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One of many dinosaur eggs discovered at the Sanagasta site. From the Nature Communications paper.

Even though they grew to be some of the largest animals ever to walk the earth, sauropod dinosaurs started off small. From numerous nesting sites found all over the world it appears that gravid female sauropods, rather than putting all their effort into laying a few enormous eggs, created large nests of numerous, relatively small eggs. But why they selected particular nesting sites has long been a mystery. Now, in the journal Nature Communications, paleontologists Gerald Grellet-Tinner and Lucas Fiorelli provide evidence that nesting female sauropods picked at least one site based upon its natural heat.

In northwestern Argentina’s La Rioja Province lies a bed of white Cretaceous rock called the Los Llanos Formation. Within that formation, paleontologists have found numerous clutches of eggs at Sanagasta. The eggs are very similar to those of sauropod dinosaurs found elsewhere in Argentina, but the focus of the new study is not so much the eggs as the environment they were deposited in. In one particular area, designated sub-site E, the egg clutches are found dispersed three to ten feet away from geysers, vents, and other hydrothermal features which were active between 134 and 110 million years ago—that is, the eggs were laid in a naturally-heated nursery incubated between 140 and 212 degrees Fahrenheit. During the time the dinosaurs occupied this site, it must have looked somewhat reminiscent of some areas of Yellowstone National Park, but with sauropods wandering among the hot springs instead of elk and bison.

Although this is a wonderful discovery, the fact that these dinosaurs came back to the hydrothermally-active site again and again is not unusual. Some ground-nesting birds, such as the Polynesian megapode, seek out sites warmed by volcanic activity to create their nests, and so it seems that sauropod dinosaurs, too, were very selective about where they created their nests. With this in mind, paleontologists can take a closer look at other nesting sites around the world for clues as to why certain sites were “hot spots” for dinosaur nests.

For more on this discovery, see Not Exactly Rocket Science and Nature News.

Gerald Grellet-Tinner & Lucas E. Fiorelli (2010). A new Argentinean nesting site showing neosauropod dinosaur reproduction in a Cretaceous hydrothermal environment. Nature Communications, 1-8 : 10.1038/ncomms1031

Works sit on the famous Dinosaur National Monument quarry wall. From Wikipedia.

When I was growing up, almost every documentary I saw or dinosaur book I read showed images of the great wall of Jurassic dinosaurs laid out at the Dinosaur National Monument visitor center. The wall, which is the enduring legacy of paleontologist Earl Douglass, who discovered the rich assemblage of bones during the early 20th century, is embedded with the remains of Allosaurus, Stegosaurus, Ceratosaurus, Diplodocus, Apatosaurus and others, many of which were left in place for visitors to come see. It was something I desperately wanted to see one day.

Unfortunately, the glass building constructed over the quarry proved to be dangerously unstable and the visitors center was closed recently. I did not get to see the great wall of dinosaurs when I visited last year. Thanks to an infusion of government funding, however, construction on a new visitor center is presently underway. Even better, the park’s paleontologist, Dan Chure, has been documenting the step-by-step process of creating the new building on his blog Dinosaur National Monument Quarry Visitor Center Project. In the most recent update, titled “Painfully Paneless,” Chure discusses the challenge posed by the building’s glass walls:

It was known that lead paint was almost certainly present on the frames. Fifty years of painting in the Quarry Visitor Center has left a structure with a paint stratigraphy in which the oldest layers are lead based. So lead abatement was planned for in the removal. What was unexpected was that asbestos was in the glazing holding the panes in their frames. That discovery delayed the project as a new abatement plan was developed. Ultimately a crane was brought in and the contractors erected a negative pressure chamber on the basket and dressed in “moon suits” and wearing breathing apparatus, used electric saws to cut away the panes and their frames.

Despite such unexpected events, though, Chure’s photos show how the visitor center is rapidly being transformed. I can’t wait to see how it looks when it reopens in the fall of next year.

A screenshot from Battle of Giants: Dinosaur Strike. From IGN.

