List of the prehistoric life of Maryland facts for kids

This article lists the amazing prehistoric animals and plants whose fossils have been found in the US state of Maryland. These fossils help scientists understand what life was like millions of years ago in this region.

Ancient Life in Maryland: The Paleozoic Era

The Paleozoic Era was a very long time ago, from about 541 to 252 million years ago. During this time, early life forms like sea creatures and insects first appeared. Maryland's rocks from this era show us many ancient ocean dwellers.

Some Paleozoic Fossils Found in Maryland

Here are some of the interesting prehistoric creatures from the Paleozoic Era found in Maryland:

• †Amphiscapha
• †Amplexopora
• †Archimylacris
• †Atrypa
  • †Atrypa reticularis
• †Aviculopecten
• †Bassipterus
• †Bellerophon
• 

  Fossil of the trilobite Calymene
  †Calymene was a type of trilobite, an ancient sea creature with a hard, segmented shell. They lived from the Early Ordovician to Early Devonian periods.
  • †Calymene camerata
  • †Calymene cresapensis
  • †Calymene niagarensis
• †Camarotoechia
  • †Camarotoechia andrewsi
  • †Camarotoechia litchfieldensis
  • †Camarotoechia tonolowayensis
• †Chonetes
  • †Chonetes novascoticus
• †Cincinnetina
  • †Cincinnetina multisecta
• †Clitendoceras
• †Composita
  • †Composita ovata
• †Cornulites
• †Cypricardinia
  • †Cypricardinia elegans
• †Dakeoceras
• 

  Fossil of the trilobite Dalmanites
  †Dalmanites was another type of trilobite, living from the Late Ordovician to Middle Devonian periods.
  • †Dalmanites limulurus
• †Dolichopterus
• †Edmondia
• †Eldredgeops
  • †Eldredgeops rana
• †Ellesmeroceras
• †Encrinurus
• †Eospirifer
• †Erettopterus
• †Euomphalus
• †Eurypterus was a "sea scorpion," an ancient relative of modern scorpions and spiders.
  • †Eurypterus remipes
• †Favosites
  • †Favosites niagarensis
• †Flexicalymene
• †Goniatites
• †Gyrodoma
• †Hallopora
• †Holopea
• †Hyolithes
• †Isotelus
• †Lingula
• 

  Life restoration of the snake-like amphibian Lysorophus
  †Lysorophus was a snake-like amphibian that lived during the Permian period.
• †Mcqueenoceras
• †Megamolgophis
• †Meristina
• †Metacoceras
• †Naticopsis
• †Neospirifer
  • †Neospirifer dunbari
• †Obolella
• †Obolus
• †Olenellus
• †Ormoceras
• †Orthoceras
• †Platyceras
• †Proterocameroceras
• 

  Life restoration of the eurypterid Pterygotus
  †Pterygotus was another large "sea scorpion" from the Silurian-Middle Devonian.
• †Ribeiria
• †Rioceras
• Solemya
• † Solenopsis
• †Sowerbyella
• †Spirifer
  • †Spirifer vanuxemi
• †Stenosiphon
• †Strophomena
• †Tainoceras
• 

  Fossilized shells of the probable mollusc Tentaculites
  †Tentaculites were small, cone-shaped creatures, likely molluscs.
• †Trigonocera
• †Trimerus
• †Waeringopterus
• †Worthenia

Dinosaurs and More: The Mesozoic Era

The Mesozoic Era, often called the "Age of Dinosaurs," lasted from about 252 to 66 million years ago. Maryland has yielded fossils from dinosaurs, ancient sharks, and other fascinating creatures from this time.

