''Cothurnocystis'' is a genus of small enigmatic
echinoderm
An echinoderm () is any member of the phylum Echinodermata (). The adults are recognisable by their (usually five-point) radial symmetry, and include starfish, brittle stars, sea urchins, sand dollars, and sea cucumbers, as well as the sea ...
s that lived during the Ordovician. Individual animals had a flat boot-shaped body and a thin rod-shaped appendage that may be a stem, or analogous to a foot or a tail. Fossils of ''Cothurnocystis'' species have been found in Nevada, Scotland, Czech Republic, France and Morocco.
Taxonomy
The position of the
Stylophora
The stylophorans are an extinct, possibly polyphyletic group allied to the Paleozoic Era echinoderms, comprising the prehistoric cornutes and mitrates. It is synonymous with the subphylum Calcichordata. Their unusual appearances have led to a va ...
, of which ''Cothurnocystis'' is a prominent representative, has been in a state of flux. Some scientists claim to be able to see a structurally very basic
notochord
In anatomy, the notochord is a flexible rod which is similar in structure to the stiffer cartilage. If a species has a notochord at any stage of its life cycle (along with 4 other features), it is, by definition, a chordate. The notochord consis ...
in the tail, and consequently consider the Stylophora to be a group of primitive
chordate
A chordate () is an animal of the phylum Chordata (). All chordates possess, at some point during their larval or adult stages, five synapomorphies, or primary physical characteristics, that distinguish them from all the other taxa. These fiv ...
s, calling them the "Calcichordata". Alternatively these animals are considered related to
echinoderm
An echinoderm () is any member of the phylum Echinodermata (). The adults are recognisable by their (usually five-point) radial symmetry, and include starfish, brittle stars, sea urchins, sand dollars, and sea cucumbers, as well as the sea ...
s, as the shell (or
test
Test(s), testing, or TEST may refer to:
* Test (assessment), an educational assessment intended to measure the respondents' knowledge or other abilities
Arts and entertainment
* ''Test'' (2013 film), an American film
* ''Test'' (2014 film), ...
) is similar in structure and composition to the tests of echinoderms. However, stylophorans are asymmetric organisms that lack either the
radial symmetry
Symmetry in biology refers to the symmetry observed in organisms, including plants, animals, fungi, and bacteria. External symmetry can be easily seen by just looking at an organism. For example, take the face of a human being which has a pla ...
typical of most echinoderms, or the
bilateral symmetry
Symmetry in biology refers to the symmetry observed in organisms, including plants, animals, fungi, and bacteria. External symmetry can be easily seen by just looking at an organism. For example, take the face of a human being which has a pla ...
of the chordates.
Etymology
* ''C. americana'' refers to the continent where it was found.
* ''C. curvata'' is named for the curved form of its theca.
* ''C. elizae'' honors
Elizabeth Gray, who collected the specimens upon which the description of this species is based.
Distribution
* ''C. americana'' is known from the Lower Ordovician of Nevada (lowest Tremadocian,
Whipple Cave Formation, near Lund, White Pine County).
* ''C. curvata'' occurs at the Upper Ordovician of Scotland (
Starfish Bed of the
Drummock Group
The Drummock Group is a geologic group in Scotland. It preserves fossils dating back to the Ordovician period.
See also
* List of fossiliferous stratigraphic units in Scotland
See also
*Lists of fossiliferous stratigraphic units in Europ ...
, ''Dicellograptus anceps''-zone, Thraive Glen, Girvan, Ayrshire).
* ''C. elizae'' has been collected in the Lower Ordovician of Morocco (highest Tremadocian to mid Floian, Zagora region), the Upper Ordovician of Scotland (Starfish Bed of the Drummock Group, ''Dicellograptus anceps''-zone, Thraive Glen, Girvan, Ayrshire).
* ''C. fellinensis'' is found at the Lower Ordovician of France (
Saint-Chinian Formation, Montaigne Noire).
Description
The body of ''Cothurnocystis'' consists of a chalice (or theca) and a stem (tail or foot). The theca is flattened, boot-shaped and asymmetrical. The edges of the flat sides of the theca seem to consist of 14 elements, 11 defining the outline of the theca, and 3 are processes, one forming a "toe"-spike, a second a heel-spike and a third a lip-spike. The so-called "obverse"-side ("toe" pointing left), is covered with one thin integument, at the "reverse"-side the integument is interrupted by a "strut" formed by a branch of an element near the attachment of the stem, and a branch of an element at the top of the theca. Approximately from the attachment of the stem to the "toe"-spike, is a structure reminiscent of a windpipe, that has been interpreted as a series of slits in the integument. The attachment of the stem seems to consist of four sets of left and right elements, becoming narrower further from the theca. Further down single and uniform elements of the stem seem comparable to the anatomy of sealily stems.
The "instep" of the boot seems to hold both the mouth and the anus.
References
* D. Lambert, D. Naish and E. Wyse (2001) "Encyclopedia of Dinosaurs and prehistoric life", p. 32, Dorling Kindersley Limited, London.
{{Taxonbar, from=Q4459847
Homalozoa
Prehistoric echinoderm genera
Ordovician echinoderms
Prehistoric echinoderms of Africa
Ordovician Africa
Fossils of Morocco
Ordovician echinoderms of Europe
Ordovician France
Ordovician Scotland
Fossils of the Czech Republic
Fossils of France
Fossils of Great Britain
Ordovician echinoderms of North America
Ordovician geology of Nevada
Fossils of the United States
Wheeler Shale
Fossil taxa described in 1913