Tusoteuthis and Cretaceous Giant Squid

Note: Phil Eyden welcomes discussion on this article in the Cephalopod Fossils forum.




Architeuthis and Mesonychoteuthis, the giant and colossal squid, are enigmatic and awe inspiring animals. Very little is known about the lifestyle of these spectacular animals, despite the examination of numerous corpses of Architeuthis, much of what we know about the animals' behaviour and lifestyle boils down to educated speculation. What is not so well known is that these modern squid were not the first giant squid in the Earths oceans, we have tantalising remains of animals that were at least as large as these modern species that shared the oceans with the ammonites, mosasaurs, giant turtles and plesiosaurs about 80 million years ago during the Late Cretaceous period. Imagine the difficulties of reconstructing these ancient animals when all we have to go on are fragmentary fossilised remains of the pens, or gladius, of these animals!

The teuthid gladius is the internal remnant of the exterior shell of the primitive nautiloid ancestral cephalopods. The gladius is contained within a "shell sac" to which the muscles are attached, the gladius providing strengthening and support for the mantle, the main body of the squid. "Fossil Teuthids" are largely identified and classified by variations in the shape of the gladius alone and comparisons with living species of cephalopods; soft bodied parts, in those rare cases of exceptional preservation, are not generally diagnostic or much use in determining species interrelationships. Unfortunately the gladius alone does not help us to understand how these animals appeared and behaved in much detail; one only has to think of the wide variety of body shapes, visual displays, variations in habitat and behavioural differences in living cephalopods to imagine how much we have lost and will never be able to reconstruct with these ancient animals.


Upper Cretaceous "teuthid" remains are very poorly known from North America; as an example the trachyteuthid Actinosepia canadensisis the most common specimen and this is known from just 25 examples (1987 figure). Prehistoric giant squid remains are known purely from the shallow Western Interior Seaway, which was a vast sea that bisected North America, so vast that at times it connected the Gulf of Mexico to the Arctic covering the great American Plains of today. These seas arose during the Early Cretaceous following a period of rapid global warming, sea floor spreading and rise. This seaway is thought to have been very shallow, generally less than 600 feet deep, with a flat muddy bottom. The seaway was biologically extremely active and squid were seemingly common animals, five species have been described, the large squids Kansasteuthis lindneri and Enchoteuthis melanae but the largest of all were Niobrarateuthis bonneri, Niobrarateuthis walkeri and Tusoteuthis longa. Each of these species was described on the basis of a single specimen. All these animals are known from remains of the gladius alone, the stiffening rod running the length of the mantle, the different species were known from variations in the size and form of this cuttlebone until recent revisions grouped all these animals together under one genus.


These four genera of squid were roughly contemporary; "teuthid" remains have been found in the vast 85-80 million year old Niobrarachalk deposits that stretch from south-west Kansas to Manitoba in Canada. Niobrarateuthis is chiefly known from the Upper Niobrarachalk formations in Logan County at the Smoky Hills in Kansas. Fossils have also been identified in the Pembina member of the Pierre Shale that lies immediately above the chalk at a date of 79 million years old. Tusoteuthis remains have now been identified from these Pierre Shale deposits in Kansas, North and South Dakota and from six specimens from southern Manitoba in Canada. All are from deposits at the Eastern margin of the Western Interior Basin.

To date two species of Niobrarateuthis have been identified, N. bonneri and N. walkeri. N. bonneri was described by H.W. Miller in 1957 on the basis of three specimens found in the late thirties in the Niobrara Chalk at the Smoky Hills, and N. walkeri in 1977 by R.G. Green on the basis of one very badly crushed specimen. Miller regarded Niobrarateuthis distinct from Tusoteuthis longa in that Tusoteuthis had a lance-shaped gladius and lacked a prominent keel. However, it may be misleading to identify these large squid as separate animals; a 1987 paper by Nicholls and Isaak (1987) has suggested that all five teuthid species from the Western Interior Sea can in fact be regarded as one species, Tusoteuthis longa. The differences in morphology noted above could be explained as artifacts of preservation, deformations caused by crushing during the process of fossilization and misinterpretation of dorsal and ventral surfaces. The sole specimen of the gladius of Niobrarateuthis walkeri was considered by Nicholls and Isaak to be so badly broken and crushed that any attempt at reconstruction would be largely hypothetical. This theory has now achieved general acceptance; all recorded examples of Niobrarateuthis, Kansasteuthis and Enchoteuthis are now in fact regarded as one and the same genus, Tusoteuthis longa. The nameTusoteuthis has been adopted as the common name as it was the earliest name used (Logan 1898) and took precedence over the others.