Amazing Mesozoic Animals of Maryland

Here are some of the prehistoric animals from the Mesozoic Era found in Maryland:

• Acirsa
• 

  Life restoration of the theropod dinosaur Acrocanthosaurus
  †Acrocanthosaurus was a large meat-eating dinosaur from the Early Cretaceous period.
• †Acteon
• †Aenona
• †Agerostrea
• †Allognathosuchus
• †Allosaurus was another large predatory dinosaur.
• †Amyda
• †Ancilla
• †Anomia
• †Anomoeodus
• Arrhoges
• Astarte
• 

  Life restoration of the sauropod dinosaur Astrodon
  †Astrodon was a huge, long-necked plant-eating dinosaur. Its fossils are very important to Maryland's dinosaur history.
  • †Astrodon johnstoni – This species was first identified from fossils found in Maryland.
• †Baculites were straight-shelled ammonites, a type of ancient mollusc.
  • †Baculites baculus
• †Bottosaurus was an ancient crocodile relative.
  • †Bottosaurus harlani
• Botula
  • †Botula conchafodentis
  • †Botula ripleyana
• Cadulus
• Caestocorbula
  • †Caestocorbula crassaplica
  • †Caestocorbula crassiplica
  • †Caestocorbula percompressa
  • †Caestocorbula terramaria
• Carcharias
• †Caveola
• 

  Life restoration of the lungfish Ceratodus
  †Ceratodus was a type of lungfish.
• Cerithium
• Chiloscyllium
• †Cimoliasaurus was a type of plesiosaur, a long-necked marine reptile.
• †Coelosaurus was a small, agile dinosaur.
  • †Coelosaurus affinis
  • †Coelosaurus antiquus
• †Coelurus was another small dinosaur.
  • †Coelurus gracilis – This species was first identified from fossils found in Maryland.
• †Corax
• Corbula
• †Crenella
  • †Crenella elegantula
  • †Crenella serica
• 

  Fossil of the shark Cretolamna
  †Cretolamna was an ancient shark.
  • †Cretolamna appendiculata
• Cucullaea
  • †Cucullaea capax
• Cuspidaria
  • †Cuspidaria ampulla
• Cylichna
  • †Cylichna diversilirata
  • †Cylichna incisa
• †Cylindracanthus
• †Cymella
• Dasyatis
• 

  Life restoration of the dromaeosaur Deinonychus
  †Deinonychus was a "raptor" dinosaur known for its sharp claws.
  • †Deinonychus antirrhopus
• †Deinosuchus was a giant crocodile relative.
  • †Deinosuchus rugosus
• †Dentalium
  • †Dentalium leve
• †Discoscaphites were a type of ammonite.
  • †Discoscaphites conradi
  • †Discoscaphites gulosus
  • †Discoscaphites iris
• †Egertonia
• †Enchodus was a fish with long, needle-like teeth.
  • †Enchodus dirus
• †Eulima
  • †Eulima monmouthensis
• †Euspira
• 

  Illustration of a fossilized shell of the nautiloid Eutrephoceras
  †Eutrephoceras was a nautiloid, a type of cephalopod with a coiled shell.
• †Ewingia
• †Exogyra was a type of oyster.
  • †Exogyra costata
• Galeorhinus
• Ginglymostoma
• Glossus
• Glycimeris
• Glycymeris
  • †Glycymeris rotundata
• †Glyptops
• †Goniopholis was another ancient crocodile.
• 

  Fossil footprint of the theropod dinosaur Grallator
  †Grallator is a type of dinosaur footprint, likely made by a small theropod.
• †Halisaurus was a type of mosasaur, a large marine lizard.
  • †Halisaurus platyspondylus
• †Hamatia – This genus was first identified from fossils found in Maryland.
• †Hamulus
• Heterodontus
• † Heteromorpha
• †Hoploparia
• †Hybodus was a type of shark.
• †Hyposaurus was a crocodile relative.
  • †Hyposaurus rogersii
• †Inoceramus was a large clam.
• †Ischyodus
• †Ischyrhiza was a sawfish-like ray.
  • †Ischyrhiza avonicola
  • †Ischyrhiza mira
• 

  Fossilized shell of the ammonoid Jeletzkytes
  †Jeletzkytes was a type of ammonite.
  • †Jeletzkytes nebrascensis
• Latiaxis
• Lepisosteus
• Lima
• Limatula
• †Linearis
• Lithophaga
• Lopha was a type of oyster.
  • †Lopha falcata
  • †Lopha mesenterica
• †Mathilda
• †Modiolus
  • †Modiolus sedesclaris
  • †Modiolus sedesclarus
  • †Modiolus trigonus
• †Morea
• 

