Newfound 'snaky croc-face' sea monster unearthed in Wyoming

Jennifer Nalewicki - Monday

Millions of years ago, an enormous, long-necked marine reptile undulated through the waters of an ancient seaway in what is now Wyoming, whipping its snaky neck back and forth and using its crocodilelike jaws to snap up fish and other small sea creatures.


An artist's rendition of what the plesiosaur may have looked like millions of years ago.© Nathan Rogers

Paleontologists discovered fossils of this sinuous sea monster in 1995 during a dig in the minimally explored uppermost portion of Pierre Shale, a geological formation dating to the Upper Cretaceous period (approximately 101 million to 66 million years ago). And unlike other plesiosaurs, this animal had physical characteristics that set it apart from other members of this extinct clade of marine reptiles.

Now, researchers have revealed their findings about this new species in a study published online Sept. 26 in the journal iScience.

"Plesiosaurs typically come in two distinct flavors or morphological types and have either a long, snakelike neck with a small head, or a short neck and a long crocodilelike jaw," Walter Scott Persons IV, a paleontologist from the College of Charleston in South Carolina and the study's lead author, told Live Science. "In this case, this weird, unique beast is a cross between the two."

Related: Giant 'sea monsters' evolved big bodies to offset long necks being a total drag

Paleontologists dubbed the animal Serpentisuchops pfisterae, which translates to "snaky crocface." This 23-foot-long (7 meter) creature's remains have been on display in the Glenrock Paleontological Museum near Casper, Wyoming, since the fossils were unearthed more than 25 years ago.

"The first time I saw Serpentisuchops pfisterae," Persons said, "I was still in elementary school."

In the decades since, paleontologists have conducted detailed studies of the animal's remains, which represent about 35% of the body and include its "beautifully preserved lower jaw, sizable amount of its skull, its complete neck, vertebrae, the majority of its tail and some ribs," Persons said.

"The only pieces that we're missing are elements of its limbs or paddles," which it used for swimming, he added.

Also found at the shale-rich site — described by Persons as resembling "the surface of the moon" or "a trip to Mordor" — were 19 teeth; just one was still in place in the specimen's jaw, while the rest were scattered among the remains. However, according to the study, the presence of roots in the jaw confirmed that the teeth were from this particular specimen and not another plesiosaur.

"The tall, conical teeth are smooth and not serrated with a cutting edge, so this animal wouldn't have been able to bite through thick bones," he said. "The teeth had a single function, which was to do a very good job at stabbing and skewering prey. It likely went after slippery prey that wouldn't put up much of a fight, such as small fish or abundant cephalopods."

This new finding "reveals a whole new ecotype, an animal that is specialized in a way that's different from all the other plesiosaurs that were around at the same time," with adaptations, " to do something different and become good at making a living amongst the other animals that shared its environment," he said.

Originally published on Live Science.

Fish fossil catch from China includes oldest teeth ever

By MADDIE BURAKOFF, AP Science Writer - 

NEW YORK (AP) — A big catch of fish fossils in southern China includes the oldest teeth ever found — and may help scientists learn how our aquatic ancestors got their bite.


This illustration provided by Heming Zhang in September 2022 depicts some of the fossil fish, more than 400 million years old, which were found by researchers in southern China, announced in a series of studies published in the journal Nature on Wednesday, Sept. 28, 2022. The fossils date back to the Silurian period when scientists believe our backboned ancestors, who were still swimming around on a watery planet, may have started evolving teeth and jaws around this time. (Heming Zhang via AP)© Provided by Associated Press

The finds offer new clues about a key period of evolution that’s been hard to flesh out because until now scientists haven't found many fossils from that era. In a series of four studies, published Wednesday in the journal Nature, researchers detail some of their finds, from ancient teeth to never-before-seen species.


This illustration provided by Heming Zhang in September 2022 depicts Xiushanosteus mirabilis, one of the fossil fish, more than 400 million years old, which were found by researchers in southern China, announced in a series of studies published in the journal Nature on Wednesday, Sept. 28, 2022. The fossils date back to the Silurian period when scientists believe our backboned ancestors, who were still swimming around on a watery planet, may have started evolving teeth and jaws around this time. (Heming Zhang via AP)© Provided by Associated Press

The fossils date back to the Silurian period, an important era for life on earth from 443 million years ago to 419 million years ago. Scientists believe our backboned ancestors, who were still swimming around on a watery planet, may have started evolving teeth and jaws around this time.

