Sunday, 27 November 2016
40 DEGREES OF LATITUDE: THE ROCKIES
But the niggling thought is still there. Is there one a single element I could name that epitomizes this vast, diverse landscape? Sea to Sky, lakes to mountains, I've kayaked, hiked, sailed and lovingly explored a great deal of it. Through 40 degrees of latitude, from Yukon to Mexico, the Rocky Mountains are North America's geographic backbone.
This is the Great Continental Divide, where the interminable flatness of the interior collides with the Western Cordillera, a major mountain system of the world. From the highest ridges of the Rockies, the rivers flow to opposite corners of the land, north to the Beaufort Sea, south to the Gulf of Mexico, east to Hudson Bay and west to the Pacific.
Friday, 25 November 2016
KWAS'KWAS: OUR BEAUTIFUL BLUE JAYS
Tuesday, 15 November 2016
Monday, 14 November 2016
AMMONITES OF THE ARNIOCERAS BEDS
Several ammonites species can be found here including Arnioceras semicostatum & Arnioceras miserable. The two gastropods you see in the central block have yet to be identified to species. Here's hoping a nice grad student takes an interest. The rare but lovely gastros from this area would make an excellent thesis. Perhaps comparing their distribution to their counterparts in Europe.
Saturday, 12 November 2016
CRETACEOUS BONE BEDS
The most commonly suggested reason is that a herd of animals was suddenly killed by a natural disaster, like a volcanic eruption or flood.
Their bodies were buried and remained in proximity to each other as they preserved, and today excavations uncover the remains of the unfortunate herd. Multiple other monospecific bonebeds have been found for other species of horned dinosaurs, such as Achelousaurus, causing researchers to suggest some groups of horned dinosaurs did exhibit herding behaviour— and that sometimes they met sudden unfortunate ends. But is sudden mass death from a natural disaster the only reason for monospecific bonebeds?
Researchers say no. While the monospecific nature is still largely argued to represent herding in many cases, natural disaster is not always the cause of death. Sometimes large numbers of animals die from disease or starvation. Their carcasses could later be pushed together and buried by an event like a mudflow unrelated to their deaths. Their bones could also sit on the surface for years before an event that buries them.
To understand the cause of a bonebed, researchers look at the bones themselves and the sediment that surrounds them. Bonebeds can tell us a lot about how these animals were living— but there is a lot to be learned from trying to figure out how they died, too.
Currie, P. J., & Padian, K. (Eds.). (1997). Encyclopedia of dinosaurs. Elsevier. • Rogers, R. R. (1989). Taphonomy of three monospecific dinosaur bone beds in the Late Cretaceous Two Medicine Formation northwestern Montana: Evidence for dinosaur mass mortality related to episodic drought. Graduate Student Theses, Dissertations, & Professional Papers. 5871. • Sampson, S. D. (1995).
Two new horned dinosaurs from the Upper Cretaceous Two Medicine Formation of Montana; with a phylogenetic analysis of the Centrosaurinae (Ornithischia: Ceratopsidae). Journal of Vertebrate Paleontology, 15(4), 743-760. • Schmitt, J. G., Jackson, F. D., & Hanna, R. R. (2014). Debris flow origin of an unusual late Cretaceous hadrosaur bonebed in the Two Medicine Formation of western Montana. Hadrosaurs. Indiana Press, Bloomington, 486-501.