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Dinosaurs are much more than real monsters that fire our imaginations, but, let’s face it, part of their persistent appeal is that many were enormous prehistoric oddities. And it’s just that aspect of dinosaurian nature that is raising ire in a historically-rich California town and on an Australian golf course.

San Juan Capistrano, California is famous for the local cliff swallows and the historic Spanish architecture, but the town has recently been in the news because of an unwelcome dinosaur. According to the LA Times, a huge sauropod statue erected in the town’s petting zoo has drawn the ire of those who seek to retain some semblance of southern California’s past. Where kids and the zoo’s owner sees the dinosaur as a fanciful distraction, local historians argue that the dinosaur is totally out of place with the rest of the town’s decor. The dinosaur is staying put for now, but may yet be removed if the city decides that there’s just no place for a dinosaur in a place where Californian history and modern life already mix.

A different dinosaur is frustrating Australia’s professional golfers. The wealthy owner of the Palmer Coolum Resort has installed a 26 foot long, animatronic Tyrannosaurus rex in the middle of the course. Along with other recent installations, ESPN reports, the dinosaur is expected to adversely affect the games of Australian PGA Championship golfers set to play there. With the resort’s owner promising more dinosaurs on the way, the sports group has decided to move the tournament elsewhere after this year. Whether a sauropod looks out of place is one thing–having a T. rex get in the way of your shot is another.

Not everyone is so bothered by giant dinosaurs, though. A Best Western hotel in Colorado is taking on an entirely prehistoric theme, including fossil casts and dinosaur sculptures. In addition to attracting tourists, the hotel’s owner says he wants to draw attention to Colorado’s exceptional fossil sites, such as the nearby track site at Dinosaur Ridge. Dinosaur sculptures are frustrating eyesores to some and paleo-vacation essentials to others.

The giant sauropod Futalognkosaurus (at left) with some of its Cretaceous neighbors. Art by Maurilio Oliveira.

Which was the biggest dinosaur ever? We don’t know. Even though the size-based superlative draws a great deal of attention, paleontologists have uncovered so many scrappy sauropod skeletons that it’s difficult to tell who was truly the most titanic dinosaur of all. But, among the current spread of candidates, Futalognkosaurus dukei is one of the most complete giant dinosaurs yet found.

Discovered in 2000, and named in 2007 by Universidad Nacional del Comahue paleontologist Jorge Calvo and colleagues, Futalognkosaurus was one of many dinosaurs found in an exceptionally rich, roughly 90-million-year0old deposit in northwest Argentina. From fossil plants to pterosaurs, fish and dinosaurs, the one site entombed vestiges of a vibrant Cretaceous ecosystem. And, on that landscape, no dinosaur was as grand the newly named titanosaur.

Contrary to what you might expect given their skeletal sturdiness, the biggest sauropods are often found as partial skeletons. Our knowledge of Argentinosaurus, Puertasaurus, Supersaurus, Diplodocus hallorum and other giants is frustratingly incomplete, and figuring out how large they truly were relies on estimation from more complete representatives of other species.

The lack of complete tails from these dinosaurs makes the matter even more problematic. Dinosaur tails varied in length from individual to individual, and different subgroups had proportionally longer or shorter tails. In the case of Diplodocus hallorum, for example, a great deal of the dinosaur’s estimated  100-foot-plus length comes from the fact that other Diplodocus species had very long, tapering tails.

We don’t really know how long Futalognkosaurus was because, with the exception of a single vertebra, the dinosaur’s tail is entirely missing. Nevertheless, the sauropod that Calvo and coauthors described is remarkable for encompassing the entire neck, back and associated ribs, and the majority of the hips. Together, these elements represent over half the skeleton and comprise the most complete giant sauropod individual yet known.

