Tag: Reptiles

Efforts over 15 years to protect the species in the US have helped boost the wolves’ numbers. This has been so successful that last year the US Fish and Wildlife Service removed Endangered Species Act (ESA) protection for wolves in Idaho and Montana, though not in Wyoming. But last week, district judge Donald Malloy overturned that decision. He ruled that the law did not allow one part of the population to be hunted and another part protected. “This decision is a significant victory for wolves, for the integrity of the ESA, and for all Americans who care deeply about conservation,” says Rodger Schlickeisen, president of Defenders of Wildlife, which was a plaintiff in the case. However, Carolyn Sime, statewide wolf coordinator at Montana Fish, Wildlife and Parks, says the decision will be costly for farmers. “A minimum of 100 cattle and in some years up to 200 sheep are confirmed killed by wolves each year in Montana. That represents a significant financial burden if you’re a livestock owner,” Sime says. “The ability to manage a wolf population under fair chase hunting is now lost.”

There are more than 1700 grey wolves in the northern Rockies – an area that includes all of Idaho, Montana and Wyoming, plus portions of Washington, Oregon and Utah. Once abundant throughout North America, by the 1930s grey wolves had been exterminated in Montana, Idaho, Wyoming and south-western Canada. They were listed as endangered in 1974 under the ESA and reintroduced to the northern Rockies in the mid-1990s. “The service’s decision to delist the wolf in Idaho and Montana reflected the strong commitments from the states of Idaho and Montana to manage grey wolves in a sustainable manner,” says Tom Strickland of the US Fish and Wildlife Service. “Today’s ruling makes it clear this wolf population cannot be delisted until the state of Wyoming has instituted an adequate management programme, similar to those of Idaho and Montana.” “The million-dollar question is how to manage the wolves with these new legal hurdles,” says Sime. She says the parks service is looking at a range of options, including appealing the decision.

New Scientist
August 31, 2010

Original web page at New Scientist

Michael Knell carried a 75-million-year-old turtle into Bozeman Deaconess hospital recently, then laid it carefully on the bed that slides into the CT scanner. Hardly an ordinary patient, the turtle fossil was only the second in the world found with eggs inside it, said Knell, a Montana State University graduate student in earth sciences. His turtle (from the genus Adocus) came from the Grand Staircase-Escalante National Monument in Kanab, Utah. The previously described turtle, which was found in Alberta, is also an Adocus and lived about the same time. Knell wanted his fossil scanned to see if he could find a skull and more eggs and learn whether or not the eggs contained embryos. “It allows us to peer inside without digging into it,” Knell said. “It gives us a hands-off look without having to break anything.” “It’s very cool,” added Frankie Jackson, an MSU paleontologist who specializes in eggs. The CT machine looks like a giant doughnut with a narrow bed attached. Patients normally lie on the bed, then ride through the scanner while it takes images of a particular area. In this case, Knell wanted to scan the entire turtle. Although the edges of its shell were missing, the fossil measured about one foot across and weighed 40 to 50 pounds.

“It’s a lot easier than scanning people,” said CT technician Tanya Spence. Spence, who has scanned dinosaur fossils for MSU’s Museum of the Rockies, said she didn’t need to tell the fossil what it would experience during the CT scan. She didn’t need to ask the turtle to hold her breath. She didn’t worry about IV tubes or claustrophobia. “We get to see bodies everyday, but not these,” Spence said. “It’s fun.” Spence operated the scanner from an adjoining room while Knell and Jackson looked over her shoulders. As the CT scanner took cross-sections of the fossil, white images appeared — slice by slice — on Spence’s computer screen. “It’s very, very dense,” Spence said of the shell. “You can lose some detail when that happens. You have to penetrate enough to see, but you can sometime lose detail that way.” “Usually embryo bone doesn’t show up too well on a CT scan, so we might no be able to see embryos very well, but it could clue you in that you need to look at the eggs a little closer,” Jackson added.