Giant prehistoric squid are also known from other parts of the world. At Richmond, in Queensland, Australia a 100 million year old 1.3 metre gladius was discovered by 14 year old Sonia Ievers, and has been christened Boreopeltis soniae in her honour. This is currently on display at the Richmond Marine Fossil Museum. Students in Queensland located a contemporary second gladius in 1998 that measured over a meter in length and possibly shows evidence of predation by Kronosaurus, a large pliosaur. Smaller related species of Boreopeltisare known from the Mid Cretaceous (Aptian age) Isle of Heligoland black shale deposits, Heligoland is a small island 50 km off the north German coast and has a 1m thick shale deposit that has preserved a number of fossil teuthid forms in exceptional detail, other genera found there include Mastigophora, Plesioteuthis, Maioteuthis and Trachyteuthis.



The whole working system of fossil "teuthid" taxonomy is still being compiled. The evolutionary history of the orders of squid and other non-belemnoid coleoid cephalopods is very poorly understood chiefly due to the lack of fossils of these creatures; normally the only part of the animal that tends to become fossilised is the chitinous gladius, or pen, and even that is very rarely preserved due to its delicate nature. Much of what is currently understood about evolutionary relationships of these animals has not been agreed upon; there are two or three differing models of the coleoid tree, each new discovery may call for the models to be reworked. The only really well preserved coleoid faunas are at localities such the 150 million year old Late Jurassic German Solnhofen and Holzmaden deposits and the 100 million year old Cretaceous Hajoula deposits from Lebanon, and a handful of other lesser known localities. These represent snapshots of biodiversity; what happened in between them is tantamount to educated guesswork with rare and isolated specimens providing evolutionary clues. Most collections in museums are labelled simply as "Fossil Teuthids".

Nonetheless, a little of the evolutionary history has been determined, even if it is somewhat speculative. It is currently thought that these ancient giant squid were members of the vampyromorpha based on similarities in the shape and structure of the gladius to the only extant member, Vampyroteuthis, the Vampire Squid. This is in common with many of the Jurassic "teuthids" from Germany and the Cretaceous animals from Lebanon. Tusoteuthis is believed to be only very distantly related to Architeuthis, and was originally assigned by Adolf Naef to a completely separate branch of the family tree, the Family Palaeololiginidae, of the Suborder Mesoteuthina, a vampyromorph group that failed to survive the mass extinction at the end of the Cretaceous. These Palaeololiginidae are well documented in Germany from the Late Jurassic lithographic limestones. Adolf Naef identified this group in 1921 but he later admitted that he had not examined the actual gladius fossils themselves when assigning Tusoteuthis to the Paleololiginidae and was working from a description; Nichols and Isaac revised the family to the Kelaenidae in 1987. (Miller had also assigned Niobrarateuthis to the Kalaenidaein 1968)

The taxonomy of Tusoteuthis can now be provisionally placed as follows:

Species: LONGA

(Disclaimer: not all researchers would accept this alignment, some place the Mesoteuthina with the Teuthida, and a different family tree model.)


