Series: Invertebrate Fossils in National Parks

National parks contain a rich diversity of invertebrate fossils. Some groups, particularly mollusks, are present in many national parks, but others are much more rare. Most invertebrate fossils in national parks are of marine organisms, although some parks have freshwater mollusks, and a few have fossils of terrestrial arthropods, mostly insects.

• Article 1: Fossil Sponges

  

  Sponges (phylum Porifera) are simple animals with a fossil record dating back to the Precambrian. Only sponges with hard parts (such as spicules) are capable of being fossilized. Sponges were important reef builders in the Paleozoic and most sponge fossils that have been documented in national parks are in Paleozoic rocks. Read more

• Article 2: Fossil Cnidarians - Corals, Jellyfish, and Sea Anemones

  

  Fossils of bryozoans (“moss animals”) that are typically found as part of marine assemblages in many national parks. These filter-feeding colonial animals were individually microscopic so even their colonies, usually shaped like branching twigs or net-like and lacy forms, themselves are quite small. Read more

• Article 3: Fossil Bryozoans

  

  Fossils of bryozoans (“moss animals”) that are typically found as part of marine assemblages in many national parks. These filter-feeding colonial animals were individually microscopic so even their colonies, usually shaped like branching twigs or net-like and lacy forms, themselves are quite small. Read more

• Article 4: Fossil Brachiopods

  

  Brachiopods are one of the most common marine invertebrate fossils found in Paleozoic rocks in national parks. They were a dominant group of marine organisms during the Paleozoic, filling many of the ecological niches in Paleozoic oceans that bivalves have occupied since the end of Permian extinction, when most brachiopods became extinct. Read more

• Article 5: Fossil Mollusks

  

  Most mollusks are of either bivalves, cephalopods, or gastropods. Cephalopods including nautiloids and ammonites were exclusively marine, bivalves inhabited both marine and freshwater environments, and gastropods lived in both aquatic and terrestrial environment. Overall, mollusks are the most common type of fossils found in national parks. Read more

• Article 6: Fossil Arthropods - Trilobites, Insects and Spiders, and Others

  

  Arthropods have segmented bodies and external skeletons. Trilobites and ostracodes are the most common marine arthropod fossils in national parks. Fossils of insect and spiders are quite rare in parks except at Florissant Fossil Beds National Monument where fine-grained shales provided the perfect conditions to preserve the remains of these delicate organism. Read more

• Article 7: Fossil Echinoderms – Crinoids, Blastoids, and Others

  

  Crinoids are the most common echinoderm fossils in national parks, found mostly in Paleozoic rocks. Echinoderms have 5-sided symmetry and have skeletons composed of numerous small pieces, which break apart after death. Thus, most echinoderm fossils are only small bits of the larger organism. Read more

• Article 8: Fossil Graptolites

  

  Graptolites are important index fossils for the early Paleozoic. They look like pencil marks on rock faces but are the remains of tiny colonial animals. Graptolite fossils are known from a handful of national parks. Read more