Connecticut was a very different place in the late Triassic. Around 220 million years ago, Connectict was part of Pangaea, the giant landmass that contained all of today's continents. However, Pangaea didn't have long left. It already was pulling apart, and Connecticut was directly in the rifting zone. As North America pulled away from Africa, great parts of the crust broke and sank, forming valleys that are still part of Connecticut's geography today.
It was a lot warmer back then. There was four times the amount of carbon dioxide in the atmosphere than there is now, and it was so warm that there wasn't even ice at the poles. In that heat, reptiles ruled. Dinosaurs roamed Connecticut, but they weren't always the biggest or most dangerous animals around in those days. Often, the biggest predators in an area were the ancestors and ancient relatives of crocodiles. These weren't the sluggish water-dwelling crocodiles that we're used to today. They were land-dwelling, fast, and sometimes very large. Once of the most fierce of these ancient crocodiles was Postosuchus, and soon Postosuchus will be making the Bruce Museum its home.
Postosuchus was 13-16 feet in length, an apex predator of Triassic Connecticut. Based on the image above, it'd be pretty easy to mistake Postosuchus for a dinosaur, despite it being more closely related to crocodiles. Like theropod dinosaurs, they held their limbs underneath their bodies when they walked, kept their long tails held high, and were dangerous, active land predators. This is an excellent example of convergent evolution, when two different groups of animals look similar, but evolved along different pathways.
This is our Postosuchus. We received its disassembled bones from another institution and are working on putting it together in time for November 19th, the opening of our new science exhibit: Last Days of Pangaea. Sometimes we borrow fossils for our science shows, but Postosuchus is too amazing to let go. After the show, it will be added to our permanent collection and will be with the Bruce for years to come!
Our Postosuchus is a pretty impressive specimen. It's so long that it barely fits onto our work table. It must have been quite the frightening beast when it was alive!
After laying out the spine, we put the rest of the bones into their rough positions. These aren't actual fossils, they're replicas cast in a special resin. There aren't that many Postosuchus skeletons, and replicas are a way great way to bring them to wider audiences. Plus, real fossils are heavy and fragile. It's a lot easier to work with resin!
This is one of the front arms of Postosuchus. Postosuchus had shorter arms than legs. It probably spent some amount of time standing, or even walking, using only its back legs.
We've been working on putting the skull together too. If you look at the skull now, you might think this is an elderly Postosuchus that lost all its teeth. Did you know that crocodiles, dinosaurs, and Postosuchus all could replace worn out teeth constantly throughout life? If a tooth fell out, a new tooth grew into its place. Our Postosuchus will get its teeth restored later in the process.
Here, the Curator of Science, Dr. Daniel Ksepka, discusses with Tim Walsh and Sean Murtha the proper positioning of a Postosuchus ankle. The large bone in his left hand is the ankle bone, and the two bones in his right hand are the tibia and fibula, the bones of the lower leg. Crocodile ankles are different from dinosaur ankles. It's one of the ways that paleontologists know that Postosuchus is an ancient crocodile instead of a dinosaur!
We still have a lot to do before Postosuchus is ready for its big debut. It needs to be painted, positioned, and mounted, and all of these things take a lot of time and expertise. Keep an eye out for more blog posts on Postosuchus progress, and come check it out in person once the exhibit opens in November!
- Kate Dzikiewicz, Paul Griswold Howes Fellow