Even if skeletal incompleteness keeps us from knowing exactly how big Futalognkosaurus was, the collected bones can leave no doubt that this was a truly enormous dinosaur. Calvo and coauthors estimated that the whole animal stretched between 105 and 112 feet in length, which would put it in the same class as the more famous (and less complete) Argentinosaurus. As the paleontologists at SV-POW! said when they posted images of Futalognkosaurus bones next to Juan Porfiri, who helped describe the dinosaur, there’s no doubt that the sauropod was “darned big.” The challenge is finding and filling in the parts of the dinosaur’s body that have not yet been found. There will undoubtedly be other challengers for the title of biggest dinosaur, but, for now, Futalognkosaurus remains our most detailed representative of the biggest of the big.

References:

Calvo, J., Porfiri, J., González-Riga, B., Kellner, A. 2007. A new Cretaceous terrestrial ecosystem from Gondwana with the description of a new sauropod dinosaur. Anais da Academia Brasileira de Ciências. 79, 3: 529-541

Calvo, J., Porfiri, J., González-Riga, B., Kellner, A. 2007. Anatomy of Futalognkosaurus dukei Calvo, Porfiri, González Riga, & Kellner, 2007 (Dinosauria, Titanosauridae) from the Neuquen Group, Late Cretaceous, Patagonia, Argentina. Arquivos do Museu Nacional 65, 4: 511–526.

Novas, F. 2009. The Age of Dinosaurs in South America. Bloomington: Indiana University Press. pp. 201-202

Mamenchisaurus, one of the longest-necked dinosaurs of all time, perfectly represents the bizarre nature of sauropods. Art by Steveoc 86, image from Wikimedia Commons.

Sauropods were extreme dinosaurs. From the relatively small dwarfed species–still a respectable 12 feet long or so–to giants that stretched over 100 feet long, these small-headed, column-limbed, long-necked dinosaurs were among the strangest creatures ever to walk the earth. Don’t be fooled by the familiarity of species like Apatosaurus and Brachiosaurus; the anatomy of sauropods was so strange that paleontologists are still debating basic issues of their biology. How sauropods mated, fed, pumped blood from their hearts to their heads and even how they held their necks have all provided rich grounds for debate among specialists. Among the longest-running mysteries is how such enormous and undoubtedly active animals prevented themselves from overheating. Perhaps the solution lies in an anatomical quirk shared with birds.

Diplodocus and kin might have had a problem with body temperature. Multiple lines of evidence, from histology to limb proportions, have indicated that extinct dinosaurs had physiological profiles more like those of avian dinosaurs and mammals than any reptile, but maintaining an active metabolism and high body temperature came at a cost for gigantic dinosaurs. The bigger the dinosaur, the more difficult it would have been to dump excess heat. If a hot-running sauropod had to hoof it to catch up with a mate or escape a stalking theropod, the dinosaur could run the risk of overheating through exercise.

The difficulty big sauropods must have faced with shedding heat has sometimes been cited as a reason that these dinosaurs must have had an ectothermic, crocodile-like physiology, or that they were “gigantotherms” that only maintained relatively high body temperatures by virtue of their size and therefore had a little more leeway with heat generated through exercise. As paleontologist Matt Wedel argued in a 2003 review of sauropod biology, though, these positions are based upon assumptions about dinosaur respiratory systems and physiology that used crocodylians as models. Not only has evidence from bone microstructure indicated that sauropods grew at an extremely rapid pace on par with that of mammals, but paleontologists have found that sauropods had birdlike respiratory systems that combined lungs with a system of air sacs. Such a system would have been attuned to cope with an active, endothermic lifestyle, including a way to dump excess heat.

