Vendiamorpha is a

class Class or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytical concept used differentl ...

of extinct animals within the Ediacaran phylum

Proarticulata Proarticulata is a proposed phylum of extinct, bilaterally symmetrical animals known from fossils found in the Ediacaran (Vendian) marine deposits, and dates to approximately . The name comes from the Greek () = "before" and Articulata, i.e. ...

. The typical vendiamorph had an oval-shaped or round-shaped body divided completely into segmented

isomers In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. ...

, that were arranged alternately in two rows with reference to the longitudinal axis of the body.

Description

The phenomenon of left-right alternating segments is called ''

glide reflection In 2-dimensional geometry, a glide reflection (or transflection) is a symmetry operation that consists of a reflection over a line and then translation along that line, combined into a single operation. The intermediate step between reflection ...

symmetry'', and is a diagnostic feature of

proarticulata Proarticulata is a proposed phylum of extinct, bilaterally symmetrical animals known from fossils found in the Ediacaran (Vendian) marine deposits, and dates to approximately . The name comes from the Greek () = "before" and Articulata, i.e. ...

ns. Transverse elements decrease in size from one end to the other and are inclined in the same direction. The larger isomers cover the smaller ones externally and the first isomer is much larger than the rest. Typically, the first few, or largest isomers are fused together to form a headshield-like structure, leading some researchers to have originally considered them to be ancestral or related to

arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and cuticle made of chiti ...

s, though, overwhelming evidence of them being

ns have since led researchers to discard this hypothetical relationship. Some vendiamorphs (e.g., ''Vendia'' and ''Paravendia'') supposedly demonstrate a digestive-distributive system consisting of a simple axial tube and lateral appendages, with one lateral appendage corresponding to one isomer. Class Vendiamorpha currently includes only one

Family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Vendiidae (originally referred to as Vendomiidae as the

type genus In biological taxonomy, the type genus is the genus which defines a biological family and the root of the family name. Zoological nomenclature According to the International Code of Zoological Nomenclature, "The name-bearing type of a nominal ...

''Vendomia'', before ''V. menneri'' was redescribed as a member of '' Dickinsonia'' ) that consist of species ''Vendia sokolovi'', ''V. rachiata'', ''Paravendia janae'' and possibly ''Karakhtia nessovi'', from Ediacaran (Vendian) rocks of the

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Name

The clade name ''

Pseudovendia The "ivesheadiomorphs" are a group of fossilised structures known from Ediacaran localities in England and Newfoundland. They are considered to be taphomorphs, representing the poorly preserved biological remains of various contemporary taxa suc ...

'' refers to the resemblances to a fossil imprint described as ''Vendia sokolovi''. Originally, that fossil was interpreted as an arthropod, later as a

n, then conjectured as possibly a frond-like organism. Current scientific consensus now recognizes the poorly preserved holotype of ''Pseudovendia'' as a

pseudofossil Pseudofossils are inorganic objects, markings, or impressions that might be mistaken for fossils. Pseudofossils may be misleading, as some types of mineral deposits can mimic lifeforms by forming what appear to be highly detailed or organized str ...

References

External links

* {{Ediacaran-stub Prehistoric animal classes

Description

Name

See also

References

External links