This let the fish hunt for prey instead of “grubbing around" as bottom feeders, filtering out food from the muck. It also sparked a series of other changes in their anatomy, including different kinds of fins, said Philip Donoghue, a University of Bristol paleontologist and an author on one of the studies.


This illustration provided by Qiuyang Zheng in September 2022 depicts fauna from Chongqing Lagerstätte, where fossil fish, more than 400 million years old, which were found by researchers in southern China, announced in a series of studies published in the journal Nature on Wednesday, Sept. 28, 2022. The fossils date back to the Silurian period when scientists believe our backboned ancestors, who were still swimming around on a watery planet, may have started evolving teeth and jaws around this time. (Qiuyang Zheng via AP)© Provided by Associated Press

“It’s just at this interface between the Old World and the New World,” Donoghue said.

But in the past, scientists haven’t found many fossils to show this shift, said Matt Friedman, a University of Michigan paleontologist who was not involved in the research. They’ve been relying on fragments from the time — a chunk of spine here, a bit of scale there.

The fossils from China are expected to fill in some of those gaps as researchers around the world pore over them

A field team discovered the fossil trove in 2019, Min Zhu, a paleontologist at the Chinese Academy of Sciences who led the research, said in an email. On a rainy day, after a frustrating trip that hadn't revealed any fossils, researchers explored a pile of rocks near a roadside cliff. When they split one rock open, they found fossilized fish heads looking back at them.

After hauling more rocks back to the lab for examination, the research team wound up with a huge range of fossils that were in great condition for their age.

The most common species in the bunch is a little boomerang-shaped fish that likely used its jaws to scoop up worms, said Per Erik Ahlberg of Sweden’s Uppsala University, an author on one of the studies.


This illustration provided by Heming Zhang in September 2022 depicts Fanjingshania renovata, one of the fossil fish, more than 400 million years old, which were found by researchers in southern China, announced in a series of studies published in the journal Nature on Wednesday, Sept. 28, 2022. The fossils date back to the Silurian period when scientists believe our backboned ancestors, who were still swimming around on a watery planet, may have started evolving teeth and jaws around this time. (Heming Zhang via AP)© Provided by Associated Press

Another fossil shows a sharklike creature with bony armor on its front — an unusual combination. A well-preserved jawless fish offers clues to how ancient fins evolved into arms and legs. While fossil heads for these fish are commonly found, this fossil included the whole body, Donoghue said.


This illustration provided by Qiuyang Zheng in September 2022 depicts Tujiaaspis vividus, one of the fossil fish, more than 400 million years old, which were found by researchers in southern China, announced in a series of studies published in the journal Nature on Wednesday, Sept. 28, 2022. The fossils date back to the Silurian period when scientists believe our backboned ancestors, who were still swimming around on a watery planet, may have started evolving teeth and jaws around this time. (Qiuyang Zheng via AP)© Provided by Associated Press

And then there are the teeth. The researchers found bones called tooth whorls with multiple teeth growing on them. The fossils are 14 million years older than any other teeth found from any species — and provide the earliest solid evidence of jaws to date, Zhu said.

Alice Clement, an evolutionary biologist at Australia’s Flinders University who was not involved with the research, said the fossil find is “remarkable” and could rewrite our understanding of this period.


This illustration provided by Heming Zhang in September 2022 depicts Qianodus duplicis, one of the fossil fish, more than 400 million years old, which were found by researchers in southern China, announced in a series of studies published in the journal Nature on Wednesday, Sept. 28, 2022. The fossils date back to the Silurian period when scientists believe our backboned ancestors, who were still swimming around on a watery planet, may have started evolving teeth and jaws around this time. (Heming Zhang via AP)© Provided by Associated Press

The wide range of fossils suggests there were plenty of toothy creatures swimming around at this time, Clement said in an email, even though it's the next evolutionary era that is considered the “Age of Fishes.”

———

The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education. The AP is solely responsible for all content.


This illustration provided by Heming Zhang in September 2022 depicts Shenacanthus vermiformis, one of the fossil fish, more than 400 million years old, which were found by researchers in southern China, announced in a series of studies published in the journal Nature on Wednesday, Sept. 28, 2022. The fossils date back to the Silurian period when scientists believe our backboned ancestors, who were still swimming around on a watery planet, may have started evolving teeth and jaws around this time. (Heming Zhang via AP)© Provided by Associated Press


This illustration provided by Heming Zhang in September 2022 depicts Tujiaaspis vividus, one of the fossil fish, more than 400 million years old, which were found by researchers in southern China, announced in a series of studies published in the journal Nature on Wednesday, Sept. 28, 2022. The fossils date back to the Silurian period when scientists believe our backboned ancestors, who were still swimming around on a watery planet, may have started evolving teeth and jaws around this time. (Heming Zhang via AP)© Provided by Associated Press

 

How the fish got its shoulder

Peer-Reviewed Publication

IMPERIAL COLLEGE LONDON

 

IMAGE: 

A CT SCAN OF A FISH FOSSIL IN THE STUDY

view more 

CREDIT: M. BRAZEAU & M. CASTIELLO

A new analysis of the bones and muscles in ancient fish gives new clues about how the shoulder evolved in animals – including us.

