Tommotian

The Tommotian Age, named after the mollusc Tommotia, which began approx. 530 million years ago is an early part of the Cambrian period and lasted for only about 3 million years.

Paleogeography

World climate during the Tommotian was mild; there was no glaciation. Most of North America lay in warm southern tropical and temperate latitudes, which supported the growth of extensive shallow-water archaeocyathid reefs all through the Lower Cambrian. Siberia, which also supported abundant reefs, was a separate continent due east of North America. Baltica - what is now Scandinavia, eastern Europe, and European Russia - lay to the south. Most of the rest of the continents were joined in a supercontinent known as proto-Gondwana. What is now China and east Asia was fragmented at the time. Western Europe was also in pieces, with most of the pieces lying northwest of what is now the north African coastline.

Fauna

The Tommotian saw the rise of diversified metazoans with skeletons, small shelly fauna, the first archaeocyathids, primitive molluscs - monoplacophorans, Lapworthella, and inarticulate brachiopods. Archaeocyaths are sponges with a simple morphology. Their calcareous skeleton consists of an inner and an outer wall that are variably connected. The small shelly fauna consists of various calcareous (also some silica, some calcium phosphate) fossils some 1-5 mm long. They represented a variety of organisms: sponges, molluscs, annelids, lobopods, and other forms that do not seem to belong to any recent phylum. Many of these organisms were recognized either as of unknown affinity or as representatives or groups that became extinct before the end of the Cambrian. The most primitive stage is marked by characteristic elements, such as anabaritids, tommotiids, and hyolithellids, also known as the "Tommotian fauna".

The origin of the many kinds of skeletons during this time was a major evolutionary development. The rapid evolution of a variety of external skeletons was probably in response to the evolution of advanced predators.

References

Mollusca
Linnaeus, 1758

Classes

Caudofoveata
Aplacophora
Polyplacophora
Monoplacophora
Bivalvia
Scaphopoda
Gastropoda
Cephalopoda
† Rostroconchia
† Helcionelloida
† ?Bellerophontida
The molluscs
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Tommotia

Tommotia is an extinct genus of mollusc. Although it had cephalopod-like traits such as squid-like tentacles, it also had a snail-like foot. It is considered to be a primitive cephalopod.
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The Cambrian is a major division of the geologic timescale that begins about 542 ± 1.0 Ma (million years ago) at the end of the Proterozoic eon and ended about 488.3 ± 1.7 Ma with the beginning of the Ordovician period (ICS, 2004).
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Climate is the average and variations of weather over long periods of time. Climate zones can be defined using parameters such as temperature and rainfall.
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glacier is a large, slow moving river of ice, formed from compacted layers of snow, that slowly deforms and flows in response to gravity. Glacier ice is the largest reservoir of fresh water on Earth, and second only to oceans as the largest reservoir of total water.
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Archaeocyatha

The Archaeocyatha or archaeocyathids ("ancient cups") were sessile, reef-building[1] marine organisms of warm tropical and subtropical waters that lived during the early (lower) Cambrian period.
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The Cambrian is a major division of the geologic timescale that begins about 542 ± 1.0 Ma (million years ago) at the end of the Proterozoic eon and ended about 488.3 ± 1.7 Ma with the beginning of the Ordovician period (ICS, 2004).
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Siberia (Russian: Сиби́рь, Sibir); is a vast region on the eastern and North-Eastern part of the Russian Federation constituting almost all of Northern Asia and comprising a large part of the
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reef is a rock, sandbar, or other feature lying beneath the surface of the water yet shallow enough to be a hazard to ships. Many reefs result from abiotic processes—deposition of sand, wave erosion planning down rock outcrops, and other natural processes—but the
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Gondwana (IPA: /ɡɒnˈdwɑːnə/[1], originally Gondwanaland) included most of the landmasses in today's southern hemisphere, including Antarctica, South America, Africa, Madagascar,
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Archaeocyatha

The Archaeocyatha or archaeocyathids ("ancient cups") were sessile, reef-building[1] marine organisms of warm tropical and subtropical waters that lived during the early (lower) Cambrian period.
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Mollusca
Linnaeus, 1758

Classes

Caudofoveata
Aplacophora
Polyplacophora
Monoplacophora
Bivalvia
Scaphopoda
Gastropoda
Cephalopoda
† Rostroconchia
† Helcionelloida
† ?Bellerophontida
The molluscs
..... Click the link for more information.
Monoplacophora
Odhner, 1940

Orders
  • Cyrtonellida
  • Tryblidiida
  • Pelagiellida
Monoplacophora is a class of mollusks thought to be extinct until April 1952, when a living animal was dredged up from deep marine sediments in the Middle
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Brachiopoda
Duméril, 1806

Diversity
About 4000 genera

Subphyla and classes
See Classification

Brachiopods (from Latin bracchium, arm + New Latin -poda, foot) are a nearly extinct, small phylum of benthic invertebrates.
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The small shelly fauna is the name given to an obscure collection of small hard-shelled fossils found worldwide in beds a bit older than the earliest trilobites and archeocyathids from the Nekamit-Daldynian and Tommotian stages (Lower Cambrian).
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Calcareous refers to a sediment, sedimentary rock, or soil type which is formed from or contains a high proportion of calcium carbonate in the form of calcite or aragonite.

It is also used to refer to relatively alkaline soil.
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Calcium phosphate is the name given to a family of minerals containing calcium ions (Ca2+) together with orthophosphates (PO43-), metaphosphates or pyrophosphates (P2O74-) and occasionally hydrogen or hydroxide ions.
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Porifera
Grant in Todd, 1836

Classes
Calcarea
Hexactinellida
Demospongiae
The sponges or poriferans (from Latin "pore" and "to bear") are animals of the phylum Porifera. Porifera translates to "Pore-bearer".
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Mollusca
Linnaeus, 1758

Classes

Caudofoveata
Aplacophora
Polyplacophora
Monoplacophora
Bivalvia
Scaphopoda
Gastropoda
Cephalopoda
† Rostroconchia
† Helcionelloida
† ?Bellerophontida
The molluscs
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Annelida
Lamarck, 1809

Classes and subclasses

Class Polychaeta (paraphyletic?)
Class Clitellata*
   Oligochaeta - earthworms, etc.
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The Tommotian Age, named after the mollusc Tommotia, which began approx. 530 million years ago is an early part of the Cambrian period and lasted for only about 3 million years.

Paleogeography

World climate during the Tommotian was mild; there was no glaciation.
..... Click the link for more information.
Microsoft PowerPoint is a presentation program developed by Microsoft for its Microsoft Office system. Microsoft PowerPoint runs on Microsoft Windows and the Mac OS computer operating systems.
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cleanup to meet Wikipedia's quality standards.

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Uppsala [ˈɵpˌsɑːla] (older spelling Upsala) is the seat of Uppsala County (Uppsala län) and the fourth largest city of Sweden.
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