The Cretaceous Period is the last period in the Mesozoic Era, a time in earth history commonly called "The Age of the Reptiles." This period lasted from approximately 144 to 65 million years ago.

Delaware was mostly an area of rivers, swamps, and dry land during the early part of the Cretaceous Period. During the late part of the Cretaceous, the sea covered most of Delaware. These ancient seas left deposits that contain the remains of marine life that lived on the sea bottom and swam in the water.

This web site is designed to show some of the fossil remains of this Cretaceous marine life that have been found in Delaware. Many fossils have been collected in the past from Cretaceous deposits exposed along the Chesapeake and Delaware (or C&D) Canal in northern Delaware. Most of the good collecting localities have been covered in recent years as the canal has been widened and improved, but in places fossils still can be found in "spoil piles," which are piles of material dug from the bottom of the canal when it is deepened or cleaned.

This web site describes many of the types of fossils that are known from the Cretaceous deposits of Delaware. It includes pictures and drawings of many of the fossils. It also provides a checklist of Delaware's Cretaceous as well as some maps that show collecting sites and the geology of the area.

Whether you are interested in collecting yourself, or just want to learn about Delaware's fossils, we hope this web page will give you helpful information.

Protozoans are one-celled organisms that include the amoeba. One group of protozoans, the Foraminifera ("forams"), are among the most common fossils found in the Cretaceous of Delaware -- but are hard to study without a microscope. Forams build a hard outer covering -- some by secreting calcium carbonate or opaline silica, some by cementing sand grains -- in order to provide support and protection. The resulting many-chambered shells, which are commonly called "tests," are the parts preserved as fossils. Some are very simple, and others are very ornate.

Foraminifera live almost exclusively in marine environments. Some foraminifera live on the sea bottom or within sea bottom sediments -- these are referred to as benthic foraminifera. Others float in the water -- these are called planktonic. Certain species of benthic foraminifera are known to prefer to live in certain marine environments, making them useful in interpreting the marine conditions that existed in the past. Planktonic foraminifera are commonly useful for determining the age of ancient sediments because of the rapid evolution through time of many groups.

Forams are usually collected by special filtration and floatation techniques and studied under the microscope because of their tiny size. However, two genera from the Cretaceous of Delaware, Dentalina and Citharina, are large enough to be seen in a magnifying glass and are fairly common in the Mount Laurel dredge spoils.

Phylum Porifera is a group of simple animals that includes the sponges. Porifera have no internal organs, nervous tissue, circulatory system, or digestive systems, making them the most primitive of the multi-cellular animals. To support and protect their soft bodies, sponges produce skeletons of calcium carbonate, silica, or a soft organic material called spongin. The most common fossil sponge in the Cretaceous sediments of Delaware is the genus Cliona. Cliona sponges lived on rocks and shells of the seafloor and commonly bored holes in these objects, in which it lived. To obtain food, the sponges filtered the water around them as it passed through tiny pores located on their outer walls. The sponge is common in the Mount Laurel Formation along the Canal.

Gastropods is the group of molluscs that includes the snails. Many types secrete a single coiled or uncoiled shell for protection, and these shells may be found as fossils. Some species spend their lives crawling along the sea floor, eating algae or debris from rocks and bottom sediments. Others are predatory and feed on other molluscs such as clams and oysters by drilling with a "radula" or rasping tongue.

Most of the Cretaceous gastropod fossils from the Canal are internal casts (steinkerns). They are difficult to identify, and most can only be assigned to a family or genus. Gastropods are abundant in the spoils from the Mount Laurel Formation on both sides of the Canal in the vicinity of Reedy Point.

Phylum Mollusca
Class Cephalopoda
Cephalopods are a group of molluscs that include the pearly chambered Nautilus, squids, and the octopus. They can be divided into three categories: the Nautiloidea (chambered Nautilus), the Ammonoidea (the extinct ammonites), and the Dibranchiata (squids, the extinct belemnites, and octopuses).

