This is probably THE most asked question, especially by children. Humans seem to have a fascination with size, always striving to find the biggest of something, and dinosaurs are no exception. As a result, many sources (some more accurate than others) have catered to this compulsion. In this post, we'll take a look at the most frequently cited candidates, and examine their credentials in more detail. (And for the purposes of this article, I'm using biggest to mean tallest/longest not heaviest - simply because weight is nearly impossible to guess for fossils)
Candidate Number 1: Seismosaurus
Seismosaurus (the Earth-Shaking Lizard) was a sauropod (as are all the contenders for largest dinosaur ever). In the early 1990s there was a dinosaur magazine series (called DINOSAURS!) that had an FAQ on the back cover of each issue. These involved asking Dr. David Norman (who is probably the country's leading expert on dinosaurs, specialising in iguanodonts) a series of questions. When asked what the biggest dinosaur was, he said Seismosaurus (Orbis, 1992) giving a length of 36.5m. Seismosaurus hallorum (Hall's Earth-Shaking Lizard - originally called halli but had to change due to grammar rules (Olshevsky, 1998)) was described by David Gillette in 1991 and was first estimated to be 39-51m (Gillette, 1991). However, we can discount Seismosaurus (sort of) because in 2006 it was found to be the same as Diplodocus (Carpenter, 2006). There is currently disagreement as to whether it is a valid species of Diplodocus (as Diplodocus hallorum) or whether it should be further synonymised with another species, Diplodocus longus (Marsh, 1878).
Candidate Number 2: Giraffatitan
Oh this one. You probably already know about this dinosaur because for most of the 20th century it was regarded as being a species of Brachiosaurus (Arm Lizard) (Riggs, 1903) (Brachiosaurus brancai (Branca's Arm Lizard), Janensch, 1914) (and indeed pretty much everything written about Brachiosaurus was based on this one rather than the original species). As a result, what you know of as Brachiosaurus is actually Giraffatitan (Titan Giraffe) (Paul, 1988), although this didn't become widely accepted until around 2003/4. Anyway, this dinosaur is known from the largest complete skeleton of a dinosaur ever discovered, found in Tanzania, East Africa between 1909-1912. The skeleton is now housed in the Berlin Museum of Natural History. It is 21.8 m long (Mazzetta, et al., 2004). However, despite its great size, this specimen is believed to only be a subadult and a larger, more mature specimen has been found (Taylor, 2009) which measures approximately 26 m (Holtz, 2008).
Candidate Number 3: Diplodocus
Continuing on from Seismosaurus above, it has now been shown that not only is Seismosaurus the same as Diplodocus (Double Beam), but also that Gillette overestimated the size. The current size estimate for Diplodocus (Marsh, 1878) is 33 m (Lucas, et al., 2004). Not much more to say really.
Candidate Number 4: Argentinosaurus
OK, now we get to sauropods that we are less certain of in terms of size. Argentinosaurus huinculensis (Argentine Lizard from Huincul) (Bonaparte and Coria, 1993) is known only from vertebrae, a few ribs and a tibia (shin bone). Size estimates have included: 30-35 m (Paul, 1994), 30 m (Carpenter, 2006) and 22-26 m (Mortimer, 2001).
Candidate Number 5: Supersaurus
Supersaurus vivianae (Vivian's Super Lizard) (Jensen, 1985) might sound like the sort of name a 5-year-old would come up with but it is a genuine dinosaur. It also includes another generic-sounding taxon named in the same paper, Ultrasauros mcintoshi (McIntosh's Ultra Lizard) (Jensen, 1985) (Originally called Ultrasaurus but this name had already been taken by a sauropod from South Korea (Kim, 1983) and so it was subsequently re-named Ultrasauros (Olshevsky, 1991)). Ultrasauros was found to be a chimaera (a taxon composed of more than one animal), in this case the vertebra belonged to Supersaurus and the scapula (shoulder blade) to Brachiosaurus (actual Brachiosaurus not Giraffatitan) (Curtice, et al., 1996). Anyway, Supersaurus has been estimated to attain a length of 33-34 m (Lovelace, et al., 2007).
Candidate Number 6: Sauroposeidon
Sauroposeidon proteles (Perfect Before the End Lizard Poseidon) (Because it was one of the last sauropods and Poseidon was the Greek God of Earthquakes, again likening its footsteps to an earthquake) (Wedel et al., 2000a) received a lot of media attention when announced back in 2000, with many outlets proclaiming it to be "THE BIGGEST DINOSAUR EVARZZZ!!!!!!111", which, while possible, is too premature given the current specimens known. It was certainly the tallest dinosaur, able to raise its head 17 m above the ground (Wedel et al., 2000b), but as for its length, estimates have ranged from 28-34 m (Wedel and Cifelli, 2005, Wedel et al., 2000b, Carpenter, 2006).