  Life restoration of two Mosasaurus
  †Mosasaurus was a giant marine reptile, a top predator of the Late Cretaceous seas.
  • †Mosasaurus conodon
• Myliobatis
• †Mytilus
• Nebrius
• Nucula was a small clam.
  • †Nucula camia
  • †Nucula cuneifrons
  • †Nucula percrassa
  • †Nucula severnensis
• 

  A living Odontaspis sand shark
  Odontaspis is a type of sand shark.
• †Osteopygis was an ancient turtle.
• Panopea
• †Paralbula
• †Peritresius was an ancient turtle.
• Pholas
• †Pinna
• †Placenticeras was a type of ammonite.
• †Pleurocoelus was a large sauropod dinosaur.
  • †Pleurocoelus nanus – This species was first identified from fossils found in Maryland.
• †Plicatoscyllium
• Polinices
• 

  Illustration of a fossilized tooth of the armored dinosaur Priconodon
  †Priconodon was an armored dinosaur.
  • †Priconodon crassus – This species was first identified from fossils found in Maryland.
• †Prognathodon was another type of mosasaur.
  • †Prognathodon rapax
• †Propanoplosaurus was a small armored dinosaur.
  • †Propanoplosaurus marylandicus – This species was first identified from fossils found in Maryland.
• †Protocardia
• †Pteria
• †Pterotrigonia was a type of clam.
  • †Pterotrigonia eufalensis
  • †Pterotrigonia eufaulensis
  • †Pterotrigonia thoracica
• †Ptychotrygon
• Pycnodonte was a type of oyster.
  • †Pycnodonte vesicularis
• Raja
• Rhinobatos
• 

  Restoration of the ray Rhombodus
  †Rhombodus was an ancient ray.
• Ringicula
  • †Ringicula clarki
  • †Ringicula pulchella
• Rissoina
• †Sargana
• †Scaphites was a type of ammonite.
  • †Scaphites hippocrepis
• Serpula
• †Serratolamna was a type of shark.
  • †Serratolamna serrata
• †Sphenodiscus was a type of ammonite.
  • †Sphenodiscus lobatus
  • †Sphenodiscus pleurisepta
• 

  Life restoration of the shark Squalicorax
  Squalicorax was a "crow shark."
  • †Squalicorax falcatus
  • †Squalicorax kaupi
  • †Squalicorax pristodontus
• Squatina
• †Stephanodus
• Tellina
• †Tenea
• 

  Life restoration of the Iguanodon relative Tenontosaurus
  †Tenontosaurus was a plant-eating dinosaur related to Iguanodon.
• †Thoracosaurus was a crocodile relative.
• Trachycardium
  • †Trachycardium eufaulensis
• Turritella was a type of sea snail with a tall, spiral shell.
  • †Turritella bilira
  • †Turritella hilgardi
  • †Turritella paravertebroides
  • †Turritella tippana
  • †Turritella trilira
  • †Turritella vertebroides
• †Zephyrosaurus

Mammals and Modern Life: The Cenozoic Era

The Cenozoic Era began about 66 million years ago and continues to the present day. This era is known as the "Age of Mammals," as mammals became the dominant large animals after the dinosaurs died out. Maryland's fossils from this era include ancient whales, camels, and many animals similar to those we see today.

Notable Cenozoic Fossils from Maryland

Here are some of the prehistoric animals from the Cenozoic Era found in Maryland:

• †Abra
• Acipenser
• Acropora
  • †Acropora palmata
• Acteocina
• Acteon
• †Adocus was an ancient turtle.
• 

  Life restoration of the long-necked camel Aepycamelus
  †Aepycamelus was a long-necked camel.
• Aetobatus
• †Aglaocetus was an ancient whale.
• Alca
  • †Alca torda
• †Ambystoma were salamanders.
  • †Ambystoma maculatum
  • †Ambystoma tigrinum
• Amia
• 

  Life restoration of the beardog Amphicyon
  †Amphicyon was a "beardog," a large predatory mammal.
• Amyda
• Anachis
• Anadara
  • †Anadara ovalis
  • †Anadara transversa
• Anas
  • †Anas crecca
• Ancilla
• Angulus
• Anomia
  • †Anomia simplex
• Anticlimax
• †Aphelops
• Aporrhais
• Aquila
  • †Aquila chrysaetos
• †Araeodelphis was an ancient dolphin.
• Arca
• †Archaeohippus was an early horse.
• Architectonica
• †Arctodus was a giant short-faced bear.
  • †Arctodus pristinus
• Argopecten
  • †Argopecten irradians
• †Armatobalanus
• 