We know sauropods had air sacs because of their bones. In the neck, especially, air sacs stemming from the core of the respiratory system invaded the bone and left distinctive indentations behind. (While not always as extensive, theropod dinosaurs show evidence of these air sacs, too. To date, though, no one has found solid evidence of air sacs in the ornithischian dinosaurs, which includes the horned ceratopsians, shovel-beaked hadrosaurs and armored ankylosaurs.) In addition to lightening the skeletons of sauropods and boosting their breathing efficiency, this complex system may have played a role in allowing sauropods to dump heat through evaporative cooling in the same way that large birds do today. The concept is similar to what makes a swamp cooler work–the evaporation of water in the moist tissues of a sauropod’s trachea during exhalation would have helped the dinosaur dump heat into outgoing air.

But the role of air sacs in such a system, much less an animal 80 feet long or more, is unclear. The inference is obvious–like birds, sauropods had the anatomical hardware to cool themselves–but the mechanics of the process are still obscure given that we can’t observe a living Mamenchisaurus. Earlier this fall, however, biologist Nina Sverdlova and colleagues debuted research that may help paleontologists more closely examine sauropod breathing.

Using observations from living birds, Sverdlova created a virtual model of a chicken’s trachea and air sac with an eye towards simulating heat exchange. The researchers found that their relatively simple model was able to approximate experimental data from living birds, and so similar models may help paleobiologists estimate how sauropods dumped heat. We’ll have to wait for what future studies find. This line of evidence won’t totally resolve the debate over sauropod physiology and body temperature, but it may help paleobiologists more closely investigate the costs and benefits of being so big.

References:

Sander, P., Christian, A., Clauss, M., Fechner, R., Gee, C., Griebeler, E., Gunga, H., Hummel, J., Mallison, H., Perry, S., Preuschoft, H., Rauhut, O., Remes, K., Tutken, T., Wings, O., Witzel, U. 2011. Biology of the sauropod dinosaurs: the evolution of gigantism. Biological Reviews 86: 117-155

Sverdlova, N., Lambertz, M., Witzel, U., Perry, S. 2012. Boundary conditions for heat transfer and evaporative cooling in the trachea and air sac system of the domestic fowl: A two-dimensional CFD analysis. PLOS One 7,9. e45315

Wedel, M. 2003. Vertebral pneumaticity, air sacs, and the physiology of sauropod dinosaurs. Paleobiology 29, 2: 243-255

A mount of Cetiosaurus at the New Walk Museum in Leicester. While the neck of this sauropod is almost completely known, no skull has ever been described. Photo by Flickr user Paul Stainthorp.

Sauropods were magnificent dinosaurs. These long-necked, small-headed titans were unlike anything that has evolved before or since, and they were so strange that paleontologists are still debating the basics of how Apatosaurus and kin actually lived. As iconic as their skeletons are now, though, the first sauropod ever described was initially envisioned as a very different sort of creature. The great Cetiosaurus was originally seen as a gargantuan, plesiosaur-crunching crocodile.

In 1841, the British anatomist Richard Owen described a curious collection of limb bones and vertebrae found at various locations in England. The limb elements reminded Owen of the same bones in crocodiles, and the vertebrae were reminiscent of those in whales. The scattered elements seemed to correspond in structure to aquatic animals, and since function was dictated by skeletal form, Owen believed that Cetiosaurus–the “whale lizard”–must have been a marine predator larger than anything that had been found before.

The following year, in his massive Report on British fossil reptiles, Part II, Owen reassessed the various prehistoric reptiles from his country. This was the landmark monograph in which Owen coined the term “Dinosauria,” but he didn’t include Cetiosaurus within the newly named group. The animal seemed vastly different from Megalosaurus, Iguanodon and Hylaeosaurus. Dinosaurs, in Owen’s view, were terrestrial animals with upright limbs, and he saw Cetiosaurus as a marine carnivore. Owen grouped the poorly known animals with crocodiles, instead.

It wasn’t until 1869 that Cetiosaurus was formally recognized as a dinosaur. Thomas Henry Huxley, Owen’s chief academic rival, proposed that Cetiosaurus was a close relative of Iguanodon, although he later changed his mind and suggested that the puzzling animal was an oddball that didn’t belong with crocodiles or dinosaurs. Other researchers were more confident that Cetiosaurus belonged among the dinosaurs. John Phillips, in an 1871 monograph, proposed that Cetiosaurus was an herbivorous dinosaur, and in 1875 Owen conceded that his creature was a huge, aquatic dinosaur.

