21. The mountain is formed with quartzites and metamorphosed slates of the Proterozoic Eon and Cambrian Period . 22. Sutures are found in animals with hard parts from the Cambrian period to the present day. 23. It preserves trilobite fossils from the Cambrian Period . 24. Lyrarapax " "'is an anomalocaridid that lived in the early Cambrian period 520 million years ago. 25. It is the most long-lived anomalocaridan clade, lasting from the Cambrian period to the Devonian period. 26. The earliest probable species of tunicate appears in the fossil record in the early Cambrian period . 27. It is an ancient group, with fossils dating from 530 million years ago, in the Cambrian period . 28. Oxygen levels seem to have a positive correlation with diversity in eukaryotes well before the Cambrian period . 29. These first appear after the boundary between the Proterozoic and Phanerozoic eons or Ediacaran and Cambrian periods . 30. They lived during the Middle Cambrian period .
