Prehistoric / Fossil Sharks

[ramonmercado]

A real giant shark... fossil.

Giant predatory shark fossil unearthed in Kansas
http://news.bbc.co.uk/earth/hi/earth_ne ... 530995.stm
By Matt Walker
Editor, Earth News

A nurse shark may be similar in shape, but not size to the prehistoric fossil
A nurse shark may be similar in shape but not size to the prehistoric fossil

The fossilised remains of a gigantic 10m-long predatory shark have been unearthed in Kansas, US.

Scientists dug up a gigantic jawbone, teeth and scales belonging to the shark which lived 89 million years ago.

The bottom-dwelling predator had huge tooth plates, which it likely used to crush large shelled animals such as giant clams.

Palaeontologists already knew about the shark, but the new specimen suggests it was far bigger than previously thought.

The scientists who made the discovery, published in the journal Cretaceous Research, last week also released details of other newly discovered giant plankton-eating fish that swam in prehistoric seas for more than 100 million years.

The size of the jaw fragment in fact supports the contention that P. mortoni was a gigantic animal
Dr Kenshu Shimada, DePaul University

But this new fish, called Ptychodus mortoni, is both bigger and more fierce, having a taste for flesh rather than plankton.

It may even have been the largest shellfish-eating animal ever to have roamed the Earth.

Dr Kenshu Shimada of DePaul university in Chicago, Illinois, US found the fossilized remains of the shark in rocks known as the Fort Hays Limestone in Kansas.

"Kansas back then was smack in the middle of an inland sea known as the Western Interior Seaway that extended in a north-south direction across North America," says Dr Shimada.
Diagram showing jaw fragment and line drawing of giant shark
The jawbone fragment came from a huge fish (diagram courtesy of Dr Shimada)

Along with a piece of jaw, Dr Shimada and colleagues uncovered a piece of jaw, teeth and scales.

"Although it represents a fraction of the entire body of the shark, the jaw fragment is gigantic. The estimated jaw length was almost 1m long, and that would suggest that the shark was likely at least 10m in length," says Dr Shimada.

Due to the lack of a complete skeleton, it is difficult to gauge the physical appearance of the shark.

But Dr Shimada suspects it had a body shaped much like that of a modern nurse shark (Ginglymostoma cirratum), with a broad rounded head and stout body.

MARINE PREDATORS: FIND OUT MORE
Pliosaur (Mark Witton)

A colossal sea monster, a 16m-long pliosaur, was recently discovered along the coast of Dorset, UK
One of the rarest giants of the ocean, the smalleye stingray, was only caught on film for the first time last year: watch it here
Great white sharks of South Africa select a particular anchor point, and search for their next victim close to this location
The odd-shaped head of the hammerhead shark gives it outstanding binocular vision and an ability to see through 360 degrees
The modern whale shark is the largest fish in the world, the longest ever recorded being 13.5m in length: watch video of it here

However, its teeth and lifestyle would have been very different.

Hundreds of robust teeth line the upper and lower parts of the shark's mouth, forming large slab-like plates capable of crushing shellfish.

"This in turn suggests that P. mortoni was probably a sluggish bottom-dwelling shark, rather than an actively fast swimmer," says Dr Shimada.

Fossils of this and other closely-related species have long been known.

"While there have been many teeth and a few incomplete skeletal remains of P. mortoni in museum collections, the significance of this new specimen is that it contains one of the largest teeth of this species that were found with a gigantic jaw fragment.

"The size of the jaw fragment in fact supports the contention that P. mortoni was likely a gigantic animal," says Dr Shimada.

The scientists have dated the fossil at 88.7 million years old.

At that time, a variety of animals, such as giant clams, other sharks, bony fishes, and predatory marine reptiles called mosasaurs and plesiosaurs inhabited the same water.

Some, including certain mosasaurs would also have grown to gigantic proportions, reaching lengths of 10m or more.
Dr Shimada excavates the jawbone
Dr Shimada excavates the jawbone

Why P. mortoni became so huge is still a mystery.

"The emergence of large ptychodontids roughly coincides with the timing of when many other kinds of organisms, including clams as well as sharks and bony fishes, became bigger," explains Dr Shimada.

"Clearly, the food resources must have been abundant enough in the marine ecosystem to support such large organisms.

"Becoming big does have advantages such as deterring predators and being able to travel faster, but it does come with disadvantages as well, most notably needing more food for energy."
Ptychodus mortoni's tooth
Ptychodus mortoni's tooth, close up

Another specimen of P. mortoni has been found alongside another type of meat-eating shark called Squalicorax, with some scientists suggesting that the meat-eating shark may have been scavenging on the body of its larger relative.

Last week, Dr Shimada and colleagues published details in the journal Science of how a dynasty of large plankton-eating fish roamed the oceans between 66 and 172 million years ago.