Candidate Number 7: Bruhathkayosaurus
Now we get into the "very-likely-to-be-hoaxes" category. Bruhathkayosaurus matleyi (Matley's Huge-Bodied Lizard) (Yadagiri and Ayyasami, 1989) was initially described as an Allosauroid theropod (somehow?!?!). But there are a number of problems with this one: 1) The description was brief and vague and I doubt the authors have a firm grasp of English 2) The drawings and photographs are...well see for yourself:
(why the text is upside-down I don't know)
3) The authors have only ever published one other paper on dinosaurs in which they named Dravidosaurus blanfordi (Blanford's Dravidanadu Lizard) (Yadagiri and Ayyasami, 1979), claiming it to be the smallest, youngest and only Gondwanan stegosaurian. That was until the 1990s when the poorly preserved remains were re-identified as being plesiosaurian (Chatterjee and Rudra, 1996). Therefore, their credentials and opinions shouldn't be taken at face value.
4) The guy who classified them as sauropod (and also re-identified Dravidosaurus as a plesiosaur), Sankar Chatterjee, has a...questionable reputation for getting things wrong (A good example is Protoavis texensis (First Bird from Texas) (Chatterjee, 1991) which he claimed was the oldest bird, being 75-60 million years older than Archaeopteryx (Ancient Wing) (Meyer, 1861) but is more likely to be some random reptile that vaguely looks like a bird)
5) And, to top it all off, the fossils were never fully dug out of the ground and were washed away in a monsoon. I am not kidding.
As a result of this, I think we can ignore Bruhathkayosaurus. Oh, and no actual sizes were ever given.
Candidate number 8: Amphicoelias fragillimus
We finally get to the final candidate and my personal favourite for the title of "World's Largest Dinosaur". Amphicoelias fragillimus (Most Fragile Double Cavities) (Cope, 1878) is based on a partial vertebra discovered by Oramel Lucas in 1877 in Garden Park, Colorado. The vertebra was huge, 2.7 m high (Carpenter, 2006). The most recent size estimate (Carpenter, 2006) is 58 m long - TWICE as long as any of the other candidates here, and longer than even the Blue Whale. Unfortunately, like Bruhathkayosaurus, the fossil has seemingly disappeared, having simply disintegrated on the train as it was being transported (Hence the name fragillimus).
And that's it. These are the most common candidates for the largest dinosaur ever. The next FAQ will look at dinosaur age and growth. Next week will look at the first non-dinosaur post as we take a closer look at The Rules.
See also:
More dinosaurs
More about Edward Drinker Cope, the guy who named Amphicoelias fragillimus
References
Bonaparte, J. and Coria, S. (1993) 'Un nuevo y gigantesco sauropodo titanosaurio de la Formación Río Limay (Albaniano-Cenomanio) de la Provincia del Neuquén, Argentina', [A new gigantic sauropod titanosaur from the Río Limay Formation (Albanian-Cenomanian) of the Province of Neuquén, Argentina], Ameghiniana, 30 (3), pp. 271-282
Carpenter, K. (2006) 'Biggest of the big: a critical re-evaluation of the mega-sauropod Amphicoelias fragillimus' in Foster, J. and Lucas, S. (Eds) Paleontology and Geology of the Upper Jurassic Morrison Formation, Albuquerque: New Mexico Museum of Natural History and Science
Chatterjee, S. (1991) 'Cranial anatomy and relationships of a new Triassic bird from Texas', Philosophical Transactions of the Royal Society B: Biological Sciences, 332 (1265), pp. 277-342
Chatterjee, S. and Rudra, D. (1996) 'KT events in India: impact, rifting, volcanism and dinosaur extinctions', in Novas, F. and Molnar, R. (Eds) Proceedings of the Gondwanan Dinosaur Symposium, Brisbane, Memoirs of the Queensland Museum, 39 (3), pp. 489-532
Cope, E. (1878) 'A new species of Amphicoelias'', American Naturalist 12 (8), pp. 563-564
Curtice, B., Steadman, K. and Curtice, L. (1996) 'A reassessment of Ultrasaurus mcintoshi (Jensen, 1985)' in Morales, M. (Ed), The Continental Jurassic, Flagstaff: Museum of Northern Arizona
Gillette, D. (1991) 'Seismosaurus halli, gen. et sp. nov., a new sauropod dinosaur from the Morrison Formation (Upper Jurassic/Lower Cretaceous) of New Mexico, USA', Journal of Vertebrate Paleontology, 11 (4), pp. 417-433, doi: 10.1080/02724634.1991.10011413