The shoulder girdle – the configuration of bones and muscles that in humans support the movement of the arms – is a classic example of an evolutionary ‘novelty’. This is where a new anatomical feature appears without any obvious precursors; where there is no smoking gun of which feature clearly led to another.

The new research, which draws together a range of evolutionary investigation techniques including fossils, developmental biology, and comparative anatomy, suggests a new way of looking at how major anatomical features like shoulders evolved.

The results of the study, led by Imperial College London’s Dr Martin Brazeau and Natural History Museum researchers, are published today in Nature.

One theory of the shoulder’s origin is that it was part of how fins formed in pairs on either side of the fish body, the evolution of which allowed fish more swimming control and eventually spurred the move from water to land. The ‘gill-arch’ hypothesis suggests that these fins evolved from the bony ‘loops’ that support the gills, which also formed the shoulder. However, it has been difficult to gather any evidence for this hypothesis, as the features are rarely preserved in fossils.

A different theory of how the fins formed, the ‘fin-fold’ hypothesis, suggests the precursors of the paired fins instead evolved out of a line of muscle on the flanks of the fish. This theory has gained a lot of supportive evidence in the 150 years since both were proposed, but it cannot explain how the associated shoulder girdle evolved.

Now, by reanalysing an ancient fossil fish skull from soon after the shoulder girdle emerged, alongside other lines of evidence, the team suggest the truth may lie in a modified version of the gill-arch hypothesis that reconciles it with the fin-fold hypothesis.

The fossil the team looked at is a placoderm, of the species Kolymaspis sibirica, which lived around 407 million years ago and was among earliest jaw-bearing fishes. The fossil has a well-preserved brain case – the hard inner parts of the skull that record imprints and other features of the brain.

Dr Brazeau realised that despite the poor or absent preservation of the gill arches in such fossils, evidence for them could be well preserved in the brain case: the cartilaginous or bony ‘box’ that surrounds the brain and supports the sensory structures like eyes and ears. The brain case showed a curious head-shoulder joint highlighted by the configuration of muscles and blood vessels.

By comparing this feature in the jawed fish fossil with the brain case features of their precursors, the jawless fish, he and the team discovered new ways the two could be compared. They found the unusual head-shoulder joint bears similarities with the gill arches in earlier fish, suggesting it was these that were retained and incorporated into the formation of the shoulder at an early stage.

While most jawless fish have 5-20 gill arches, jawed fish almost never have more than five. Combining this with the new brain-case evidence, the team suggest the sixth gill arch was incorporated into the shoulder, becoming a crucial boundary that separated the head from the body. Intriguingly, the blood supply to the fins of jawless fishes emerges between the sixth and seventh gill arches.

Dr Brazeau, from the Department of Life Sciences at Imperial, said: “The gill arches seem to have been involved in the early separation of the head and body via the shoulder. But we no longer have gill arches – though the shoulder was templated on them, they don’t need to still be around today.

“This is consistent with some earlier studies that showed muscles can remain highly stable, while the specific bones that support them gradually take over one from the other. Gill arches may have done their part and been replaced as the shoulder took on a new configuration, including supporting things like our necks.”

This finding also means it doesn’t have to be an either/or in terms of how the paired fins evolved. Dr Brazeau added: “Our study shows how there is merit to both theories without accepting one or the other wholesale. Instead, we can rationalise the areas that overlap.”

Dr Zerina Johnson, Researcher at the Natural History Museum, adds: “The team will next focus on specimens from the Natural History Museum’s fossil fish collection. This will include jawless fish that have fins but lack a distinct shoulder girdle.

“We are currently processing many gigabytes worth of data, and I can hardly wait to see what these important specimens from the collection will add to the story”.