Like many other early dinosaur finds, the identity of Cetiosaurus was obscured by a lack of material and the unfamiliarity of the Mesozoic curiosities. When O.C. Marsh, E.D. Cope and other North American paleontologists began to uncover relatively complete skeletons of dinosaurs such as Diplodocus and “Brontosaurus” from the American West during the late 19th century, a more accurate vision of Cetiosaurus as a sauropod started to come into focus. All the same, researchers named multiple species of this dinosaur from various sites of different ages. Cetiosaurus became a taxonomic wastebasket for numerous scrappy sauropods found in England.

Paleontologists Paul Upchurch and John Martin sorted out the mess in 2003. Out of 13 different species named from bones belonging to different kinds of sauropods that lived millions of years apart, Upchurch and Martin recognized only one valid taxon–Cetiosaurus oxoniensis. This sauropod trod Jurassic England around 170 million years ago. And even though our knowledge of this dinosaur’s skeleton isn’t yet complete, discoveries both old and new have helped paleontologists outline what this historically significant dinosaur was like.

In 1868, quarry workers at Bletchingdon Station (near Oxford, England) uncovered a Cetiosaurus bonebed containing a trio of skeletons, one being much larger than the others. These bones formed the basis of Phillips’ study of the dinosaur, and, as Upchurch and Martin noted, “potentially represents one of the best preserved sauropods from the Jurassic of Europe.” A century later, in 1968, workers at Williamson Cliffe Brickworks in Rutland discovered bones in their quarry, and some of the remains were briefly described by M.D. Jones in 1970. Upchurch and Martin reexamined the Rutland material as part of their bigger Cetiosaurus project and found that the individual dinosaur is represented by an almost complete neck, various parts of the spinal column and limb elements, making it one of the best-preserved Cetiosaurus ever found.

Altogether, the bones of Cetiosaurus indicate that the sauropod was medium to large in size, though exactly how big this dinosaur was isn’t clear. (Estimating the length and mass of incompletely-known dinosaurs is a difficult task.) What makes Cetiosaurus of special interest to paleontologists, though, is that it was a relatively archaic form of sauropod. Most of the famous sauropods–Diplodocus, Camarasaurus, Brachiosaurus and their ilk–belong to lineages within a big group called the neosauropoda. Cetiosaurus seems to fall just outside this group, and so the dinosaur might clue paleontologists in to what sauropods were like just before the fantastic radiation of neosauropods during the Late Jurassic. It took three decades to change the animal from a crocodile to a dinosaur, and a century more for the sauropod’s identity to be untangled, but, now that the dinosaur has a definite name and evolutionary identity, paleontologists can start to investigate the biological secrets locked inside Cetiosaurus bones.

Check out previous entries in the Dinosaur Alphabet here.

References:

Naish, D. 2009. The Great Dinosaur Discoveries. Berkeley: University of California Press. pp. 30-31

Upchurch, P., Martin, J. 2003. The Anatomy and Taxonomy of Cetiosaurus (Saurischia, Sauropoda) from the Middle Jurassic of England. Journal of Vertebrate Palaeontology 23 (1): 208–231

Upchurch, P., Martin, J. 2002. The Rutland Cetiosaurus: the anatomy and relationships of a Middle Jurassic British sauropod dinosaur. Palaeontology, 45: 1049–1074.

Wilson, J. 2005. Overview of sauropod phylogeny and evolution, pp. 15-49  in Curry Rogers and Wilson (eds.), The Sauropods: Evolution and Paleobiology, Berkley: University of California Press.