These fish died out with the dinosaurs.

Once they had vanished from the ecosystem, mammals and cartilaginous fish such as manta rays, basking sharks and whale sharks began to adapt to fill a similar ecological role.

 

[Comfortably Numb]

HEAD OF GIANT 330-MILLION-YEAR-OLD SHARK FOUND IN WALL OF KENTUCKY CAVE

Source: newsweek.com
Date: 30 January, 2020

Researchers have uncovered the remnants of a huge, fossilized shark head in the walls of a cave in Kentucky.

The remains of the ancient animal are located in Mammoth Cave National Park, which is home to the longest known cave system on Earth—one that extends for more than 400 miles, according to the National Park Service.

The shark fossil—dated to around 330 million years ago—was first spotted alongside several others by Rick Olson and Rick Toomey, two Mammoth Cave experts who were conducting investigations of the area, the Louisville Courier Journal reported.

The pair took photos of the fossils and sent them to Vincent Santucci, a paleontologist with the National Park Service, in the hope he could identify them.

Santucci also passed the images on to John-Paul Hodnett, a paleontologist at Dinosaur Park in Maryland. This site contains rare fossil deposits from around 115 million years ago.

Hodnett was able to identify most of the shark fossils in the images, however, he became particularly interested in one set of remains.

https://www-newsweek-com.cdn.amppro...ion-year-old-shark-wall-kentucky-cave-1484825

 

[Comfortably Numb]

Wide-eyed prehistoric shark hid its sharpest teeth in nightmare jaws

Source: livescience.com
Date: 23 November, 2020

Imagine you're a fish swimming through the ocean millions of years ago, when a shark lunges at you, gaping its mouth to bite. The horror of your predicament increases as the predator's lower jaw also stretches downward on both sides, so that newer, sharper teeth that were previously lying flat along the side of the jaw now curve up.

Scientists recently discovered this nightmarish trait in a fossil of a 370 million-year-old shark that once inhabited waters near what is now Morocco. The previously undescribed species, dubbed Ferromirum oukherbouchi, had a jaw that rotated inward when the mouth was closed, and outward when the mouth was open.

Unlike modern sharks, in which worn-down teeth are constantly displaced by new teeth, this shark sprouted its newer teeth in a row on the inside of the jaw, next to the older teeth. As the new teeth grew, they curved toward the shark's tongue. When the shark opened its mouth, cartilage at the back of the jaw flexed so that the sides of the jaw "folded" down and newer teeth rotated upward, allowing the shark to bite into its prey with as many teeth as possible, according to a new study.

https://www.livescience.com/ancient-shark-nightmare-jaws.html

 

[EnolaGaia]

A previously unknown prehistoric shark - the eagle shark - had long 'wings' for its pectoral fins and probably 'flew' through the water like modern rays.

'Winged' eagle shark soared through oceans 93 million years ago

A bizarre shark with wing-like fins and a wide, gaping mouth soared through the seas of what is now Mexico about 93 million years ago, when dinosaurs still roamed the Earth, a new study finds.

This odd shark — dubbed Aquilolamna milarcae, or eagle shark of the Milarca Museum, where its fossil will go on display — looks remarkably like manta and devil rays, which also sport finned "wings." (Rays are closely related to, but are not, sharks.) This shark lived more than 30 million years before either of those creatures existed, the researchers said.

That's not the only similarity: This ancient shark was likely a filter feeder that gulped down tiny plankton-like critters when it was hungry, just like manta and devil rays do today. So, it's likely that the eagle shark lived in the same type of marine real estate that modern manta and devil rays do now ...

This winged shark is unlike any shark alive today. "One of the most striking features of Aquilolamna is that it has very long, slender pectoral [side] fins" ... "This makes the shark wider than long," with a "wingspan" of about 6.2 feet (1.9 meters) and a total body length of about 5.4 feet (1.65 meters). ...

FULL STORY: https://www.livescience.com/ancient-shark-flew-through-dinosaur-age-seas.html

 

[Lord Lucan]

An ancestor of the megalodon has been discovered...

Scientists collect specimen from new shark species and discover a deep ocean graveyard​

Scientists have made a major finding more than 5km underwater, on a voyage that has also unveiled a new species of shark.

A shark graveyard containing fossilised teeth from an ancient ancestor of the massive but mysterious megalodon has been discovered by scientists exploring the deep ocean.
The team from the CSIRO research vessel, Investigator, have also collected a specimen from a new species of shark.

The extraordinary discoveries came during biodiversity surveys around the Cocos (Keeling) Islands in the Indian Ocean and the Gascoyne marine park off Western Australia.

Scientists were conducting a final trawl survey at a depth of 5400m when they spotted the graveyard, bringing up more than 750 fossilised shark teeth.

https://www.news.com.au/technology/...d/news-story/7cc6c0890675f2e205b5f1e12eb686eb