As time went by, the scientists realized that the eggs weren’t showing up as clearly as they’d expected and they’d need to examine the images more closely. As a result, Spence saved her images to a disc and gave it to Knell. He and Jackson said they would contact the Museum of the Rockies, which has special software for looking at CT images from a variety of angles. The researchers expect to present their findings during the fourth international Symposium on Dinosaur Eggs and Babies. Knell’s adviser, David Varricchio, and Jackson are organizing the event, which will be held Aug. 8-10 at MSU. Knell said paleontologists have found about 10 different species of turtles and many fossilized egg shells in the hard sandstone of southern Utah. The team that found this Adocus in 2006 was led by Alan Titus, paleontologist at the Grand Staircase-Escalante National Monument, and Barry Albright, a researcher from the University of Northern Florida. Preparators learned that the turtle contained eggs after removing a section of its shell.

Adocus turtles generally laid small round eggs, about the same size as modern turtle eggs, Knell said. Based on what he knows about prehistoric turtles and living turtles, Knell said his Adocus was about a week away from laying the eggs when she died. He added that it’s rare to find turtle heads because the joint that connects them to the vertebrae is weak. Heads often get swept away and don’t stay with the bodies. Knell was hoping that his turtle’s skull had gone inside the shell before death.

Science Daily
May 4, 2009

Original web page at Science Daily

Dinosaurs’ hollow bones may have given them the puff to lead active lifestyles. A fossil find shows that the group of dinosaurs that included Velociraptor and Tyrannosaurus rex probably used the same super-efficient respiratory system that birds have today. The fossil, which is of a carnivorous dinosaur called Majungatholus atopus, shows that its bones included spaces for storing air. This would have allowed the species to have the quick metabolism necessary for an active predatory lifestyle.

Birds have fast metabolic rates thanks to their efficient way of extracting oxygen from the air. They have two lungs, as mammals do, but the airflow through them is controlled by a complex system of air sacs throughout the body. Most birds have nine such sacs, which also extend through their hollow bones. The fossil indicates that these animals had the potential for a high metabolic rate. “This study paints a clearer picture of how these organisms would have existed in their environment,” says O’Connor. “It indicates that these animals had the potential for a high metabolic rate.”

Birds are thought to be direct descendants of theropod dinosaurs, the group to which M. atopus belongs.
Palaeontologists already have evidence that the extinct creatures were similar to their descendants, with high growth rates, bird-like sleeping postures and even feathers. O’Connor compared the structure of air sacs in M. atopus’s vertebrae to those in more than 200 living birds. The structures were very similar, they report in Nature.”This study forms part of an increasingly robust story that says birds are essentially dinosaurs, but smaller,” says Paul Barrett, a palaeontologist at the Natural History Museum in London. “Using functional work in live animals is a nice addition, and perhaps now you could go as far as saying dinosaurs had a bird-like metabolism.” The study shows that the efficient breathing system of birds is older than previously thought, but Barrett thinks there is more to come: “To me it seems that a breathing system like this is of more ancient origin, from nearer the base of the dinosaur family tree.” He says that finding older dinosaur fossils would support this, and perhaps show that other bird-like characteristics are older than suspected.

Some palaeontologists still dispute that dinosaurs were closely related to birds, and have suggested that their breathing systems were more like those of crocodiles. “This work is another nail in the coffin for that competing theory,” says Barrett.

Nature
August 2, 2005

Original web page at Nature

A type of bone that female birds use as a calcium reserve for making eggshell has been found inside the fossilised thigh bone of a Tyrannosaurus rex. This new forensic clue could be used to sort the bones of female predatory dinosaurs from those of the males. Discerning the sex of fossilised animals is notoriously difficult. The obvious differences are in soft tissue that is not preserved. Some sex-specific traits are preserved in bones, such as differences in size or skull adornment. But without having seen living animals it is hard to be certain which sex is which, and if those differences are between individuals, species or even between the sexes of a single species.

