a fossil cephalopod similar to the nautilisk.

Ammonite

a fossil cephalopod similar to the nautilisk.

a fossil cephalopod similar to the nautilisk.

Ammonite

a fossil cephalopod similar to the nautilisk.

a fossil cephalopod similar to the nautilisk.

Ammonite

a fossil cephalopod similar to the nautilisk.

Sigillaria is the generic name assigned to this ancient arborescent lycopod. Occassionally the trunks were smooth. Extinct genus of tree-sized lycopsids from the Carboniferous Period (about 360 to 300 million years ago) that are related to modern club mosses. Sigillaria had a single or sparsely branched trunk characterized by a slender strand of wood and thick bark.

Sigillaria, An Ancient Tree

Sigillaria is the generic name assigned to this ancient arborescent lycopod. Occassionally the trunks…

The skeleton of an elasmosaurus, a dinosaur in the order of plesiosaurs.

Elasmosaurus Skeleton

The skeleton of an elasmosaurus, a dinosaur in the order of plesiosaurs.

This illustration shows the ancient fossile of an amphibian. Fossils are the mineralized or otherwise preserved remains or traces of animals, plants, and other organisms.

Fossil

This illustration shows the ancient fossile of an amphibian. Fossils are the mineralized or otherwise…

The Lingula antigua is a little bivalve shell belonging at the bottom of the class Brachiopoda. The inarticulate brachiopod genus Lingula is the oldest, relatively unchanged animal known. The oldest lingulid fossils are found in Lower Cambrian rocks dating to roughly 550 million years ago. The origin of brachiopods is unknown. A possible ancestor is a sort of ancient "armored slug" known as Halkieria that had small brachiopod-like shields on its head and tail.

Lingula Antigua

The Lingula antigua is a little bivalve shell belonging at the bottom of the class Brachiopoda. The…

The Lingula prima is a little bivalve shell belonging at the bottom of the class Brachiopoda. The inarticulate brachiopod genus Lingula is the oldest, relatively unchanged animal known. The oldest lingulid fossils are found in Lower Cambrian rocks dating to roughly 550 million years ago. The origin of brachiopods is unknown. A possible ancestor is a sort of ancient "armored slug" known as Halkieria that had small brachiopod-like shields on its head and tail.

Lingula Prima

The Lingula prima is a little bivalve shell belonging at the bottom of the class Brachiopoda. The inarticulate…

Lingula is a genus of brachiopods within the class Lingulata. Lingula is among the few brachiopods surviving today but also known from fossils over 500 million years old. Brachiopods are suspension feeding, marine, benthic lophophorates in two higher species, Inarticulata and Articulata.

Modern Lingula

Lingula is a genus of brachiopods within the class Lingulata. Lingula is among the few brachiopods surviving…

The argonauts (genus Argonauta, the only extant genus in the Argonautidae family) are a group of pelagic octopuses. They are also called paper nautiluses, referring to the paper-thin eggcase that females secrete. This structure lacks the gas-filled chambers present in chambered nautilus shells and is not a true cephalopod shell, but rather an evolutionary innovation unique to the genus Argonauta. Female argonauts produce a laterally-compressed calcareous eggcase in which they reside.

Paper Nautilus Octopuses

The argonauts (genus Argonauta, the only extant genus in the Argonautidae family) are a group of pelagic…

The argonauts (genus Argonauta, the only extant genus in the Argonautidae family) are a group of pelagic octopuses. They are also called paper nautiluses, referring to the paper-thin eggcase that females secrete. This structure lacks the gas-filled chambers present in chambered nautilus shells and is not a true cephalopod shell, but rather an evolutionary innovation unique to the genus Argonauta. Argonauts use tentacles to grab prey and drag it toward the mouth.

Paper Nautilus Octopuses

The argonauts (genus Argonauta, the only extant genus in the Argonautidae family) are a group of pelagic…

The Pearly Nautilus (Nautilus Pompilius) is the only living representative of a unique form of cephalopod, recorded in fossils for over 500 million years. The shell, pearly and beautifully colored, is spirally formed and consists of a series of chambers separated by curved cross plates thus exemplifies the "chambered shell". The nautilus is a bottom feeder on Crustaceans, usually in deep water.

Pearly Nautilus

The Pearly Nautilus (Nautilus Pompilius) is the only living representative of a unique form of cephalopod,…

Along the south shore of Lake Superior is a sandstone once regarded as belonging to the Potsdam, but probably, in part , of the age of the Calciferous, in which we search in vain for any of those fossil remains so common in Minnesota. Whaterver its geological age, the Lake Superior sandstone is a formation of remarkable interest. This section across Lake Superior shows (a) water level. (b) trap outburst north of the lake, (c) trap outburst forming Isle Royale, (d) trap outburst forming Kewenaw Point, (e) Lake Superior sandstone and conglomerate. Eözoic and other rocks underlying the sandstone (f).

