Friday, November 19, 2010
Mediterranean Sharks Resulted from Wrong Turn
A new study involving Mediterranean great white sharks suggests that they are more closely related to sharks from Australia and New Zealand, and less similar to those of the Atlantic Ocean as previously thought. It is believed that the group of Mediterranean sharks arrived about 450,000 years ago after making a "wrong turn" on their return to the location of their birth. This period of time was an interglacial period, in which extreme current variations were occurring. The change in warm and cold currents may have been significant enough to alter the course of the migrating sharks. If only a few shark pups were born in the Mediterranean waters, the study indicates that this would be all that was needed to begin a new cycle of migration to the same location for future generations. This is an interesting study which may have implications for other species migrations during interglacial periods.
Thursday, October 21, 2010
Quetzalcoatlus
Quetzalcoatlus was a Late Cretaceous pterosaur known from North America, and a member of the family Azhdarchidae - known as advanced, toothless pterosaurs characterised by long, stiffened necks. Its name comes from Quetzalcoatl, a feathered serpent deity of the peoples of central Mexico, Nicaragua, and Honduras.
Please visit Shiraishi Mineo's Jurassic Gallery, the talented artist who created this image, with a beautiful gallery of images of dinosaurs, pterosaurs, and other prehistoric animals. This was my favourite image of all the Quetzalcoatlus images I have seen so far.
The feeding style adopted by Quetzalcoatlus is controversial. Originally it was theorised that Quetzalcoatlus fed on fish, scooping them from the sea as it flew overhead. It has also been suggested that the pterosaur was a scavenger, because some remains had been found in an area devoid of lakes or rivers, and was far inland. But the shape of its jaw suggested to others that it could have fed by skimming over the sea and collecting fish in its mouth. This skimming technique was later disproved because the energy costs for the shape of the pterosaur would be too high, as well as the fact that the remains were found in an inland area rather than a coastal environment. Another theory suggests that Quetzalcoatlus hunted by terrestrial stalking, hunting small vertebrates on land or in streams. The modern analogue for this behaviour is in storks. Quetzalcoatlus would have walked on its hind legs and folded wings.
One important point to remember is that pterosaurs were not dinosaurs! Dinosaurs are terrestrial animals only! This includes plesiosaurs and similar marine creatures contemporaneous with dinosaurs, which were actually marine reptiles.
The feeding style adopted by Quetzalcoatlus is controversial. Originally it was theorised that Quetzalcoatlus fed on fish, scooping them from the sea as it flew overhead. It has also been suggested that the pterosaur was a scavenger, because some remains had been found in an area devoid of lakes or rivers, and was far inland. But the shape of its jaw suggested to others that it could have fed by skimming over the sea and collecting fish in its mouth. This skimming technique was later disproved because the energy costs for the shape of the pterosaur would be too high, as well as the fact that the remains were found in an inland area rather than a coastal environment. Another theory suggests that Quetzalcoatlus hunted by terrestrial stalking, hunting small vertebrates on land or in streams. The modern analogue for this behaviour is in storks. Quetzalcoatlus would have walked on its hind legs and folded wings.
One important point to remember is that pterosaurs were not dinosaurs! Dinosaurs are terrestrial animals only! This includes plesiosaurs and similar marine creatures contemporaneous with dinosaurs, which were actually marine reptiles.
Friday, September 24, 2010
Fossil Discovery of Utah Ceratopsians
Fossils of new species of horned dinos found in Utah (BBC)
Scientists digging in south-central Utah found two new species of ceratopsians in the Grand Staircase-Escalante National Monument, in the Kaiparowits Formation. They found a specimen with a particularly large horn over the nose and a massive head which they dubbed Utahceratops gettyi. They also found a very ornately-ornamented specimen with a total of 15 horns on its head which they called Kosmoceratops richardsoni.
Both dinosaurs lived on the ancient landmass of Laramidia, which was formed when a late Cretaceous inland seaway split the North American continent in half into the western landmass of Laramidia and the eastern landmass of Appalachia. Many fossils have been found in the northern part of the ancient Laramidia landmass, but until recently fossils from the southern portion have been lacking. The National Monument in southern Utah has produced an abundance of fossil specimens and may begin to make up the disparity between northern and southern fossils.
Further analysis could provide answers to many questions, such as why there was not a lot of exchange between dinosaurs in the northern and southern parts of Laramidia (a physical barrier?) or why there was such a high diversity of large animals living in a relatively small area (there were about two dozen different species of large dinosaurs living on a landmass a quarter of the size of the African continent).
For the scientific paper: New Horned Dinosaurs from Utah Provide Evidence for Intracontinental Dinosaur Endemism
Scientists digging in south-central Utah found two new species of ceratopsians in the Grand Staircase-Escalante National Monument, in the Kaiparowits Formation. They found a specimen with a particularly large horn over the nose and a massive head which they dubbed Utahceratops gettyi. They also found a very ornately-ornamented specimen with a total of 15 horns on its head which they called Kosmoceratops richardsoni.
 |
| Top: Utahceratops gettyi Bottom: Kosmoceratops richardsoni |
Both dinosaurs lived on the ancient landmass of Laramidia, which was formed when a late Cretaceous inland seaway split the North American continent in half into the western landmass of Laramidia and the eastern landmass of Appalachia. Many fossils have been found in the northern part of the ancient Laramidia landmass, but until recently fossils from the southern portion have been lacking. The National Monument in southern Utah has produced an abundance of fossil specimens and may begin to make up the disparity between northern and southern fossils.
 |
| Utahceratops |
Further analysis could provide answers to many questions, such as why there was not a lot of exchange between dinosaurs in the northern and southern parts of Laramidia (a physical barrier?) or why there was such a high diversity of large animals living in a relatively small area (there were about two dozen different species of large dinosaurs living on a landmass a quarter of the size of the African continent).
For the scientific paper: New Horned Dinosaurs from Utah Provide Evidence for Intracontinental Dinosaur Endemism
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