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The finds of a new saurolophine dinosaur, Kundurosaurus nagornyi, are described in PlosOne. The new dinosaur was found in the Udurchukan Formation (Maastrichtian) of Kundur (at the Amur plateau in Eastern Russia), and represented by disarticulated cranial and postcranial material. All Kundurosaurus specimens were collected in the Kundur locality, hence the name.

The Kundur locality was discovered in 1990 and Large-scale excavations started at Kundur in 1999. In four sites dinosaur bone of different species form large bonebeds extending over several hundreds of m².

I gather you can guess why these types of dinosaurs are called Duck-Billed dinosaurs when you look at the following illustration from the new paper.



Notice the similarity of the head to that of modern ducks.

Reference:
Godefroit P, Bolotsky YL, Lauters P (2012)
A New Saurolophine Dinosaur from the Latest Cretaceous of Far Eastern Russia.
PLoS ONE 7(5): e36849.
doi:10.1371/journal.pone.0036849

Tyrannosaurus rex and its closest relatives are pop culture icons. Tyrannosaurs, the group of dinosaurian carnivores that includes Tyrannosaurus rex, are also the most intensively studied extinct dinosaurs,

Tyrannosaurus rex was initially described 105 years ago, and for most of the 20th century tyrannosaurs were known almost solely from fossils of Tyrannosaurus rex and four closely related species of large, multi-ton Late Cretaceous predators. Within the last decade, however, the diversity of tyrannosaurs has more than doubled, and during the past year alone, six new species were described, some of which are 100 million years older and 1/100 the size of Tyrannosaurus rex.

A new paper reviewing recent research and the evolution of tyrannosaurs was published in the journal Science of 17 September 2010.

Approximately 20 tyrannosauroid genera are currently known, 5 of which were described during the past year. Tyrannosaurs are a long-lived group that originated by the Middle Jurassic, ~165 million years ago. Until recently, the prevailing notion was that tyrannosaur body size gradually, and progressively, increased over time. However, new discoveries have led to a reassessment. Enormous size is restricted to the latest Cretaceous tyrannosaurids, some of which grew to lengths of 13 m and masses of 5 to 8 tons. For the first 80 million years of their history tyrannosaurs were mostly small- to mid-sized animals that lived in the shadow of other giant predators, and only during the final 20 million years of the Mesozoic did they develop into some of the largest terrestrial carnivores to ever live. The dominance of tyrannosaurs as megapredators was purely a latest Cretaceous phenomenon.

Arguably palaeontologists know more about tyrannosaur biology than that of any other dinosaurs. Much of this knowledge has been gained over the past 20 years, through the collection of skeletons of both adults and juveniles, bones of their prey with bite marks, coprolites (fossil faeces, or fossilised dung if you like), stomach contents, and specimens marked by diseases.

Bite marks, coprolites, and quantitative techniques have helped to reveal what tyrannosaurs ate and how they fed. Tyrannosaurid bite marks have been found on the bones of a wide diversity of species, including various other tyrannosaurs, demonstrating that they were generalists. Bite mark patterns show that tyrannosaurids characteristically bit deeply into carcasses, often through bones, and then pulled back, creating long cuts. Some Tyrannosaurus rex bite marks and coprolites with bone chunks indicate that bone was fractured, ingested, and used for sustenance, a mammal-like attribute not seen in extant reptiles. The bite forces needed to crunch through bone would have been enormous. Biomechanical experiments have replicated the size and depth of fossilised bite marks and suggest that Tyrannosaurus rex generated bite forces of at least 13.4 kN. (For comparison the bite force exerted by an adult Nile crocodile has been shown to measure 22 kN - if you have ever seen a crocodile snap its prey, you may have an idea about what that means).

Several signs indicate that tyrannosaurs changed their habits as they grew. In Late Cretaceous tyrannosaurids, the difference in form between the lightly built, fast and nimble juveniles and the larger, bulkier adults indeed suggests that foraging behavior and targeted prey size changed as they grew. The deep and muscular adult skull, with reinforced sutures and robust teeth, is well suited for sustaining high bite forces, whereas juveniles had none of these features. Furthermore, the longer and more slender hind limbs of juveniles indicate that they were relatively faster than adults. These differences could have promoted major size-related shifts in behaviour. It is plausible that adults preferentially attacked larger, but less mobile, prey than their younger counterparts. Such a shift from juvenile to adult behaviour is not seen in many familiar predators today (e.g., lions), but is present in extant crocodilians.