Side view of the CT scan of the fossil fish skull

CREDIT

M. Brazeau & M. Castiello

JOURNAL

Nature

DOI

10.1038/s41586-023-06702-4 

ARTICLE TITLE

Fossil evidence for a pharyngeal origin of the vertebrate pectoral girdle

ARTICLE PUBLICATION DATE

1-Nov-2023

319-million-year-old fossilized fish illuminates backboned animals’ brain evolution

Peer-Reviewed Publication

UNIVERSITY OF BIRMINGHAM

Video and graphics can be downloaded at: https://drive.google.com/drive/folders/1wERuIPNbbUStm7LbkNyurdGieZ7E_l0V?usp=sharing

A 319-million-year-old fossilised fish, pulled from a coal mine in England more than a century ago, has revealed the oldest example of a well-preserved vertebrate brain.

CT-scanning, where X-rays are used to reveal internal features, shows the skull of the creature contains a brain and cranial nerves that are roughly an inch long.

Researchers at the University of Birmingham (UK) and the University of Michigan (USA) believe that the discovery opens a window into the neural anatomy and early evolution of a major group of fishes alive today - ray-finned fishes.

Their findings, published today (1 Feb) in Nature, shed new light into the preservation of soft parts in fossils of backboned animals. Most of the animal fossils in museum collections were formed from hard body parts such as bones, teeth and shells.

Senior author Sam Giles, of the University of Birmingham, commented: “This unexpected find of a three-dimensionally preserved vertebrate brain gives us a startling insight into the neural anatomy of ray-finned fish. It tells us a more complicated pattern of brain evolution than suggested by living species alone, allowing us to better define how and when present day bony fishes evolved.

“Comparisons to living fishes showed that the brain of Coccocephalus is most similar to the brains of sturgeons and paddlefish, which are often called ‘primitive’ fishes because they diverged from all other living ray-finned fishes more than 300 million years ago.”

The CT-scanned brain analysed belongs to Coccocephalus wildi, an early ray-finned fish roughly the size of a bream that swam in an estuary and likely dined on small crustaceans, aquatic insects and cephalopods, a group that today includes squid, octopuses and cuttlefish. Ray-finned fishes have backbones and fins supported by bony rods called rays.

Soft tissues such as the brain normally decay quickly and very rarely fossilise. But when this fish died, the soft tissues of its brain and cranial nerves were replaced during the fossilization process with a dense mineral that preserved, in exquisite detail, their three-dimensional structure.

Senior author Matt Friedman, from the University of Michigan, commented: “An important conclusion is that these kinds of soft parts can be preserved, and they may be preserved in fossils that we’ve had for a long time—this is a fossil that’s been known for over 100 years.”

The skull fossil from England is the only known specimen of its species, so only non-destructive techniques could be used during the U-M-led study.

Lead author Rodrigo Figueroa, also from the University of Michigan, commented: “Not only does this superficially unimpressive and small fossil show us the oldest example of a fossilised vertebrate brain, but it also shows that much of what we thought about brain evolution from living species alone will need reworking.

Scientists were not looking for a brain when they examined the skull fossil for the first time, but discovered an unusual, distinct object inside the skull. The mystery object displayed several features found in vertebrate brains: Iit was bilaterally symmetrical, it contained hollow spaces similar in appearance to ventricles, and it had multiple filaments extending toward openings in the braincase, similar in appearance to cranial nerves, which travel through such canals in living species. Significantly, the brain of Coccocephalus folds inward, unlike in all living ray-finned fishes, in which the brain folds outward.

Though preserved brain tissue has rarely been found in vertebrate fossils, scientists have had better success with invertebrates. There are roughly 30,000 ray-finned fish species, and they account for about half of all backboned animal species. The other half is split between land vertebrates—birds, mammals, reptiles and amphibians—and less diverse fish groups like jawless fishes and cartilaginous fishes.

The Coccocephalus skull fossil is on loan to the University of Michigan from Manchester Museum, in the UK. It was recovered from the roof of the Mountain Fourfoot coal mine in Lancashire and was first scientifically described in 1925. The fossil was found in a layer of soapstone adjacent to a coal seam in the mine.

Though only its skull was recovered, scientists believe that C. wildi would have been 6 to 8 inches long. Judging from its jaw shape and its teeth, it was probably a carnivore, according to Figueroa. When the fish died it was probably quickly buried in sediments with little oxygen present. Such environments can slow the decomposition of soft body parts.

The fossil captures a time before a signature feature of ray-finned fish brains evolved, providing an indication of when this trait evolved.

Notes for editors

• The University of Birmingham is ranked amongst the world’s top 100 institutions, its work brings people from across the world to Birmingham, including researchers and teachers and more than 8,000 international students from over 150 countries.
• Exceptional fossil preservation and evolution of the ray-finned fish brain - Rodrigo T. Figueroa, Danielle Goodvin, Matthew A. Kolmann, Michael I. Coates, Abigail M. Caron, Matt Friedman, and Sam Giles is published in Nature.

