Palaeozoic.

The

Palaeozoic

Era.

The Palaeozoic Era spans 322 million years, beginning with the Cambrian period 570 million years ago, and finishing with the end of the Permian period 248 million years ago.
Period 248 Million years

Permian

The Permian period begins 286 million years ago and spans 38 million years. It is the closing period of the Palaeozoic era.

Amphibians, such as Eryops, which reached a length of 1.5 metres (5 feet), and the pond dweller Diplocaulus, remain successful during the Permian period. However, the reptiles become the dominant land fauna, such as Dimetrodon which is a common carnivorous reptile. It reached a length of 3.5 metres (11 feet). The first mammal-like reptiles appeared during this period.

At the end of the Permian period, 248 million years ago, many groups of animals including the Goniatites and Trilobites become extinct.

The name Permian is derived from the Perm province in the Ural Mountains, where rocks of this age are extensively developed.

Dimetrodon.

Dimetrodon

Eryops.

Eryops

Diplocaulus.

Diplocaulus

286 Million years

Upper
Carboniferous

(Pennsylvanian)

The Carboniferous period begins 354 million years ago and spans 68 million years. It is the longest period of the Palaeozoic era.

The Pennsylvanian period is the division used in North America which corresponds with the Upper Carboniferous period in Europe. The name Pennsylvanian is derived from the coal measures of the state of Pennsylvania which were formed during this period.

During the latter part of the Carboniferous period forest swamps covered extensive areas of the Northern Hemisphere, and increasingly diverse land plants evolved.
The Carboniferous period is the time during which most of the world's coal deposits were laid down, the coal being formed from compressed layers of rotting vegetation.
These Carboniferous forest swamps were made up of plants which included tree-ferns such as Psaronius, which grew to a height of 15 metres (50 feet), and "scale-trees" such as Lepidodendron, which attained a height of about 30 metres (100 feet).
The first flying insects appeared during the Carboniferous period, and giant dragonflies such as Meganeura, which had a wing span of 70 centimetres (28 inches), inhabited the forest swamps.
Reptiles evolved towards the end of the Carboniferous period, and many types of marine fishes became extinct at the end of this period.

The name Carboniferous derives from the fact that this period contains most of the important coal producing strata.

Psaronius.

Psaronius

Lepidodendron.

Lepidodendron

Branchiosaurus.

Branchiosaurus

Meganeura.

Meganeura

Lower
Carboniferous

(Mississippian)

The Mississippian period is the division used in North America which corresponds to the Lower Carboniferous period in Europe. The name Mississippian is taken from the Mississippi Valley where marine limestone of this age were formed in a shallow sea which covered most of the United States.

Crinoids, Corals and Brachiopods all flourished in the seas during this time, the only vertebrate animals are the amphibians and fishes.

354 Million years

Devonian

The Devonian period begins 412 million years ago and spans 58 million years.

The evolutionary trends of the Silurian period continued during the Devonian period, with plants and vertebrate animals showing spectacular advances.
Among the invertebrates the Goniatites first make their appearance, along with the first flightless insects.
Both freshwater and marine fishes show a great proliferation of forms, with many heavily armoured fishes including the Pteraspids, and the Cephalaspids such as Hemicyclaspis.
The first amphibians, such as Ichthyostega, appeared towards the end of the Devonian period.

The name Devonian is derived from the county of Devonshire in England, where rocks of this age are extensively developed.

Rhynia.

Rhynia

Ichthyostega.

Ichthyostega

Hemicyclaspis.

Hemicyclaspis

Coelacanth.

Coelacanth

Dunkleosteus.

Dunkleosteus

Bothryolepis.

Bothryolepis

412 Million years

Silurian

The Silurian period begins 435 million years ago and spans 23 million years.

No new major groups of invertebrate animals appear during this period.

The "sea scorpions" or Eurypterids, an extinct group of predatory Arthropods, flourished in the seas of the Silurian period, and often reached an enormous size, such as Pterygotus which reached 2.3 metres (7.5 feet) in length.
However, significant developments occur among the vertebrate animals and plants.
Jawless fishes, the Agnathans, begin to diversify towards the middle part of the Silurian period.
The earliest know jawed fishes, the Acanthodians, appear in the Silurian period, along with the first land dwelling plants.

The Silurian period is named after the Silures, an ancient British tribe which inhabited the Welsh Borderland during the Roman times.

Pterygotus.

Pterygotus

435 Million years

Ordovician

The Ordovician period begins 492 million years ago and spans 57 million years.

The early fossils from this period show a major evolutionary burst.
Trilobites, Brachiopods and Graptolites form the three major groups of animal fossils from this period. Bivalves, and later the Nautiloids, begin to rapidly diversify during the Ordovician period.
Corals become more abundant, and Crinoids, Echinoids and Starfish become established.

The Ordovician period is named after the Ordovices, an ancient British tribe who once dwelt in the Welsh Borderland.

Starfish.

Starfish

Crinoids.

Crinoids

492 Million years

Cambrian

The Cambrian period begins 570 million years ago and spans 78 million years. It is the earliest period of the Palaeozoic era.

A great 'explosion' of life occurred in the Cambrian period, with more than 900 species being recorded, compared with the meagre evidence of life in the Precambrian. All of these Cambrian fossils are marine, with the dominant form being the Trilobites.
Brachiopods also appeared, along with Sponges, Bivalves, Gastropods, worms, jellyfish, early 'experimental' Echinoderms, and Arthropods including Crustaceans.
By the middle of the Cambrian period Graptolites appeared, along with Corals and Nautiloids.
Plant life is essentially limited to Algae.

The name Cambrian is derived from Cambria, the ancient Roman name for Wales, where rocks from this period were first studied.

Nautiloids.

Nautiloids

Bivalves.

Bivalves

Sponges.

Sponges

Trilobites.

Trilobites

Algae.

Algae

Jellyfish.

Jellyfish

570 Million years

 

Caenozoic. Mesozoic. Palaeozoic.

 

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