Living Coelacanth Latimeria Coelacanths are iconic “living fossils,” one of the most conservative groups of vertebrates. Now, paleontologists have described a new species of primitive coelacanth from fossils discovered in the Late Devonian Gogo Formation of Western Australia. Ngamgawi WirungariThe 375-million-year-old fossil fish fills an important transitional period in the differentiation and evolution of coelacanths.
coelacanth It is an evolutionarily unique lobe-finned fish that first appeared in the fossil record during the Early Devonian period, approximately 419 million years ago.
More than 175 species of coelacanth fossils are known from the Paleozoic and Mesozoic eras.
During the Mesozoic era, they diversified greatly, with some species developing unusual body shapes.
But at the end of the Cretaceous period, about 66 million years ago, they mysteriously disappeared from the fossil record.
The end-Cretaceous extinction, caused by a giant asteroid impact, wiped out about 75% of all life on Earth, including the non-avian dinosaurs.
It was therefore assumed that the coelacanth was also a victim of the same mass extinction.
However, in 1938, the first specimen of this species was discovered. Latimeria chalumnae It was caught by chance in South Africa.
The second known species, Latimeria menadoensisIt lives off the coast of Sulawesi, Indonesia.
Specimen Ngamgawi WirungariImage courtesy of John A. Long.
“Our study calls into question the idea that extant coelacanths are the oldest 'living fossils,'” said Professor Richard Cloutier, a vertebrate paleontologist at the University of Quebec.
“It first appeared in the geological record more than 410 million years ago, with fragmentary fossils found in places such as China and Australia.”
“But most of the early forms are poorly known. Ngamgawi Wirungari It is the best known of the Devonian coelacanths.
“As we slowly fill in the gaps, we can see how extant coelacanth species are LatimeriaAlthough they are commonly thought of as “living fossils,” they are in fact constantly evolving and may not deserve this enigmatic title.”
Specimen Ngamgawi Wirungari It was discovered in the Late Devonian Go Go Formation Gooniyandi Country in the Kimberley region of northern Western Australia.
Although now covered by a dry rock outcrop, around 380 million years ago the formation was part of an ancient tropical coral reef teeming with more than 50 species of fish.
Coelacanth phylogenetic relationships and divergence dates. Image courtesy of Clement others., doi:10.1038/s41467-024-51238-4.
“Ngamgawi Wirungari “This discovery gives us great insight into the early anatomy of the lineage that ultimately led to humans,” said Professor John Long, from Flinders University.
“Over 35 years, the Gogo site has yielded some perfectly preserved 3D fish fossils and many other important discoveries, including petrified soft tissue and the origin of complex sexual reproduction in vertebrates.”
“The study of this new species has allowed us to analyse the evolutionary history of all known coelacanths.”
“We calculated evolutionary rates over 410 million years of history,” they said.
“This study reveals that the evolution of coelacanths has slowed significantly since the time of the dinosaurs, with some intriguing exceptions.”
of Survey results Published in a journal Nature Communications.
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Alice M. Clement othersLate Devonian coelacanths reconstruct phylogeny, differentiation and evolutionary dynamics of Actinobacteria. Nature Communicationsin press; doi: 10.1038/s41467-024-51238-4
Source: www.sci.news
