The fossils from Mazon Creek, a Lagerstätte near Chicago, continue to teach scientists much about the ecosystems of the Illinois area 300 million years ago. Examine the fossil evidence provided in this box to connect organisms in an ancient food web. Compare your food web with a modern ecosystem's food web. Were the trophic levels different hundreds of millions of years ago? Learn about the two biotas that existed during this time in Illinois: the Essex and the Braidwood. Then, based on the adaptations observed in the fossils, sort the fossils according to the biotas in which they probably lived.