  Shell of a modern Astarte bivalve
  Astarte
  • †Astarte undata
• Asterias
  • †Asterias forbesi
• Astrangia
  • †Astrangia danae
• †Astroscopus was a type of stargazer fish.
  • †Astroscopus countermani – This species was first identified from fossils found in Maryland.
• Astyris
  • †Astyris lunata
• Athleta
• Atrina
• 

  Life restoration of the sperm whale Aulophyseter
  †Aulophyseter was an ancient sperm whale.
• Balaenoptera
• Balanus
  • †Balanus crenatus
• Bankia
• Barnea
• Blarina
  • †Blarina brevicauda
  • †Blarina carolinensis
• Bonasa
  • 

    A living Bonasa umbellus, or ruffed grouse
    †Bonasa umbellus was a ruffed grouse.
• Boreotrophon
• Brachidontes
• †Brachyprotoma was a type of skunk.
  • †Brachyprotoma obtusata
• †Brevoortia
  • †Brevoortia tyrannus
• Bufo were toads.
  • †Bufo americanus
  • †Bufo woodhousei
• Busycon was a type of sea snail.
  • †Busycon carica
• Busycotypus
  • †Busycotypus canaliculatus
• Cadulus
• Caecum
• Callinectes were blue crabs.
  • †Callinectes ornatus
  • 

    A living Callinectes sapidus, or Chesapeake blue crab
    †Callinectes sapidus
• Calliostoma
• Callista
• Calonectris
• Calyptraea
  • †Calyptraea centralis
• Cancellaria
• Cancer
  • †Cancer irroratus
• Canis were wolves and coyotes.
  • 

    Illustration of a fossilized skull of Armbruster's wolf, Canis armbrusteri
    †Canis armbrusteri was an ancient wolf. This species was first identified from fossils found in Maryland.
  • †Canis latrans was a coyote.
  • †Canis rufus was a red wolf.
• Cantharus
• Carcharhinus
• Carcharias
• Carcharodon
  • †Carcharodon hastalis was a large shark.
• Cardita
• Carphophis
  • †Carphophis amoenus
• Cassis
• Castor
  • †Castor canadensis was a beaver.
• †Cephalotropis was an ancient whale.
• Cerastoderma
• Cervus
• Cetorhinus
• 

  Life restoration of the whale Cetotherium
  †Cetotherium was an ancient baleen whale.
• Chama
• Chelone
• Chelydra
  • †Chelydra serpentina was a snapping turtle.
• †Chesapecten was a type of scallop.
  • †Chesapecten jeffersonius
• Chlamys
• Chrysemys
  • †Chrysemys picta was a painted turtle.
• Circulus
• Cirsotrema
• Clavus
• Clementia
• Clethrionomys
  • Clethrionomys gapperi
• Cliona
• Coluber
  • 

    A living Coluber constrictor, or eastern racer
    †Coluber constrictor was an eastern racer snake.
• Concavus
• Condylura
  • †Condylura cristata was a star-nosed mole.
• Conus
• Corbula
• Crassostrea
  • †Crassostrea virginica was an oyster.
• Crepidula
  • †Crepidula fornicata
  • †Crepidula plana
• 

  Fossil of the shark Cretolamna
  †Cretolamna was an ancient shark.
  • †Cretolamna appendiculata
• Crotalus
  • †Crotalus horridus was a rattlesnake.
• Crucibulum
• Cryptobranchus
• Cucullaea
• Cumingia
• Cyclocardia
• Cylichna
• Cymatosyrinx
• †Cynarctus was a type of dog.
  • †Cynarctus wangi – This species was first identified from fossils found in Maryland.
• 

  Shell of a Cypraea cowrie sea snail
  Cypraea
  • †Cyrtopleura costata
• Cythara
• †Cytheris
• Dasyatis
• Dentalium
• Diadophis
  • †Diadophis punctatus
• Diodora
• †Diorocetus was an ancient whale.
• †Dipoides was a beaver.
• Discinisca
• †Dolicholatirus
• Dosinia
• Echinocardium
• Echinophoria
• †Ecphora was a type of sea snail.
  • 