Architeuthis & appearance

According to Theo Engeser's model of coleoid evolution, the latest common ancestor of Architeuthis and these Mesoteuthina lived in the Devonian period, possibly over 380 million years ago. As these giants are not believed to be ancestral to Architeuthis and left no post-Cretaceous descendants, it appears that giants have evolved at least four times in separate families, probably once in the Mid–Cretaceous (Boreopeltis from Australia), once in the Late Cretaceous (Tusoteuthis) and twice at a fairly recent date (Architeuthis and Mesonychoteuthis). The complete lack of fossils of Architeuthis' immediate ancestors makes it impossible to determine when the recent giants arose. The difference between Architeuthis, Tusoteuthis and Niobrarateuthis can be seen when the gladius of the three animals is compared, Architeuthis' gladius is a long slender feather-shape; that of Tusoteuthis is more robust, with a broader, humped and leaf-shaped conus, whereas Niobrarateuthis' gladius resembles that of a sturdy rounded paddle. However, as mentioned above, it is now generally accepted that differences in the shape of the gladius of the ancient giants may simply be an artifact of preservation and the animals may, in fact be one and the same. The radically different shape of the gladius of Architeuthis may indicate that these Western Interior Seaway squid had a differing external appearance in the shape of the mantle, perhaps broader at posterior end of the animal.

The external appearance of these ancient giants can really only be a matter of conjecture, we have no trace of tentacles or arms with these animals; all we can really say is that it is probable that the mantle was probably of a similar length to a fully grown Architeuthis as the largest fossilised gladius is of a similar length to the modern giant. The longest rhacis of the six Manitoba specimens measures at just over 1.2m in length but the sixth and most recently recovered specimen is larger but incomplete, and would have belonged to an animal which was a third larger again; it is unknown what the maximum size adult animal would have been. If one assumes a consistent growth rate maintaining the same proportions and ratios, then this sixth gladius would have been approximately in the order of 1.8m if complete, and there is no evidence to suggest that this was fully grown. At the time of writing (May 2004), another gladius measuring six foot (1.8m) is being prepared for display at the North Dakota Heritage Centre at Bismark, this was a find from the Pierre Shale at Pembina Gorge and is probably another Tusoteuthis, (unconfirmed at time of writing). The maximum length of an Architeuthis gladiuscan be taken to be 2.15m (one specimen had a mantle length of 2.25m and the gladius almost runs the length of the mantle) so it appears that the mantle of Tusoteuthis was of comparable size, if a little shorter. With so few specimens to work from we cannot be sure what was the maximum size attained by Tusoteuthis, a future gladius discovery may yet equal or exceed Architeuthis in length.


It seems likely that these ancient animals had eight arms and no tentacles, as there is no evidence that any of the other vampyromorphs, such as Plesioteuthis or Trachyteuthis, had ten arms. Observations of ten armed fossil species have recently been reinterpreted as misinterpretation of drag marks in the silt (Fuchs, Keupp and Engeser 2003). Given that it is almost certain that these giants did not have these seizing tentacles of Architeuthis, it is likely that these animals had a Total Length (tip of tentacles to tip of mantle) shorter than Architeuthis, but the Standard Length (tip of arms to tip of mantle) may have been of a similar size. We may be looking at an adult Tusoteuthis with a Total Length of five or six meters; this is assuming, of course, that Tusoteuthis did not have exceptionally long arms! It is difficult to determine if they would have had ink sacs but it is certainly possible as many other earlier German Jurassic vampyromorphshave this feature. Arm hooks are likely, but suckers do not fossilise and their presence cannot be determined.

Another difference between Architeuthis and the ancient
giants is that of lifestyle as they lived in very different environments. Architeuthis is thought to frequent depths of 600-1000 feet, whereas the maximum depth of the Western Interior Seaway was just 600 feet. It seems logical to assume that the eyes of Tusoteuthis were probably of a lesser diameter than Architeuthis as it lived in shallower conditions with more available light. There is some indirect evidence that these ancient squid may have even lived close to the surface, as detailed below a specimen of a Tusoteuthis gladius has been discovered with bite damage, this is likely to have been caused by a mosasaur, an important marine predator in the Seaway, and not likely to have been a deep diving animal.

Evidence of Predation
Tusoteuthis probably would have constituted a major dietary component for fish and marine reptiles throughout the Western Interior Seaway. The evidence for this comes from coprolites (fossilised faeces), damaged gladius fragments and a choked fish!