Ammonite fossils occur in places in the Cretaceous of Delaware. An ammonite can be thought of as an octopus stuffed inside a straight, coiled, or spiral shell. They are uncommon finds at the C & D Canal, usually occuring as broken pieces; a complete one is a rare and exciting find. Most of the larger coiled ones are found in the Merchantville Formation. Sections of the straight-shelled Baculites are more common in the Mount Laurel Formation.

The belemnite species Belemnitella americana is the Delaware State Fossil. They are amber colored, bullet-shaped fossils that served as the internal skeleton in an extinct squid-like animal called a belemnoid. Belemnites are a common find on the Mount Laurel spoils pile because they probably traveled in large schools.

Phylum Mollusca
Class Pelecypoda
Pelecypods have two shells, or bivalves, that protect the soft parts of the animal. The valves are generally of equal size (except in groups like the oysters) and shape and are hinged at the back. Some types, such as oysters, live in large groups that create beds or low-relief banks of shells, where the animals feed by filtering plankton and organic debris from the water. Other bivalves burrow through the mud or swim about in search of debris to eat. Many bivalve fossils in Delaware are preserved as steinkerns. Pelecypods are abundant in the spoils from the Mount Laurel Formation on both sides of the Canal in the vicinity of Reedy Point.

Cnidarians are soft-bodied animals that include corals, jellyfish, and sea anemones. These soft-bodied animals have saclike digestive cavities and tentacles containing rows or stinging cells used for defense and capture of food. Many secrete calcium carbonate to support and partly enclose the soft parts; the most familiar of these are corals. The only members of the phylum found at the Canal are solitary corals. One of these corals, Micrabacia, may be the most common fossil found. Another common fossil found there, a solitary horn-shaped coral, has been given different names by different authors.

Phylum Arthropoda
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.

The most common crustacean fossils come from the ghost shrimp Callianassa. Pieces of the claws and pinchers are the most common body parts found; only around the area of the Deep Cut have complete appendages been found. More common than body parts are the burrows of this shrimp, which occur as lumpy tubes called called Ophiomorpha nodosa. These "trace fossils" are very common in the Englishtown and Marshalltown formations.

Occasionally, small crabs (Tetracarcinus subquadratus) or fragments of lobsters (Hoploparia gabbi) are found on some of the spoil areas from the Merchantville and Marshalltown Formations.

Ostracodes can be collected by studying the sand-sized residue from screenings of the Mount Laurel Formation.

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).

Like clams, the brachiopod lives in a shell consisting of two hinged valves, but the orientation of the shells is different. Brachiopods have valves covering the top and bottoms of the animal that are of different sizes and shapes, but the left and right sides are are symmetrical (or mirror images to each other). In contrast, the valves of a clam shell are mirror images of each other, but the individual valves are asymmetrically shaped.

Brachiopods spend their adult life as bottom dwelling filter-feeders. They have generally decreased in abundance and diversity since the Paleozoic Era. Some types are fairly common, easy to identify, and are restricted to certain periods of time. These features make them important index or guide fossils. The brachiopod species Terebratulina cooperi is an index fossil for the Mount Laurel Formation in Delaware.

Bryozoans, sometimes referred to as "moss animals," are a type of simple colonial animal that mostly lives in marine environments (a few inhabit freshwater). Bryozoans feed by means of a lophophore, a small ring of tentacles covered with tiny cilia that are used to filter food from the water. Bryozoan colonies are protected with a covering of organic materials or calcium carbonate. Some calcium carbonate forms may be found as fossils in the Cretaceous strata near the C & D Canal.

Three species of bryozoans have been found in the spoils piles (refuse material from excavation of the canal) in the area of Reedy Point. The origin of these bryozoans is under much debate. Their occurrences are most commonly reported from the Mt. Laurel Formation. However, an alternative view is that many are from sediments of the overlying, Tertiary-age Vincentown Formation, which is exposed to the south - if so, they would have been washed into the eastern end of the Canal by the Delaware River and then dumped on the spoils with the other dredgings.

