal
Palaeontology
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