    Illustration of a fossilized shell of the murex sea snail Ecphora gardnerae
    †Ecphora gardnerae
• †Ectopistes
  • †Ectopistes migratorius was the passenger pigeon.
• Elaphe
  • †Elaphe vulpina
• Electra
• Elphidium
• Ensis
  • †Ensis directus
• †Entobia
• †Eosuchus
• †Eosurcula
• Epitonium
  • †Epitonium humphreysii
• Eptesicus
  • †Eptesicus fuscus
• Equus were horses.
  • †Equus giganteus
• Erethizon
  • †Erethizon dorsatum was a porcupine.
• 

  Life restoration of the shrub ox Euceratherium
  †Euceratherium was a shrub ox.
  • †Euceratherium collinum
• †Euclastes
• Eulima
• Eumeces
  • †Eumeces fasciatus
• Eupleura
  • †Eupleura caudata
• †Eurhinodelphis was an ancient dolphin.
  • †Eurhinodelphis longirostris
• Euspira
  • †Euspira heros
• 

  A living Felis, or cat
  Felis
• †Ficopsis
• Fissurella
• †Fistulobalanus
• †Fulgar
• Galeocerdo were tiger sharks.
  • †Galeocerdo aduncus
  • †Galeocerdo contortus
• Galeodea
• Gari
• Gastrochaena
• Gavia
  • †Gavia immer was a loon.
• 

  Fossilized skull of the crocodile relative Gavialosuchus
  †Gavialosuchus was a crocodile relative.
• Gegania
• Gemma
  • †Gemma gemma
• Genota
• Geukensia
  • †Geukensia demissa
• Gibbula
• Glaucomys
• Globigerina
• Globigerinoides
• Glossus
• Glycimeris
• Glycymeris
  • †Glycymeris americana
• Glyptemys
  • †Glyptemys muhlenbergii
• 

  Mounted fossilized skeleton of the elephant relative Gomphotherium
  †Gomphotherium was an ancient elephant relative.
• Gulo
  • †Gulo gulo was a wolverine.
• Gyrinophilus
  • †Gyrinophilus porphyriticus
• †Hadrodelphis was an ancient dolphin.
• Haminoea
• Hastula
• Haustator
• †Heliadornis was an ancient bird.
• Hemipristis
  • †Hemipristis serra was a snaggletooth shark.
• Heterodon
  • †Heterodon platyrhinos
• Hiatella
  • †Hiatella arctica
• 

  Mounted fossilized skeleton of the horse Hippotherium
  †Hippotherium was an ancient horse.
• Hyla
  • †Hyla crucifer
• Hyotissa
• Ictalurus
• Ilyanassa
  • †Ilyanassa obsoleta
  • †Ilyanassa trivittata
• Ischadium
  • †Ischadium recurvum
• †Ischyodus
• Isognomon
• Isurus
• 

  Life restoration of the dolphin Kentriodon
  †Kentriodon was an ancient dolphin.
• Kuphus
• Kurtziella
  • †Kurtziella cerina
• Lacuna
• †Lagodon
• Lamna
• Lampropeltis
  • †Lampropeltis triangulum
• Lasiopodomys
• Lepisosteus
• †Leptophoca was an ancient seal.
  • †Leptophoca lenis – This species was first identified from fossils found in Maryland.
• Lepus
  • †Lepus americanus was a snowshoe hare.
• Libinia
  • †Libinia dubia
• Lithophaga
• Littoraria
  • †Littoraria irrorata
• Lontra
  • 

    Pair of living Lontra canadensis, or North American river otter
    †Lontra canadensis was a North American river otter.
• †Lophocetus was an ancient whale.
• Lopholatilus
• Lucina
• Lunatia
• Lyonsia
• Macoma
  • †Macoma balthica
• Macrocallista
• †Macrokentriodon was an ancient dolphin.
• †Mammut
  • †Mammut americanum was the American mastodon.
• †Mammuthus
  • †Mammuthus columbi was the Columbian mammoth.
  • 