Phylum Annelida
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.

Phylum Echinodermata
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.

Fossil Pelmatozoa are represented in Delaware by stem fragments or columnals from crinoids or sea lilies. Columnals belonging to the Cretaceous crinoid Dunnicrinus are common finds on the Reedy Point spoils. The calyx or head of this crinoid has not been found, probably because of its fragile nature.

Eleutherozoan fossils include a group of starfish-like, free-moving forms called brittle stars, and a group of armless spiny forms known as sea urchins. Complete sea urchins are rare and highly prized specimens. The most common finds along the canal are isolated spines and plates of sea urchins and small fragments of brittle stars.

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.

Chondrichthyes, or “cartilage fish,” include the sharks, skates, and rays. Teeth and vertebrae from these animals are the most common types of vertebrate fossil found. They may be found on the surface of a rock outcrop or in various spoil piles.

The most commonly found shark teeth belong to the extinct shark Squalicorax. These broad and serrated teeth are easy to identify to the genus level, but it is more difficult to distinguish between the species. Teeth of the goblin shark, Scapanorhynchus, are the largest shark teeth found at the Canal, with some specimens reaching over two inches in length. The teeth of this shark have caused workers much confusion because teeth from different parts of the mouth have different and distinct shapes. At one time there were three different names given to the teeth of this single shark species.

Osteichthyes, or “bony fish,” are represented by the dagger-like teeth of the Cretaceous predator Enchodus. Single, isolated teeth and small sections of the jaw with teeth still attached are relatively common finds. Teeth from other bony fish include Anomoeodus and Stephanodus. Vertebral columns of bony as well as cartilaginous fish are also found on the spoil piles.

Reptile remains are rare and thus the most treasured finds from the Delaware Cretaceous. Teeth of the sea-going reptile Mosasaurus and fragments from the upper and lover shells of turtles are the usual finds. Most collectors have to hunt for years before they find a single mosasaur tooth.

The Pollack Farm Site, located in Kent County, Delaware, is named for a borrow pit on the former Pollack property that was excavated during 1991 and 1992 for road material used in the construction of Delaware State Route 1. While Delaware Geological Survey staff collected earth minerals during construction of State Route 1, they came across an upper shell bed full of molluscan fossils. As digging continued, numerous fossils of various species and phylum were found. The fossils discovered range from a simple Arthropod, small insect, to large vertebrates, such as sharks. By 1993, the pit was back-filled, graded, and developed into a wetlands mitigation site.

The Delaware Geological Survey has created this web page to provide a resource of facts and photos of the numerous fossils found in central Delaware. The site includes links to four main phylum, which lead to fossil photographs containing brief descriptions.

In designing this website we hope to provide you with information that will be both educational and enjoyable!

Clams, mussels, oysters, and scallops are members to the class Bivalvia (or Pelecypodia). Bivalves have two shells, connected by a flexible ligament, which encase and shield the soft vulnerable parts of the creature. All 15,000 known species of bivalves are aquatic in nature, with close to 80% being marine (saltwater environments).

Living at the bottom of the marine environment bivalves tend to either swim using their mantle cavity to force water movement, burrow into the sand, or attach themselves to an object with sticky strings called "byssal threads."

Below is a list of notable Bivalve species found at the Pollack Farm site.

• Dallarca sp.
• Astarte distans
• Astarte sp.
• Cyclocardia castrana
• Glossus sp.
• Iphigenia sp.
• Caryocorbula subcontracta

Click the image or the link below to view the bivalvia collection!

The Class Gastropoda (in Phylum Mollusca) includes the groups pertaining to snails and slugs. The majority of gastropods have a single, usually spirally, coiled shell into which the body can be withdrawn. The shell of these creatures is often what is recovered in a fossil dig. Gastropods are by far the largest class of molluscs, comprising over 80% of all molluscs.

The presence of gastropods, at the Pollack site, provides evidence to validate the researchers beliefs that, years ago, the environment was of shallow-water, near-shore locality.

Below are a few notable taxa recovered from the Pollack Farm site.