Holtz, T. (2008) Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages, New York: Random House
Janensch, W. (1914) 'Ubersicht uber die Wirbeltierfauna der Tendaguru-Schichten, nebst einer kurzen Charakterisierung der neu aufgefuhrten Arten von Sauropoden' [Overview of the vertebrate fauna of the Tendaguru layers, along with a brief characterisation of the newly described species of sauropod], Arch. Biotol., 3, pp. 81-110
Jensen, J. (1985) 'Three new sauropod dinosaurs from the Upper Jurassic of Colorado', Great Basin Naturalist, 45 (4), pp. 697-709
Kim, H. (1983) 'Cretaceous dinosaurs from Korea', Journal of the Geological Society of Korea, 19 (3), pp. 115-126
Lucas, S., Herne, M., Heckert, A., Hunt, A. and Sullivan, R. (2004) 'Reappraisal of Seismosaurus, a Late Jurassic Sauropod dinosaur from New Mexico', Proceedings of the Annual Meeting of the Society of Vertebrate Paleontology, 36 (5), p. 422
Lovelace, D., Hartman, S. and Wahl, W. (2007) 'Morphology of a specimen of Supersaurus (Dinosauria, Sauropoda) from the Morrison Formation of Wyoming, and a re-evaluation of diplodocid phylogeny', Arquivos do Museu Nacional, 65 (4), pp. 527-544
Marsh, O. (1878) 'Principal characters of American Jurassic dinosaurs. Part I', American Journal of Science, 3 (16), pp. 411-416
Mazzetta, G., Christiansen, P. and Farina, R. (2004) 'Giants and Bizarres: Body Size of Some Southern South American Cretaceous Dinosaurs', Historical Biology, 16 (2-3), pp. 71-83
Meyer, H. von, (1861) 'Archaeopteryx lithographica (Vogel-Feder) und Pterodactylus von Solenhofen', [Archaeopteryx lithographica (Bird-Feather) and Pterodactylus of Solenhofen], Neues Jahrbuch fur Mineralogie, Geognosie, Geologie und Petrefakten-Kunde 1861, pp. 678-679
Mortimer, M. (2001) 'Titanosaurs Too Large?', [Online], Available at: http://dml.cmnh.org/2001Sep/msg00402.html, Accessed on: 30/05/2013
Olshevsky, G. (1991) Parainfraclass Archosauria Cope, 1869, Excluding the Advanced Crocodylia: Mesozoic Meanderings #2 (1st Edition), San Diego: George Olshevsky (self-published)
Olshevsky, G. (1998) Parainfraclass Archosauria Cope, 1869, Excluding the Advanced Crocodylia: Mesozoic Meanderings #2 (2nd Edition), San Diego: George Olshevsky (self-published)
Orbis (1992) 'Ask the Expert', Dinosaurs!: Discover the Giants of the Prehistoric World, Issue 1, p.25
Paul, G. (1988) 'The brachiosaur giants of the Morrison and Tendaguru with a description of a new subgenus, Giraffatitan, and a comparison of the world's largest dinosaurs', Hunteria, 2 (3), pp. 1-14
Paul, G. (1994) 'Big Sauropods - Really, Really Big Sauropods', The Dinosaur Report, Fall 1994, pp. 12-13
Riggs, E. (1903) 'Brachiosaurus altithorax, the largest known dinosaur', American Journal of Science, 4 (15), pp. 299-306
Taylor, M. (2009) 'A re-evaluation of Brachiosaurus altithorax, Riggs, 1903 (Dinosauria, Sauropoda) and its generic separation from Giraffatitan brancai (Janensch, 1914)', Journal of Vertebrate Paleontology, 29 (3), pp.787-806
Wedel, M., Cifelli, R. and Sanders, R. (2000a) 'Sauroposeidon proteles, a new sauropod from the Early Cretaceous of Oklahoma', Journal of Vertebrate Paleontology, 20 (1), pp. 109-114
Wedel, M, Cifelli, R. and Sanders, R. (2000b) 'Osteology, paleobiology, and relationships of the sauropod dinosaur Sauroposeidon', Acta Paleontologica Polonica, 45 (4), pp. 343-388
Wedel, M. and Cifelli, R. (2005) 'Sauroposeidon: Oklahoma's Native Giant', Oklahoma Geology Notes, 65 (2), pp. 40-57
Yadagiri, P. and Ayyasami, K. (1979) 'A new stegosaurian dinosaur from Upper Cretaceous sediments of south India', Journal of the Geological Society of India, 20 (11), pp. 521-530
Yadagiri, P. and Ayyasami, K. (1989) 'A carnosaurian dinosaur from the Kallamedu Formation (Maestrichtian [sic] horizon), Tamilnadu [sic]' in Sastry, M., Sastry, V. Ramanujan, C., Kapoor, H., Jagannatha Rao, B., Satsangi, P. and Mathur, U. (Eds) Symposium on Three Decades of Development in Palaeontology and Stratigraphy in India. Volume 1. Precambrian to Mesozoic, Geological Society of India Special Publication, 11 (1), pp. 523-528
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