The nearly complete remains of two extinct giant marine predators, found on what was once the bottom of a southern Alberta inland sea, are filling in the evolutionary blanks for researchers at the Royal Tyrrell Museum of Palaeontology.
For over a century, scientists didn't have enough fossil evidence to confirm what Prognathodon, a particularly large-headed mosasaur from 74 million years ago, looked like in real life.
But a mining company looking for ammolite, a rare opal-like organic gemstone found along the eastern slopes of the Rocky Mountains, discovered the fossils of two different Prognathodon specimens along the St. Mary River, south of Lethbridge. The miners had dug down over 100 metres when they discovered the fossils and called the museum.
"The time that those two marine lizard specimens were around was when the sea invaded the land of much of southern Alberta," said paleontologist Takuya Konishi in an interview with The Canadian Press.
"That doesn't mean that dinosaurs weren't around, but they had to move as the shore pushed them backward. That's when those marine carnivores flourished along with many other marine organisms, including ammolites, for example."
The remains of the Prognathodon first caught the eye of scientists more than 100 years ago but fossils were never complete — until now. These two specimens were in particularly good shape because of the muddy sediment packed around their bodies.
"It's very exciting. The two specimens kind of complement each other because the first one had beautiful flippers preserved along with the rest of the body, but its skull wasn't as good a shape. But the second one was slightly bigger, it had a beautiful skull, it had a gut content, a whole skeleton but no flippers," said Konishi.
"It eventually gave us a virtually complete image what this looked like, which is great news for us, because this particular genus was known for over 100 years. However, we only knew what it looked like based on the head because the skeleton was never found."
Konishi said there was no proof before that the Prognathodon had flippers. The body was also thought to be much larger than it actually was. The fossils show the skeleton to be rather slender.
The giant lizard was about six metres long and the head accounted for about 12 to 15 per cent of that. It would have weighed three to four tonnes.
Finding the stomach contents was a bonus since less than a dozen of the 4,000 mosasaur fossils found by scientists had the remains of their last meals.
"Those big teeth could handle both hard-shelled animals like the sea turtle, which is one of the things found in the gut contents, but also it contained the remains of a big fish about five feet long," Konishi said.
"These predators (could) handle both hard and soft prey. They could eat nearly anything that swam in the ocean."
The findings by Konishi and Donald Brinkman are published in the September 2011 edition of the Journal of Vertebrate Paleontology.
Note to readers: This is a corrected story. A previous version stated the mososaur weighed 3 thousand to 4 thousand tonnes
Author: Bill Graveland | Source: Winnipeg Free Press [September 28, 2011]
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| The nearly complete remains of two extinct giant marine predators, found on what was once the bottom of a southern Alberta inland sea, are filling in the evolutionary blanks for researchers at the Royal Tyrrell Museum of Palaeontology. The skull of Prognathodon, a particularly large-headed mosasaur [Credit: The Canadian Press/HO- Royal Tyrrell Museum] |
But a mining company looking for ammolite, a rare opal-like organic gemstone found along the eastern slopes of the Rocky Mountains, discovered the fossils of two different Prognathodon specimens along the St. Mary River, south of Lethbridge. The miners had dug down over 100 metres when they discovered the fossils and called the museum.
"The time that those two marine lizard specimens were around was when the sea invaded the land of much of southern Alberta," said paleontologist Takuya Konishi in an interview with The Canadian Press.
"That doesn't mean that dinosaurs weren't around, but they had to move as the shore pushed them backward. That's when those marine carnivores flourished along with many other marine organisms, including ammolites, for example."
The remains of the Prognathodon first caught the eye of scientists more than 100 years ago but fossils were never complete — until now. These two specimens were in particularly good shape because of the muddy sediment packed around their bodies.
"It's very exciting. The two specimens kind of complement each other because the first one had beautiful flippers preserved along with the rest of the body, but its skull wasn't as good a shape. But the second one was slightly bigger, it had a beautiful skull, it had a gut content, a whole skeleton but no flippers," said Konishi.
"It eventually gave us a virtually complete image what this looked like, which is great news for us, because this particular genus was known for over 100 years. However, we only knew what it looked like based on the head because the skeleton was never found."
Konishi said there was no proof before that the Prognathodon had flippers. The body was also thought to be much larger than it actually was. The fossils show the skeleton to be rather slender.
The giant lizard was about six metres long and the head accounted for about 12 to 15 per cent of that. It would have weighed three to four tonnes.
Finding the stomach contents was a bonus since less than a dozen of the 4,000 mosasaur fossils found by scientists had the remains of their last meals.
"Those big teeth could handle both hard-shelled animals like the sea turtle, which is one of the things found in the gut contents, but also it contained the remains of a big fish about five feet long," Konishi said.
"These predators (could) handle both hard and soft prey. They could eat nearly anything that swam in the ocean."
The findings by Konishi and Donald Brinkman are published in the September 2011 edition of the Journal of Vertebrate Paleontology.
Note to readers: This is a corrected story. A previous version stated the mososaur weighed 3 thousand to 4 thousand tonnes
Author: Bill Graveland | Source: Winnipeg Free Press [September 28, 2011]