So far the only sure way of identifying a dinosaur’s sex has been to find unlaid eggs inside a female, and only a couple of such fossils have been discovered – a Sinosauropteryx and an oviraptor. Now a structure called medullary bone, previously found only inside the leg bones of living female birds, has been identified inside the same T. rex femur which seems to have preserved blood vessels for nearly 70 million years.

Densely mineralised and rich in blood vessels, medullary bone can be deposited quickly when females ovulate and can quickly release calcium when it is needed to form eggshell, says Mary Schweitzer at North Carolina State University in Raleigh, US, and one of the study team. The calcium reserves are critical for female birds because they have strong but lightly-structured bones. Without medullary bone deposited in their marrow cavities, the calcium used for egg shells would come from their bones, giving them avian osteoporosis. Forming the shells depletes medullary bone, which in living birds remains depleted during brooding and until their next ovulation.

Schweitzer recognised the distinctive structure of medullary bone under the microscope. In the study, she shows the T. rex medullary bone is similar to that found in living emus and ostriches – large animals which are close to the evolutionary roots of modern birds. The similarity bolsters the case that birds evolved from theropod dinosaurs – two-legged predators such as Velociraptor and T. rex.

Living crocodiles do not have medullary bone, Schweitzer notes, and there is no evidence as yet that non-theropod dinosaurs did. “We have never seen anything like this in another dinosaur,” adds Jack Horner of Montana State University in Bozeman, US, and also on the team. Ancestral theropods were small animals with hollow bones, while other dinosaurs had very small marrow cavities with no room for such structures.

Journal reference: Science (vol 308, p 1456)

New Scientist
June 21, 2005

Original web page at New Scientist

The rare discovery of eggs inside a dinosaur has given scientists new clues about the reproductive biology of the creatures and more support for the theory that birds came from dinosaurs. The pair of shelled eggs is the first of its kind found inside a dinosaur, said researchers who reported the discovery in Friday’s issue of the journal Science.

Scientists found the dinosaur produced eggs in some ways like a crocodile and in other ways like a bird. Crocodiles and similar primitive reptiles have two ovaries enabling them to lay a clutch of eggs. Birds have a single ovary and can only lay one egg at a time. The dinosaur’s egg-producing capability lay somewhere in between, suggesting a link with the modern bird, researchers said. It could produce more than one egg, but only one from each ovary at a time.

The theory that birds came from dinosaurs has been supported by many researchers, said Tamaki Sato of the Canadian Museum of Nature in Ottawa. But this latest research helps advance it, she added, calling it “strong evidence.” There have been previous findings of round objects around dinosaur skeletons and scientists have suspected they might be eggs but because they did not have shells, there wasn’t certainty, Sato said. “You have egg shells with this one,” she said of the specimen at the National Museum of Natural Science in Taiwan that was excavated from China. “This is the first time for sure.”

The scientists studied a dinosaur from a group of dinosaurs called oviraptorosaurians. This type of dinosaur — probably 10 feet to 13 feet long — is a subgroup of the theropods, thought to have been the ancestors to modern birds. The remains of the shelled eggs looked like pineapple-sized potatoes. The similar size of the eggs suggests the creature’s two oviducts each produced a single, shelled egg at the same time, the report said. Matt Carrano, curator of dinosaurs at the National Museum of Natural History in Washington, said the findings provide greater insights into the biology of the dinosaur and the evolution of birds. “It’s a window into a particular stage of evolution,” he said. “This particular dinosaur has characteristics that are birdlike but retains reptillian-like features.” “You have oviducts but they’re only doing one egg at time. Its biology is half way there between a bird and reptile.” Carrano also said it tells something about birds.

“The evolution of one egg at a time happened very early, before birds could fly, and then the evolution of only one oviduct happened later,” he said. “That might be related to the origin of flight,” he said, explaining that maybe birds wanted to lighten their body and so developed one oviduct.