    Life restorations of an American mastodon (right) and a wooly mammoth (left)
    †Mammuthus primigenius was the woolly mammoth.
• Marginella
• Marmota
  • †Marmota monax was a groundhog.
• Martesia
• Mathilda
• †Megalonyx was a giant ground sloth.
• Megaptera
• Melampus
  • †Melampus bidentatus
• Melanitta
  • †Melanitta deglandi
• Meleagris
  • 

    A wild male Meleagris gallopavo, or turkey
    †Meleagris gallopavo was a wild turkey.
• Membranipora
• Menestho
• Mephitis
  • †Mephitis mephitis was a striped skunk.
• Mercenaria
  • †Mercenaria mercenaria was a hard clam.
• Meretrix
• †Merychippus was an ancient horse.
• †Mesocetus was an ancient whale.
• †Metaxytherium was a sea cow.
• Microtus
  • †Microtus chrotorrhinus
  • †Microtus pennsylvanicus
• 

  Restoration of the American cheetah Miracinonyx
  †Miracinonyx was the American cheetah.
  • †Miracinonyx inexpectatus
• Mitra
• Modiolus
  • †Modiolus modiolus
• †Moira
• †Monotherium was an ancient seal.
• Mulinia
  • †Mulinia lateralis
• Mustela
  • †Mustela vison was a mink.
• †Mya
  • †Mya arenaria was a softshell clam.
• Myliobatis
• 

  Fossilized skeleton of the peccary Mylohyus
  †Mylohyus was a peccary.
  • †Mylohyus fossilis – This species was first identified from fossils found in Maryland.
• Myotis
  • †Myotis grisescens
• Mytilus
• †Nanosiren was a sea cow.
• Napaeozapus
  • †Napaeozapus insignis was a woodland jumping mouse.
• Narona
• Nassa
• 

  A living Nassarius, or nassa mud snail
  Nassarius
  • †Nassarius vibex
• Neofiber
• Neotoma was a woodrat.
  • †Neotoma floridana
• Nerodia
  • †Nerodia sipedon
• Neverita
• Notophthalmus
  • †Notophthalmus viridescens
• Notorynchus
  • 

    Close-up portrait of a living Notorynchus cepedianus, or broadnose sevengill shark
    †Notorynchus cepedianus was a broadnose sevengill shark. This species was first identified from fossils found in Maryland.
• Novocrania
• Nucula
  • †Nucula proxima
  • †Nuculana acuta
• Ochotona
  • †Ochotona princeps
• Odocoileus
  • †Odocoileus virginianus was a white-tailed deer.
• Odontaspis
• Odostomia
• Ondatra
  • †Ondatra zibethicus was a muskrat.
• Opheodrys
  • †Opheodrys vernalis
• †Orycterocetus was an ancient whale.
• †Osteopygis was an ancient turtle.
• Ostrea
• †Otodus
  • 

    Diagram illustrating the size of the giant shark Carcharocles megalodon (sometimes Carcharodon or Otodus megalodon) compared to other sharks and a human
    †Otodus megalodon was the famous giant shark, Megalodon!
• Otus
• †Oxyrhina
  • †Oxyrhina desorii
• Pagurus
  • †Pagurus pollicaris
• †Palaeocarcharodon
• †Palaeophis was a giant sea snake.
• Pandora
• Panopea
• Panopeus
  • †Panopeus herbstii
• Panthera
  • †Panthera leo was a lion.
  • †Panthera onca was a jaguar.
• Parascalops
  • †Parascalops breweri was a hairy-tailed mole.
• 

  Life restoration of the baleen whale Parietobalaena and calf
  †Parietobalaena was an ancient baleen whale.
  • †Parietobalaena palmeri – This species was first identified from fossils found in Maryland.
• Pecten
• Pekania
• †Pelocetus was an ancient whale.
• Perisoreus
  • †Perisoreus canadensis was a Canada jay.
• Peromyscus
  • †Peromyscus leucopus
• Petricola
  • †Petricola pholadiformis
• †Phenacodus
• Phenacomys
• †Phocageneus was an ancient seal.
• Pholadomya
• †Physeterula was an ancient sperm whale.
• Pinna
• Pipistrellus
• Pitar
  • †Pitar morrhuanus
• Pitymys
• Placopecten
• 

