The Trigonoceratoidea are a superfamily within the
Nautilida that ranged from the
Devonian
The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, whe ...
to the
Triassic, thought to have contained the source for the
Nautilaceae in which ''
Nautilus'' is found.
Trigonoceratoidea are characterized by open-spiraled,
gyroconic, to closed,
nautiliconic shells in which the
Whorl
A whorl ( or ) is an individual circle, oval, volution or equivalent in a whorled pattern, which consists of a spiral or multiple concentric objects (including circles, ovals and arcs).
Whorls in nature
File:Photograph and axial plane flo ...
section is
quadrate
Quadrate may refer to:
* Quadrate bone
* Quadrate (heraldry)
* Quadrate lobe of liver
* Quadrate tubercle
The quadrate tubercle is a small tubercle found upon the upper part of the femur. It serves as a point of insertion of the quadratus femori ...
in primitive forms; the
venter Venter or Venters is an Afrikaans (and rarely, Jewish) surname, and may refer to:
Venter
* AJ Venter (b. 1973), South African rugby union footballer
* Al J Venter, author
* André Venter (b. 1970), South African rugby union footballer
* Ben Venter ...
typically narrow to acute, the dorsum broad. In some advanced forms, the venter may become concave or broad and rounded, and in some, the surfaces may be strongly
lirate
Lirae (singular lira) are fine lines or ridges (much finer than ribs) that are a sculptural feature of the outside of the shells of various animals. The term is commonly applied to the shells of molluscs such as gastropods, bivalve
Biv ...
.
Classification and phylogeny
The Trigonoceratoidea are based on the family
Trigonoceratidae
The Trigonoceratidae is a family of coiled nautiloid cephalopods that lived during the period from the Early Carboniferous ( Mississippian) to the Early Permian.
Diagnosis
Trigonoceratidae comprise members of the order Nautilida characterized ...
of
Alpheus Hyatt, 1884, with which other
phylogenetically related families are combined, and are equivalent to the abandoned Centroceratida of Flower in Flower and Kümmel 1950, and to the Centroceratina of
Shimanskiy 1957, revised to the Centrocerataceae, Shimanskiy 1962.
The Trigonoceratoidea combine five families, the type, Trigonoceratidae, along with the
Centroceratidae,
Grypoceratidae
Grypoceratidae is the longest-lived family of the Trigonoceratoidea, or of the near equivalent Centroceratina; members of the Nautilida from the Upper Paleozoic and Triassic.Kummel,B. 1964. Nautiloidea-Nautilida, Treatise on Invertebrate Paleonto ...
,
Permoceratidae, and
Syringonautilidae
Syringonautilidae is a family of Nautiloidea from the middle to late Triassic. Syringonautilidae comprise the last of the Trigonoceratoidea and are the source for the Nautilaceae which continued the Nautiloidea through the Mesozoic and into th ...
. Phylogenetic study and age show that the Centroceratidae are the root stock in spite of having been first recognized 16 years after the Trigonoceratidae were first described.
The Centroceratidae gave rise to the Trigonoceratidae and Grypoceratidae in the early
Mississippian
Mississippian may refer to:
* Mississippian (geology), a subperiod of the Carboniferous period in the geologic timescale, roughly 360 to 325 million years ago
*Mississippian culture, a culture of Native American mound-builders from 900 to 1500 AD ...
, while continuing until the very
Early Permian 01 or '01 may refer to:
* The year 2001, or any year ending with 01
* The month of January
* 1 (number)
Music
* '01 (Richard Müller album), 01'' (Richard Müller album), 2001
* 01 (Son of Dave album), ''01'' (Son of Dave album), 2000
* 01 (Urban ...
. The Trigonoceratidae which ranged into the Permian left no descendants. The Grypoceratidae which ranged almost to the end of the Triassic gave rise to two small families, the Permian Permoceratidae and the Triassic Syringonautilidae. The Syringonautilidae, in turn, are the source for the Nautilidae (Nautilaceae) which contain the genus ''Nautilus''.
Families
The
Trigonoceratidae
The Trigonoceratidae is a family of coiled nautiloid cephalopods that lived during the period from the Early Carboniferous ( Mississippian) to the Early Permian.
Diagnosis
Trigonoceratidae comprise members of the order Nautilida characterized ...
, type family, named by Hyatt, 1884, are loosely coiled to
evolute, with oval to