adplus-dvertising
Connect with us

Science

Fish finger fossils show the beginnings of hands

Published

 on

About 374 million years ago, life on Earth began to transition out of the world’s oceans to walk on land. This gave rise to the tetrapods, or four-limbed vertebrates, that included dinosaurs, land animals and eventually humans. Scientists consider this transition from water to land, and animals acquiring hands and feet, to be one of the most significant events in the history of life on Earth.
But the fossil record about the evolutionary step between marine and land life is sparse. Researchers have focused their efforts on tetrapod-like fish, called elpistostegalians, that lived between 359 and 393 million years ago during the Middle and Late Devonian periods.
Here's how the 'unicorns of the sea' got their tusks
Until now, they had never found the complete skeleton of the pectoral fin, also known as the fore-fin. But researchers have discovered one of the most complete elpistostegalian fossils yet: a 5-foot-long fossilized fish in Miguasha, Quebec.
CT scans of the skeleton revealed at least two skeletal digits that resembled fingers, as well as three more potential ones. They also found an arm, elbow, forearm and wrist attached to the finger-like digits.
All of them were still contained within a fin ray, or webbed flipper-like appendage, but the researchers believe it’s the missing link between fish fins and vertebrate hands.
This is an artist's reconstruction of the fish and its fin, which contained finger-like digits.This is an artist's reconstruction of the fish and its fin, which contained finger-like digits.
The study published Wednesday in the journal Nature.
“Today we announce in the journal Nature our discovery of a complete specimen of a tetrapod-like fish, called Elpistostege, which reveals extraordinary new information about the evolution of the vertebrate hand,” said John Long, study author and Strategic Professor in Palaeontology at Flinders University in Australia.
“This is the first time that we have unequivocally discovered fingers locked in a fin with fin-rays in any known fish. The articulating digits in the fin are like the finger bones found in the hands of most animals.”
The researchers analyzed the fin to determine its skeletal structure.The researchers analyzed the fin to determine its skeletal structure.
To date, this skeletal arrangement is the most similar to previously found tetrapods. And the fact that it was located in the fore-fin suggests it was more like a hand.
This appendage would have aided fish as they explored shallow water habits during the Late Devonian period.
This Jurassic flesh-eating fish with piranha-like teeth is the stuff of nightmaresThis Jurassic flesh-eating fish with piranha-like teeth is the stuff of nightmares
“The origin of digits relates to developing the capability for the fish to support its weight in shallow water or for short trips out on land,” said Richard Cloutier, study co-author and professor at the Universite du Quebec a Rimouski. “The increased number of small bones in the fin allows more planes of flexibility to spread out its weight through the fin.”
“The other features the study revealed concerning the structure of the upper arm bone or humerus, which also shows features present that are shared with early amphibians,” Cloutier said. “Elpistostege is not necessarily our ancestor, but it is [the] closest we can get to a true ‘transitional fossil’, an intermediate between fishes and tetrapods.”
A comparison of the fish skeleton and a human skeleton show the similarities.A comparison of the fish skeleton and a human skeleton show the similarities.
Previously, researchers have studied these tetrapod-like fish to better understand how creatures adapted to breathing, hearing and eating on land as they emerged from the water.
Elpistostege watsoni, as the fish has been dubbed, would have been the largest predator dominating Quebec’s shallow marine and estuary habitat 380 million years ago. Sharp fangs helped it snack on other large fish, whose fossils were found in the same area.
Fragments of fossils belonging to this fish were initially found in Quebec in 1938. At the time, they only found a portion of the skull’s roof and assumed it was a tetrapod.
Newly discovered strange 'grinning' crocodile-like creature lived 372 million years agoNewly discovered strange 'grinning' crocodile-like creature lived 372 million years ago
Another piece of the puzzle was found in 1985, revealing it was a lobe-finned fish. Lobe-finned fish differ from others because their fleshy fins connect to the body through a single bone.
This tree shows the different branches of evolution as creatures transitioned from sea to land.This tree shows the different branches of evolution as creatures transitioned from sea to land.
And the most complete fossil, which was part of the this study, was originally found in 2010. CT scans of the fossil, followed by detailed analysis of its backbone and fin, occurred after the discovery. The researchers partnered with colleagues from other institutions to continue CT scans, which revealed the digits found in the fin. Their work was finally completed in 2019.
Their years of analysis revealed that this was the most evolutionary fish of its kind.
“This finding pushes back the origin of digits in vertebrates to the fish level, and tells us that the patterning for the vertebrate hand was first developed deep in evolution, just before fishes left the water,” Long said.

Source link

Continue Reading

Science

Giant prehistoric salmon had tusk-like teeth for defence, building nests

Published

 on

The artwork and publicity materials showcasing a giant salmon that lived five million years ago were ready to go to promote a new exhibit, when the discovery of two fossilized skulls immediately changed what researchers knew about the fish.

