Cephalopod size
Extinct taxa

Cephalopod size

Section Title: Extinct taxa
Table Section Text: None

Ammonoidea (ammonoids)

Species	Maximum shell diameter (length for heteromorphs)	References	Notes

Parapuzosia seppenradensis	2.55–3.5 m (estimate)	Landois (1895:100); Landois (1898:27); Teichert & Kummel (1960:6); Summesberger (1979:128); Holland (1987:6); Kennedy & Kaplan (1995:21); Lewy (2002:66)	Widely recognised as the largest ammonite specimen ever found (Payne et al., 2009:27; Grulke, 2014:124). Discovered in 1895 in a quarry in Seppenrade, Coesfeld, Germany, the original is on display at the Westfälisches Museum für Naturkunde in Münster.

Parapuzosia bradyi	>1.8 m (estimate)	Larson et al. (1997:44); Lewy (2002:66)	Largest known North American ammonite. Estimate based on incomplete specimen measuring 1.37 m in diameter (missing at least half a whorl of the body chamber).

Peltoceratinae gen. et sp. indet.	1.78 m (estimate)	Poulton (1989)	Estimate based on small portion of outer whorl measuring 1.2 m along the venter and subtending a chord of 1.13 m.

Eopachydiscus sp.	1.67 m	Grulke (2014:125)	This specimen, from the Albian Duck Creek Formation of Texas, has been exhibited at the Tucson Fossil Show and in a New York auction.

Pachydesmoceras cf. pachydiscoide	1.65 m (estimate)	Kin & Niedźwiedzki (2012:19)	Estimate based on 0.98 m diameter specimen representing an apparently complete phragmocone (previously referred to Lewesiceras peramplum or Parapuzosia). A more complete and therefore larger specimen (1.18 m diameter) consisting of a complete phragmocone and near-complete body chamber is also known (Kin & Niedźwiedzki, 2012:17).

Lytoceras taharoaense	1.5 m	Stevens (1978a:3); Stevens (1978b:2); Stevens (1979a:33); Stevens (1979b:6); Stevens (1979c:166); Stevens (1985:153); Grulke (2014:126)	Size based on essentially complete shell with only some damage to the aperture.

Mesopuzosia mobergi	<1.5 m	Kin & Niedźwiedzki (2012:19)

Parapuzosia austeni	<1.5 m	Kin & Niedźwiedzki (2012:19)	Puzosia mayoriana is a synonym.

Moutoniceras sp.	1.47 m [heteromorph]	Grulke (2014:126)	In private collection of Wolfgang Grulke, according to whom it is likely the largest heteromorph ammonite ever found (Grulke, 2014:126). Originating from Morocco it is displayed in part of the original rock matrix with sympatric Gassendiceras heteromorphs.

Parapuzosia bosei	1.45 m	Scott & Moore (1928:276); Lewy (2002:66)	From the Austin Chalk of the Rio Grande region, Texas. The largest known specimen was reported by Scott & Moore (1928:273) to be 4 ft 9 in (1.45 m) in diameter and "impossible to extract from its matrix".

Parapuzosia americana	1.37 m (estimate)	Scott & Moore (1928:276)	From the Austin Chalk of the Rio Grande region, Texas.

"Titanites" occidentalis	1.37 m	Frebold (1957:66); Westermann (1966)	Size based on specimen consisting of an imprint and part of the last whorl preserved as an internal mould.

Diplomoceras maximum	>1 m [heteromorph]	Olivero & Zinsmeister (1989)

Tropaeum imperator	almost 1 m	Grulke (2014:126)	Largest ammonite known from Australia. Grulke (2014:126) writes: "No exact size is available but it could be almost 1 m across".

Belemnoidea (belemnoids)

Species	Maximum rostrum measurements	References	Notes

Megateuthis sp.	0.7 m TL (Dvms: 30 mm; Dvma: 50 mm)	Schlegelmilch (1998:1); Weis & Mariotti (2007:166); Iba et al. (2015:23–24)	Megateuthis elliptica is "the longest belemnite species known", with rostra from the Humphriesianum Zone in Rumelange and Luxembourg reaching 60–70 cm (Weis & Mariotti, 2007:166).

Belemnitina gen. et sp. indet.	? TL (Dvms: 30 mm; Dvma: ?)	Iba et al. (2015:23)	Known from a single incomplete rostrum (TCSM-J1-0001) from the Pliensbachian Teradani Formation in Teradani, Toyama Prefecture, Japan. The specimen is missing the apical and alveolar regions and comprises only the middle (stem) region of the rostrum.

Acroteuthis sp.	? TL (Dvms: 39 mm; Dvma: 42 mm)	Iba et al. (2015:23)	One of "the largest belemnites ever observed", with a rostrum comparable to that of the indeterminate belemnitinid from Teradani.

Pachyteuthis sp.	? TL (Dvms: 39 mm; Dvma: 40 mm)	Iba et al. (2015:23)	One of "the largest belemnites ever observed", with a rostrum comparable to that of the indeterminate belemnitinid from Teradani.

Belemnitina gen. et sp. indet.	? TL (Dvms: ?; Dvma: >33 mm)	Iba et al. (2015:23)	From the Hettangian Niranohama Formation of northeastern Japan. One of "the largest belemnites ever observed", with a rostrum comparable to but likely slightly smaller than that of the indeterminate belemnitinid from Teradani.