A total of five specimens of coprolites have been collected from separate locations (1987 figure). Two of these coprolites were collected from a Niobrara chalk exposure in Rooks County, Kansas and contain three broken fragments of gladius between them. Three more coprolites containing small Tusoteuthis inclusions were obtained from the chalk at the junction with the Pierre Shale in Gove County, Kansas, one of which also contains fish teeth and vertebrae. From the coprolites alone it is difficult to determine what animal was eating Tusoteuthis, but from the small size of these coprolites researchers have concluded that this was probably some form of large predatory fish (largest is 4.78cm x 3.82cm). Another specimen from the chalk at Logan county consists of a mass of varied fish vertebrae, jaws, skull fragments and teeth along with fragments of a large teuthid gladius, it is believed that this is probably the stomach contents of a large carnivore of indeterminate origin. This specimen measures 26.7cm x 16.5cm x 4.4cm is currently held at Fick Fossil Museum, Oakley, Kansas.

For two specimens of Tusoteuthis from the Pierre Shale at Red
Bird, Wyoming, the predators are identifiable. A spectacular discovery of a partial specimen of the predatory fish Cimolichthys nepabolica contained a nearly complete gladius of Tusoteuthis that had been swallowed whole, and was so large it had probably choked the fish to death. Cimolichthys was a large primitive teleost probably related to the salmon and resembling a barracuda in form with conical and widely spaced teeth suitable for puncturing flesh. It is believed to have been an open water predator adapted for sustained swimming and rapid bursts of speed and was a long-ranging and common species in the Western Interior Seaway. This particular specimen of the fish is incomplete, the preserved section measures 152cm in length but it contains a nearly complete 66cm gladius of an immature Tusoteuthis. The squid is lodged in the area of the stomach of the fish with the expanded rear of the gladius stuck in the ribcage in the area of the shoulder of the fish. The rhacis or 'handle' of the gladiusprojects towards the mouth where it appears to be broken below the left gill cover. It seems likely that Cimolichthys approached the squid from the rear, attacked and attempted to swallow the animal whole; the head and arms of the squid would have projected from the mouth and it probably struggled, death for the fish probably came from the fractured gladius ripping through the skin of the squid and causing interior gill damage or the size of the body of the squid forcing the gullet to remain open. This amazing specimen is currently held at the University of Colorado Museum.

Mosasaurs are also believed to have been predators of Tusoteuthis and other cephalopods. Ammonites have been reported with mosasaur bite damage and fossils have also been found with teuthid hooks in their gut contents. A 128cm Tusoteuthis gladius also housed at the University of Colorado Museum bears three punctures along the length of the rhacis. These punctures forced the rod bundles from which the rhacis is composed to splay apart and cause some severe twisting to the structure. The punctures are widely spaced, the distance of 31cm between two of the punctures has been interpreted as an oblique angle of attack by the mosasaur. The number of times the mosasaur bit the squid is unknown, it is unclear if the struggling squid was released or the body was severed allowing the gladius and mantle to sink to the sea floor. This specimen was collected from the Sharon Springs Member of the Pierre Shale, and it is thought that the predator was probably Tylosaurus proriger known from the same deposits.


Yezoteuthis giganteus
Potentially the largest fossil coleoid to be discovered to date was published in January 2006 by Kazaushiga Tanabe, Yoshinori Hikida and Yasuhiro Iba. It consisted of one half of an enormous set of jaws discovered in Late Cretaceous Campanian (83-71 mya) sediments at Wakkaweenbetsu Creek, Nakagawa Town, Hokkaido, Japan. The fossil was composed of a black phosphatic material and was contained inside a calcareous nodule. Included with the specimen were numerous bivalves and specimens of the heteromorphic ammonite Polyptychoceras. The fossil came from the Upper Yezo Group of mudstones, 'Yezo' being an old name for Hokkaido. The fossil is an upper jaw that measures 97mm in length and is 22.5mm wide at its maximum point. It has a very sharply pointed rostrum that is angled acutely, and both the inner and outer lamellae are present.

