PBDB Taxon

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Morphology	Ecology and taphonomy	External Literature Search	Age range and collections

Perisphinctes (Arisphinctes) trifidus

Cephalopoda - Ammonoida - Perisphinctidae

Taxonomy

Ammonites trifidus was named by Sowerby (1821).

It was recombined as Perisphinctes (Arisphinctes) trifidus by Pandey et al. (2012).

Sister species lacking formal opinion data

P. africanus, P. andium, P. mairei-matheyi, P. malinowskae, P. panderi, P. polygyratus, P. praestenocyclus, P. progeron, P. quadratus, P. scythicus, P. siemiradzkii, P. eucostatus, P. quadratus, P. pickeringius, P. buckmani, P. buckmanni, P. luciaeformis, P. crassissimus, P. A, P. B, P. anguiculus, P. patturatensis, P. siemirazkii, P. roedereri, P. alatus, P. andelotensis, P. densecostatus, P. pumilus, P. dorsoplanus, P. dacquei, P. polygyratus

Synonymy list

Year	Name and author
1821	Ammonites trifidus Sowerby pp. 194 [pro 167] figs. Pl 292, 293
2012	Perisphinctes (Arisphinctes) trifidus Pandey et al. p. 506 figs. Pl. XII, figs. 6, 7; Fig. 30; Tab. 17

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Rank	Name	Author
kingdom	Animalia	()
—	Bilateria
—	Eubilateria	Ax 1987
—	Protostomia
—	Spiralia
superphylum	Lophotrochozoa
phylum	Mollusca
class	Cephalopoda	Cuvier 1797
subclass	Coleoidea	Bather 1888

Rank	Name	Author
order	Ammonoida	(Haeckel 1866)
order	Ammonitida	Haeckel 1866
suborder	Ammonitina	Hyatt 1889
superfamily	Perisphinctoidea	(Steinman 1890)
family	Perisphinctidae	Steinmann 1890
subfamily	Perisphinctinae	Steinmann 1890
genus	Perisphinctes	()
subgenus	Arisphinctes	(Buckman 1924)
species	trifidus	()

If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.

†Perisphinctes (Arisphinctes) trifidus Sowerby 1821

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Diagnosis

Reference	Diagnosis
D.K. Pandey et al. 2012	Shells small, evolute, incomplete. Whorl section compressed and rounded to subrectangular (Fig. 30A, B). Feebly arched lanks merge into venter at obtusely rounded ventrolateral shoulder. Maximum thickness of whorl at one-third of lank height. Ornamentation consists of ine, isocostate, prorsiradiate primary ribs, bifurcating regularly at the ventrolateral shoulder (Fig. 30C). Secondaries cross the venter with slight forward-directed convexity. Four constrictions per whorl.