Tainoceras Hyatt, 1883

Korn, Dieter & Hairapetian, Vachik, 2025, Late Permian nautiloids from Baghuk Mountain (Central Iran), European Journal of Taxonomy 1019, pp. 1-76 : 45-48

publication ID

https://doi.org/10.5852/ejt.2025.1019.3071

publication LSID

lsid:zoobank.org:pub:E24EBF4A-9FE2-47E4-A656-E1698F88BB41

DOI

https://doi.org/10.5281/zenodo.17278894

persistent identifier

https://treatment.plazi.org/id/03E487D4-FFF7-492F-FDA3-5DA18197FE64

treatment provided by

Plazi

scientific name

Tainoceras Hyatt, 1883
status

 

Genus Tainoceras Hyatt, 1883 View in CoL

Type species

Nautilus quadrangulus McChesney, 1860 ; original designation.

Diagnosis

Genus of the family Tainoceratidae with a subinvolute or subevolute conch; whorl profile more or less strongly depressed, ranging from subquadrate and hexagonal to polygonal with a distinct midventral longitudinal groove. Umbilical margin usually pronounced and subangular in the intermediate stage, rounded in the adult stage. Sculpture usually with two rows of conical nodes on the venter and additional rows on the flank. Suture line strongly depending on the shape of the whorl profile, usually with shallow external lobe and broadly rounded lateral lobe. Siphuncle narrow with subcentral position ventrad of septum centre.

Included Carboniferous species

North America ( McChesney 1860; Miller et al. 1933; Miller & Unklesbay 1942; Lintz 1958; Tucker & Mapes 1978; Sturgeon et al. 1982): Nautilus quadrangulus McChesney, 1860 , Gzhelian, Illinois; Nautilus nodocarinatus McChesney, 1860 , Gzhelian, Illinois; Tainoceras monilifer Miller, Dunbar & Condra, 1933 , Gzhelian, Texas; Tainoceras rotundatum Miller, Dunbar & Condra, 1933 , Gzhelian, Texas; Tainoceras murrayi Miller & Unklesbay, 1942 , Gzhelian, Nebraska; Metacoceras marylandica Lintz, 1958 , Gzhelian, Maryland; Tainoceras sexlineatum Tucker, 1976 , Kasimovian, Illinois; Tainoceras collinsi Sturgeon, Windle, Mapes & Hoare, 1982 , Gzhelian, Ohio.

Donets Basin ( Dernov 2024): Tainoceras luxaeterna Dernov, 2024 , Kasimovian.

Western Russia ( Waagen 1879): Nautilus Trautscholdi Waagen, 1879 , Gzhelian, Moscow Basin.

Included Permian species

North America ( Swallow 1860; Hyatt 1891, 1893; Miller et al. 1933; Miller & Thomas 1936; Miller & Unklesbay 1942; Miller & Kemp 1947; Miller & Youngquist 1949): Nautilus occidentalis Swallow, 1860 , Artinskian, Kansas; Tainoceras cavatum Hyatt, 1891 , Asselian, Texas; Tainoceras Duttoni Hyatt, 1893 , Asselian, New Mexico; Tainoceras nebrascense Miller, Dunbar & Condra, 1933 , Artinskian, Nebraska; Tainoceras wyomingense Miller & Thomas, 1936 , Asselian, Wyoming; Tainoceras schellbachi Miller & Unklesbay, 1942 , Kungurian, Arizona; Tainoceras clydense Miller & Kemp, 1947 , Kungurian, Texas; Tainoceras unklesbayi Miller & Youngquist, 1949 , Kungurian, Texas.

