A team of paleontologists from the United States has determined that Tullimonstrum gregarium (popularly known as the Tully monster) — a large soft-bodied animal from the late Carboniferous Mazon Creek biota (309-307 million years ago) of Illinois — was a vertebrate, with gills and a stiffened rod that supported its body. According to the team, T. gregarium is part of the same lineage as the modern lamprey. A reconstruction of Tullimonstrum...