  Restoration of a herd of peccaries of the genus Platygonus
  †Platygonus was a type of peccary.
• Plecotus
• Plethodon
• Pleurotomella
• Pogonias
  • †Pogonias cromis
• Polydora
• Polystira
• †Presbyornis was an ancient bird.
• †Prionodon
• Prionotus
  • †Prionotus evolans
• Propebela
• Prophaethon
• †Protocardia
• Pseudacris
  • †Pseudacris triseriata
• Pseudoliva
• Pteria
• †Ptychosalpinx
• 

  A living Puffinus shearwater
  Puffinus
• Pycnodonte
• Quinqueloculina
• †Rana were frogs.
  • †Rana clamitans
  • †Rana pipiens
  • †Rana sylvatica
• Rangia
• Ranzania
• Retusa
• 

  A school of living Rhinoptera, or cownose rays
  Rhinoptera were cownose rays.
• Rhynchobatus
• †Roccus
  • †Roccus saxatilis was a striped bass.
• †Rotalia
• Salamandra
• †Scala
• †Scaldicetus was an ancient sperm whale.
• †Scapanorhynchus was a type of shark.
• Scaphander
• Scaphella
• Sceloporus
  • †Sceloporus undulatus
• 

  Fossilized skull of the toothed whale Schizodelphis
  †Schizodelphis was an ancient toothed whale.
• Schizoporella
  • †Schizoporella unicornis
• Sciaenops
• Sciurus
  • †Sciurus carolinensis was a gray squirrel.
• †Scutella was a sand dollar.
• †Sediliopsis
• Seila
  • †Seila adamsii
• Semele
• Semele
• Serpulorbis
• Siphonalia
• 

  Life restoration of the saber-tooth cat Smilodon
  †Smilodon was the famous saber-tooth cat.
  • †Smilodon fatalis
• †Solarium
• Solen
• Sorex
  • †Sorex cinereus
  • †Sorex fumeus
• Spermophilus
  • †Spermophilus tridecemlineatus
• †Sphyraenodus
• Sphyrna
• Spilogale
  • †Spilogale putorius was a spotted skunk. This species was first identified from fossils found in Maryland.
• Spisula
• 

  Life restoration of the shark-toothed dolphin Squalodon
  †Squalodon was a "shark-toothed dolphin."
  • †Squalodon calvertensis – This species was first identified from fossils found in Maryland.
• Squatina
• Squilla
  • †Squilla empusa
• Stewartia
• Stramonita
• Strioterebrum
• †Syllomus was an ancient turtle.
• Sylvilagus
  • †Sylvilagus floridanus was an eastern cottontail rabbit.
• 

  Illustration of a living Synaptomys, or bog lemming
  Synaptomys was a bog lemming.
  • †Synaptomys cooperi
• Syrnola
• Tagelus
• Tamias
  • †Tamias striatus was an eastern chipmunk.
• Tamiasciurus
  • †Tamiasciurus hudsonicus was an American red squirrel.
• †Tapiravus was an ancient tapir.
• 

  A living Tapirus, or tapir
  Tapirus was a tapir.
• †Tasbacka was an ancient turtle.
• Taxidea
  • †Taxidea taxus was a badger. This species was first identified from fossils found in Maryland.
• Teinostoma
• Tellina
• Terebra
• Terebratula
• Teredo
• Terrapene
  • †Terrapene carolina was a box turtle.
• Testudo
• Textularia
• Thamnophis
• 

  Fossilized skeleton of the gavial relative Thecachampsa
  †Thecachampsa was a crocodile relative.
  • †Thecachampsa antiqua
• Thomomys
• Thracia
• Tremarctos
  • †Tremarctos floridanus was a Florida cave bear.
• Triloculina
• Trionyx
• Triphora
• Tritonium
• Trochita
• †Trygon
• †Tuba
• Turricula
• Turris
• Turritella
• 

  A living Tursiops, or bottlenose dolphin
  Tursiops was a bottlenose dolphin.
• Typhis
• Umbraculum
• Urosalpinx
  • †Urosalpinx cinerea
• Ursus
  • †Ursus americanus was a black bear.
• Venericardia
• Vespertilio
• Vitrinella
• Volutifusus
• Vulpes
• 

  Fossilized skeleton of the whale Xiphiacetus
  †Xiphiacetus was an ancient whale.
• Xiphias
• Yoldia
  • †Yoldia limatula