• Gastrapoda:
• Turritella cumberlandia
• Diastoma insulaemaris
• Epitonium charlestonensis
• Urosalpinx cumberlandianus
• Tritonopsis ecclesiastica
• Nassarius sopora
• Oliva simonsoni
• Inodrillia whitfieldi

Click the image or the link below to view the gastropod collection!

The lower Miocene Pollack Farm Fossil Site has yielded few avian fossils in comparison to the other classes of vertebrates and invertebrates. Only eleven fossil fragments, assignable to six taxa, were collected at the Pollack site. Of the eleven avian fossils collected, representations from three distinctive orders were recovered: Gaviiformes (divers and loons, seen below), Charadriiformes (gulls and shore birds), Pelecaniformes (cormorants and pelicans).

Fossil fragments such as the proximal end of right scapula(order Charadriiformes), Middle trochlea of left tarsometatarsus (order Pelecaniformes) are some of the few materials paleontologist were able to gather.

Other taxa represented include:

Gavia small sp. (1 specimen and possibly another) Morus cf. M. loxostylus (5 specimens)
large species of pseudodontorn (1 specimen)

Although the number of remains is relatively small to other phylum and classes collected, the groups importance can not be undermined due to the information they provide in explaining the past environment of the lower Miocene bed. Because the majority of the birds represent groups that are largely or entirely marine, it further strengthens the hypothesis that the lower Miocene formation was once a near shore area of an embayment.

Click the image or the link below to view the avian fossil collection.

While sampling the lower Miocene Calvert Formation at the Pollack Farm Site, 30 fossil fish taxa were collected, consisting of 24 cartilaginous and 6 osteichthyes fishes. The fossils found in the lower Miocene bed have similar characteristics to an equally aged Formation in southern Delaware suggesting deposition occured in a subtropical, shallow-water, near shore environment.

The early Miocene Fish fossils found in Delaware are of two kinds, Chondrichthyes(consisting mainly of Sharks and rays) and Osteichthyes(commonly known as bony fish).

Paleontologists, at the Pollack Farm, were able to collect a large number of teeth and vertebrae from Chondrichthyes. However, because their bodies do not contain a true bone, full body fossils are very rare to find.

Osteichthyes, differ than Chondrichthyes, in that their skeleton is made of a stiffer bone, compared to their cartilaginous counterparts. Osteichthyes are often associated with dagger-like, isolated teeth

The stingray, dayatis americana, (shown above) is just one of the many Chondrichthyes and fish fauna found at the Pollack Farm Site, in Delaware! Click the image or the link below to view the fish collection.

The majority of Arthropods recovered at the lower Miocene bed are from various species of crustaceans (lobsters, shrimp, barnacles). Fossils from crustaceans often consist of small body parts such as claws. However, crustaceans such as ghost shrimp (callichirus) tend to construct burrows that resemble lumpy tubes called Ophiomorpha. These corn-stalked resembling tunnels, are created from mud and depository waste to form burrows in which the creatures reside. In comparison to claws and pincher fossils, "trace fossils", such as Ophiomorpha tubes, are often commonly found in greater number than that of various body parts.

Arthropods include an exceedingly diverse group of taxa such as insects, crustaceans, spiders, scorpions, and centipedes. There are more species of arthropods than species in all other phyla combined. The name Arthropod means "jointed foot." All arthropods have segmented bodies and are enclosed in a jointed, protective armor called an exoskeleton. Most arthropods have a pair of compound eyes and one to several simple ("median") eyes or ocelli.

In addition to shrimp and other shellfish, barnacles are commonly found in the lower Miocene bed. Barnacles are separated into two groups sessil and stalked. Both have soft bodies that are protected by an outer wall, which resembles either an acorn (sessil) or stalk. Living in a tight grouping with other barnacles these creatures attach themselves to any suitable surface (rocks, boats, even whales and turtles!) in effort to aid in reproduction.

