| Saarina | |
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| A fossil of Saarina juliae | |
| Scientific classification | |
| Kingdom: | |
| Phylum: | |
| Family: | Saarinidae Sokolov, 1965 |
| Genus: | SaarinaSokolov, 1965 |
| Species | |
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Saarina are cloudinimorph fossils from the Ediacaran (Vendian) and Early Cambrian marine deposits of European Russia and Laurentia. They are tubes made up of stacked conical elements. These fossils are comparable to the dwelling tubes of worms or cnidarians.
Fossils of the type species, S. tenera, were found in a core from the Gatchina No.13 borehole in the Leningrad Region, Russia. The most conspicuous deposits associated with these fossils are referred to as the Lomonosov Fm., Lontova Horizon, and lower Tommotian (=Cambrian Stage 2).
S. kirsanovi fossils were found in a core from the Vorob'evo No.1 borehole, Moscow Region and in a core from the Malinovka borehole, near Obozersky in the Arkhangelsk Region.
S. juliae was found in a core from the Gavrilov-Yam No.5 borehole, Yaroslavl Region. The deposites with S. kirsanovi and S. juliae are referred to the Redkino Horizon, Upper Vendian (Ediacaran), and are about 558 mya old.
They are also known from early Cambrian rocks in the USA. [1]
Saarina was a tube-dwelling organism of unknown biological affinity, known from its siliciclastic deposits dating to the late Ediacaran (Vendian) and lowest Cambrian of the Russian Platform. It was funnel-shaped, consisting of dense, thinly-walled and annulated, ringlike segments. The fossils are preserved in the substrate as a result of superficial mineralization during the early stages of decomposition.
The fossils are typically found in mudstone and preserved in the form of flat pyrite ribbons as a result of superficial pyritization in the early stage of organic decomposition.
Saarina tubes were cylindrical in form, conical at the base, consisting of funnel-shaped narrow rings. The wall of the tube was thin, originally organic-walled, not chitinous. The tubes attained widths up to 7 mm.
The species of the Saarina differ mainly in the forms of the funnels:
The Cambrian Period is the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million years ago (mya) to the beginning of the Ordovician Period 485.4 mya. Its subdivisions, and its base, are somewhat in flux.
The Ediacaran Period is a geological period of the Neoproterozoic Era that spans 96 million years from the end of the Cryogenian Period at 635 Mya, to the beginning of the Cambrian Period at 538.8 Mya. It is the last period of the Proterozoic Eon as well as the so-called Precambrian "supereon", before the beginning of the subsequent Cambrian Period marks the start of the Phanerozoic Eon, where recognizable fossil evidence of life becomes common.
The cloudinids, an early metazoan family containing the genera Acuticocloudina, Cloudina and Conotubus, lived in the late Ediacaran period about 550 million years ago. and became extinct at the base of the Cambrian. They formed millimetre-scale conical fossils consisting of calcareous cones nested within one another; the appearance of the organism itself remains unknown. The name Cloudina honors the 20th-century geologist and paleontologist Preston Cloud.
Pteridinium is an erniettomorph found in a number of Precambrian deposits worldwide. It is a member of the Ediacaran biota.
Dickinsonia is a genus of extinct organism that lived during the late Ediacaran period in what is now Australia, China, Russia and Ukraine, most likely a basal animal. It is one of the best known members of the Ediacaran biota. The individual Dickinsonia typically resembles a bilaterally symmetrical ribbed oval. Its affinities are presently unknown; its mode of growth has been considered consistent with a stem-group bilaterian affinity, though various other affinities have been proposed. The discovery of cholesterol molecules in fossils of Dickinsonia lends support to the idea that Dickinsonia was an animal, though these results have been questioned.
Ausia fenestrata is a curious Ediacaran period fossil represented by only one specimen 5 cm long from the Nama Group, a Vendian to Cambrian group of stratigraphic sequences deposited in the Nama foreland basin in central and southern Namibia. It has similarity to Burykhia from Ediacaran (Vendian) siliciclastic sediments exposed on the Syuzma River of Arkhangelsk Oblast, northwest Russia. This fossil is of the form of an elongate bag-like sandstone cast tapering to a cone on one end. The surface of the fossil is covered with oval depressions ("windows") regularly spaced over the surface in the manner of concentric/parallel rows. The taxonomic identity of Ausia is unresolved.