Sandstone

Along the south shore of Lake Superior is a sandstone once regarded as belonging to the Potsdam, but…

An illustration of various sea urchin fossils. "1, Palaeechinus; Carboniferous; 2, A plate and radiole of Archaeolcidaris; 3, A radiole of Cidaris; Jurassic; 4, Hemicidaris; Mid. Jurassic; 5, Salenia; Cretaceous; 6, Dyaster; Jurassic; 7, Enallaster; Cretaceous; 8, Catopygus; Cretaceous." -Britannica, 1910

Sea Urchin Fossils

An illustration of various sea urchin fossils. "1, Palaeechinus; Carboniferous; 2, A plate and radiole…

Following the species of simple septa and straight shells, came the Trocholites ammoulus, of simple septa and coiled chambered shells of the Trenton period.

Coiled Chambered Shell

Following the species of simple septa and straight shells, came the Trocholites ammoulus, of simple…

The Clymenia Sedgwickii represents a coiled shell with angulated or bent septa.

Coiled Chambered Shell

The Clymenia Sedgwickii represents a coiled shell with angulated or bent septa.

Goniatites are extinct ammonoids, shelled cephalopods related to squid, octopus, and belemnites, that form the order Goniatitida. The goniatites all possessed an external shell, which is divided internally into chambers. The animal lived in the largest of the external chambers, and the internal chambers would have been filled with gas, making the animal buoyant in the water.

Coiled Chambered Shell

Goniatites are extinct ammonoids, shelled cephalopods related to squid, octopus, and belemnites, that…

Chambered shell, endless in their variations, in the earliest periods were a species with simple septa and straight shells as in Ormoceras tenuifilum, which shows a large annulated central siphon.

Straight Chambered Shell

Chambered shell, endless in their variations, in the earliest periods were a species with simple septa…

Baculites is a genus of extinct marine animals in the Phylum Mollusca and Class Cephalopoda. They are a nearly straight-shelled type of heteromorph ammonite. This fragment is of a straight chambered shell, Baculites ovatus of Mesozoic Time, belonging to the Ammonite family.

Coiled Chambered Shell

Baculites is a genus of extinct marine animals in the Phylum Mollusca and Class Cephalopoda. They are…

Pecopteris, frond of an ancient tree fern, was a form genus of leaves from several unrelated plant groups that flourished the early Carboniferous period and on to c. 250 Ma. Pecopteris first appeared in the Devonian period, but flourished in the Carboniferous, especially the Pennsylvanian. Plants bearing these leaves went extinct around the beginning of the Permian period.

Pecopteris Tree Fern

Pecopteris, frond of an ancient tree fern, was a form genus of leaves from several unrelated plant groups…

Asaphus is a genus containing at least 35 species of Ordovician trilobites found primarily in Europe. All were benthic predators or detritivores. The typical individual was about 2–7.5 cm in length. The cephalon was smooth, and the glabellum tends not to be distinct from the cephalon. The segments of the pygidium are fused together, though some hint of segmentation may be apparent.

Asaphus Gigas a Trilobite

Asaphus is a genus containing at least 35 species of Ordovician trilobites found primarily in Europe.…

Trilobites ("three-lobes") are extinct marine arthropods that form the class Trilobita. Why the trilobites became extinct is not clear. Their numbers began to decrease with the appearance of the first sharks and other early gnathostomes (jawed vertebrates) in the Silurian and their subsequent rise in diversity during the Devonian period. Trilobites may have provided a rich source of food for these new animals.

Dicellocephalus Minnesotenis a Trilobite

Trilobites ("three-lobes") are extinct marine arthropods that form the class Trilobita. Why the trilobites…

Trilobites ("three-lobes") are extinct marine arthropods that form the class Trilobita. Why the trilobites became extinct is not clear. Their numbers began to decrease with the appearance of the first sharks and other early gnathostomes (jawed vertebrates) in the Silurian and their subsequent rise in diversity during the Devonian period. Trilobites may have provided a rich source of food for these new animals. Fossilised trilobites are often found enrolled (curled up) like modern woodlice for protection; evidence suggests enrollment helped protect against exploitation of arthropod cuticle weakness by Anomalocarid predator attacks.

Dicellocephalus Minnesotenis a Trilobite

Trilobites ("three-lobes") are extinct marine arthropods that form the class Trilobita. Why the trilobites…

Trilobites ("three-lobes") are extinct marine arthropods that form the class Trilobita.The earliest trilobites had complex, compound eyes with lenses made of calcite, a unique characteristic of all trilobite eyes. The trilobite eyes were typically compound, with each lens being an elongated prism. The number of lenses in such an eye varied: some trilobites had only one, while some had thousands of lenses in a single eye. In these compound eyes, the lenses were typically arranged hexagonall (b).

Dicellocephalus Minnesotenis a Trilobite

Trilobites ("three-lobes") are extinct marine arthropods that form the class Trilobita.The earliest…