- Robert Pagini 2019
Dr. Peter M. LeTourneau, Adjunct Professor of Environmental Science and Geology, investigates 200 million-year-old dinosaur tracks for clues about the ecology and lifestyles of some of the earliest ancestors of modern birds, theropod dinosaurs, at Dinosaur State Park in Connecticut.
When the three-toed footprints of animals were first discovered in rocks of the Connecticut Valley in 1835, scientists thought they had been left in the once soft sand and mud by ancient birds.
From the first, the fossil footprints presented a dilemma to early geologists and paleontologists. Dating from the early Jurassic Period, millions of years older than any previously known bird fossils, the curious tracks did not match any other known forms of animals.
Later correctly identified as the footprints of meat-eating dinosaurs, the tracks were evidence of the very early cousins of larger and more familiar Allosaurus and Tyrannosaurus rex.
In last few decades, however, studies have confirmed that the theropod dinosaursthat left their footprints in soft sediment almost 200-million-years-ago, including Dilophosaurus, were early ancestors of modern birds. The dinosaur footprints from the Connecticut Valley look remarkably like those of some modern birds because their feet are what paleontologists call ‘conservative,’ or little-changing, evolutionary features.
Now preserved as solid rock, the ancient footprints and trackways at Dinosaur State Park excite thousands of visitors and hundreds of school groups every year. This ‘Jurassic Park’ is also a world-class destination for scientists studying dinosaurs and the climate of the past.
Containing evidence of ancient landscapes, the track-bearing rocks at Dinosaur State Park and other localities in the region are deciphered by comparing features such as type of sediment, wave and current ripple marks, and plant and animal fossils.
To their surprise, Dr. LeTourneau and colleagues Columbia Professor Paul E. Olsen and Yale Visiting Collections Curator, Nicholas McDonald determined that the ancient theropod dinosaurs from the Connecticut Valley were largely, or entirely dependent on freshwater fish obtained from the large lakes occupying the region hundreds of millions of years ago.
One of the main clues that led to the team’s conclusion that the theropod dinosaurs were fish-eaters was the presence of too many carnivore footprints compared with the footprints of herbivorous dinosaurs. In the time of the early dinosaurs, the normal food pyramid was upside-down, at least in the Connecticut Valley.
“The techniques we used to interpret the paleoenvironments of the ancient Connecticut Valley, are the same methods and concepts I use to teach my students at Marymount about present-day biomes, habitats, and food webs. The present is the key to the past. By understanding our modern world, we can reconstruct the lost worlds of ancient times. If we can understand past climates and life, we can learn what our planet might look like in the future,” lead investigator LeTourneau said.
The results of this and related studies are slated for publication in Connecticut Dragons, a book of collected papers about the fossil footprints and dinosaurs of the Connecticut Valley by University of Indiana Press (2022).
Dr. LeTourneau teaches in the Environmental Studies program at MMC.
McDonald, N. G., LeTourneau, P. M., Olsen, P. E., and Huber, P. 2022. Early Jurassic lake-shoreline environments of the Hartford Basin: Fossils, food-chains and implications for the facies-linked distribution of dinosaur tracks and track-makers. In: J. O. Farlow and J. Hyatt (eds), Connecticut Dragons. Bloomington: University of Illinois Press
LeTourneau, P.M. 2022. Fraught with Strange Meanings: The Hitchcock Collection of footprints and early models of dinosaur anatomy and physiology. In: J. O. Farlow and J. Hyatt (eds), Connecticut Dragons. Bloomington: University of Illinois Press.
LeTourneau, P.M. 2022.First Tracks from the Connecticut Valley In: J. O. Farlow and J. Hyatt (eds), Connecticut Dragons. Bloomington: University of Illinois Press.