Vertebrates: Phylum Chordata
Phylum Chordata includes the vertebrates. Although not as common as the invertebrates, teeth and bones from different classes of vertebrate animals can be found at Canal sites.
146 to 65 mya
Phylum Chordata includes the vertebrates. Although not as common as the invertebrates, teeth and bones from different classes of vertebrate animals can be found at Canal sites.
Echinoderms are "spiny-skinned" invertebrate animals that live only in marine environments. Two major divisions are recognized by biologists: principally attached, usually stalked forms of the Pelmatozoa; and unattached free-moving forms of the Eleutherozoa.
Arthropods are animals with a segmented body, external skeleton, and jointed appendages. The Arthropoda includes insects and crustaceans. Only two groups of arthropods are common as fossils in the Cretaceous of the C&D Canal area, and both are types of crustaceans: the Malacostraca (crabs, lobsters, and shrimp) and the microscopic Ostracoda.
Annelids are segmented worms. The remains of the soft-bodied segmented worms are not usually preserved as fossils. Some marine (salt-water) types, however, secrete tubes of calcium carbonate to use both as a home and to provide protection from their enemies. These tubes can be found as isolated specimens or attached to larger shells. Two genera, Serpula and Hamulus, are fairly common in formations near the C&D canal.
Cephalopoda is the scientific name for the mollusc group that includes the chambered Nautilus, squid, and octopus. Two extinct types are found at the C & D canal: the Nautilus-like ammonites and the superficially squid-like belemnites. Ammonites are uncommon, especially complete specimens, but can be very useful for age determination. The belemnite species Belemnitella americana has been so abundant at some canal localities that it was named the state fossil of Delaware.
Pelecypoda is the group of molluscs referred to as the bivalves. Most pelecypods have a pair of hinged shells of generally equal size. Clams, oysters, and scallops are well-known types. Pelecypods can be abundant in the sediments of the C & D canal area.
Gastropoda is the scientific name for the group of animals more commonly called snails. Gastropods have a single coiled or uncoiled shell and are common fossil types in the Cretaceous sediments of the C & D canal area.
Dark-red, gray, pink, and white silty clay to clayey silt and very fine to medium sand beds. Beds of gray clayey silt to very fine sand that contain pieces of charcoal and lignite are common. Deposited in a fluvial setting in a tropical to subtropical environment as indicated by abundant paleosol horizons. Ranges from 20 ft updip to over 1600 ft thick in southern New Castle County.
This report presents a new time-stratigraphic framework for the subsurface Potomac Formation of New Castle County, Delaware, part of adjacent Cecil County, Maryland, and nearby tie-in boreholes in New Jersey. The framework is based on a geophysical well-log correlation datum that approximates the contact between Upper and Lower Cretaceous sediments. This datum is constrained by age determinations based on published and unpublished results of studies of fossil pollen and spores in samples of sediment cores from boreholes in the study area.
Brachiopods are shelled invertebrate that look somewhat like bivalved molluscs. However, the animal living in the shell is a filter feeder that collects food with a special organ called a lophopore (bryzozoa also have lophophores).