Even though most are not around today, except birds, dinosaurs are in fact reptiles and deserve their time in the herpetology spot light! In a current National Geographic article they discuss the discovery of new species of not only dinosaurs but also other reptiles like crocodiles and turtles.
Since about 2000, men like the Miller brothers, Scott Sampson (chief curator at the Denver Museum of Natural History) and Joe Sertich (Denver Museum of Natural History's museum paleontologist) have been on a quest within Utah. That quest is to discover new plants and animals fossils from the "lost continent" of Laramidia. 90 million years ago in the late Cretaceous, the sea levels were dramatically rising and the North American continent was divided into two section down the middle by the Cretaceous Interior Seaway. The area to the west of the sea way (the west coast) was Laramidia. Accessing the layers of mudstone and sandstone from Laramidia today is very difficult because over time other layers have been deposited. The only areas we are able to access today have undergone erosion from wind and rain surfacing these layers with the main area of interest being the Kaiparowits formation aged between 77 and 75 million years old. Within this area not only have they discovered thousands of plants and animal fossils but these include crocodiles, turtles and many dinosaurs. To add on to this not only were these remains unearthed and discovered in such large numbers, but the species diversity is mind boggling! These remains show animals of almost all new species! Even though many of the animals found were related, they were so different. For example in 2002 Gryposaurus monumentensis was recognized as a new species because even though it looked similar to Gryposaurus found in Canada, the overall size and other small details made them as they say in the article "the Arnold Schwarzenager of duck-billed dinosaurs". As well as a rhino sized Triceratops that had 15 horns which is a new record!
Although the question remains of why such species diversification with not only dinosaurs but also lizards, turtles, crocodiles, mammals and fishes? Why did they evolve so differently from their neighbors? Sampson and the other men claim that having a mountain range or a large river between populations should have not been so dramatic for some of these guys because they could just walk over them, like has already been observed. Instead two ideas were considered. First being that once populations are spread out through out a massive amount of land, those individuals become accustomed to climate zones and vegetation effecting natural selection eventually causing speciation. The other idea is more based upon the use of sexual selection. Finally the other question that came from the fact that these animals discovered were of such massive size! So why the massive size? Miller claims that unlike what some believe, 75 million years ago this area was more similar to the Amazon not a desert. Large, dense amounts of vegetation were easily available so many of the animals did not need to travel far for food at all. At the end they say that they are still working on the remains they discovered and further work is being completed.
This is not just a find, this is a HUGE find! Finding not only finding new species but also studying the ecology of the area with the diversity of animals helps show a clear example of evolution throughout a smaller range based on some similar trends we find today. Laramidia still holds so many of its secrets and is now becoming uncovered. Examining the time of the dinosaurs, the giant reptiles in this area is so diverse from any others it is like examining Darwin's finches that change from island to island but during the Cretaceous with dinosaurs and other reptiles. I am really interested in the work that will be uncovered soon with more research.
Kimmy Profitko
Herps in the News
(National Geographic article link)
http://ngm.nationalgeographic.com/2014/05/utah-dinosaurs/miller-text
1 comment:
Very exciting story! Thanks for sharing this!
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