Vertebrates developed about 550 million years ago. The oldest vertebrate fossils are those of with no jaws.?

The oldest vertebrate fossils, dating back about 550 million years, belong to jawless fish, specifically groups such as agnathans. These early vertebrates lacked jaws and were characterized by their simple structures, relying on filter-feeding or scavenging for sustenance. Over time, vertebrates evolved more complex features, including jaws, which allowed for a greater variety of feeding strategies and contributed to their diversification.