Initial fossil discoveries of the 2.7-metre-long salmon in Oregon in the 1970s were incomplete and had led researchers to mistakenly suggest the fish had fang-like teeth.

It was dubbed the “sabre-toothed salmon” and became a kind of mascot for the Museum of Natural and Cultural History at the University of Oregon, says researcher Edward Davis.

But then came discovery of two skulls in 2014.

300x250x1

Davis, a member of the team that found the skulls, says it wasn’t until they got back to the lab that he realized the significance of the discovery that has led to the renaming of the fish in a new, peer-reviewed study.

“There were these two skulls staring at me with sideways teeth,” says Davis, an associate professor in the department of earth sciences at the university.

In that position, the tusk-like teeth could not have been used for biting, he says.

“That was definitely a surprising moment,” says Davis, who serves as director of the Condon Fossil Collection at the university’s Museum of Natural and Cultural History.

“I realized that all of the artwork and all of the publicity materials and bumper stickers and buttons and T-shirts we had just made two months prior, for the new exhibit, were all out of date,” he says with a laugh.

Davis is co-author of the new study in the journal PLOS One, which renames the giant fish the “spike-toothed salmon.”

It says the salmon used the tusk-like spikes for building nests to spawn, and as defence mechanisms against predators and other salmon.

The salmon lived about five million years ago at a time when Earth was transitioning from warmer to relatively cooler conditions, Davis says.

It’s hard to know exactly why the relatives of today’s sockeye went extinct, but Davis says the cooler conditions would have affected the productivity of the Pacific Ocean and the amount of rain feeding rivers that served as their spawning areas.

Another co-author, Brian Sidlauskas, says a fish the size of the spike-toothed salmon must have been targeted by predators such as killer whales or sharks.

“I like to think … it’s almost like a sledgehammer, these salmon swinging their head back and forth in order to fend off things that might want to feast on them,” he says.

Sidlauskas says analysis by the lead author of the paper, Kerin Claeson, found both male and female salmon had the “multi-functional” spike-tooth feature.

“That’s part of our reason for hypothesizing that this tooth is multi-functional … It could easily be for digging out nests,” he says.

“Think about how big the (nest) would have to be for an animal of this size, and then carving it out in what’s probably pretty shallow water; and so having an extra digging tool attached to your head could be really useful.”

Sidlauskas says the giant salmon help researchers understand the boundaries of what’s possible with the evolution of salmon, but they also capture the human imagination and a sense of wonder about what’s possible on Earth.

“I think it helps us value a little more what we do still have, or I hope that it does. That animal is no longer with us, but it is a product of the same biosphere that sustains us.”

This report by The Canadian Press was first published April 24, 2024.

Brenna Owen, The Canadian Press

Adblock test (Why?)

728x90x4

Source link

Continue Reading

Science

Giant prehistoric salmon had tusk-like spikes used for defence, building nests: study

Published

 on

A new paper says a giant salmon that lived five million years ago in the coastal waters of the Pacific Northwest used tusk-like spikes as defense mechanisms and for building nests to spawn.

The initial fossil discoveries of the 2.7-metre-long salmon in Oregon in the 1970s were incomplete and led researchers to suggest the fish had fang-like teeth.

The now-extinct fish was dubbed the “saber-tooth salmon,” but the study published in the peer-reviewed journal PLOS One today renames it the “spike-toothed salmon” and says both males and females possessed the “multifunctional” feature.

Study co-author Edward Davis says the revelation about the tusk-like teeth came after the discovery of fossilized skulls at a site in Oregon in 2014.

300x250x1

Davis, an associate professor in the department of earth sciences at the University of Oregon, says he was surprised to see the skulls had “sideways teeth.”

Contrary to the belief since the 1970s, he says the teeth couldn’t have been used for any kind of biting.

“That was definitely a surprising moment,” Davis says of the fossil discovery in 2014. “I realized that all of the artwork and all of the publicity materials … we had just made two months prior, for the new exhibit, were all out of date.”

Adblock test (Why?)

728x90x4

Source link

Continue Reading

Science

SpaceX sends 23 Starlink satellites into low-Earth orbit

Published

 on

April 23 (UPI) — SpaceX launched 23 Starlink satellites into low-Earth orbit Tuesday evening from Space Launch Complex 40 at Cape Canaveral Space Force Station in Florida.

Liftoff occurred at 6:17 EDT with a SpaceX Falcon 9 rocket sending the payload of 23 Starlink satellites into orbit.

The Falcon 9 rocket’s first-stage booster landed on an autonomous drone ship in the Atlantic Ocean after separating from the rocket’s second stage and its payload.

The entire mission was scheduled to take about an hour and 5 minutes to complete from launch to satellite deployment.

300x250x1

The mission was the ninth flight for the first-stage booster that previously completed five Starlink satellite-deployment missions and three other missions.

Adblock test (Why?)

728x90x4

Source link

Continue Reading

Trending