Nautiloidea (nautiloids)

Species	Maximum shell length	References	Notes

Endoceras giganteum	8.15 m (estimate)	Teichert & Kummel (1960:5); Holland (1987:6)	Estimate based on incomplete 3-metre-long shell deposited at the Museum of Comparative Zoology, Harvard University, assuming body chamber-to-phragmocone ratio of 1:2.

Cameroceras sp.	6 m	Frey (1995:73)	Given as maximum size for genus as a whole.

Cameroceras proteiforme	3.0–4.6 m (10–15 ft)	Clarke (1897:778); Teichert & Kummel (1960:1)	Size based on "entire shells" (Clarke, 1897:778).

Rayonnoceras solidiforme	2.8 m (estimate)	Klug et al. (2015:270)	From the Visean of Arkansas. Shell volume estimated at 62.5 litres.

Deiroceras hollardi	2.6 m (estimate)	Klug et al. (2015:270)	From the early Emsian of "Jebel Mdouar". Shell volume estimated at 68.3 litres.

Actinocerida gen. et sp. indet.	1.911 m (estimate)	Klug et al. (2015:270)	From the Llandovery of Gotland. Shell volume estimated at 8.9 litres.

Orthocerida gen. et sp. indet.	1.783 m (estimate)	Klug et al. (2015:270)	From the Ludlow of Gotland. Shell volume estimated at 4.1 litres.

Ormoceras TUG 1308-1	1.72 m (estimate)	Klug et al. (2015:270)	From the Sandbian of Estonia. Shell volume estimated at 2.7 litres.

Ormoceras giganteum MB.C.11940	1.71 m (estimate)	Klug et al. (2015:270)	From the Darriwillian. Shell volume estimated at 2.7 litres.

Lambeoceras lambii	1.405 m (estimate)	Leith (1942:130); Teichert & Kummel (1960:4)	Estimate based on incomplete 1.155 m long shell.

Orthoceras regarium	1.39 m (estimate)	Klug et al. (2015:270)	From the Wenlock of Joachimsthal[disambiguation needed]. Shell volume estimated at 5.1 litres.

Temperoceras aequinudum	1.333 m (estimate)	Klug et al. (2015:270)	From the Lochkovian of "Ouidane Chebbi". Shell volume estimated at 9.2 litres.

Zeravshanoceras priscum	1.299 m (estimate)	Klug et al. (2015:270)	From the Eifelian. Shell volume estimated at 1.6 litres.

Ordogeisonoceras amplicameratum	>1.25 m	Frey (1995:40)	Shell diameter up to 10.5 cm. Originally described as Orthoceras amplicameratum. Orthoceras ludlowense is considered a synonym.

Cameroceras hennepini	<1.2 m (4 ft) (estimate)	Clarke (1897:779)	Size estimate based on "the most complete of the fragments which represent it".

Actinoceras vaughanianum	1.198 m (estimate)	Klug et al. (2015:270)	From the Serpukhovian of Oklahoma. Shell volume estimated at 8.7 litres.

Polygrammoceras? cf. P. sp. A	1.13 m (estimate)	Frey (1995:69)	Estimate based on a "single, very large fragment of a phragmocone". Shell diameter to 9.0 cm.

Plagiostomoceras sp.	1.1 m (estimate)	Klug et al. (2015:270)	From the Givetian of Onondaga, New York. Shell volume estimated at 0.0052 litres.

Endoceras decorahense	1.06 m (estimate; phragmocone only)	Miller & Kummel (1944); Teichert & Kummel (1960:2)	Size estimate based on two portions of an internal mould of the phragmocone, measuring 62.5 cm and 32 cm, with an estimated missing middle section of 11.5 cm.

Proterovaginoceras incognitum	1 m (estimate)	Klug et al. (2015:270)	From the Dapingian of Jämtland, Sweden. Shell volume estimated at 0.8 litres.

Teuthida (squids)

Species	Maximum mantle length	References	Notes

Yezoteuthis giganteus	≈1.7 m (estimate)	Tanabe et al. (2006:142)	Size estimate based on preserved upper jaw measuring 97.0 mm in maximum length, similar to that of the largest giant squid (Architeuthis dux).

Boreopeltis soniae	1.3 m+ (estimate)	Eyden (2003b)	Size based on 1.3 m gladius from Queensland, Australia. A second gladius measuring more than a metre and showing possible evidence of predation by Kronosaurus is also known (Eyden, 2003b).

Vampyromorphida (vampyromorphids)

Species	Maximum mantle length	References	Notes

Tusoteuthis longa	over 1.8 m (estimate)	Eyden (2003b)	May have reached 5–6 m in total length. Enchoteuthis, Kansasteuthis, and Niobrarateuthis are likely synonyms (Eyden, 2003b).

Sentence(s)

The largest confirmed ammonite, a Cephalopod specimen of Parapuzosia seppenradensis discovered in a German quarry in 1895, in diameter (Kennedy & Kaplan, 1995:21).

final_sentence: The largest confirmed ammonite, a Cephalopod specimen of Parapuzosia seppenradensis discovered in a German quarry in 1895, in diameter (Kennedy & Kaplan, 1995:21).