Yahoo
April 26, 2005

Original web page at Yahoo

Palaeontologists have extracted soft, flexible structures that appear to be blood vessels from the bone of a Tyrannosaurus rex that died 68 million years ago. They also have found small red microstructures that resemble red blood cells. The discovery suggests biological information can be recovered from a wider range of fossil material than realised, which would greatly help the tracing of evolutionary relationships. The preservation found by the researchers is extraordinary – far better than traditionally expected in dinosaur bone. But that may be because researchers have not been looking hard enough at their finds. Mary Schweitzer at North Carolina State University, US, has also extracted similar soft structures from a few other dinosaur bones.

The leg bone came from a skeleton called B-rex found in a remote canyon in South Dakota, in 2000 by a member of Jack Horner’s research team at the Museum of the Rockies in Montana. The 107-centimetre-long femur – small for a T. rex – was intact when found, and its hollow interior had not been filled with minerals. That is unusual for a long-buried bone. However, with a protective plaster jacket built around it, the bone was too heavy for a helicopter to retrieve it from the remote site and it had to be broken in half. When Horner’s group split the bone, they carefully took samples for Schweitzer, then working at the Museum of the Rockies.

Bones are built by cells called osteocytes which are nourished by a rich fabric of blood vessels. The osteocytes secrete proteins which collect the calcium compounds that give bones their strength. To see what remained of this internal structure, Schweitzer soaked samples of the core of the bone in a solution that dissolved the calcium compounds. This left what she describes as “a flexible vascular tissue that demonstrates great elasticity and resilience”. For comparison, she then examined ostrich bones, as these birds are the largest and closest living relatives of T. rex. She found similar structures when she removed the calcium from the ostrich bones and treated the mixture with enzymes to break down collagen fibre in the bony matrix.

Other researchers have previously recovered traces of protein from dinosaur bones, and indeed just two weeks ago Schweitzer reported traces of protein in 70 million year old dinosaur eggs. “[The T. rex paper] suggests that biological and biochemical information might be recoverable from a wide range of fossil material,” says Angela Milner of the Natural History Museum, in London, UK, who has detected proteins in Iguanadon bone. “There certainly seem to be blood vessels,” she told New Scientist.

The next step will be to isolate proteins and try to sequence them. Comparing protein sequences could help trace relationships with other prehistoric beasts and with animals alive today. Schweitzer decline to discuss DNA because she does not work with it, but DNA is far less stable than proteins so is usually broken into fragments, even in tissue that has been frozen since the ice age.

Journal reference: Science (vol 307, p 1952)

New Scientist
April 12, 2005

Original web page at New Scientist

A new species of crocodile which lived 40 million years ago has been discovered in tropical Australia, filling a gap in the evolution of the prehistoric-looking crocodile, researchers said on Thursday. Two nearly complete skulls and a lower jaw of a new species of crocodile that belonged to a group called Mekosuchinae were unearthed by miners in the northern state of Queensland, said Australia’s Monash University researcher Lucas Buchanan. “There is a big gap from about 30 to 60 million years ago of which we have no clue, except for these guys,” Buchanan told Reuters on Thursday.

Buchanan said the new species of crocodile was living in the early Tertiary period, from 65 million years ago until five million years ago, during which time climate change possibly had a major impact on the evolution of the modern-day crocodile. During the period, Australia and Antarctica broke apart and most of eastern Australia became warmer, leading to an increase in rainforests — an ideal environment for crocodiles. Buchanan said the new species of crocodile was very similar to the modern-day freshwater crocodile, suggesting the modern crocodile had changed little in millions of years of evolution.

“This croc would have looked much like a modern freshwater crocodile, which is the beautiful thing about crocodiles. They found something that works and stuck with it all through history,” he said. However, the ancient crocodile had sharper and laterally compressed teeth enabling it to sheer prey and an extra jaw muscle to give a stronger, more powerful bite. Buchanan said researchers were examining more crocodile fossils and hoped to add to the crocodile evolution puzzle. “It will also help us place this unique Australian group with the bigger picture of where they fit in with other lines of crocodiles,” he said.

Yahoo
March 15, 2005

Original web page at Yahoo