In order to determine the systematic relationship of the specimen, the authors performed a cladistic analysis based on 5 morphological characteristics of the jaw in comparison with 22 other extant coleoids and Nautilus. As a result of this and from a physical comparison of the shape of the rostrum and wings, the authors determined that the specimen is closest to the sub-order Oegopsina. The authors then attempted to estimate a total size for the animal, by examining the ratio of the maximum length of the upper jaw (LUJ) to total mantle length (ML) in eight extant coleoid species. Applying these derived ratios to the fossil jaw and plotting it along with these other specimens, it was concluded that the Mantle Length was probably akin to Architeuthis. The jaw is similar to Architeuthis not only in overall size, but in shape, and structure. It differs in that the crest margin is more convex in shape and has more prominent growth lines on the inner lamella.

The authors conclude that this specimen represents a large new species, Yezoteuthis giganteus, that would have been present in Late Cretaceous Northwest Pacific along with many small ammonoid and nautiloid shelled cephalopods. The jaw is currently housed at the Nakagawa Museum of Natural History.



In summary, Tusoteuthis was probably a major component of the ecosystem of the Western Interior Seaway and a favoured prey item of assorted marine predators. It probably lived in shallow depths and would have been a fast moving muscular squid as demonstrated by its robust gladius providing anchorage for powerful musculature. Possibly as large as Architeuthis, it would have thrived in a very different and extremely biologically active environment.

On display:

Tusoteuthis longa

1) Morden District Museum, Manitoba, Canada. http://www.mordenmuseum.com/

2) North Dakota Heritage Centre at Bismarck (expected late 2004?). Welcome to the State Historical Society of North Dakota3) Natural History Museum of Los Angeles County, California as part of the "Savage Ancient Seas" Exhibit. NHM Home Page

Niobrarateuthis bonneri:

Sternberg Museum of Geology at the University of Kansas, Fort Hays, Kansas. Sternberg Museum Virtual Tour

Boreopeltis soniae:

A painting and gladius can be seen at the Australian Richmond marine fossil museum "Kronosaurus Corner". Kronosaurus Korner - Home



ELLIS, R. Aquagenesis. Viking, 2001.

FUCHS, D., KEUPP, H., and ENGESER, T., New records of soft parts of Muensterella scutellaris Muenster, 1842 (Coleoida) from the late Jurassic Plattenkalks of Eichstatt and their significance for Octobrachian relationships. Berliner Palaobiol.Abh. 03: 101-111 Berlin 2003.

KAUFFMAN, E. G., Cretaceous fish predation on a large squid. Evolutionary Paleobiology of Behaviour and Coevolution, 1990: 195-197.

MILLER, H.W., Niobrarateuthis bonneri, a new genus and species of squid from the Niobrara Formation of Kansas. Journal of Palaeontology, 31:809-814.

NICHOLLS, E.L., and ISAAK, H., Statigraphic and taxonomic significance of Tusoteuthis longa Logan (Coleoida, Teuthida) from the PembinaMember, Pierre Shale (Campanian), of Manitoba. Journal of Palaeontology, 61 (4) 727-737, 1987.

STEWART, J.D., and CARPENTER, K,. Examples of vertebrate predation on cephalopods in the late Cretaceous of the Western Interior. Evolutionary Paleobiology of Behaviour and Coevolution, 1990: 203-207.
TANABE, K., HIKIDA, Y., and IBA, Y., Two coleoid jaws from the Upper Cretaceous of Hokkaido, Japan. Journal of Paleontology 80 (1) 138-145, 2006.

Thanks to:

Geoff Couling, Mike Everhart, Tracy Ford, Jean McKinnon, Dr Troy Myers, Dan Varner, Chris Vencevich, Mark Montague (Monty).


Phil Eyden

Posted May 2004 -- Updated January 2006
Original publish date
May 18, 2004
About the Author
Phil joined the TONMO.com staff in April 2003. He collects fossils as a hobby, frequently plundering a quarry at Folkestone in the U.K. He has a degree in British archaeology and works for a government department at Dover in England.


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