Whether Tyrannosaurus rex and other large tyrannosaurs were scavengers or predators has generated much speculation and dispute. Tyrannosaur stomach contents indicate that tyrannosaurs were capable of active predation, but like most carnivores, tyrannosaurs probably both scavenged and hunted.

Tyrannosaur fossils have mainly been found in Asia and North America, but they were likely present on the southern continents during their early evolutionary history. It is likely that tyrannosaurs preferred wetter habitats (isn’t that what we have always been told?), but this assumption may reflect a sampling bias.

Tyrannosaurus rex is just the tip of the iceberg of tyrannosaur diversity, and is quite abnormal when compared with other members of the group.

Reference:
Brusatte et al.
Tyrannosaur Paleobiology: New Research on Ancient Exemplar Organisms
Science 17 September 2010:
Vol. 329. no. 5998, pp. 1481 - 1485
DOI: 10.1126/science.1193304

• http://www.sciencemag.org/cgi/content/abstract/329/5998/1481
• http://www.sciencedaily.com/releases/2010/09/100916145131.htm

A near-complete fossil of the (so far) oldest feathered bird-like dinosaur has been found in the Chinese province Liaoning. It has been dated to earliest late Jurassic - 151-161 million years ago - and this Anchiornis huxleyi is (it seems) older than Archaeopteryx lithographica that lived in the late Jurassic Period around 150–145 million years ago.

Long feathers cover the arms and tail, but also the feet, suggesting that a four-winged stage may have existed in the transition to birds. It is by the way not the first four-winged dinosaur found. Microraptor gui e.g. was another (with six specimens also found in the rich fossil beds of Liaoning Province in northeastern China).

Find by find provides yet more evidence that birds evolved from dinosaurs, and more links unravelling how a group of ground-dwelling flightless dinosaurs evolve to a feathered animal capable of flying. The transition from dinosaurs to birds is still poorly understood because of the lack of well-preserved fossils and, although supported by most palaeontologists, still many scientists argue that bird-like dinosaurs appear too late in the fossil record to be the true ancestors of birds. Earlier finds of Anchiornis huxleyi were much less complete, and it was previously thought to be a primitive bird, but closer inspection reveals that it should be assigned to the Troodontidae — a group of dinosaurs closely related to birds.

• http://www.nature.com/news/2009/090925/full/news.2009.949.html
• http://www.nature.com/nature/journal/v461/n7264/full/nature08322.html
• http://www.sciencedaily.com/releases/2009/09/090928205415.htm

In Danish:

• http://www.videnskab.dk/composite-3085.htm

In Norwegian:

• http://www.forskning.no/artikler/2009/september/230631

As I mentioned yesterday Earth volcanic activity is one of the two leading scenarios proposed to explain the mass extinctions in the last 600 million years, while the other involves asteroid impacts. The most “popular” mass extinction took place at the end of the Cretaceous, when the Dinosaurs died out.

Are Volcanic Gases Serial Killers? Extremely large volumes of flood basalt erupted 67 to 65 million years ago, forming the Deccan Traps in India. The impact of these flood basalt eruptions on the global atmosphere and the coeval end-of-Cretaceous mass extinction is still not quite certain. The eruptions would have had a widespread environmental impact through the release of primarily sulphur and chlorine and possibly fluorine.

An analysis by Stephen Self of the Open University in Milton Keynes, England, and colleagues lends new support to the volcanism scenario. By looking at tiny bits of glass (glass inclusions) that formed inside the lava flows, they’ve been able to reconstruct how much sulphur and chlorine were released. The findings are reported in the journal Science of 21 march 2008 under the title "Sulphur and Chlorine in Late Cretaceous Deccan Magmas and Eruptive Gas Release”. The findings demonstrates unambiguously that the capacity of Deccan basalts to discharge sulphur into the atmosphere was similar to that of present-day erupting basalts. Although this may sound trivial, it means that comparisons with historic eruptions like Laki in 1783-1784 make sense.

Other volatiles (gasses) may also have altered the climate, however, in particular halogens (fluorine, chlorine, bromine, iodine). In addition to having regional devastating effects, halogens may dramatically affect both tropospheric and stratospheric chemistries, with severe impacts on the ozone layer.

It is however still too early to prove a causal link between mass extinction and volcanism either right or wrong, so the Chicxulub impact crater is still in the running.

• http://www.sciencemag.org/cgi/content/abstract/319/5870/1654
• http://www.nytimes.com/2008/03/25/science/25obexti.html