Some of the critters went extinct (fossils!)
This province (Provincia Chubut) is super rich in life forms. But even more diverse than the organisms living today are those that have gone extinct. From east (near the coast) to west (near the Andes), sedimentary deposits are progressively older and have fossils from the Cenozoic (age of mammals), Mesozoic (age of reptiles, including dinosaurs), and Paleozoic (old life, including trilobites). Paleontologists from around the world flock here to help with excavations and study the specimens.
We are staying near the town of Trelew, which is known for its Museo Paleontológico Egidio Feruglio (fossil museum – if you google the name you’ll find their excellent web site). We were fortunate to have two scientists from the museum guide us on a field trip to Parque Bryn Gwyn, where we could see fossils in sediments ranging in age from 40 – 10 million years ago. Here you can see Anita and our awesome guides: Pedro, an astronomer who leads the educational programs for the museum, and Amalia, a biologist/paleontologist who explained what we were seeing along the way.
For a sedimentologist (me!) there were lots of cool features to see – strata formed by moving ripples, ancient soils, beds of volcanic ash. But the features most interesting to nongeologists are usually the fossils – our record of how life has evolved through time. There were land animals – anteaters, several types of marsupials and other life forms not living today. Then the ocean flooded the land and the sediments contained sharks, whales, and smaller life forms such as oysters. The most impressive of these was a thick layer of shells that were preserved in their life position (see picture below). In Anita’s hand you can see their large size – imagine having these on the half shell!
Then it was off to the museum. You have probably read about some of the fossils from the area, because they include the largest dinosaur yet found. It is a vegetarian sauropod that is named Argentinosaurus! It was 80-100 tons and 10-12 meters long. The photo shows its legs with Anita for scale. Are we glad they don’t live now? But they eat plants; more frightening would have been the tyrannosaurus who was even bigger than the Rex. The museum has a large number of fossils from all of the time periods found in Chubut province and is well worth a visit should you find yourself in Trelew (meanwhile, check out their website).