 

---

JOURNAL

Nature

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Exceptional fossil preservation and evolution of the ray-finned fish brain

ARTICLE PUBLICATION DATE

1-Mar-2023

319-million-year-old fish preserves the earliest fossilized brain of a backboned animal

Peer-Reviewed Publication

UNIVERSITY OF MICHIGAN

Video  //  Graphics 

The CT-scanned skull of a 319-million-year-old fossilized fish, pulled from a coal mine in England more than a century ago, has revealed the oldest example of a well-preserved vertebrate brain.

The brain and its cranial nerves are roughly an inch long and belong to an extinct bluegill-size fish. The discovery opens a window into the neural anatomy and early evolution of the major group of fishes alive today, the ray-finned fishes, according to the authors of a University of Michigan-led study scheduled for publication Feb. 1 in Nature.

The serendipitous find also provides insights into the preservation of soft parts in fossils of backboned animals. Most of the animal fossils in museum collections were formed from hard body parts such as bones, teeth and shells.

 

The CT-scanned brain analyzed for the new study belongs to Coccocephalus wildi, an early ray-finned fish that swam in an estuary and likely dined on small crustaceans, aquatic insects and cephalopods, a group that today includes squid, octopuses and cuttlefish. Ray-finned fishes have backbones and fins supported by bony rods called rays.

 

When the fish died, the soft tissues of its brain and cranial nerves were replaced during the fossilization process with a dense mineral that preserved, in exquisite detail, their three-dimensional structure.

 

"An important conclusion is that these kinds of soft parts can be preserved, and they may be preserved in fossils that we've had for a long time—this is a fossil that's been known for over 100 years," said U-M paleontologist Matt Friedman, a senior author of the new study and director of the Museum of Paleontology.

 

The lead author is U-M doctoral student Rodrigo Figueroa, who did the work as part of his dissertation, under Friedman, in the Department of Earth and Environmental Sciences.

 

"Not only does this superficially unimpressive and small fossil show us the oldest example of a fossilized vertebrate brain, but it also shows that much of what we thought about brain evolution from living species alone will need reworking," Figueroa said.

 

"With the widespread availability of modern imaging techniques, I would not be surprised if we find that fossil brains and other soft parts are much more common than we previously thought. From now on, our research group and others will look at fossil fish heads with a new and different perspective."

 

The skull fossil from England is the only known specimen of its species, so only nondestructive techniques could be used during the U-M-led study.

 

The work on Coccocephalus is part of a broader effort by Friedman, Figueroa and colleagues that uses computed tomography (CT) scanning to peer inside the skulls of early ray-finned fishes. The goal of the larger study is to obtain internal anatomical details that provide insights about evolutionary relationships.

 

In the case of C. wildi, Friedman was not looking for a brain when he fired up his micro-CT scanner and examined the skull fossil.

 

"I scanned it, then I loaded the data into the software we use to visualize these scans and noticed that there was an unusual, distinct object inside the skull," he said. 

 

The unidentified blob was brighter on the CT image—and therefore likely denser—than the bones of the skull or the surrounding rock.

 

"It is common to see amorphous mineral growths in fossils, but this object had a clearly defined structure," Friedman said.

 

The mystery object displayed several features found in vertebrate brains: It was bilaterally symmetrical, it contained hollow spaces similar in appearance to ventricles, and it had multiple filaments extending toward openings in the braincase, similar in appearance to cranial nerves, which travel through such canals in living species.

 

"It had all these features, and I said to myself, 'Is this really a brain that I'm looking at?'" Friedman said. "So I zoomed in on that region of the skull to make a second, higher-resolution scan, and it was very clear that that's exactly what it had to be. And it was only because this was such an unambiguous example that we decided to take it further."

 

Though preserved brain tissue has rarely been found in vertebrate fossils, scientists have had better success with invertebrates. For example, the intact brain of a 310-million-year-old horseshoe crab was reported in 2021, and scans of amber-encased insects have revealed brains and other organs. There is even evidence of brains and other parts of the nervous system recorded in flattened specimens more than 500 million years old.

 

The preserved brain of a 300-million-year-old shark relative was reported in 2009. But sharks, rays and skates are cartilaginous fishes, which today hold relatively few species compared to the ray-finned fish lineage containing Coccocephalus. Early ray-finned fishes like Coccocephalus can tell scientists about the initial evolutionary phases of today's most diverse fish group, which includes everything from trout to tuna, seahorses to flounder.