Alps and Southern Europe ( Gemmellaro 1889; Simić 1933; Schréter 1974; Prinoth & Posenato 2007): Pleuronautilus Toulai Gemmellaro, 1890 , Wordian, Sicily; Tainoceras zmajevatense Simić, 1933 ; Wuchiapingian, Serbia; Tainoceras bükkense Schréter, 1974 ; Changhsingian, Bűkk Mountains; Tainoceras crassicostatum Schréter, 1974 ; Changhsingian, Bűkk Mountains; Tainoceras balestense Prinoth & Posenato, 2007 , Changhsingian, Dolomites; Tainoceras malsineri Prinoth & Posenato, 2007 , Changhsingian, Dolomites.

NW Iran ( Korn & Ghaderi 2025): Tainoceras admonens Korn & Ghaderi, 2025 , Wuchiapingian; Tainoceras latecostatum Korn & Ghaderi, 2025 , Wuchiapingian; Tainoceras unitum Korn & Ghaderi, 2025 , Changhsingian.

Central Iran (this paper): Tainoceras hystatum sp. nov., Changhsingian.

Pakistan ( Reed 1931, 1944): Tainoceras Noetlingi var. subglobosa Reed, 1931 , Wuchiapingian, Salt Range; Tainoceras comptum Reed, 1944 , Changhsingian, Salt Range; Tainoceras debile Reed, 1944 , Changhsingian, Salt Range; Tainoceras trimuense Reed, 1944 , Wuchiapingian, Salt Range.

South China ( Kayser 1883; Chao 1954; Zheng 1984): Nautilus mingshanensis Kayser, 1883 , Wuchiapingian, Jiangxi; Nautilus orientalis Kayser, 1883 , Wuchiapingian, Jiangxi; Tainoceras changlingpuense Chao, 1954 , Roadian, Hunan; Tainoceras hunanense Chao, 1954 , Roadian, Hunan; Tainoceras gibbosum Zheng, 1984 , Changhsingian, Guizhou; Tainoceras guizhouense Zheng, 1984 , Changhsingian, Guizhou; Tainoceras lateronodosum Zheng, 1984 , Changhsingian, Guizhou.

Japan ( Hayasaka 1957, 1962; Ehiro & Araki 1997): Tainoceras abukumense Hayasaka, 1957 , Capitanian; Tainoceras kitakamiense Hayasaka, 1962 , Roadian; Tainoceras carinatum Ehiro & Araki, 1997 , Capitanian.

Remarks

Tainoceras is considered one of the cardinal genera within the order Nautilida ; it stands as a typical representative for the family, superfamily and suborder named after it. Around 40 species of Tainoceras have been described so far and it has a long stratigraphic range, extending from the latest Carboniferous to the latest Permian. Nevertheless, only a few efforts have been made to clearly define the genus in its morphological range. While Miller et al. (1933: 147) and Miller & Youngquist (1949: 80) gave detailed characteristics of the genus, Shimansky (1962b: 121) and Kummel (1964: K413) characterised the genus Tainoceras with just one sentence: “Like Metacoceras but with a double row of nodes on the venter.” Sturgeon et al. (1997: 29) became more precise: “Similar to Metacoceras but possessing two ventral rows of nodes or ribs separated by a median sulcus.” They gave a more detailed outline of the characters typically present in Tainoceras .

It is apparent that a simple definition is not adequate to define the rather complex genus, especially in view of the fact that other tainoceratids have been described in recent decades. A precise morphological delineation and taxonomic interpretation of Tainoceras requires a discussion of several questions: (1) What are the morphological characters that can be used to clearly distinguish Tainoceras from other genera?

(2) Were the tainoceratids ( Tainoceras and derived Late Permian genera) really a monophyletic unit?

(3) Did long-lived evolutionary lines with stable morphologies exist within Tainoceras , or did similar conch shapes and sculptures emerge iteratively?