Most dinosaur-themed video games seem to fall into one of two categories—the ones that give players a ridiculous arsenal of weapons to gun down dinosaurs and those that allow players to be the dinosaurs. To be honest, I have always found the latter type of game to be a bit dull—one can only bite, stomp, and tail-whip virtual opponents for so long before it gets old—but gaming giant Nintendo is hoping to breathe new life into dino-fight games with its forthcoming Battle of Giants: Dinosaur Strike.

According to previews of the game given at the E3 gaming conference, Battle of Giants will allow players to navigate a customizable dinosaur through a virtual world. As they run through the jungle they will occasionally encounter dinosaur opponents, at which point the game will shift to pit one dinosaur against the other in a bit of button-mashing action. Interestingly, Battle of Giants is going to be released for the new Nintendo 3DS system, a handheld bit of hardware that claims to achieve 3-D effects without the need for glasses. This gimmick alone will surely draw some attention, and perhaps we will see more 3-D dinosaur adventures in the future.

A comparison of the skull of a multituberculate mammal with tooth marks made on a dinosaur rib. From the Palaeontology paper.

Mammals have long been characterized as the underdogs of the Mesozoic world. They diversified in habitats ecologically dominated by dinosaurs, but, even though most were small, they did not simply cower in their burrows until the non-avian dinosaurs were wiped out 65 million years ago. In fact, Mesozoic mammals were more varied in anatomy and habits than is often appreciated, and, as has just been reported in Palaeontology, some small mammals gnawed the bones of the giant archosaurs.

As described by paleontologists Nicholas Longrich and Michael Ryan, a number of fossil bones from the Cretaceous rock of Alberta, Canada were damaged by bites which could only have been made by mammals. A dinosaur rib fragment, a piece of dinosaur limb bone, a partial lower jaw from the marsupial mammal Eodelphis and a femur from a reptile called a champosaur bear bite marks made by an animal with closely-spaced, paired teeth. This bite pattern matches the tooth placement of an extinct variety of mammal called multituberculates—these mammals had long incisor teeth at the front of their jaw separated from the other teeth by a gap, thus explaining why the only toothmarks on the bones were made by incisors. While other mammals could potentially have been the culprit, the anatomy of the multituberculates make them the best fit.

The multicuberculate-made toothmarks are, at present, the oldest known fossil traces of mammal toothmarks. More than that, the authors suggest that some multituberculates used their incisors to gnaw on hard, resistant food items, meaning that they were perhaps more versatile in their diets than had previously been presumed. From the traces on the bones it appears that these small mammals scavenged dead dinosaurs and other creatures for food (leaving behind the relatively shallow tooth marks on some of the specimens) and sometimes bit into the bone itself, perhaps to obtain minerals like calcium (as seen by the deeper bite marks). Now that these traces have been recognized, perhaps other paleontologists will see similar marks in bones they collect, potentially helping us better understand the lives of the mammals that lived alongside the dinosaurs.

LONGRICH, N., & RYAN, M. (2010). Mammalian tooth marks on the bones of dinosaurs and other Late Cretaceous vertebrates Palaeontology DOI: 10.1111/j.1475-4983.2010.00957.x

An animatronic theropod dinosaur on display at the Brookfield Zoo. The list of robotic dinosaurs which will be present in Alberta's Jurassic Forest has not yet been announced. From Flickr user jimdeane.

As much as I love spotting dinosaurs along the road and in “prehistoric parks,” I have to admit that most of them look terrible. Not only are they often misshapen and woefully out of date, but many have been in a state of disrepair for years. It seems that many roadside dinosaurs are the products of an earlier wave of dinomania that have been left to rot, but now some people are creating the next generation of dinosaur parks.

Next month will see the opening of the Jurassic Forest dinosaur park in Gibbons, Alberta, Canada. It will open with about 40 dinosaurs—some of which were recently flown in by helicopter—but they are not going to be immobile statues. Instead, following the continuing dino-motion trend, the dinosaurs will be animatronic robots that will have the usual behavioral repertoire of blinking, growling, and waggling their appendages for visitors. Photos from early news reports show that the park will be home to at least two robotic Parasaurolophus, but a list of the full dinosaur menagerie has yet to be released.

More information about the park will be made available at its website, JurassicForest.com

[Hat-tip to Darren Tanke for letting us know about this story]