 

There are roughly 30,000 ray-finned fish species, and they account for about half of all backboned animal species. The other half is split between land vertebrates—birds, mammals, reptiles and amphibians—and less diverse fish groups like jawless fishes and cartilaginous fishes.

 

The Coccocephalus skull fossil is on loan to Friedman from England's Manchester Museum. It was recovered from the roof of the Mountain Fourfoot coal mine in Lancashire and was first scientifically described in 1925. The fossil was found in a layer of soapstone adjacent to a coal seam in the mine.

 

Though only its skull was recovered, scientists believe that C. wildi would have been 6 to 8 inches long. Judging from its jaw shape and its teeth, it was probably a carnivore, according to Figueroa.

 

When the fish died, scientists suspect it was quickly buried in sediments with little oxygen present. Such environments can slow the decomposition of soft body parts.

 

In addition, a chemical micro-environment inside the skull's braincase may have helped to preserve the delicate brain tissues and to replace them with a dense mineral, possibly pyrite, Figueroa said.

 

Evidence supporting this idea comes from the cranial nerves, which send electrical signals between the brain and the sensory organs. In the Coccocephalus fossil, the cranial nerves are intact inside the braincase but disappear as they exit the skull.

 

"There seems to be, inside this tightly enclosed void in the skull, a little micro-environment that is conducive to the replacement of those soft parts with some kind of mineral phase, capturing the shape of tissues that would otherwise simply decay away," Friedman said.

 

Detailed analysis of the fossil, along with comparisons to the brains of modern-fish specimens from the U-M Museum of Zoology collection, revealed that the brain of Coccocephalus has a raisin-size central body with three main regions that roughly correspond to the forebrain, midbrain and hindbrain in living fishes.

 

Cranial nerves project from both sides of the central body. Viewed as a single unit, the central body and the cranial nerves resemble a tiny crustacean, such as a lobster or a crab, with projecting arms, legs and claws.

 

Notably, the brain structure of Coccocephalus indicates a more complicated pattern of fish-brain evolution than is suggested by living species alone, according to the authors. 

 

"These features give the fossil real value in understanding patterns of brain evolution, rather than simply being a curiosity of unexpected preservation," Figueroa said.

 

For example, all living ray-finned fishes have an everted brain, meaning that the brains of embryonic fish develop by folding tissues from the inside of the embryo outward, like a sock turned inside out.

 

All other vertebrates have evaginated brains, meaning that neural tissue in developing brains folds inward.

 

"Unlike all living ray-finned fishes, the brain of Coccocephalus folds inward," Friedman said. "So, this fossil is capturing a time before that signature feature of ray-finned fish brains evolved. This provides us with some constraints on when this trait evolved—something that we did not have a good handle on before the new data on Coccocephalus."

 

Comparisons to living fishes showed that the brain of Coccocephalus is most similar to the brains of sturgeons and paddlefish, which are often called "primitive" fishes because they diverged from all other living ray-finned fishes more than 300 million years ago.

 

Friedman and Figueroa are continuing to CT scan the skulls of ray-finned fish fossils, including several specimens that Figueroa brought to Ann Arbor on loan from institutions in his home country, Brazil. Figueroa said his doctoral dissertation was delayed by the COVID-19 pandemic but is expected to be completed in summer 2024.

 

The Nature study includes data produced at U-M's Computed Tomography in Earth and Environmental Science facility, which is supported by the Department of Earth and Environmental Sciences and the College of Literature, Science, and the Arts.

 

The other authors of the paper are Sam Giles of London's Natural History Museum and the University of Birmingham; Danielle Goodvin and Matthew Kolmann of the U-M Museum of Paleontology; and Michael Coates and Abigail Caron of the University of Chicago.

 

Friedman and Figueroa said the discovery highlights the importance of preserving specimens in paleontology and zoology museums.

 

"Here we've found remarkable preservation in a fossil examined several times before by multiple people over the past century," Friedman said. "But because we have these new tools for looking inside of fossils, it reveals another layer of information to us.

 

"That's why holding onto the physical specimens is so important. Because who knows, in 100 years, what people might be able to do with the fossils in our collections now."