A trace fossil, also known as an ichnofossil, is a fossil record of biological activity by lifeforms but not the preserved remains of the organism itself. Trace fossils contrast with body fossils, which are the fossilized remains of parts of organisms' bodies, usually altered by later chemical activity or mineralization. The study of such trace fossils is ichnology and is the work of ichnologists.
Vendobionts or Vendozoans (Vendobionta) are a proposed very high-level, extinct clade of benthic organisms that made up of the majority of the organisms that were part of the Ediacaran biota. It is a hypothetical group and at the same time, it would be the oldest of the animals that populated the Earth about 580 million years ago, in the Ediacaran period. They became extinct shortly after the so-called Cambrian explosion, with the introduction of fauna formed by more recognizable groups and more related to modern animals. It is very likely that the whole Ediacaran biota is not a monophyletic clade and not every genus placed in its subtaxa is an animal.
Cephalonega stepanovi is a fossil organism from Ediacaran deposits of the Arkhangelsk Region, Russia. It was described by Mikhail A. Fedonkin in 1976
Parvancorina is a genus of shield-shaped bilaterally symmetrical fossil animal that lived in the late Ediacaran seafloor. It has some superficial similarities with the Cambrian trilobite-like arthropods.
Namacalathus is a problematic metazoan fossil occurring in the latest Ediacaran. The first, and only described species, N. hermanastes, was first described in 2000 from the Nama Group of central and southern Namibia.
Vendia is a genus of oval-shaped, Ediacaran fossils ranging from 4.5 to 12.5 mm long. The body is completely segmented into isomers, which are arranged alternately in two rows longitudinal to the axis of the body. The larger isomers cover the smaller ones externally but the posterior ends of all the isomers remain free. The transverse elements decrease in size from anterior to posterior and are all inclined in the same direction.
The Ediacaranbiota is a taxonomic period classification that consists of all life forms that were present on Earth during the Ediacaran Period. These were enigmatic tubular and frond-shaped, mostly sessile, organisms. Trace fossils of these organisms have been found worldwide, and represent the earliest known complex multicellular organisms. The term "Ediacara biota" has received criticism from some scientists due to its alleged inconsistency, arbitrary exclusion of certain fossils, and inability to be precisely defined.
Albumares brunsae is a tri-radially symmetrical fossil animal that lived in the late Ediacaran seafloor. It is a member of the extinct group Trilobozoa.
Conulariida are an extinct group of medusozoan cnidarians known from fossils spanning from the latest Ediacaran up until the Late Triassic. They are almost exclusively known from their hard external structures, which were pyramidal in shape and made up of numerous lamellae.
The small shelly fauna, small shelly fossils (SSF), or early skeletal fossils (ESF) are mineralized fossils, many only a few millimetres long, with a nearly continuous record from the latest stages of the Ediacaran to the end of the Early Cambrian Period. They are very diverse, and there is no formal definition of "small shelly fauna" or "small shelly fossils". Almost all are from earlier rocks than more familiar fossils such as trilobites. Since most SSFs were preserved by being covered quickly with phosphate and this method of preservation is mainly limited to the late Ediacaran and early Cambrian periods, the animals that made them may actually have arisen earlier and persisted after this time span.
Calyptrina striata is an Ediacaran tubular fossil, probably belonging to some kind of tube-dwelling annelid worm. The tubes is preserved as a flat carbonaceous organic or pyrite shadows left behind in shales, and as a relief imprints and casts in sandstones. Specimens have been found and documented in numerous Ediacaran localities of the White Sea area of Russia and possibly in Southeast China.
Kuibisia glabra is a sac-like and polyp-like solitary Ediacaran organism. The fossil of Kuibisia was dated to be around 610–640 million years old and was found in a pteridinium deposit at Aar Farm in Namibia, South Africa.
A "Palaeopascichnid" describes a multitude of elongate fossils made up of multiple sausage-shaped chambers. They appear only in Ediacaran sediments. Fossils of Palaeopascichnids consist of an occasionally branching series of globular or elongate chambers. These fossils started appearing in the Vendian about 580 million years ago. Fossils of Palaeopascichnids are found in East European platform, Siberia, South China (Lantian), Australia, India (Tethys), Avalonia
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