One of the vertebrae–as seen from the front (a) and back (b)–used to name the dinosaur Arkharavia heterocoelica. Although originally thought to come from a sauropod, it turns out that this bone belonged to a hadrosaur. From Alifanov and Bolotsky, 2010.

Dinosaurs come and go. Even though paleontologists are naming new dinosaurs at a fantastic rate–hardly a week seems to go by without the announcement of a previously-unknown species–researchers are also sinking and revising previously-discovered taxa as new finds are compared against what has already been found. The ever-growing ontogeny debate–which threatens the horned dinosaur Torosaurus and the hadrosaur Anatotitan, among others–is just one part of these paleontological growing pains. Sometimes dinosaur identity crises can be even more drastic.

Yesterday I wrote about a new paper by paleontologist Pascal Godefroit of the Royal Belgian Institute of Natural Sciences and co-authors that redescribes the charismatic hadrosaur Olorotitan. As I read through the paper, a brief, but significant, side note caught my eye. In the section describing the deposits in which the known Olorotitan skeletons were found, the paper mentions that paleontologists V.R. Alifanov and Yuri Bolotsky described a sauropod–one of the long-necked, heavy bodied dinosaurs–from the same locality. On the basis of a tooth and several isolated tail vertebrae, Alifanov and Bolotsky named the dinosaur Arkharavia in their 2010 description. Since the encasing rock was deposited during the latest Cretaceous, around 70 million years ago or so, this was apparently one of the last sauropods on earth.

Only Godefroit and colleagues, including Yuri Bolotsky, have now revised the identity of Arkharavia. In their paper on Olorotitan, the paleontologists make the passing comment that “those vertebrae [used to name the sauropod] likely belong to hadrosaurid dinosaurs.” Rather than being a previously-unknown kind of sauropod, then, the fossils used to name “Arkharavia” probably belonged to one of the two hadrosaurs that dominate the locality–Olorotitan or Kundurosaurus.

This isn’t the first time a hadrosaur has been confused for a sauropod. Two years ago, paleontologists Michael D’Emic and Jeffrey Wilson of the University of Michigan and Richard Thompson of the University of Arizona determined that so-called “sauropod” vertebrae found in the 75-million-year-old rock of Arizona’s Santa Rita Mountains should actually be attributed to a hadrosaur akin to Gryposaurus. Fragmentary dinosaurs can be extremely tricky to identify correctly.

These changes aren’t frivolous. Identifications of isolated bones affect our understanding of dinosaur evolution and history. In the case of the misidentified hadrosaur bones from Arizona, the revised diagnosis altered the picture of when sauropods returned to North America after an absence spanning tens of millions of years. (This is called the “sauropod hiatus” by specialists.)

In the case of Arkharavia, the fossils represented one of the last dinosaurs in eastern Russia before the end-Cretaceous mass extinction. Misunderstood as sauropod bones, the fossils appeared to be the scrappy evidence for an entire group of dinosaurs at the locality. Properly understood as hadrosaur tail bones, though, the fossils become isolated elements from a group already known to be numerous in the fossil beds. While these changes might sound small, they can certainly influence grand-scale analyses of when certain groups of dinosaurs appeared or went extinct. There’s a big difference between sauropods living alongside hadrosaurs just before the end-Cretaceous mass extinction and a habitat dominated by hadrosaurs and devoid of sauropods. Even isolated bones can make a big difference.

References:

Alifanov, V., Bolotsky, Y. (2010). Arkharavia heterocoelica gen. et sp. nov., a New Sauropod Dinosaur from the Upper Cretaceous of the Far East of Russia Paleontological Journal, 44 (1), 84-91 DOI: 10.1134/S0031030110010119

Godefroit, P., Bolotsky, Y.L., and Bolotsky, I.Y. (2012). Olorotitan arharensis, a hollow-crested hadrosaurid dinosaur from the latest Cretaceous of Far Eastern Russia. Acta Palaeontologica Polonica DOI: 10.4202/app.2011.0051