Study: Exceptional fossil preservation and evolution of the ray-finned fish brain (DOI 10.1038/s41586-022-05666-1, will be available once the embargo lifts)

 

---

JOURNAL

Nature

DOI

10.1038/s41586-022-05666-1 

 

Dinosaur study challenges Bergmann’s rule

UNIVERSITY OF ALASKA FAIRBANKS

 

IMAGE: 

NANUQSAURUS, STANDING IN THE BACKGROUND, AND PACHYRHINOSAURUS, SKULL IN THE FOREGROUND, WERE AMONG THE DINOSAUR SPECIES INCLUDED IN A NEW STUDY LED BY SCIENTISTS AT THE UNIVERSITY OF ALASKA FAIRBANKS AND THE UNIVERSITY OF READING THAT CALLS INTO QUESTION BERGMANN’S RULE.

view more 

CREDIT: ART BY JAMES HAVENS

When you throw dinosaurs into the mix, sometimes you find that a rule simply isn’t.

A new study led by scientists at the University of Alaska Fairbanks and the University of Reading calls into question Bergmann’s rule, an 1800s-era scientific principle stating that animals in high-latitude, cooler climates tend to be larger than close relatives living in warmer climates.

The fossil record shows otherwise.

“Our study shows that the evolution of diverse body sizes in dinosaurs and mammals cannot be reduced to simply being a function of latitude or temperature,” said Lauren Wilson, a UAF graduate student and a lead author of a paper published today in the journal Nature Communications. “We found that Bergmann’s rule is only applicable to a subset of homeothermic animals (those that maintain stable body temperatures), and only when you consider temperature, ignoring all other climatic variables. This suggests that Bergmann’s ‘rule’ is really the exception rather than the rule.”

The study started as a simple question Wilson discussed with her undergraduate advisor: Does Bergmann’s rule apply to dinosaurs?

After evaluating hundreds of data points gleaned from the fossil record, the answer seemed a solid “no.”

The dataset included the northernmost dinosaurs known to scientists, those in Alaska’s Prince Creek Formation. They experienced freezing temperatures and snowfall. Despite this, the researchers found no notable increase in body size for any of the Arctic dinosaurs.

Next the researchers tried the same evaluation with modern mammals and birds, the descendants of prehistoric mammals and dinosaurs. The results were largely the same: Latitude was not a predictor of body size in modern bird and mammal species. There was a small relationship between the body size of modern birds and temperature, but the same was not the case for prehistoric birds.

The researchers say the study is a good example of how scientists can and should use the fossil record to test current-day scientific rules and hypotheses.

“The fossil record provides a window into completely different ecosystems and climate conditions, allowing us to assess the applicability of these ecological rules in a whole new way,” said Jacob Gardner, a postdoctoral researcher at the University of Reading and the other lead author of the paper.

Scientific rules should apply to fossil organisms in the same way they do modern organisms, said Pat Druckenmiller, director of the University of Alaska Museum of the North and one of the co-authors of the paper.

“You can’t understand modern ecosystems if you ignore their evolutionary roots,” he said. “You have to look to the past to understand how things became what they are today.”

ADDITIONAL INFORMATION: Read the paper in Nature Communications.

ADDITIONAL CONTACTS: Lauren Wilson, lnkeller@alaska.edu, 406-223-4762. Jacob Gardner, jacob.gardner@reading.ac.uk. Pat Druckenmiller, psdruckenmiller@alaska.edu, 907-474-6989. Chris Organ, Montana State University, organ@montana.edu.

NOTE TO EDITORS: An illustration is available on the UAF news website.

---

JOURNAL

Nature Communications

DOI

10.1038/s41467-024-46843-2 

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Global latitudinal gradients and the evolution of body size in dinosaurs and mammals

ARTICLE PUBLICATION DATE

5-Apr-2024

In the evolution of walking, the hip bone connected to the rib bones

New data from a 375-million-year-old fossil fish gives clues to changes in the axial skeleton that might have helped our ancestors climb out of the water

PENN STATE

 

IMAGE: 

NEW RECONSTRUCTION OF THE SKELETON OF THE 375-MILLION-YEAR-OLD FOSSIL FISH, TIKTAALIK ROSEAE. IN A NEW STUDY, RESEARCHERS USED MICRO-CT TO REVEAL VERTEBRAE AND RIBS OF THE FISH THAT WERE PREVIOUSLY HIDDEN BENEATH ROCK. THE NEW RECONSTRUCTION SHOWS THAT THE FISH’S RIBS LIKELY ATTACHED TO ITS PELVIS, AN INNOVATION THOUGHT TO BE CRUCIAL TO SUPPORTING THE BODY AND FOR THE EVENTUAL EVOLUTION OF WALKING.

view more 

CREDIT: THOMAS STEWART, PENN STATE

UNIVERSITY PARK, Pa. — Before the evolution of legs from fins, the axial skeleton — including the bones of the head, neck, back and ribs — was already going through changes that would eventually help our ancestors support their bodies to walk on land. A research team including a Penn State biologist completed a new reconstruction of the skeleton of Tiktaalik, the 375-million-year-old fossil fish that is one of the closest relatives to limbed vertebrates. The new reconstruction shows that the fish’s ribs likely attached to its pelvis, an innovation thought to be crucial to supporting the body and for the eventual evolution of walking.

