Posted on 18th November 2008 by Judy Breck in biology | general science | paleontology | sciences
dinosaur, jurassic, mouth, reptile, teeth, tooth
This learn node features a tiny dinosaur with big canine teeth that the Natural History Museum reports shows for the first time how one of the earliest dinosaurs grew into an adult. The webpage explains:
The turkey-sized reptile called Heterodontosaurus lived around 190 million years ago in the Early Jurassic period and had an unusual combination of molar-like and canine teeth.
Reptiles usually have small same-sized teeth along the length of their mouth but Heterodontosaurus had 2 fang-like canines at the front.
The image posted here is from a video narrated by Dr. Richard Butler, a dinosaur expert at the museum and featured on the page linked above.
For nodes of related learning: An excellent overview article about Anatomy and Physiology of the Reptile Mouth is provided at PetEducation.com. For time frames for the dinosaurs, the big picture can be seen in the Chart of Geological Ages at Connexions.
Posted on 18th January 2008 by Judy Breck in biology | paleontology
burgess, cambrian, evolution, gould, jay, laurentia, shale, stephen
The map illustrating this learn node, from the University of California Museum of Paleontology, shows the Cambrian Period 500 million years ago and explains: “The location of the Burgess fauna is indicated by a star on the continent of Laurentia (western North America). Notice that Canada is located just south of the equator!” A Smithsonian web exhibit called Strange Creatures: A Burgess Shale Fossil Sampler begins: “more than half a billion years old, the fossils of the Burgess Shale preserves an intriguing glimpse of early life on Earth.” Britain’s Open University includes the Burgess Shale in a Science and Nature course on the Cambrian explosion.
The Burgess Shale became well known to the public through the late Stephen Jay Gould’s 1990 best selling book Wonderful Life: The Burgess Shale and the Nature of History. The fossils in the Burgess Shale have evoked awe and controversy over the century since they were first discovered. 
Called “Showdown on the Burgess Shale,” two lectures in The Unofficial Stephen Jay Gold Archive provide a framework for learning some of the basic ideas and issues for the evolution of life. The first lecture is “The Challenge” by Simon Conway Morris which is followed by Gould’s “The Reply.” In the latter, Gould writes:
The Burgess Shale, in the Canadian Rockies, contains the world’s most important fossil fauna—a detailed and exquisite record (with rarely preserved soft parts included) of marine life about 520 million years ago, just following the Cambrian explosion and therefore permitting us to census the results of this seminal episode in the history of animal life on earth.
More learn nodes at: learnodes.com
