Carnegie Museums of Pittsburgh





Back Issues 






When Crocodiles Ruled

Dec 8, 2001 thru May 12, 2002

Changing Exhibits Gallery


Dinosaurs ruled the world from 200 to 65 million years ago, and we know there are human beings today.  But what happened after the dinosaurs were gone?  Evidence  points to a time when crocodiles were a dominant life form.


This new exhibit by the Science Museums of Minnesota gives a glimpse of the life, ecosystems, species and climates of 60 million years ago, and unites research from paleontology digs around the world with rich evidence from the Wannagan Creek quarry in North Dakota.  Carnegie Museum of Natural History is the first stop for this exhibit after it premiered at the Science Museum of Minnesota.  After Pittsburgh it continues on a ten-year tour of international museums and cultural sites.


Visitors first see dioramas as they step back into the Paleocene era, a time when North Dakota and the upper Midwest were a lush, warm, sub-tropical swamp. In this prehistoric world you walk under the branches of cypress, magnolia and oak, and hear the sounds of frogs and dragonflies. Alligator-like creatures--champosaurs--are around you.  With their nostrils on the tips of their snouts, they could live suspended underwater, floating vertically with only their noses exposed.


The second part of the exhibit is interactive, with virtual displays and activities that let you test the bite-force of a crocodile jaw, and follow a brood of 40 baby crocks from hatching to adulthood, witnessing how only two survive the perils of predators and the environment.  A periscope lets you see what is living at the bottom of a swampy lake, and you can hear crocodiles' "voices" reveal their moods, from crabby adults to amorous adolescents to hungry babies.  You can also see and understand other life forms, from plants and moths to meat-eating flies and hungry hippos, and you can see the world through a geologist's eyes.  In the theater area you see how North America changed in 65 million years, and in a Field Camp you learn how researches live and work as they uncover the past.


When Crocodile Ruled is a fascinating experience for the entire family.



The Paleolab                               


"Behind the scenes" goes public


The new paleontology laboratory that opened in November next to the Hall of Dinosaurs puts on view the laboratory work which has made the museum popular with visitors, but which until now has largely been restricted to the lower level of the building. 


The Paleolab at the entrance to the Hall of Dinosaurs lets you lean against the 32-foot rail that separates visitors from staff preparators, and look through the glass wall into the lab. The glass controls the dust, noise and ventilation, but lets you see such apparatus as the huge fume hood used to work with epoxy and solvents. You can also see the wheeled A-frame lifting system that moves fossil-bearing rock into working position. In the rear of the lab is the sand box used in holding pieces of bone together while the glue resets the bones.  All the systems needed to operate a working laboratory have been installed: electricity, plumbing, a sink to wash specimens, and a pneumatic line for air tools.


Currently being worked on is the removal of a Camarasaurus from its bed of stone, or matrix. Two computers with touch screens and a streaming video feed bring you very close to the process of removing these bones from the stone matrix where they have been imbedded for millions of years.  The informational panels give you an overview of the process and describe the tools used by scientific staff.  The computer also has an Online Diary of the work--a "progress report" or running archive of the work being done. Outside the Lab at an Education Desk staff will be available to answer questions.


Wild Blue Planet, formerly in that space, is now installed on the balcony above the dinosaurs (second floor), where it continues to be a public resource about Earth history.


Science Update


A Swimming Frog from the deserts of Yemen                


You probably don't know Xenopus--an aquatic frog with long toes (and probably webbed feet)--but it was similar to a popular frog species from the southern hemisphere commonly sold today in pet shops.  Very little has been understood about its fossil history until scientific preparator Amy Henrici recently documented the first occurrence of Xenopus (Anura: Pipidae) on the Arabian Peninsula in the Journal of Paleontology (July 2001).  This discovery documents the oldest occurrence of the species and reveals information about its past distribution.  It also provides information about the climate of present day Yemen 26 million years ago.   The presence of this strictly aquatic frog in Yemen during the Oligocene era adds to a growing body of evidence that in the past the Arabian Peninsula was not always covered by a desert, but probably had tropical forests and savannas.


Ice Mice --the first mammals to migrate from North America to Europe are found in the Arctic                                                   


The fossilized teeth of extinct rodents found within the Arctic Circle are the first documented evidence that mammals originating in North American crossed to Western Europe over a North Atlantic landmass. Paleontologist Mary Dawson recently described the evidence in the Canadian Journal of Earth Sciences (July, 2001). 


Plate tectonics theory says that the cold, treeless area of today was once part of a warm climate land bridge connecting North America to Western Europe.  Although there is evidence that closely related animals existed in both land masses 50 million years ago when the age of mammals was just beginning, proof that they migrated over this route was still missing.  The fossils of small rodents, called microparamyines, were unearthed from Canada’s high Arctic Ellesmere Island.  Situated at about 78 degrees north latitude, the area today is covered with tundra and ice and is home to polar bears, walruses, seals, musk oxen, foxes, Arctic wolves, lemmings, and hares, as well as a rich diversity of bird life.  Fifty million years ago, when these mouse-sized rodents lived, the climate was warm and temperate, similar to present day South Carolina.


Why the peacock lost its spots--or the loss of sexually selected traits


In many animal species the males have unusual ornaments and behaviors to increase their attractiveness to females, but these traits not help their chances for survival.  Consider the bright plumage of peacocks--an attraction to females but an equal signal for predators.  A display such as this is thought to be part of  sexual selection, as opposed to natural selection.  Traditionally, research in sexual selection has focused exclusively on explaining how these male traits originated, and female preferences for them.  John J. Wiens, associate curator of the  section of Amphibians and Reptiles,  has published in Trends in Ecology and Evolution (September 2001) an explanations of why these sexually-selected traits are frequently lost


By using new phylogenetic trees, Wiens demonstrates that the loss of these traits  occurs in a wide variety of animals, including insects, fish, birds, reptiles, and mammals.   In some groups losses may greatly outnumber origins.  Wiens also found that in many groups of organisms, the elaborate traits seen in males may also evolve in females--as often or more frequently than in males.  Explaining these unusual findings is an exciting new area for research in sexual selection.






Back Issues 


Copyright (c) 2002 CARNEGIE magazine 
All rights reserved.