A paper describing the new reconstruction, which used microcomputed tomography (micro-CT) to scan the fossil and reveal vertebrae and ribs of the fish that were previously hidden beneath rock, appeared April 2 in the journal Proceedings of the National Academy of Sciences.

“Tiktaalik was discovered in 2004, but key parts of its skeleton were unknown,” said Tom Stewart, assistant professor of biology in the Eberly College of Science at Penn State and one of the leaders of the research team. “These new high-resolution micro-CT scans show us the vertebrae and ribs of Tiktaalik and allow us to make a full reconstruction of its skeleton, which is vital to understanding how it moved through the world.”

Unlike most fish, which have vertebrae and ribs that are the same along the length of the trunk, the axial skeletons of limbed vertebrates show dramatic differences in the vertebrae and ribs from the head region to the tail region. The evolution of this regionalization allowed the performance of specialized functions, one of which was a mechanical linkage between ribs in the sacral region to the pelvis that enabled support of the body by the hind limbs.

The pelvic fins of fish are evolutionarily related to hind limbs in tetrapods — four-limbed vertebrates, including humans. In fish, the pelvic fins and bones of the pelvic girdle are relatively small and float freely in the body. For the evolution of walking, the researchers explained, the hind limbs and pelvis became much larger and formed a connection to the vertebral column as a way of bracing the forces related to supporting the body.

“Tiktaalik is remarkable because it gives us glimpses into this major evolutionary transition,” Stewart said. “Across its whole skeleton, we see a combination of traits that are typical of fish and life in water as well as traits that are seen in land-dwelling animals.”

The original description of Tiktaalik focused on the front portion of the skeleton. Fossils were meticulously prepared to remove the surrounding matrix of rock and expose the skull, shoulder girdle and pectoral fins. The ribs in this area were large and expanded, suggesting that they may have supported the body in some way, but it was unclear exactly how they would have functioned. In 2014, the fish’s pelvis, discovered in the same location as the rest of the skeleton, was also cleaned of matrix and described.

“From past studies, we knew that the pelvis was large, and we had a sense that the hind fins were large too, but until now couldn’t say if or how the pelvis interacted with the axial skeleton,” Stewart said. “This reconstruction shows, for the first-time, how it all fit together and gives us clues about how walking might have first evolved.”

The researchers explained that, unlike our own hips where our bones fit tightly together, the connection between the pelvis and axial skeleton of Tiktaalik was likely a soft-tissue connection made of ligaments.

“Tiktaalik had specialized ribs that would have connected to the pelvis by a ligament,” Stewart said. “It’s astonishing really. This creature has so many traits — large pair of hind appendages, large pelvis, and connection between the pelvis and axial skeleton — that were key to the origin of walking. And while Tiktaalik probably wasn’t walking across land, it was definitely doing something new. This was a fish that could likely prop itself up and push with its hind fin.”

The new reconstruction of the skeleton also sheds light on specializations for head mobility in Tiktaalik and new details of the fish’s pelvic fin anatomy.

"It's incredible to see the skeleton of Tiktaalik captured in such vivid detail,” said Neil Shubin, Robert R. Bensley Distinguished Service Professor of Organismal Biology and Anatomy at the University of Chicago and one of the authors of the paper. “This study sets the stage for ones that explore how the animal moved about and interacted with its environment 375 million years ago."

In addition to Stewart and Shubin, the research team includes Justin B. Lemberg, Emily J. Hillan, and Isaac Magallanes at The University of Chicago, and Edward B. Daeschler at Academy of Natural Sciences of Drexel University.

Support from the Brinson Foundation, the Biological Sciences Division of The University of Chicago, an anonymous donor to the Academy of Natural Sciences of Drexel University, and the U.S. National Science Foundation funded this research. Fieldwork was made possible by the Polar Continental Shelf Project of Natural Resources, Canada; the Department of Heritage and Culture, Nunavut; the hamlets of Resolute Bay and Grise Fiord of Nunavut; and the Iviq Hunters and Trappers of Grise Fiord.

---

JOURNAL

Proceedings of the National Academy of Sciences

DOI

10.1073/pnas.231610612 

ARTICLE TITLE

The axial skeleton of Tiktaalik roseae