The first question is not easy to answer. The previously used feature of the double row of nodes on the venter cannot be applied universally as the cardinal separating tool, as some species possess only one row of ventral nodes or no ventral nodes at all in the adult stage (e.g., the Late Carboniferous T. collinsi Sturgeon, Windle, Mapes & Hoare, 1982 and T. marylandicum (Lintz, 1858) and the Late Permian T. balestense Prinoth & Posenato, 2007 ). Rather, other assisting features must be used, such as the presence of the midventral groove. It should be made clear that in Tainoceras this groove indents a broadly rounded venter. This is in contrast to genera such as Metacoceras , in which a concave venter, if present at all, always occurs as a depression of the entire venter.

The second question is easier to answer. Although the morphological spectrum of Tainoceras is rather broad and somewhat variable, the combination of several morphological characters, such as the presence of the midventral groove, the rows of nodes on the venter and ventrolateral shoulder and the pronounced umbilical margin, indicate a monophyletic series of forms. Because of the complexity of the morphology, a polyphyletic origin of Tainoceras can be excluded.

To answer the third question, it is necessary to evaluate the characters of conch and sculpture with regard to their variation within the genus Tainoceras . The following characters have proven to be particularly variable (with some representative examples):

- General shape of the whorl profile: it can range from rectangular ( T. nebrascense ) to octagonal or polygonal ( T. clydense , T. admonens ); the ww/wh ratio can range from approximately equidimensional ( T. cavatum ) to weakly depressed ( T. schellbachi , T. admonens ) and moderately depressed ( T. duttoni ).

- General shape of the venter: in all of the species, the venter is more or less tripartite, but the degree of tripartition varies from weak with nearly convex venter ( T. cavatum ) to very strong with clearly defined ventrolateral applanation forming a tectiform venter ( T. clydense , T. duttoni ).

- Position and shape of the flanks: the flanks can be divergent ( T. quadrangulum , T. admonens ), parallel ( T. quadrangulum ) or convergent ( T. duttoni ). They can be flattened ( T. cavatum ) or weakly concave ( T. duttoni , T. admonens ).

- Shape of the umbilical margin and umbilical wall: while the umbilical margin is usually narrowly rounded ( T. nebrascense ) or subangular ( T. duttoni ), the umbilical wall ranges from oblique ( T. cavatum , T. clydense ) to steep ( T. duttoni ) and from weakly convex ( T. nebrascense ) to flattened ( T. duttoni , T. admonens ).

- Width and depth of the midventral groove: the groove can vary from narrow ( T. nebrascense , T. clydense ) to wide ( T. schellbachi , T. admonens ) and from shallow ( T. collinsi , T. cavatum , T. admonens ) to deep ( T. duttoni , T. wyomingense ).

- Formation of the ventral nodes: ventral sculptural elements may appear as short plications ( T. collinsi ), small tubercles ( T. monilifer , T. nodocarinatum , T. admonens ), or also large conical, blunt ( T. clydense ) or pointed nodes or spines ( T. quadrangulum , T. schellbachi ). Some species possess coarse ventral radial ribs ( T. unklesbayi ). The ventral tubercles can be arranged symmetrically ( T. nebrascense ) or alternating on the right and left side of the midventral groove ( T. monilifer ).

- Formation of the ventrolateral nodes: ventrolateral sculptural elements are present in most of the species; they range from being small tubercles ( T. nebrascense , T. admonens ) to large conical nodes or spines ( T. monilifer , T. schellbachi ).

- Formation of lateral ribs: lateral ribs do not occur in many of the North American species, but are present in species from other regions ( T. debile , T. admonens ).

- Formation of the umbilical nodes: umbilical sculptural elements are present in some species; they range from being small tubercles ( T. clydense ) to large conical nodes ( T. schellbachi ).

The list of mostly bipolar character pairs shows numerous theoretical possible combinations; however, covariation is very common and some of the characters often appear simultaneously.

Kingdom

Animalia

Phylum

Mollusca

Class

Cephalopoda

SubClass

Nautiloidea

Order

Nautilida

SubOrder

Tainoceratina

SuperFamily

Tainoceratoidea

Family

Tainoceratidae

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