By Phil Eyden - 2003
Note: Phil 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
Upper Cretaceous "teuthid"
remains are very poorly known from North America; as an example the trachyteuthid Actinosepia
canadensis is 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
These four genera of squid were roughly
contemporary; "teuthid" remains have been found in
the vast 85-80 million year old
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 name Tusoteuthis
has been adopted as the common name as it was the earliest name used (
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 Boreopeltis are 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
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
The taxonomy of Tusoteuthis can now be provisionally placed as follows:
(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 MidCretaceous (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 gladius can 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 vampyromorphs have 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
For two specimens of Tusoteuthis from the Pierre Shale at Red Bird,
Mosasaurs are also believed to have been predators of Tusoteuthis and other
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.
1) Morden District Museum, Manitoba, Canada. http://www.mordenmuseum.com/
2) North Dakota Heritage Centre at Bismarck (expected late 2004?). http://www.state.nd.us/hist/hcenter.htm 3) Natural History Museum of Los Angeles County, California as part of the "Savage Ancient Seas" Exhibit. http://www.nhm.org/
A painting and gladius can be seen at the Australian Richmond marine fossil museum "Kronosaurus Corner". http://www.kronosauruskorner.com.au/
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 Pembina Member, Pierre Shale (Campanian), of Manitoba. Journal of Palaeontology, 61 (4) 727-737, 1987.
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vertebrate predation on
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