The trace fossils for Arhtropods found at the Pollock Site include Ophiomorpha nodosa (burrow tubes dug by shrimp) and Skolithos linearis (burrow tubes left by ground-dwelling insects).

Click the image or the link below to view the Arthropod collection.

Land mammal fossils were discovered in 1992 in the lower part of the Calvert formation at the Pollack Farm site. During the short time the pit was open, the collection grew to become the most diverse tertiary land mammal fauna known north of Florida on the eastern half of North America.

The gathering, collected from the lower Miocene formation, includes at least 26 species representing at least 17 families in 7 orders (listed below).

Orders:

• Soricomorpha (Shrews, moles)
• Erinaceomorpha (Hedge hogs)
• Chiroptera (Bats)
• Rodentia (Rats, mice)
• Carnivora (Bears, wolves)
• Perissodactyla (Rhinoceros, horses)
• Artiodactyla (Deer)

The Collection of Miocene land mammal fossils, especially north of Florida, is relatively minimal. Only four localities distancing between Georgia and New Jersey yielded significant Miocene fossil beds. Although single teeth and parts of postcranial elements represent the majority of land mammals of the Pollack Farm local fauna, the sites diversity of species elevates the importance of the Pollack Farms location.

Click the image or the link below to view the Land Mammal collection!

The Pollack Farm Site, in the Cheswold sands of the lower Miocene Calvert Formation, produced a fragmentary marine mammal fauna. The Pollack location yielded at least six cetaceans (whales, porpoises), a sirenian(manatee), along with one of the earliest records of a true seal (Listed below).

Marine mammals have the same characteristics as all other mammals, but they have adapted or adjusted to life in the ocean. For instance, many species residing in the deep oceans have a thick layer of blubber, which holds their body temperature warm. Marine mammals also have greater amounts of blood than land mammals, in proportion to their body sizes. This feature allows the blood to be sent to vital organs that in turn slows the heartbeat and minimizes the use of oxygen allowing longer dives underwater.

Species:

• Porpoises - Squalodon calvertensis, Phocageneus venustus, Zarhachis flagellator, Rhabdosteus, & kentriodontid
• Sperm Whale
• Manatee
• Seal - Leptophoca lenis

The collections of marine mammals, from the Miocene Calvert, are less diverse and more fragmentary than the other phylum. However, the Pollack site does extend the marine mammal fossil record into Delaware, which thus validates findings from other locations.

Click the image or the link below to view the Marine Mammal collection!

The Pollack Farm Site has provided the first legitimate window of Miocene reptilian life in North America east of the great plains and north of Florida. In years prior to the excavation of the Pollack site, records of particular small lizards and snakes were non-existent in locations of the mid-Atlantic and northeast, thus providing a significant value to the Miocene fossils recovered.

The fossils recovered from the lower Miocene bed, have provided considerable information to the regions past ecology and environment. The fossils of crocodiles and aquatic turtles gives evidence to a large shallow lake or a river oxbow setting; furthermore, the remaining reptiles probably preferred open brush or grassy environments with loose or sandy soil.

The lower Miocene dig was responsible for the findings of a number of different orders and families of reptiles. Below is a list of species with their fossils recovered from the Pollack Farm Site.

• Kinosternon sp. Mud Turtle(fragmentary costals, hyoplastra, hypoplastra)
• "Chrysemys group" turtle. Painted turtle, cooter, slider group(nuchal, costals)
• Geochelone sp. Very large land tortoise(Entoplastron, hypoplastron)
• cf. Crocodylus sp. Very large crocodile (Tooth)
• Ophisaurus sp. Legless Lizard (trunk vertebra)
• Pterygoboa delawarensis. New species of distinctive small boid genus(trunk vertebra)
• Calamagras sp. small boid (fragmentary vertebra)
• Ameiseophis robinsoni. Extinct genus and species of small colubrid snake (trunk vertebra)
• Pollackophis depressus. Distinctive new genus and species of small colubrid snake (trunk vertebra)
• cf. Crotalinae. et. sp. Viperid snake (two vertebrae)