Modern examples are jellyfish, flat worms, and annelid worms. Rocks of about this age contain the first calcium carbonate shell bearing fossils. Invasion of the lands - Vascular plants have tubes and vessels that convey fluids from one part of the plant to another. Psilophytes - the first vasular plants are found in the middle Silurian. These plants evolved in the Devonian.
Jawless fish appear in the Upper Cambrian.
Placoderms were Silurian fish with jaws and plates for skin. Lungfish has evolved by the Devonain. By Mississippian time, Amphibians had started to emerge. Reptiles are found by Early Pennsylvanian. Vertebrates of the Mesozoic included Reptiles and Birds with a few small mammals starting to evolve.